335 results on '"Newman AH"'
Search Results
2. Purification of a cGMP-inhibited cAMP Phosphodiesterase from Vascular Smooth Muscle
- Author
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Newman Ah, P. Belfrage, A. Rascon, Sam Lindgren, L. Stavenow, K. E. Andersson, E. Degerman, and V. C. Manganiello
- Subjects
chemistry.chemical_compound ,Cyclic nucleotide ,Cilostamide ,Vascular smooth muscle ,Cyclic nucleotide phosphodiesterase ,Biochemistry ,Chemistry ,Phosphodiesterase 3 ,medicine ,Milrinone ,Phosphodiesterase ,PDE10A ,medicine.drug - Abstract
Cyclic nucleotide phosphodiesterases (PDEs) constitute a complex group of enzymes, multiple forms of which are found in various amounts and proportions in most mammalian cells. These enzymes differ in subcellular localization, substrate affinities, kinetic characteristics, physiochemical properties, responsiveness to various effectors or drugs and mechanisms of regulation (Wells et al., 1977; Beavo et al., 1982; Manganiello et al., 1987). At least 6-7 distinct major classes of PDEs have been isolated, purified and characterized. One class, the cGMP inhibited low Km PDE (hereafter referred as cGI-PDE) is very sensitive to inhibition by a number of inotropic and antithrombotic agents including cilostamide and other OPC derivatives, imazodan, milrinone, fenoxamine, LY 195115, Y 590, anegrelide. Inhibition of cGI-PDEs from heart and platelets by therapeutically effective concentrations of these drugs correlates with physiological effects.
- Published
- 1990
3. Dynorphin A-(1-17) induces alterations in free fatty acids, excitatory amino acids, and motor function through an opiate-receptor-mediated mechanism
- Author
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Bakshi, R, primary, Newman, AH, additional, and Faden, AI, additional
- Published
- 1990
- Full Text
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4. Purification of the putative hormone-sensitive cyclic AMP phosphodiesterase from rat adipose tissue using a derivative of cilostamide as a novel affinity ligand
- Author
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Per Belfrage, Vincent C. Manganiello, Newman Ah, K.C. Rice, and E. Degerman
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Cilostamide ,Chromatography ,biology ,Phosphodiesterase ,Cell Biology ,Biochemistry ,Enzyme assay ,chemistry.chemical_compound ,chemistry ,Affinity chromatography ,Sephadex ,medicine ,biology.protein ,Diisopropyl fluorophosphate ,Phosphodiesterase inhibitor ,Molecular Biology ,Polyacrylamide gel electrophoresis ,medicine.drug - Abstract
A "low Km" cAMP phosphodiesterase with properties of a peripheral membrane protein accounts for approximately 90% of total cAMP phosphodiesterase activity in particulate (100,000 X g) fractions from rat fat cells. Incubation of fat cells with insulin for 10 min increased particulate (but not soluble) cAMP phosphodiesterase activity, with a maximum increase (approximately 100%) at 1 nM insulin. Most of the increase in activity was retained after solubilization (with non-ionic detergent and NaBr) and partial purification (approximately 20-fold) on DEAE-Sephacel. The solubilized enzyme from adipose tissue was purified approximately 65,000-fold to apparent homogeneity (yield approximately 20%) by chromatography on DEAE-Sephacel and Sephadex G-200 and affinity chromatography on aminoethyl agarose conjugated with the N-(2-isothiocyanato)ethyl derivative of the phosphodiesterase inhibitor cilostamide (OPC 3689). A 63,800 +/- 200-Da polypeptide (accounting for greater than 90% of the protein eluted from the affinity column) was identified by polyacrylamide gel electrophoresis in sodium dodecyl sulfate (with or without reduction). Enzyme activity was associated with the single protein band after electrophoresis under nondenaturing conditions. On gel permeation, Mr(app) was 100,000-110,000, suggesting that the holoenzyme is a dimer. A pI of 4.9-5.0 was estimated by isoelectric focusing. At 30 degrees C, the purified enzyme hydrolyzed both cAMP and cGMP with normal Michaelis-Menten kinetics; the pH optimum was 7.5. The Km(app) for cAMP was 0.38 microM and Vmax, 8.5 mumol/min/mg; for cGMP, Km(app) was 0.28 microM and Vmax, 2.0 mumol/min/mg. cGMP competitively inhibited cAMP hydrolysis with a Ki of approximately 0.15 microM. The enzyme was also inhibited by several OPC derivatives and "cardiotonic" drugs, but not by RO 20-1724. It was very sensitive to inhibition by agents which covalently modify protein sulfhydryls, but not by diisopropyl fluorophosphate. The activation by insulin and other findings indicate that the purified enzyme, which seems to belong to a subtype of low Km cAMP phosphodiesterases that is specifically and potently inhibited by cGMP, cilostamide, other OPC derivatives, and certain cardiotonic drugs, is likely to account for the hormone-sensitive particulate low Km cAMP phosphodiesterase activity of rat adipocytes.
- Published
- 1987
5. Involvement of dopamine D3 receptor in impulsive choice decision-making in male rats.
- Author
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Shen H, Ma Z, Hans E, Duan Y, Bi GH, Chae YC, Bonifazi A, Battiti FO, Newman AH, Xi ZX, and Yang Y
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- Animals, Male, Rats, Reward, Nucleus Accumbens metabolism, Nucleus Accumbens drug effects, Receptors, Dopamine D1 metabolism, Receptors, Dopamine D1 antagonists & inhibitors, Dopamine Antagonists pharmacology, Rats, Sprague-Dawley, Receptors, Dopamine D3 metabolism, Impulsive Behavior drug effects, Impulsive Behavior physiology, Delay Discounting drug effects, Delay Discounting physiology, Receptors, Dopamine D2 metabolism, Decision Making drug effects, Decision Making physiology, Choice Behavior drug effects, Choice Behavior physiology
- Abstract
Impulsive decision-making has been linked to impulse control disorders and substance use disorders. However, the neural mechanisms underlying impulsive choice are not fully understood. While previous PET imaging and autoradiography studies have shown involvement of dopamine and D2/3 receptors in impulsive behavior, the roles of distinct D1, D2, and D3 receptors in impulsive decision-making remain unclear. In this study, we used a food reward delay-discounting task (DDT) to identify low- and high-impulsive rats, in which low-impulsive rats exhibited preference for large delayed reward over small immediate rewards, while high-impulsive rats showed the opposite preference. We then examined D1, D2, and D3 receptor gene expression using RNAscope in situ hybridization assays. We found that high-impulsive male rats exhibited lower levels of D2 and D3, and particularly D3, receptor expression in the nucleus accumbens (NAc), with no significant changes in the insular, prelimbic, and infralimbic cortices. Based on these findings, we further explored the role of the D3 receptor in impulsive decision-making. Systemic administration of a selective D3 receptor agonist (FOB02-04) significantly reduced impulsive choices in high-impulsive rats but had no effects in low-impulsive rats. Conversely, a selective D3 receptor antagonist (VK4-116) produced increased both impulsive and omission choices in both groups of rats. These findings suggest that impulsive decision-making is associated with a reduction in D3 receptor expression in the NAc. Selective D3 receptor agonists, but not antagonists, may hold therapeutic potentials for mitigating impulsivity in high-impulsive subjects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
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- 2024
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6. Contrasting the Reinforcing Effects of the Novel Dopamine Transport Inhibitors JJC8-088 and JJC8-091 in Monkeys: Potential Translation to Medication Assisted Treatment .
- Author
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Allen MI, Rahimi O, Johnson BN, Cao J, Newman AH, and Nader MA
- Abstract
Despite considerable efforts, there remains no FDA-approved medications for cocaine use disorder (CUD). One strategy to mitigate cocaine craving and relapse is to elevate dopamine (DA). The DA transport inhibitor and releaser d -amphetamine has been shown to decrease cocaine self-administration (SA), although it has abuse liability. Recently, several modafinil analogues reduced cocaine SA in rats and monkeys, including JJC8-088, characterized as "cocaine like" in rats, and JJC8-091, characterized as "atypical" and not SA by rats. The present studies evaluated the reinforcing effects of both compounds in monkeys under several conditions. For Experiment 1, four male cocaine-experienced rhesus monkeys self-administered cocaine (0.001-0.3 mg/kg/injection), JJC8-088 (0.001-0.3 mg/kg/injection), and JJC8-091 (0.1-3.0 mg/kg/injection) under a progressive-ratio (PR) schedule of reinforcement. Both JJC compounds functioned as reinforcers with equal reinforcing strength to cocaine. Although JJC8-091 was less potent than cocaine, JJC8-088 and cocaine had similar potencies. For Experiment 2, one male and two females drug-naïve cynomolgus monkeys responded on a fixed-ratio schedule of food reinforcement. JJC8-091 was self-administered at rates higher than saline in all three monkeys. In Experiment 3, monkeys from Experiment 2 responded under a concurrent drug vs. food choice paradigm and given access to cocaine or JJC8-091 under these conditions. At doses equal to or one-half log-units higher than doses used in Experiment 2, cocaine, but not JJC8-091, was chosen over food. Together, these results demonstrate that while JJC8-091 may be reinforcing under some conditions, its reinforcing strength, in the presence of an alternative reinforcer, is substantially less than cocaine. Significance Statement JJC8-088 and JJC8-091 have shown efficacy is reducing cocaine self-administration in rats and in nonhuman primates. This study found that both compounds maintained self-administration in monkeys responding under several conditions. However, when given access to an alternative reinforcer during the self-administration session, JJC8-091 was not reinforcing, suggesting that JJC8-091 may be a viable candidate for CUD since, in the human population, alternatives to drug use are often available., (U.S. Government Work not Protected by U.S. Copyright.)
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- 2024
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7. A bitopic agonist bound to the dopamine 3 receptor reveals a selectivity site.
- Author
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Arroyo-Urea S, Nazarova AL, Carrión-Antolí Á, Bonifazi A, Battiti FO, Lam JH, Newman AH, Katritch V, and García-Nafría J
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- Humans, Binding Sites, HEK293 Cells, Ligands, Protein Binding, Animals, Models, Molecular, Cryoelectron Microscopy, Receptors, Dopamine D3 metabolism, Receptors, Dopamine D3 chemistry, Receptors, Dopamine D3 agonists
- Abstract
Although aminergic GPCRs are the target for ~25% of approved drugs, developing subtype selective drugs is a major challenge due to the high sequence conservation at their orthosteric binding site. Bitopic ligands are covalently joined orthosteric and allosteric pharmacophores with the potential to boost receptor selectivity and improve current medications by reducing off-target side effects. However, the lack of structural information on their binding mode impedes rational design. Here we determine the cryo-EM structure of the hD
3 R:GαO βγ complex bound to the D3 R selective bitopic agonist FOB02-04A. Structural, functional and computational analyses provide insights into its binding mode and point to a new TM2-ECL1-TM1 region, which requires the N-terminal ordering of TM1, as a major determinant of subtype selectivity in aminergic GPCRs. This region is underexploited in drug development, expands the established secondary binding pocket in aminergic GPCRs and could potentially be used to design novel and subtype selective drugs., (© 2024. The Author(s).)- Published
- 2024
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8. The selective D 3 Receptor antagonist VK4-116 reverses loss of insight caused by self-administration of cocaine in rats.
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Panayi MC, Shetty S, Porod M, Bahena L, Xi ZX, Newman AH, and Schoenbaum G
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- Animals, Male, Rats, Cocaine-Related Disorders drug therapy, Conditioning, Operant drug effects, Cues, Dopamine Antagonists pharmacology, Dopamine Antagonists administration & dosage, Dopamine Uptake Inhibitors administration & dosage, Dopamine Uptake Inhibitors pharmacology, Rats, Sprague-Dawley, Self Administration, Sucrose administration & dosage, Cocaine administration & dosage, Cocaine pharmacology, Receptors, Dopamine D3 antagonists & inhibitors
- Abstract
Chronic psychostimulant use causes long-lasting changes to neural and cognitive function that persist after long periods of abstinence. As cocaine users transition from drug use to abstinence, a parallel transition from hyperactivity to hypoactivity has been found in orbitofrontal-striatal glucose metabolism and striatal D
2 /D3 -receptor activity. Targeting these changes pharmacologically, using highly selective dopamine D3 -receptor (D3 R) antagonists and partial agonists, has shown promise in reducing drug-taking, and attenuating relapse in animal models of cocaine and opioid use disorder. However, much less attention has been paid to treating the loss of insight, operationalized as the inability to infer likely outcomes, associated with chronic psychostimulant use. Here we tested the selective D3 R antagonist VK4-116 as a treatment for this loss in rats with a prior history of cocaine use. Male and female rats were first trained to self-administer cocaine or a sucrose liquid for 2 weeks. After 4 weeks of abstinence, performance was assessed using a sensory preconditioning (SPC) learning paradigm. Rats were given VK4-116 (15 mg/kg, i.p.) or vehicle 30 min prior to each SPC training session, thus creating four drug-treatment groups: sucrose-vehicle, sucrose-VK4-116, cocaine-vehicle, cocaine-VK4-116. The control groups (sucrose-vehicle, sucrose-VK4-116) showed normal sensory preconditioning, whereas cocaine use (cocaine-vehicle) selectively disrupted responding to the preconditioned cue, an effect that was reversed in the cocaine-VK4-116 group, which demonstrating responding to the preconditioned cue at levels comparable to controls. These preclinical findings demonstrate that highly selective dopamine D3 R antagonists, particularly VK4-116, can reverse the long-term negative behavioral consequences of cocaine use., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)- Published
- 2024
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9. Development of Novel Tools for Dissection of Central Versus Peripheral Dopamine D2-Like Receptor Signaling in Dysglycemia.
- Author
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Bonifazi A, Ellenberger M, Farino ZJ, Aslanoglou D, Rais R, Pereira S, Mantilla-Rivas JO, Boateng CA, Eshleman AJ, Janowsky A, Hahn MK, Schwartz GJ, Slusher BS, Newman AH, and Freyberg Z
- Subjects
- Animals, Mice, Male, Mice, Inbred C57BL, Insulin Resistance physiology, Blood Glucose metabolism, Blood Glucose drug effects, Humans, Central Nervous System metabolism, Central Nervous System drug effects, Receptors, Dopamine D3 metabolism, Receptors, Dopamine D3 agonists, Receptors, Dopamine D2 metabolism, Receptors, Dopamine D2 agonists, Bromocriptine pharmacology, Bromocriptine therapeutic use, Signal Transduction drug effects, Dopamine Agonists pharmacology, Dopamine Agonists therapeutic use
- Abstract
Dopamine (DA) D2-like receptors in both the central nervous system (CNS) and the periphery are key modulators of metabolism. Moreover, disruption of D2-like receptor signaling is implicated in dysglycemia. Yet, the respective metabolic contributions of CNS versus peripheral D2-like receptors, including D2 (D2R) and D3 (D3R) receptors, remain poorly understood. To address this, we developed new pharmacological tools, D2-like receptor agonists with diminished and delayed blood-brain barrier capability, to selectively manipulate D2R/D3R signaling in the periphery. We designated bromocriptine methiodide (BrMeI), a quaternary methiodide analog of D2R/D3R agonist and diabetes drug bromocriptine, as our lead compound based on preservation of D2R/D3R binding and functional efficacy. We then used BrMeI and unmodified bromocriptine to dissect relative contributions of CNS versus peripheral D2R/D3R signaling in treating dysglycemia. Systemic administration of bromocriptine, with unrestricted access to CNS and peripheral targets, significantly improved both insulin sensitivity and glucose tolerance in obese, dysglycemic mice in vivo. In contrast, metabolic improvements were attenuated when access to bromocriptine was restricted either to the CNS through intracerebroventricular administration or delayed access to the CNS via BrMeI. Our findings demonstrate that the coordinated actions of both CNS and peripheral D2-like receptors are required for correcting dysglycemia. Ultimately, the development of a first-generation of drugs designed to selectively target the periphery provides a blueprint for dissecting mechanisms of central versus peripheral DA signaling and paves the way for novel strategies to treat dysglycemia., (© 2024 by the American Diabetes Association.)
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- 2024
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10. Presynaptic and Postsynaptic Mesolimbic Dopamine D 3 Receptors Play Distinct Roles in Cocaine Versus Opioid Reward in Mice.
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Xi ZX, Bocarsly ME, Galaj E, Hempel B, Teresi C, Shaw M, Bi GH, Jordan C, Linz E, Alton H, Tanda G, Freyberg Z, Alvarez VA, and Newman AH
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- Animals, Male, Mice, Female, Receptors, Dopamine D1 metabolism, Receptors, Dopamine D1 genetics, Dopamine metabolism, Mice, Inbred C57BL, Mesencephalon metabolism, Mesencephalon drug effects, Dopamine Uptake Inhibitors pharmacology, Dopamine Uptake Inhibitors administration & dosage, Cocaine pharmacology, Cocaine administration & dosage, Receptors, Dopamine D3 metabolism, Receptors, Dopamine D3 genetics, Reward, Dopaminergic Neurons metabolism, Dopaminergic Neurons drug effects, Dopaminergic Neurons physiology, Analgesics, Opioid pharmacology, Nucleus Accumbens metabolism, Nucleus Accumbens drug effects, Receptors, Dopamine D2 metabolism, Receptors, Dopamine D2 genetics
- Abstract
Background: Past research has illuminated pivotal roles of dopamine D
3 receptors (D3 R) in the rewarding effects of cocaine and opioids. However, the cellular and neural circuit mechanisms that underlie these actions remain unclear., Methods: We employed Cre-LoxP techniques to selectively delete D3 R from presynaptic dopamine neurons or postsynaptic dopamine D1 receptor (D1 R)-expressing neurons in male and female mice. We utilized RNAscope in situ hybridization, immunohistochemistry, real-time polymerase chain reaction, voltammetry, optogenetics, microdialysis, and behavioral assays (n ≥ 8 animals per group) to functionally characterize the roles of presynaptic versus postsynaptic D3 R in cocaine and opioid actions., Results: Our results revealed D3 R expression in ∼25% of midbrain dopamine neurons and ∼70% of D1 R-expressing neurons in the nucleus accumbens. While dopamine D2 receptors (D2 R) were expressed in ∼80% dopamine neurons, we found no D2 R and D3 R colocalization among these cells. Selective deletion of D3 R from dopamine neurons increased exploratory behavior in novel environments and enhanced pulse-evoked nucleus accumbens dopamine release. Conversely, deletion of D3 R from D1 R-expressing neurons attenuated locomotor responses to D1 -like and D2 -like agonists. Strikingly, deletion of D3 R from either cell type reduced oxycodone self-administration and oxycodone-enhanced brain-stimulation reward. In contrast, neither of these D3 R deletions impacted cocaine self-administration, cocaine-enhanced brain-stimulation reward, or cocaine-induced hyperlocomotion. Furthermore, D3 R knockout in dopamine neurons reduced oxycodone-induced hyperactivity and analgesia, while deletion from D1 R-expressing neurons potentiated opioid-induced hyperactivity without affecting analgesia., Conclusions: We dissected presynaptic versus postsynaptic D3 R function in the mesolimbic dopamine system. D2 R and D3 R are expressed in different populations of midbrain dopamine neurons, regulating dopamine release. Mesolimbic D3 R are critically involved in the actions of opioids but not cocaine., (Published by Elsevier Inc.)- Published
- 2024
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11. Linkers in Bitopic Agonists Shape Bias Profile among Transducers for the Dopamine D2 and D3 Receptors.
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Semeano A, Garland R, Bonifazi A, Lee KH, Famiglietti J, Zhang W, Jo YJ, Battiti FO, Shi L, Newman AH, and Yano H
- Abstract
Bitopic ligands bind both orthosteric and allosteric or secondary binding sites within the same receptor, often resulting in an improvement of receptor selectivity, potency, and efficacy. In particular, for both agonists and antagonists of the dopamine D2 and D3 receptors (D2R and D3R), the primary therapeutic targets for several neurological and neuropsychiatric disorders, bitopic ligand design has proved advantageous in achieving better pharmacological profiles in vitro . Although the two pharmacophores within a bitopic ligand are typically considered the main drivers of conformational change for a receptor, the role of the linker that connects the two has not yet been systematically studied for its relevance in receptor activity profiles. Here, we present a comprehensive analysis of sumanirole and PF592,379-based indole-containing bitopic compounds in agonist activity at D2R and D3R, with a focus on linker chemical space and stereochemistry through testing six distinct chirally resolved linkers and a simple aliphatic linker. The structure activity relationships (SARs) of these linkers are examined extensively, beyond the conventional level, by characterizing the activation of all putative transducers over a 44 min time course. Our multiparametric analysis reveals previously unappreciated specific linker-dependent effects on primary pharmacophores, receptors, transducer activation kinetics, and bias, highlighting the utility of this comprehensive approach and the significance of the linker type in shaping transducer bias profiles., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)
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- 2024
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12. A novel fluorescently labelled ligand for the detection of DAT in immune cells by flow cytometry.
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Camacho-Hernandez GA and Newman AH
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- 2024
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13. Potential therapeutics for effort-related motivational dysfunction: assessing novel atypical dopamine transport inhibitors.
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Ecevitoglu A, Meka N, Rotolo RA, Edelstein GA, Srinath S, Beard KR, Carratala-Ros C, Presby RE, Cao J, Okorom A, Newman AH, Correa M, and Salamone JD
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- Animals, Male, Female, Rats, Choice Behavior drug effects, Choice Behavior physiology, Modafinil pharmacology, Dopamine Uptake Inhibitors pharmacology, Conditioning, Operant drug effects, Benzhydryl Compounds pharmacology, Motivation drug effects, Motivation physiology, Rats, Sprague-Dawley, Dopamine Plasma Membrane Transport Proteins metabolism, Dopamine Plasma Membrane Transport Proteins antagonists & inhibitors
- Abstract
People with depression and other neuropsychiatric disorders can experience motivational dysfunctions such as fatigue and anergia, which involve reduced exertion of effort in goal-directed activity. To model effort-related motivational dysfunction, effort-based choice tasks can be used, in which rats can select between obtaining a preferred reinforcer by high exertion of effort vs. a low effort/less preferred option. Preclinical data indicate that dopamine transport (DAT) inhibitors can reverse pharmacologically-induced low-effort biases and increase selection of high-effort options in effort-based choice tasks. Although classical DAT blockers like cocaine can produce undesirable effects such as liability for misuse and psychotic reactions, not all DAT inhibitors have the same neurochemical profile. The current study characterized the effort-related effects of novel DAT inhibitors that are modafinil analogs and have a range of binding profiles and neurochemical actions (JJC8-088, JJC8-089, RDS3-094, and JJC8-091) by using two different effort-related choice behavior tasks in male Sprague-Dawley rats. JJC8-088, JJC8-089, and RDS3-094 significantly reversed the low-effort bias induced by the VMAT-2 inhibitor tetrabenazine, increasing selection of high-effort fixed ratio 5 lever pressing vs. chow intake. In addition, JJC8-089 reversed the effects of tetrabenazine in female rats. JJC8-088 and JJC8-089 also increased selection of high-effort progressive ratio responding in a choice task. However, JJC8-091 failed to produce these outcomes, potentially due to its unique pharmacological profile (i.e., binding to an occluded conformation of DAT). Assessment of a broad range of DAT inhibitors with different neurochemical characteristics may lead to the identification of compounds that are useful for treating motivational dysfunction in humans., (© 2024. The Author(s), under exclusive licence to American College of Neuropsychopharmacology.)
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- 2024
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14. The Structural Basis of the Activity Cliff in Modafinil-Based Dopamine Transporter Inhibitors.
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Lee KH, Camacho-Hernandez GA, Newman AH, and Shi L
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- Humans, Binding Sites, Dopamine Uptake Inhibitors chemistry, Dopamine Uptake Inhibitors pharmacology, Structure-Activity Relationship, Protein Binding, Modafinil chemistry, Modafinil pharmacology, Dopamine Plasma Membrane Transport Proteins chemistry, Dopamine Plasma Membrane Transport Proteins antagonists & inhibitors, Dopamine Plasma Membrane Transport Proteins metabolism, Molecular Dynamics Simulation
- Abstract
Modafinil analogs with either a sulfoxide or sulfide moiety have improved binding affinities at the human dopamine transporter (hDAT) compared to modafinil, with lead sulfoxide-substituted analogs showing characteristics of atypical inhibition (e.g., JJC8-091). Interestingly, the only distinction between sulfoxide and sulfide substitution is the presence of one additional oxygen atom. To elucidate why such a subtle difference in ligand structure can result in different typical or atypical profiles, we investigated two pairs of analogs. Our quantum mechanical calculations revealed a more negatively charged distribution of the electrostatic potential surface of the sulfoxide substitution. Using molecular dynamics simulations, we demonstrated that sulfoxide-substituted modafinil analogs have a propensity to attract more water into the binding pocket. They also exhibited a tendency to dissociate from Asp79 and form a new interaction with Asp421, consequently promoting an inward-facing conformation of hDAT. In contrast, sulfide-substituted analogs did not display these effects. These findings elucidate the structural basis of the activity cliff observed with modafinil analogs and also enhance our understanding of the functionally relevant conformational spectrum of hDAT.
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- 2024
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15. Dual DAT and sigma receptor inhibitors attenuate cocaine effects on nucleus accumbens dopamine dynamics in rats.
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Hersey M, Mereu M, Jones CS, Bartole MK, Chen AY, Cao J, Hiranita T, Chun LE, Lopez JP, Katz JL, Newman AH, and Tanda G
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- Animals, Male, Rats, Benzhydryl Compounds pharmacology, Microdialysis methods, Modafinil pharmacology, Piperidines pharmacology, Rats, Sprague-Dawley, Cocaine pharmacology, Dopamine metabolism, Dopamine Plasma Membrane Transport Proteins antagonists & inhibitors, Dopamine Uptake Inhibitors pharmacology, Nucleus Accumbens drug effects, Nucleus Accumbens metabolism, Receptors, sigma antagonists & inhibitors
- Abstract
Psychostimulant use disorders (PSUD) are prevalent; however, no FDA-approved medications have been made available for treatment. Previous studies have shown that dual inhibitors of the dopamine transporter (DAT) and sigma receptors significantly reduce the behavioral/reinforcing effects of cocaine, which have been associated with stimulation of extracellular dopamine (DA) levels resulting from DAT inhibition. Here, we employ microdialysis and fast scan cyclic voltammetry (FSCV) procedures to investigate the effects of dual inhibitors of DAT and sigma receptors in combination with cocaine on nucleus accumbens shell (NAS) DA dynamics in naïve male Sprague Dawley rats. In microdialysis studies, administration of rimcazole (3, 10 mg/kg; i.p.) or its structural analog SH 3-24 (1, 3 mg/kg; i.p.), compounds that are dual inhibitors of DAT and sigma receptors, significantly reduced NAS DA efflux stimulated by increasing doses of cocaine (0.1, 0.3, 1.0 mg/kg; i.v.). Using the same experimental conditions, in FSCV tests, we show that rimcazole pretreatments attenuated cocaine-induced stimulation of evoked NAS DA release but produced no additional effect on DA clearance rate. Under the same conditions, JJC8-091, a modafinil analog and dual inhibitor of DAT and sigma receptors, similarly attenuated cocaine-induced stimulation of evoked NAS DA release but produced no additional effect on DA clearance rate. Our results provide the neurochemical groundwork towards understanding actions of dual inhibitors of DAT and sigma receptors on DA dynamics that likely mediate the behavioral effects of psychostimulants like cocaine., (Published 2024. This article is a U.S. Government work and is in the public domain in the USA.)
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- 2024
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16. Empowering Voices: Inspiring Women in Medicinal Chemistry.
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Blanco MJ, Bronson JJ, DiMauro EF, Dzierba C, Eggen M, Garner AL, Georg G, Giarolla J, Goodwin NC, Grenier-Davies MC, Haskell-Luevano C, Holzgrabe U, Huang R, Lagiakos HR, Leftheris K, Martin Y, Matos MJ, May-Dracka TL, Müller CE, Newman AH, Parmee E, Petter JC, Tamayo NA, Wexler RR, Bolognesi ML, Ripka A, and Young W
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- Humans, Female, Chemistry, Pharmaceutical, Power, Psychological
- Abstract
As we celebrate International Women's Day 2024 with the theme "Inspire Inclusion", the women of the ACS Medicinal Chemistry Division (MEDI) want to foster a sense of belonging, relevance, and empowerment by sharing uplifting stories of what inspired them to become medicinal chemists. In this editorial, we are featuring female medicinal chemistry scientists to provide role models, encouragement, and inspiration to others. We asked women medicinal chemists to contribute a brief paragraph about what inspired them to become medicinal chemists or what inspires them today as medicinal chemists. The responses and contributions highlight their passions and motivations, such as their love of the sciences and their drive to improve human health by contributing to basic research and creating lifesaving drugs.
- Published
- 2024
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17. Development of novel tools for dissection of central versus peripheral dopamine D 2 -like receptor signaling in dysglycemia.
- Author
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Bonifazi A, Ellenberger M, Farino ZJ, Aslanoglou D, Rais R, Pereira S, Mantilla-Rivas JO, Boateng CA, Eshleman AJ, Janowsky A, Hahn MK, Schwartz GJ, Slusher BS, Newman AH, and Freyberg Z
- Abstract
Dopamine (DA) D
2 -like receptors in both the central nervous system (CNS) and the periphery are key modulators of metabolism. Moreover, disruption of D2 -like receptor signaling is implicated in dysglycemia. Yet, the respective metabolic contributions of CNS versus peripheral D2 -like receptors including D2 (D2R) and D3 (D3R) receptors remain poorly understood. To address this, we developed new pharmacological tools, D2 -like receptor agonists with diminished and delayed blood-brain barrier capability, to selectively manipulate D2R/D3R signaling in the periphery. We designated bromocriptine methiodide (BrMeI), a quaternary methiodide analogue of D2/3R agonist and diabetes drug bromocriptine, as our lead compound based on preservation of D2R/D3R binding and functional efficacy. We then used BrMeI and unmodified bromocriptine to dissect relative contributions of CNS versus peripheral D2R/D3R signaling in treating dysglycemia. Systemic administration of bromocriptine, with unrestricted access to CNS and peripheral targets, significantly improved both insulin sensitivity and glucose tolerance in obese, dysglycemic mice in vivo . In contrast, metabolic improvements were attenuated when access to bromocriptine was restricted either to the CNS through intracerebroventricular administration or delayed access to the CNS via BrMeI. Our findings demonstrate that the coordinated actions of both CNS and peripheral D2 -like receptors are required for correcting dysglycemia. Ultimately, the development of a first-generation of drugs designed to selectively target the periphery provides a blueprint for dissecting mechanisms of central versus peripheral DA signaling and paves the way for novel strategies to treat dysglycemia., Competing Interests: Conflict of interest: The authors have declared that no conflict of interest exists.- Published
- 2024
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18. Development of a Fluorescently Labeled Ligand for Rapid Detection of DAT in Human and Mouse Peripheral Blood Monocytes.
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Camacho-Hernandez GA, Gopinath A, Okorom AV, Khoshbouei H, and Newman AH
- Abstract
The dopamine transporter (DAT) is one of the key regulators of dopamine (DA) signaling in the central nervous system (CNS) and in the periphery. Recent reports in a model of Parkinson's disease (PD) have shown that dopamine neuronal loss in the CNS impacts the expression of DAT in peripheral immune cells. The mechanism underlying this connection is still unclear but could be illuminated with sensitive and high-throughput detection of DAT-expressing immune cells in the circulation. Herein, we have developed fluorescently labeled ligands (FLL) that bind to surface-expressing DAT with high affinity and selectivity. The diSulfoCy5-FLL ( GC04-38 ) was utilized to label DAT in human and mouse peripheral blood mononuclear cells (PBMCs) that were analyzed via flow cytometry. Selective labeling was validated using DAT KO mouse PBMCs. Our studies provide an efficient and highly sensitive method using this novel DAT-selective FLL to advance our fundamental understanding of DAT expression and activity in PBMCs in health and disease and as a potential peripheral biomarker., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)
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- 2024
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19. Modifications to 1-(4-(2-Bis(4-fluorophenyl)methyl)sulfinyl)alkyl Alicyclic Amines That Improve Metabolic Stability and Retain an Atypical DAT Inhibitor Profile.
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Okorom AV, Camacho-Hernandez GA, Salomon K, Lee KH, Ku TC, Cao J, Won SJ, Friedman J, Lam J, Paule J, Rais R, Klein B, Xi ZX, Shi L, Loland CJ, and Newman AH
- Subjects
- Rats, Mice, Animals, Dopamine Plasma Membrane Transport Proteins, Amines pharmacology, Structure-Activity Relationship, Serotonin Plasma Membrane Transport Proteins metabolism, Piperidines pharmacology, Cocaine, Central Nervous System Stimulants pharmacology
- Abstract
Atypical dopamine transporter (DAT) inhibitors have shown therapeutic potential in the preclinical models of psychostimulant use disorders (PSUD). In rats, 1-(4-(2-((bis(4-fluorophenyl)methyl)sulfinyl)ethyl)-piperazin-1-yl)-propan-2-ol ( JJC8-091, 3b ) was effective in reducing the reinforcing effects of both cocaine and methamphetamine but did not exhibit psychostimulant behaviors itself. Improvements in DAT affinity and metabolic stability were desirable for discovering pipeline drug candidates. Thus, a series of 1-(4-(2-bis(4-fluorophenyl)methyl)sulfinyl)alkyl alicyclic amines were synthesized and evaluated for binding affinities at DAT and the serotonin transporter (SERT). Replacement of the piperazine with either a homopiperazine or a piperidine ring system was well tolerated at DAT ( K
i range = 3-382 nM). However, only the piperidine analogues ( 20a - d ) showed improved metabolic stability in rat liver microsomes as compared to the previously reported analogues. Compounds 12b and 20a appeared to retain an atypical DAT inhibitor profile, based on negligible locomotor activity in mice and molecular modeling that predicts binding to an inward-facing conformation of DAT.- Published
- 2024
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20. Series of (([1,1'-Biphenyl]-2-yl)methyl)sulfinylalkyl Alicyclic Amines as Novel and High Affinity Atypical Dopamine Transporter Inhibitors with Reduced hERG Activity.
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Ku TC, Cao J, Won SJ, Guo J, Camacho-Hernandez GA, Okorom AV, Salomon KW, Lee KH, Loland CJ, Duff HJ, Shi L, and Newman AH
- Abstract
Currently, there are no FDA-approved medications for the treatment of psychostimulant use disorders (PSUD). We have previously discovered "atypical" dopamine transporter (DAT) inhibitors that do not display psychostimulant-like behaviors and may be useful as medications to treat PSUD. Lead candidates (e.g., JJC8-091, 1 ) have shown promising in vivo profiles in rodents; however, reducing hERG (human ether-à-go-go -related gene) activity, a predictor of cardiotoxicity, has remained a challenge. Herein, a series of 30 (([1,1'-biphenyl]-2-yl)methyl)sulfinylalkyl alicyclic amines was synthesized and evaluated for DAT and serotonin transporter (SERT) binding affinities. A subset of analogues was tested for hERG activity, and the IC
50 values were compared to those predicted by our hERG QSAR models, which showed robust predictive power. Multiparameter optimization scores (MPO > 3) indicated central nervous system (CNS) penetrability. Finally, comparison of affinities in human DAT and its Y156F and Y335A mutants suggested that several compounds prefer an inward facing conformation indicating an atypical DAT inhibitor profile., Competing Interests: The authors declare no competing financial interest., (© 2024 American Chemical Society.)- Published
- 2024
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21. Structure of the dopamine D3 receptor bound to a bitopic agonist reveals a new specificity site in an expanded allosteric pocket.
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Arroyo-Urea S, Nazarova AL, Carrión-Antolí Á, Bonifazi A, Battiti FO, Lam JH, Newman AH, Katritch V, and García-Nafría J
- Abstract
Although aminergic GPCRs are the target for ~25% of approved drugs, developing subtype selective drugs is a major challenge due to the high sequence conservation at their orthosteric binding site. Bitopic ligands are covalently joined orthosteric and allosteric pharmacophores with the potential to boost receptor selectivity, driven by the binding of the secondary pharmacophore to non-conserved regions of the receptor. Although bitopic ligands have great potential to improve current medications by reducing off-target side effects, the lack of structural information on their binding mode impedes rational design. Here we determine the cryo-EM structure of the hD
3 R coupled to a GO heterotrimer and bound to the D3 R selective bitopic agonist FOB02-04A. Structural, functional and computational analyses provide new insights into its binding mode and point to a new TM2-ECL1-TM1 region, which requires the N-terminal ordering of TM1, as a major determinant of subtype selectivity in aminergic GPCRs. This region is underexploited in drug development, expands the established secondary binding pocket in aminergic GPCRs and could potentially be used to design novel and subtype selective drugs.- Published
- 2023
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22. Illuminating the monoamine transporters: Fluorescently labelled ligands to study dopamine, serotonin and norepinephrine transporters.
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Camacho-Hernandez GA, Jahan K, and Newman AH
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- Humans, Ligands, Animals, Serotonin Plasma Membrane Transport Proteins metabolism, Dopamine Plasma Membrane Transport Proteins metabolism, Fluorescent Dyes, Norepinephrine Plasma Membrane Transport Proteins metabolism, Microscopy, Fluorescence
- Abstract
Fluorescence microscopy has revolutionized the visualization of physiological processes in live-cell systems. With the recent innovations in super resolution microscopy, these events can be examined with high precision and accuracy. The development of fluorescently labelled small molecules has provided a significant advance in understanding the physiological relevance of targeted proteins that can now be visualized at the cellular level. One set of physiologically important target proteins are the monoamine transporters (MATs) that play an instrumental role in maintaining monoamine signalling homeostasis. Understanding the mechanisms underlying their regulation and dysregulation is fundamental to treating several neuropsychiatric conditions such as attention deficit hyperactivity disorder (ADHD), anxiety, depression and substance use disorders. Herein, we describe the rationale behind the small molecule design of fluorescently labelled ligands (FLL) either as MAT substrates or inhibitors as well as their applications to advance our understanding of this class of transporters in health and disease., (Published 2022. This article is a U.S. Government work and is in the public domain in the USA.)
- Published
- 2023
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23. Effects of selective dopamine D3 receptor partial agonist/antagonists on oxycodone self-administration and antinociception in monkeys.
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Woodlief K, Allen MI, Cornelissen JC, Banks ML, Newman AH, and Nader MA
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- Animals, Female, Male, Analgesics, Opioid pharmacology, Dopamine Agonists pharmacology, Dopamine Antagonists pharmacology, Dose-Response Relationship, Drug, Naltrexone pharmacology, Self Administration, Macaca fascicularis, Opioid-Related Disorders, Oxycodone administration & dosage, Receptors, Dopamine D3 drug effects
- Abstract
Recent studies suggest that dopamine D3 receptors (D3R) may be a therapeutic target for opioid use disorders (OUD). This study examined the effects of the D3R partial agonist (±)VK4-40 and the D3R-selective antagonist (±)VK4-116, compared to the mu-opioid receptor antagonist naltrexone (NTX), in nonhuman primate models of OUD and antinociception. Adult male and female (N = 4/sex) cynomolgus monkeys were trained to self-administer oxycodone (0.003-0.1 mg/kg/injection) first under a fixed-ratio (FR) and then a progressive-ratio (PR) schedule of reinforcement during daily 1- and 4-hr sessions, respectively. Under the FR schedule, intravenous NTX (0.01-0.1 mg/kg), (±)VK4-116 (1.0-10 mg/kg), and (±)VK4-40 (1.0-10 mg/kg) were studied in combination with the peak oxycodone dose and a dose on the descending limb of the dose-effect curve; NTX and (±)VK4-40 were also studied at the peak of the PR dose-response curve (N = 4). Following saline extinction, each compound was examined on oxycodone-induced reinstatement. Finally, these compounds were assessed in adult male rhesus monkeys (N = 3) in a warm-water (38 °C, 50 °C, 54 °C) tail withdrawal assay. NTX decreased responding on the peak of the FR oxycodone dose-response curve, but increased responding on the descending limb. (±)VK4-40, but not (±)VK4-116, significantly decreased peak oxycodone self-administration; (±)VK4-40 did not increase responding on the descending limb. NTX and (±)VK4-40, but not (±)VK4-116, attenuated oxycodone-induced reinstatement. Under PR responding, NTX and (±)VK4-40 decreased breakpoints. Oxycodone-induced antinociception was attenuated by NTX, but not by (±)VK4-40 or (±)VK4-116. Together, these results suggest that further research evaluating the effects of (±)VK4-40 as a novel pharmacotherapy for OUD is warranted., (© 2023. The Author(s), under exclusive licence to American College of Neuropsychopharmacology.)
- Published
- 2023
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24. Pharmacology and Therapeutic Potential of Benzothiazole Analogues for Cocaine Use Disorder.
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Boateng CA, Nilson AN, Placide R, Pham ML, Jakobs FM, Boldizsar N, McIntosh S, Stallings LS, Korankyi IV, Kelshikar S, Shah N, Panasis D, Muccilli A, Ladik M, Maslonka B, McBride C, Sanchez MX, Akca E, Alkhatib M, Saez J, Nguyen C, Kurtyan E, DePierro J, Crowthers R, Brunt D, Bonifazi A, Newman AH, Rais R, Slusher BS, Free RB, Sibley DR, Stewart KD, Wu C, Hemby SE, and Keck TM
- Subjects
- Humans, Animals, Rats, Serotonin, Benzothiazoles pharmacology, Benzothiazoles therapeutic use, Brain, Substance-Related Disorders, Cocaine pharmacology
- Abstract
Pharmacological targeting of the dopamine D
4 receptor (D4 R)─expressed in brain regions that control cognition, attention, and decision-making─could be useful for several neuropsychiatric disorders including substance use disorders (SUDs). This study focused on the synthesis and evaluation of a novel series of benzothiazole analogues designed to target D4 R. We identified several compounds with high D4 R binding affinity ( Ki ≤ 6.9 nM) and >91-fold selectivity over other D2 -like receptors (D2 R, D3 R) with diverse partial agonist and antagonist profiles. Novel analogue 16f is a potent low-efficacy D4 R partial agonist, metabolically stable in rat and human liver microsomes, and has excellent brain penetration in rats (AUCbrain/plasma > 3). 16f (5-30 mg/kg, i.p.) dose-dependently decreased iv cocaine self-administration in rats, consistent with previous results produced by D4 R-selective antagonists. Off-target antagonism of 5-HT2A or 5-HT2B may also contribute to these effects. Results with 16f support further efforts to target D4 R in SUD treatment.- Published
- 2023
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25. The selective D3-Receptor antagonist VK4-116 effectively treats behavioral inflexibility in rats caused by self-administration and withdrawal from cocaine.
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Panayi MC, Shetty S, Porod M, Bahena L, Xi ZX, Newman AH, and Schoenbaum G
- Abstract
Chronic psychostimulant use can cause long lasting changes to neural and cognitive function that persist even after long periods of abstinence. As cocaine users transition from drug use to abstinence, a parallel transition from hyperactivity to hypoactivity has been found in orbitofrontal-striatal glucose metabolism, and striatal D2/D3 receptor activity. Targeting these changes pharmacologically, using highly selective dopamine D3 receptor (D
3 R) antagonists and partial agonists, has shown significant promise in reducing drug-taking, and attenuating relapse in animal models of cocaine and opioid use disorder. However, much less attention has been focused on treating inflexible and potentially maladaptive non-drug behaviors following chronic psychostimulant use. Here we tested the selective D3 R antagonist VK4-116 as a treatment for the long-term behavioral inflexibility in abstinent male and female rats with a prior history of chronic cocaine use. Rats were first trained to self-administer cocaine (0.75 mg/kg/reinforcer) or a sucrose liquid (10%, .04 mL/reinforcer) for 2 weeks (FR1 schedule, max 60 reinforcers in 3 hrs/ day), followed by 4 weeks of abstinence. Cognitive and behavioral flexibilities were then assessed using a sensory preconditioning (SPC) learning paradigm. Rats were given an VK4-116 (15 mg/kg, i.p.) or vehicle 30 mins prior to each SPC training session, thus creating four drug-treatment groups: sucrose-vehicle, sucrose-VK4-116, cocaine-vehicle, cocaine-VK4-116. The control groups (sucrose-vehicle, sucrose-VK4-116) demonstrated significant evidence of flexible SPC behavior, whereas cocaine use (cocaine-vehicle) disrupted SPC behavior. Remarkably, the D3 R antagonist VK4-116 mitigated this cocaine deficit in the cocaine-VK4-116 group, demonstrating flexible SPC to levels comparable to the control groups. These preclinical findings demonstrate that highly selective dopamine D3 R antagonists, particularly VK4-116, show significant promise as a pharmacological treatment for the long-term negative behavioral consequences of cocaine use disorder.- Published
- 2023
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26. Disruptive mutations in the serotonin transporter associate serotonin dysfunction with treatment-resistant affective disorder.
- Author
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Støier JF, Jørgensen TN, Sparsø T, Rasmussen HB, Kumar V, Newman AH, Blakely RD, Werge T, Gether U, and Herborg F
- Abstract
Affective or mood disorders are a leading cause of disability worldwide. The serotonergic system has been heavily implicated in the complex etiology and serves as a therapeutic target. The serotonin transporter (SERT) is a major regulator of serotonin neurotransmission, yet the disease-relevance of impaired SERT function remains unknown. Here, we present the first identification and functional characterization of disruptive coding SERT variants found in patients with psychiatric diseases. In a unique cohort of 144 patients characterized by treatment-resistant chronic affective disorders with a lifetime history of electroconvulsive therapy, we identified two previously uncharacterized coding SERT variants: SERT-N217S and SERT-A500T. Both variants were significantly enriched in the patient cohort compared to GnomAD (SERT-N217S: OR = 151, P = 0.0001 and SERT-A500T: OR = 1348, P = 0.0022) and ethnicity-matched healthy controls (SERT-N217S: OR ≥ 17.7, P ≤ 0.013 and SERT-A500T: OR = ∞, P = 0.029). Functional investigations revealed that the mutations exert distinct perturbations to SERT function, but their overall effects converge on a partial loss-of-function molecular phenotype. Thus, the SERT-A500T variant compromises the catalytic activity, while SERT-N217S disrupts proper glycosylation of SERT with a resulting dominant-negative trafficking deficiency. Moreover, we demonstrate that the trafficking deficiency of SERT-N217S is amenable to pharmacochaperoning by noribogaine. Collectively, our findings describe the first disease-associated loss-of-function SERT variants and implicate serotonergic disturbances arising from SERT dysfunction as a risk factor for chronic affective disorders.
- Published
- 2023
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27. Pharmacological and Physicochemical Properties Optimization for Dual-Target Dopamine D 3 (D 3 R) and μ-Opioid (MOR) Receptor Ligands as Potentially Safer Analgesics.
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Bonifazi A, Saab E, Sanchez J, Nazarova AL, Zaidi SA, Jahan K, Katritch V, Canals M, Lane JR, and Newman AH
- Subjects
- Humans, Dopamine, Ligands, Analgesics pharmacology, Receptors, Dopamine D3 agonists, Receptors, Opioid, mu agonists, Analgesics, Opioid pharmacology, Analgesics, Opioid chemistry, Opioid-Related Disorders
- Abstract
A new generation of dual-target μ opioid receptor (MOR) agonist/dopamine D
3 receptor (D3 R) antagonist/partial agonists with optimized physicochemical properties was designed and synthesized. Combining in vitro cell-based on-target/off-target affinity screening, in silico computer-aided drug design, and BRET functional assays, we identified new structural scaffolds that achieved high affinity and agonist/antagonist potencies for MOR and D3 R, respectively, improving the dopamine receptor subtype selectivity (e.g., D3 R over D2 R) and significantly enhancing central nervous system multiparameter optimization scores for predicted blood-brain barrier permeability. We identified the substituted trans -(2 S ,4 R )-pyrrolidine and trans -phenylcyclopropyl amine as key dopaminergic moieties and tethered these to different opioid scaffolds, derived from the MOR agonists TRV130 ( 3 ) or loperamide ( 6 ). The lead compounds 46 , 84 , 114, and 121 have the potential of producing analgesic effects through MOR partial agonism with reduced opioid-misuse liability via D3 R antagonism. Moreover, the peripherally limited derivatives could have therapeutic indications for inflammation and neuropathic pain.- Published
- 2023
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28. An FSCV Study on the Effects of Targeted Typical and Atypical DAT Inhibition on Dopamine Dynamics in the Nucleus Accumbens Shell of Male and Female Mice.
- Author
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Hersey M, Chen AY, Bartole MK, Anand J, Newman AH, and Tanda G
- Subjects
- Female, Mice, Male, Animals, Modafinil pharmacology, Dopamine Plasma Membrane Transport Proteins metabolism, Dopamine metabolism, Nucleus Accumbens metabolism, Mice, Inbred C57BL, Dopamine Uptake Inhibitors pharmacology, Central Nervous System Stimulants pharmacology, Cocaine pharmacology, Cocaine metabolism
- Abstract
Understanding the neurochemistry underlying sex differences in psychostimulant use disorders (PSUD) is essential for developing related therapeutics. Many psychostimulants, like cocaine, inhibit the dopamine transporter (DAT), which is largely thought to account for actions related to their misuse and dependence. Cocaine-like, typical DAT inhibitors preferentially bind DAT in an outward-facing conformation, while atypical DAT inhibitors, like modafinil, prefer a more inward-facing DAT conformation. Modafinil and R -modafinil have emerged as potential therapeutic options for selected populations of individuals affected by PSUD. In addition, analogs of modafinil (JJC8-088 and JJC8-091) with different pharmacological profiles have been explored as potential PSUD medications in preclinical models. In this work, we employ fast scan cyclic voltammetry (FSCV) to probe nucleus accumbens shell (NAS) dopamine (DA) dynamics in C57BL/6 male and female mice. We find that cocaine slowed DA clearance in both male and female mice but produced more robust increases in evoked NAS DA in female mice. R -Modafinil produced mild increases in evoked NAS DA and slowed DA clearance across the sexes. The modafinil analog JJC8-088, a typical DAT inhibitor, produced increases in evoked NAS DA in female and male mice. Finally, JJC8-091, an atypical DAT inhibitor, produced limited increases in evoked NAS DA and slowed DA clearance in both sexes. In this work we begin to tease out how sex differences may alter the effects of DAT targeting and highlight how this may help focus research toward effective treatment options for PSUD.
- Published
- 2023
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29. Are There Prevalent Sex Differences in Psychostimulant Use Disorder? A Focus on the Potential Therapeutic Efficacy of Atypical Dopamine Uptake Inhibitors.
- Author
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Hersey M, Bartole MK, Jones CS, Newman AH, and Tanda G
- Subjects
- Female, Humans, Male, Dopamine Uptake Inhibitors pharmacology, Modafinil therapeutic use, Modafinil pharmacology, Sex Characteristics, Benzhydryl Compounds pharmacology, Benzhydryl Compounds therapeutic use, Dopamine, Central Nervous System Stimulants pharmacology, Cocaine pharmacology
- Abstract
Psychostimulant use disorders (PSUD) affect a growing number of men and women and exert sizable public health and economic burdens on our global society. Notably, there are some sex differences in the onset of dependence, relapse rates, and treatment success with PSUD observed in preclinical and clinical studies. The subtle sex differences observed in the behavioral aspects of PSUD may be associated with differences in the neurochemistry of the dopaminergic system between sexes. Preclinically, psychostimulants have been shown to increase synaptic dopamine (DA) levels and may downregulate the dopamine transporter (DAT). This effect is greatest in females during the high estradiol phase of the estrous cycle. Interestingly, women have been shown to be more likely to begin drug use at younger ages and report higher levels of desire to use cocaine than males. Even though there is currently no FDA-approved medication, modafinil, a DAT inhibitor approved for use in the treatment of narcolepsy and sleep disorders, has shown promise in the treatment of PSUD among specific populations of affected individuals. In this review, we highlight the therapeutic potential of modafinil and other atypical DAT inhibitors focusing on the lack of sex differences in the actions of these agents.
- Published
- 2023
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30. Interactions of calmodulin kinase II with the dopamine transporter facilitate cocaine-induced enhancement of evoked dopamine release.
- Author
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Keighron JD, Bonaventura J, Li Y, Yang JW, DeMarco EM, Hersey M, Cao J, Sandtner W, Michaelides M, Sitte HH, Newman AH, and Tanda G
- Subjects
- Dopamine, Dopamine Plasma Membrane Transport Proteins, Dopamine Uptake Inhibitors pharmacology, Calcium-Calmodulin-Dependent Protein Kinases, Cocaine pharmacology, Central Nervous System Stimulants
- Abstract
Typical and atypical dopamine uptake inhibitors (DUIs) prefer distinct conformations of the dopamine transporter (DAT) to form ligand-transporter complexes, resulting in markedly different effects on behavior, neurochemistry, and potential for addiction. Here we show that cocaine and cocaine-like typical psychostimulants elicit changes in DA dynamics distinct from those elicited by atypical DUIs, as measured via voltammetry procedures. While both classes of DUIs reduced DA clearance rate, an effect significantly related to their DAT affinity, only typical DUIs elicited a significant stimulation of evoked DA release, an effect unrelated to their DAT affinity, which suggests a mechanism of action other than or in addition to DAT blockade. When given in combination, typical DUIs enhance the stimulatory effects of cocaine on evoked DA release while atypical DUIs blunt them. Pretreatments with an inhibitor of CaMKIIα, a kinase that interacts with DAT and that regulates synapsin phosphorylation and mobilization of reserve pools of DA vesicles, blunted the effects of cocaine on evoked DA release. Our results suggest a role for CaMKIIα in modulating the effects of cocaine on evoked DA release without affecting cocaine inhibition of DA reuptake. This effect is related to a specific DAT conformation stabilized by cocaine. Moreover, atypical DUIs, which prefer a distinct DAT conformation, blunt cocaine's neurochemical and behavioral effects, indicating a unique mechanism underlying their potential as medications for treating psychostimulant use disorder., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
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- 2023
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31. The Effects of the Dopamine Transporter Ligands JJC8-088 and JJC8-091 on Cocaine versus Food Choice in Rhesus Monkeys.
- Author
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Rahimi O, Cao J, Lam J, Childers SR, Rais R, Porrino LJ, Newman AH, and Nader MA
- Subjects
- Male, Rats, Animals, Dopamine Plasma Membrane Transport Proteins metabolism, Macaca mulatta metabolism, Dopamine Uptake Inhibitors pharmacology, Self Administration, Dose-Response Relationship, Drug, Cocaine pharmacology
- Abstract
Although there are no Food and Drug Administration-approved treatments for cocaine use disorder, several modafinil analogs have demonstrated promise in reducing cocaine self-administration and reinstatement in rats. Furthermore, the range of dopamine transporter (DAT) compounds provides an opportunity to develop pharmacotherapeutics without abuse liability. This study extended the comparison of JJC8-088 and JJC8-091, the former compound having higher DAT affinity and predicted abuse liability, to rhesus monkeys using a concurrent cocaine versus food schedule of reinforcement. First, binding to striatal DAT was examined in cocaine-naïve monkey tissue. Next, intravenous pharmacokinetics of both JJC compounds were evaluated in cocaine-experienced male monkeys ( n = 3/drug). In behavioral studies, acute and chronic administration of both compounds were evaluated in these same monkeys responding under a concurrent food versus cocaine (0 and 0.003-0.1 mg/kg per injection) schedule of reinforcement. In nonhuman primate striatum, JJC8-088 had higher DAT affinity compared with JJC8-091 (14.4 ± 9 versus 2730 ± 1270 nM, respectively). Both JJC compounds had favorable plasma pharmacokinetics for behavioral assessments, with half-lives of 1.1 hours and 3.5 hours for JJC8-088 (0.7 mg/kg, i.v.) and JJC8-091 (1.9 mg/kg, i.v.), respectively. Acute treatment with both compounds shifted the cocaine dose-response curve to the left. Chronic treatment with JJC8-088 decreased cocaine choice in two of the three monkeys, whereas JJC8-091 only modestly reduced cocaine allocation in one monkey. Differences in affinities of JJC8-091 DAT binding in monkeys compared with rats may account for the poor rodent-to-monkey translation. Future studies should evaluate atypical DAT blockers in combination with behavioral interventions that may further decrease cocaine choice. SIGNIFICANCE STATEMENT: Cocaine use disorder (CUD) remains a significant public health problem with no Food and Drug Administration-approved treatments. The ability of drugs that act in the brain in a similar manner to cocaine, but with lower abuse liability, has clinical implications for a treatment of CUD., (U.S. Government work not protected by U.S. copyright.)
- Published
- 2023
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32. Effects of buprenorphine, methadone, and cariprazine on economic choice between remifentanil and food in squirrel monkeys.
- Author
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Amirali AS, Hecker JC, Figueroa HM, Effinger DP, Montoro RA, Jedema HP, Vogt CD, Newman AH, Schindler CW, and Bradberry CW
- Abstract
We recently reported an economic choice task in which squirrel monkeys chose between differing amounts of remifentanil, a fast-acting opioid, or a food reward to develop a preclinical screen for evaluating potential pharmacotherapies for opioid dependence. Herein, two known opioid addiction treatments are evaluated using this task, as well as a potential new agent, cariprazine, a dopamine D2/D3 receptor partial agonist currently used to treat bipolar disorder and schizophrenia. Preclinical rodent studies suggest this class of compounds may reduce opiate self-administration. Squirrel monkeys were pretreated daily with clinically relevant doses of each compound during the five days of treatment evaluation using the economic choice task. Shifts in drug preference were measured as changes in subjects' indifference values, where the probability of drug and milk choice are equivalent. Buprenorphine produced a significant shift in indifference value between baseline and treatment weeks, indicating a decrease in drug preference. Subjects treated with methadone and cariprazine did not show any significant shift in drug preference. Differences between the buprenorphine and methadone results likely reflect a lack of opioid dependence in the subjects. The cariprazine results suggest that it does not alter opioid reward in non-dependent primates over a five day period., Competing Interests: Declaration of Interest: None.
- Published
- 2023
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33. 3,4-Methylenedioxypyrovalerone High-Responder Phenotype as a Tool to Evaluate Candidate Medications for Stimulant Use Disorder.
- Author
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Doyle MR, Peng LN, Cao J, Rice KC, Newman AH, and Collins GT
- Subjects
- Animals, Female, Humans, Male, Rats, Dopamine, Dose-Response Relationship, Drug, Haloperidol, Self Administration, Serotonin, Synthetic Cathinone, Cocaine, Receptors, sigma
- Abstract
Despite decades of research, there are no medications approved by the United States Food and Drug Administration to treat stimulant use disorders. Self-administration procedures are widely used to screen candidate medications for stimulant use disorder, although preclinical reductions in stimulant self-administration have not translated to meaningful reductions in stimulant use in humans. One possible reason for this discordance is that most preclinical studies evaluate candidate medications under conditions that promote predictable, and well-regulated patterns of drug-taking rather than the dysregulated and/or compulsive patterns of drug-taking characteristic of a stimulant use disorder. A subset of rats ("high-responders") that self-administer 3,4-methelyendioxypyrovalerone (MDPV), a monoamine uptake inhibitor, develop high levels of dysregulated drug-taking consistent with behaviors related to stimulant use disorders. Because MDPV acts on dopamine, serotonin (5-HT), and sigma receptor systems, the current studies compared the potency and effectiveness of a dopamine D
3 receptor partial agonist (VK4-40) or antagonist (VK4-116), a sigma receptor antagonist (BD1063), a dopamine D2 /D3 /sigma receptor antagonist (haloperidol), and a 5-HT2C receptor agonist (CP-809,101) to reduce MDPV (0.0032-0.1 mg/kg/infusion) self-administration in high- and low-responding rats as well as rats self-administering cocaine (0.032-1 mg/kg/infusion). VK4-40, VK4-116, haloperidol, and CP-809,101 were equipotent and effective at reducing drug-taking in all three groups of rats, including the high-responders; however, VK4-116 and CP-809,101 were less potent at reducing drug-taking in female compared with male rats. Together, these studies suggest that drugs targeting dopamine D3 or 5-HT2C receptors can effectively reduce dysregulated patterns of stimulant use, highlighting their potential utility for treating stimulant use disorders. SIGNIFICANCE STATEMENT: There are no United States Food and Drug Administration-approved treatments for stimulant use disorder, perhaps in part because candidate medications are most often evaluated in preclinical models using male subjects with well-regulated drug-taking. In an attempt to better model aberrant drug taking, this study found compounds acting at dopamine D3 or 5-HT2C receptors can attenuate drug-taking in male and female rats that self-administered two different stimulants and exhibited either a high or low substance use disorder-like phenotype., (U.S. Government work not protected by U.S. copyright.)- Published
- 2023
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34. Dopamine D 3 /D 2 Receptor Ligands Based on Cariprazine for the Treatment of Psychostimulant Use Disorders That May Be Dual Diagnosed with Affective Disorders.
- Author
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Gogarnoiu ES, Vogt CD, Sanchez J, Bonifazi A, Saab E, Shaik AB, Soler-Cedeño O, Bi GH, Klein B, Xi ZX, Lane JR, and Newman AH
- Subjects
- Rats, Animals, Receptors, Dopamine D3, Ligands, Dopamine Agonists, Dopamine, Central Nervous System Stimulants
- Abstract
Highly selective dopamine D
3 receptor (D3 R) partial agonists/antagonists have been developed for the treatment of psychostimulant use disorders (PSUD). However, none have reached the clinic due to insufficient potency/efficacy or potential cardiotoxicity. Cariprazine, an FDA-approved drug for the treatment of schizophrenia and bipolar disorder, is a high-affinity D3 R partial agonist ( Ki = 0.22 nM) with 3.6-fold selectivity over the homologous dopamine D2 receptor (D2 R). We hypothesized that compounds that are moderately D3 R/D2 R-selective partial agonists/antagonists may be effective for the treatment of PSUD. By systematically modifying the parent molecule, we discovered partial agonists/antagonists, as measured in bioluminescence resonance energy transfer (BRET)-based assays, with high D3 R affinities ( Ki = 0.14-50 nM) and moderate selectivity (<100-fold) over D2 R. Cariprazine and two lead analogues, 13a and 13e , decreased cocaine self-administration (FR2; 1-10 mg/kg, i.p.) in rats, suggesting that partial agonists/antagonists with modest D3 R/D2 R selectivity may be effective in treating PSUD and potentially comorbidities with other affective disorders.- Published
- 2023
- Full Text
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35. Current Perspectives on Selective Dopamine D 3 Receptor Antagonists/Partial Agonists as Pharmacotherapeutics for Opioid and Psychostimulant Use Disorders.
- Author
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Newman AH, Xi ZX, and Heidbreder C
- Subjects
- Humans, Analgesics, Opioid therapeutic use, Dopamine, Receptors, Dopamine D3 agonists, Receptors, Dopamine D3 therapeutic use, Dopamine Antagonists pharmacology, Dopamine Antagonists therapeutic use, Central Nervous System Stimulants pharmacology, Substance-Related Disorders drug therapy
- Abstract
Over three decades of evidence indicate that dopamine (DA) D
3 receptors (D3 R) are involved in the control of drug-seeking behavior and may play an important role in the pathophysiology of substance use disorders (SUD). The expectation that a selective D3 R antagonist/partial agonist would be efficacious for the treatment of SUD is based on the following key observations. First, D3 R are distributed in strategic areas belonging to the mesolimbic DA system such as the ventral striatum, midbrain, and ventral pallidum, which have been associated with behaviors controlled by the presentation of drug-associated cues. Second, repeated exposure to drugs of abuse produces neuroadaptations in the D3 R system. Third, the synthesis and characterization of highly potent and selective D3 R antagonists/partial agonists have further strengthened the role of the D3 R in SUD. Based on extensive preclinical and preliminary clinical evidence, the D3 R shows promise as a target for the development of pharmacotherapies for SUD as reflected by their potential to (1) regulate the motivation to self-administer drugs and (2) disrupt the responsiveness to drug-associated stimuli that play a key role in reinstatement of drug-seeking behavior triggered by re-exposure to the drug itself, drug-associated environmental cues, or stress. The availability of PET ligands to assess clinically relevant receptor occupancy by selective D3 R antagonists/partial agonists, the definition of reliable dosing, and the prospect of using human laboratory models may further guide the design of clinical proof of concept studies. Pivotal clinical trials for more rapid progression of this target toward regulatory approval are urgently required. Finally, the discovery that highly selective D3 R antagonists, such as R-VK4-116 and R-VK4-40, do not adversely affect peripheral biometrics or cardiovascular effects alone or in the presence of oxycodone or cocaine suggests that this class of drugs has great potential in safely treating psychostimulant and/or opioid use disorders., (© 2022. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)- Published
- 2023
- Full Text
- View/download PDF
36. A highly D 3 R-selective and efficacious partial agonist (S)-ABS01-113 compared to its D 3 R-selective antagonist enantiomer (R)-ABS01-113 as potential treatments for opioid use disorder.
- Author
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Galaj E, Bi GH, Klein B, Hempel B, Shaik AB, Gogarnoiu ES, Friedman J, Lam J, Rais R, Reed JF, Bloom SH, Swanson TL, Schmachtenberg JL, Eshleman AJ, Janowsky A, Xi ZX, and Newman AH
- Subjects
- Animals, Rats, Male, Mice, Humans, Heroin, Dopamine Antagonists pharmacology, Drug-Seeking Behavior, Analgesics, Opioid pharmacology, Dopamine Agonists pharmacology, Receptors, Dopamine D3 metabolism, Opioid-Related Disorders
- Abstract
The non-medical use of opioids has become a national crisis in the USA. Developing non-opioid pharmacotherapies for controlling this opioid epidemic is urgent. Dopamine D
3 receptor (D3 R) antagonists and low efficacy partial agonists have shown promising profiles in animal models of opioid use disorders (OUD). However, to date, advancement to human studies has been limited. Here we report the effects of (S)- and (R)-enantiomers of (±)-ABS01-113, structural analogs of the D3 R partial agonist, (±)-VK4-40, in which the 3-OH in the linking chain is replaced by 3-F group. (S)- and (R)-ABS01-113 are identical in chemical structure but with opposite chirality. In vitro receptor binding and functional assays indicate that (S)-ABS01-113 is an efficacious (55%) and potent (EC50 = 7.6 ± 3.9 nM) D3 R partial agonist, while the (R)-enantiomer is a potent D3 R antagonist (IC50 = 11.4 nM). Both (S)- and (R)-ABS01-113 bind with high affinity to D3 R (Ki = 0.84 ± 0.16 and 0.37 ± 0.06 nM, respectively); however, the (S)-enantiomer is more D3 /D2 -selective (>1000-fold). Pharmacokinetic analyses indicate that both enantiomers display excellent oral bioavailability and high brain penetration. Systemic administration of (S)- or (R)-ABS01-113 alone failed to alter open-field locomotion in male rats and mice. Interestingly, pretreatment with (S)- or (R)-ABS01-113 attenuated heroin-enhanced hyperactivity, heroin self-administration, and (heroin + cue)-induced reinstatement of drug-seeking behavior. Together, these findings reveal that both enantiomers, particularly the highly selective and efficacious D3 R partial agonist (S)-ABS01-113, demonstrate promising translational potential for the treatment of OUD., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)- Published
- 2022
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37. Phosphatidylinositol 4,5-bisphosphate (PIP 2 ) facilitates norepinephrine transporter dimerization and modulates substrate efflux.
- Author
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Luethi D, Maier J, Rudin D, Szöllősi D, Angenoorth TJF, Stankovic S, Schittmayer M, Burger I, Yang JW, Jaentsch K, Holy M, Das AK, Brameshuber M, Camacho-Hernandez GA, Casiraghi A, Newman AH, Kudlacek O, Birner-Gruenberger R, Stockner T, Schütz GJ, and Sitte HH
- Subjects
- Dimerization, Biological Transport, Inositol Phosphates, Norepinephrine, Norepinephrine Plasma Membrane Transport Proteins genetics, Phosphatidylinositols
- Abstract
The plasmalemmal norepinephrine transporter (NET) regulates cardiovascular sympathetic activity by clearing extracellular norepinephrine in the synaptic cleft. Here, we investigate the subunit stoichiometry and function of NET using single-molecule fluorescence microscopy and flux assays. In particular, we show the effect of phosphatidylinositol 4,5-bisphosphate (PIP
2 ) on NET oligomerization and efflux. NET forms monomers (~60%) and dimers (~40%) at the plasma membrane. PIP2 depletion results in a decrease in the average oligomeric state and decreases NET-mediated substrate efflux while not affecting substrate uptake. Mutation of the putative PIP2 binding residues R121, K334, and R440 to alanines does not affect NET dimerization but results in decreased substrate efflux that is not altered upon PIP2 depletion; this indicates that PIP2 interactions with these residues affect NET-mediated efflux. A dysregulation of norepinephrine and PIP2 signaling have both been implicated in neuropsychiatric and cardiovascular diseases. This study provides evidence that PIP2 directly regulates NET organization and function., (© 2022. The Author(s).)- Published
- 2022
- Full Text
- View/download PDF
38. Pharmacological targeting of G protein-coupled receptor heteromers.
- Author
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Moreno E, Casajuana-Martin N, Coyle M, Campos BC, Galaj E, Del Torrent CL, Seyedian A, Rea W, Cai NS, Bonifazi A, Florán B, Xi ZX, Guitart X, Casadó V, Newman AH, Bishop C, Pardo L, and Ferré S
- Subjects
- Animals, Rats, Mice, Receptors, Dopamine D3 agonists, Receptors, Dopamine D1 agonists, Dopamine, Receptors, G-Protein-Coupled, Ligands, Levodopa, Dyskinesias
- Abstract
A main rationale for the role of G protein-coupled receptor (GPCR) heteromers as targets for drug development is the putative ability of selective ligands for specific GPCRs to change their pharmacological properties upon GPCR heteromerization. The present study provides a proof of concept for this rationale by demonstrating that heteromerization of dopamine D
1 and D3 receptors (D1 R and D3 R) influences the pharmacological properties of three structurally similar selective dopamine D3 R ligands, the phenylpiperazine derivatives PG01042, PG01037 and VK4-116. By using D1 R-D3 R heteromer-disrupting peptides, it could be demonstrated that the three D3 R ligands display different D1 R-D3 R heteromer-dependent pharmacological properties: PG01042, acting as G protein-biased agonist, counteracted D1 R-mediated signaling in the D1 R-D3 R heteromer; PG01037, acting as a D3 R antagonist cross-antagonized D1 R-mediated signaling in the D1 R-D3 R heteromer; and VK4-116 specifically acted as a ß-arrestin-biased agonist in the D1 R-D3 R heteromer. Molecular dynamics simulations predicted potential molecular mechanisms mediating these qualitatively different pharmacological properties of the selective D3 R ligands that are dependent on D1 R-D3 R heteromerization. The results of in vitro experiments were paralleled by qualitatively different pharmacological properties of the D3 R ligands in vivo. The results supported the involvement of D1 R-D3 R heteromers in the locomotor activation by D1 R agonists in reserpinized mice and L-DOPA-induced dyskinesia in rats, highlighting the D1 R-D3 R heteromer as a main pharmacological target for L-DOPA-induced dyskinesia in Parkinson's disease. More generally, the present study implies that when suspecting its pathogenetic role, a GPCR heteromer, and not its individual GPCR units, should be considered as main target for drug development., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2022. Published by Elsevier Ltd.)- Published
- 2022
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- View/download PDF
39. Nanoscopic dopamine transporter distribution and conformation are inversely regulated by excitatory drive and D2 autoreceptor activity.
- Author
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Lycas MD, Ejdrup AL, Sørensen AT, Haahr NO, Jørgensen SH, Guthrie DA, Støier JF, Werner C, Newman AH, Sauer M, Herborg F, and Gether U
- Subjects
- Animals, Clathrin metabolism, Dopamine metabolism, Dopaminergic Neurons metabolism, Mice, Phosphatidylinositols metabolism, Qa-SNARE Proteins metabolism, Autoreceptors metabolism, Dopamine Plasma Membrane Transport Proteins metabolism
- Abstract
The nanoscopic organization and regulation of individual molecular components in presynaptic varicosities of neurons releasing modulatory volume neurotransmitters like dopamine (DA) remain largely elusive. Here we show, by application of several super-resolution microscopy techniques to cultured neurons and mouse striatal slices, that the DA transporter (DAT), a key protein in varicosities of dopaminergic neurons, exists in the membrane in dynamic equilibrium between an inward-facing nanodomain-localized and outward-facing unclustered configuration. The balance between these configurations is inversely regulated by excitatory drive and DA D2 autoreceptor activation in a manner dependent on Ca
2+ influx via N-type voltage-gated Ca2+ channels. The DAT nanodomains contain tens of transporters molecules and overlap with nanodomains of PIP2 (phosphatidylinositol-4,5-bisphosphate) but show little overlap with D2 autoreceptor, syntaxin-1, and clathrin nanodomains. The data reveal a mechanism for rapid alterations of nanoscopic DAT distribution and show a striking link of this to the conformational state of the transporter., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)- Published
- 2022
- Full Text
- View/download PDF
40. Synaptic-like axo-axonal transmission from striatal cholinergic interneurons onto dopaminergic fibers.
- Author
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Kramer PF, Brill-Weil SG, Cummins AC, Zhang R, Camacho-Hernandez GA, Newman AH, Eldridge MAG, Averbeck BB, and Khaliq ZM
- Subjects
- Axons metabolism, Cholinergic Agents, Cholinergic Fibers metabolism, Corpus Striatum physiology, Interneurons metabolism, Synaptic Transmission physiology, Dopamine physiology, Receptors, Nicotinic metabolism
- Abstract
Transmission from striatal cholinergic interneurons (CINs) controls dopamine release through nicotinic acetylcholine receptors (nAChRs) on dopaminergic axons. Anatomical studies suggest that cholinergic terminals signal predominantly through non-synaptic volume transmission. However, the influence of cholinergic transmission on electrical signaling in axons remains unclear. We examined axo-axonal transmission from CINs onto dopaminergic axons using perforated-patch recordings, which revealed rapid spontaneous EPSPs with properties characteristic of fast synapses. Pharmacology showed that axonal EPSPs (axEPSPs) were mediated primarily by high-affinity α6-containing receptors. Remarkably, axEPSPs triggered spontaneous action potentials, suggesting that these axons perform integration to convert synaptic input into spiking, a function associated with somatodendritic compartments. We investigated the cross-species validity of cholinergic axo-axonal transmission by recording dopaminergic axons in macaque putamen and found similar axEPSPs. Thus, we reveal that synaptic-like neurotransmission underlies cholinergic signaling onto dopaminergic axons, supporting the idea that striatal dopamine release can occur independently of somatic firing to provide distinct signaling., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)
- Published
- 2022
- Full Text
- View/download PDF
41. Preferential Gs protein coupling of the galanin Gal 1 receptor in the µ-opioid-Gal 1 receptor heterotetramer.
- Author
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De Oliveira PA, Moreno E, Casajuana-Martin N, Casadó-Anguera V, Cai NS, Camacho-Hernandez GA, Zhu H, Bonifazi A, Hall MD, Weinshenker D, Newman AH, Logothetis DE, Casadó V, Plant LD, Pardo L, and Ferré S
- Subjects
- Mesencephalon, Peptides, Receptors, Opioid, Analgesics, Opioid pharmacology, Galanin
- Abstract
Recent studies have proposed that heteromers of µ-opioid receptors (MORs) and galanin Gal
1 receptors (Gal1 Rs) localized in the mesencephalon mediate the dopaminergic effects of opioids. The present study reports converging evidence, using a peptide-interfering approach combined with biophysical and biochemical techniques, including total internal reflection fluorescence microscopy, for a predominant homodimeric structure of MOR and Gal1 R when expressed individually, and for their preference to form functional heterotetramers when co-expressed. Results show that a heteromerization-dependent change in the Gal1 R homodimeric interface leads to a switch in G-protein coupling from inhibitory Gi to stimulatory Gs proteins. The MOR-Gal1 R heterotetramer, which is thus bound to Gs via the Gal1 R homodimer and Gi via the MOR homodimer, provides the framework for a canonical Gs-Gi antagonist interaction at the adenylyl cyclase level. These novel results shed light on the intense debate about the oligomeric quaternary structure of G protein-coupled receptors, their predilection for heteromer formation, and the resulting functional significance., (Published by Elsevier Ltd.)- Published
- 2022
- Full Text
- View/download PDF
42. Methylphenidate Analogues as a New Class of Potential Disease-Modifying Agents for Parkinson's Disease: Evidence from Cell Models and Alpha-Synuclein Transgenic Mice.
- Author
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Casiraghi A, Longhena F, Faustini G, Ribaudo G, Suigo L, Camacho-Hernandez GA, Bono F, Brembati V, Newman AH, Gianoncelli A, Straniero V, Bellucci A, and Valoti E
- Abstract
Parkinson's disease (PD) is characterized by dopaminergic nigrostriatal neurons degeneration and Lewy body pathology, mainly composed of α-synuclein (αSyn) fibrillary aggregates. We recently described that the neuronal phosphoprotein Synapsin III (Syn III) participates in αSyn pathology in PD brains and is a permissive factor for αSyn aggregation. Moreover, we reported that the gene silencing of Syn III in a human αSyn transgenic (tg) mouse model of PD at a pathological stage, manifesting marked insoluble αSyn deposits and dopaminergic striatal synaptic dysfunction, could reduce αSyn aggregates, restore synaptic functions and motor activities and exert neuroprotective effects. Interestingly, we also described that the monoamine reuptake inhibitor methylphenidate (MPH) can recover the motor activity of human αSyn tg mice through a dopamine (DA) transporter-independent mechanism, which relies on the re-establishment of the functional interaction between Syn III and α-helical αSyn. These findings support that the pathological αSyn/Syn III interaction may constitute a therapeutic target for PD. Here, we studied MPH and some of its analogues as modulators of the pathological αSyn/Syn III interaction. We identified 4-methyl derivative I- threo as a lead candidate modulating αSyn/Syn III interaction and having the ability to reduce αSyn aggregation in vitro and to restore the motility of αSyn tg mice in vivo more efficiently than MPH. Our results support that MPH derivatives may represent a novel class of αSyn clearing agents for PD therapy.
- Published
- 2022
- Full Text
- View/download PDF
43. Corrigendum: Design and Synthesis of Fluorescent Methylphenidate Analogues for a FRET-Based Assay of Synapsin III Binding.
- Author
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Casiraghi A, Longhena F, Straniero V, Faustini G, Newman AH, Bellucci A, and Valoti E
- Published
- 2022
- Full Text
- View/download PDF
44. Chiral Cyclic Aliphatic Linkers as Building Blocks for Selective Dopamine D 2 or D 3 Receptor Agonists.
- Author
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Battiti FO, Zaidi SA, Katritch V, Newman AH, and Bonifazi A
- Subjects
- Dopamine Agonists chemistry, HEK293 Cells, Humans, Ligands, Molecular Docking Simulation, Radioligand Assay, Stereoisomerism, Dopamine Agonists pharmacology, Receptors, Dopamine D2 drug effects, Receptors, Dopamine D3 drug effects
- Abstract
Linkers are emerging as a key component in regulating the pharmacology of bitopic ligands directed toward G-protein coupled receptors (GPCRs). In this study, the role of regio- and stereochemistry in cyclic aliphatic linkers tethering well-characterized primary and secondary pharmacophores targeting dopamine D
2 and D3 receptor subtypes (D2 R and D3 R, respectively) is described. We introduce several potent and selective D2 R ( rel - trans -16b ; D2 R Ki = 4.58 nM) and D3 R ( rel - cis -14a ; D3 R Ki = 5.72 nM) agonists while modulating subtype selectivity in a stereospecific fashion, transferring D2 R selectivity toward D3 R via inversion of the stereochemistry around these cyclic aliphatic linkers [e.g., (-)-(1 S ,2 R )-43 and (+)-(1 R ,2 S )-42 ]. Pharmacological observations were supported with extensive molecular docking studies. Thus, not only is it an innovative approach to modulate the pharmacology of dopaminergic ligands described, but a new class of optically active cyclic linkers are also introduced, which can be used to expand the bitopic drug design approach toward other GPCRs.- Published
- 2021
- Full Text
- View/download PDF
45. Structure Activity Relationships for a Series of Eticlopride-Based Dopamine D 2 /D 3 Receptor Bitopic Ligands.
- Author
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Shaik AB, Boateng CA, Battiti FO, Bonifazi A, Cao J, Chen L, Chitsazi R, Ravi S, Lee KH, Shi L, and Newman AH
- Subjects
- Dose-Response Relationship, Drug, Humans, Ligands, Models, Molecular, Molecular Structure, Salicylamides chemical synthesis, Salicylamides chemistry, Structure-Activity Relationship, Receptors, Dopamine D2 metabolism, Receptors, Dopamine D3 metabolism, Salicylamides pharmacology
- Abstract
The crystal structure of the dopamine D
3 receptor (D3 R) in complex with eticlopride inspired the design of bitopic ligands that explored (1) N -alkylation of the eticlopride's pyrrolidine ring, (2) shifting of the position of the pyrrolidine nitrogen, (3) expansion of the pyrrolidine ring system, and (4) incorporation of O -alkylations at the 4-position. Structure activity relationships (SAR) revealed that moving the N - or expanding the pyrrolidine ring was detrimental to D2 R/D3 R binding affinities. Small pyrrolidine N -alkyl groups were poorly tolerated, but the addition of a linker and secondary pharmacophore (SP) improved affinities. Moreover, O -alkylated analogues showed higher binding affinities compared to analogously N -alkylated compounds, e.g., O -alkylated 33 (D3 R, 0.436 nM and D2 R, 1.77 nM) vs the N -alkylated 11 (D3 R, 6.97 nM and D2 R, 25.3 nM). All lead molecules were functional D2 R/D3 R antagonists. Molecular models confirmed that 4-position modifications would be well-tolerated for future D2 R/D3 R bioconjugate tools that require long linkers and or sterically bulky groups.- Published
- 2021
- Full Text
- View/download PDF
46. Effects of the selective dopamine D 3 receptor antagonist PG01037 on morphine-induced hyperactivity and antinociception in mice.
- Author
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Botz-Zapp CA, Foster SL, Pulley DM, Hempel B, Bi GH, Xi ZX, Newman AH, Weinshenker D, and Manvich DF
- Subjects
- Animals, Behavior, Animal drug effects, Benzamides administration & dosage, Disease Models, Animal, Female, Male, Mice, Mice, Inbred C57BL, Morphine administration & dosage, Narcotics administration & dosage, Pyridines administration & dosage, Akathisia, Drug-Induced drug therapy, Benzamides pharmacology, Morphine pharmacology, Motor Activity drug effects, Narcotics pharmacology, Nociception drug effects, Pyridines pharmacology, Receptors, Dopamine D3 antagonists & inhibitors
- Abstract
Recent preclinical studies have reported that pretreatment with the novel and highly-selective dopamine D
3 receptor (D3 R) antagonists R-VK4-40 or VK4-116 attenuates the abuse-related behavioral effects of oxycodone while enhancing its analgesic properties. However, whether these observed effects are generalizable to the broad class of D3 R antagonists and/or extend to opioids other than oxycodone has not been extensively explored. The present study sought to assess the impact of pretreatment with another selective D3 R antagonist, PG01037, on several behavioral effects of morphine in mice. C57Bl/6 J mice were pretreated with PG01037 (0-10 mg/kg) and tested for 1) hyperlocomotion induced by acute morphine (5.6-56 mg/kg), 2) locomotor sensitization following repeated morphine (56 mg/kg), 3) antinociception following acute morphine (18 mg/kg), and 4) catalepsy following administration of PG01037 alone or in combination with morphine (56 mg/kg). PG01037 dose-dependently attenuated morphine-induced hyperlocomotion and morphine-induced antinociception at doses that did not alter basal locomotion or nociception alone, but did not prevent the induction of locomotor sensitization following repeated morphine administration. Moreover, PG01037 did not induce catalepsy either alone or in combination with morphine. These results suggest that attenuation of acute opioid-induced hyperactivity may be a behavioral effect shared among D3 R-selective antagonists, thus supporting continued investigations into their use as potential treatments for opioid use disorder. However, PG01037 is unlike newer, highly-selective D3 R antagonists in its capacity to reduce opioid-induced antinociception, indicating that modulation of opioid analgesia may vary across different D3 R antagonists., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2021
- Full Text
- View/download PDF
47. Scaffold Hybridization Strategy Leads to the Discovery of Dopamine D 3 Receptor-Selective or Multitarget Bitopic Ligands Potentially Useful for Central Nervous System Disorders.
- Author
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Bonifazi A, Newman AH, Keck TM, Gervasoni S, Vistoli G, Del Bello F, Giorgioni G, Pavletić P, Quaglia W, and Piergentili A
- Subjects
- Dopamine, Humans, Ligands, Antipsychotic Agents, Central Nervous System Diseases drug therapy
- Abstract
In the search for novel bitopic compounds targeting the dopamine D
3 receptor (D3 R), the N -(2,3-dichlorophenyl)piperazine nucleus (primary pharmacophore) has been linked to the 6,6- or 5,5-diphenyl-1,4-dioxane-2-carboxamide or the 1,4-benzodioxane-2-carboxamide scaffold (secondary pharmacophore) by an unsubstituted or 3-F-/3-OH-substituted butyl chain. This scaffold hybridization strategy led to the discovery of potent D3 R-selective or multitarget ligands potentially useful for central nervous system disorders. In particular, the 6,6-diphenyl-1,4-dioxane derivative 3 showed a D3 R-preferential profile, while an interesting multitarget behavior has been highlighted for the 5,5-diphenyl-1,4-dioxane and 1,4-benzodioxane derivatives 6 and 9 , respectively, which displayed potent D2 R antagonism, 5-HT1A R and D4 R agonism, as well as potent D3 R partial agonism. They also behaved as low-potency 5-HT2A R antagonists and 5-HT2C R partial agonists. Such a profile might be a promising starting point for the discovery of novel antipsychotic agents.- Published
- 2021
- Full Text
- View/download PDF
48. Toward Reducing hERG Affinities for DAT Inhibitors with a Combined Machine Learning and Molecular Modeling Approach.
- Author
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Lee KH, Fant AD, Guo J, Guan A, Jung J, Kudaibergenova M, Miranda WE, Ku T, Cao J, Wacker S, Duff HJ, Newman AH, Noskov SY, and Shi L
- Subjects
- Ether, Humans, Machine Learning, Models, Molecular, Cocaine, Dopamine Plasma Membrane Transport Proteins
- Abstract
Psychostimulant drugs, such as cocaine, inhibit dopamine reuptake via blockading the dopamine transporter (DAT), which is the primary mechanism underpinning their abuse. Atypical DAT inhibitors are dissimilar to cocaine and can block cocaine- or methamphetamine-induced behaviors, supporting their development as part of a treatment regimen for psychostimulant use disorders. When developing these atypical DAT inhibitors as medications, it is necessary to avoid off-target binding that can produce unwanted side effects or toxicities. In particular, the blockade of a potassium channel, human ether-a-go-go (hERG), can lead to potentially lethal ventricular tachycardia. In this study, we established a counter screening platform for DAT and against hERG binding by combining machine learning-based quantitative structure-activity relationship (QSAR) modeling, experimental validation, and molecular modeling and simulations. Our results show that the available data are adequate to establish robust QSAR models, as validated by chemical synthesis and pharmacological evaluation of a validation set of DAT inhibitors. Furthermore, the QSAR models based on subsets of the data according to experimental approaches used have predictive power as well, which opens the door to target specific functional states of a protein. Complementarily, our molecular modeling and simulations identified the structural elements responsible for a pair of DAT inhibitors having opposite binding affinity trends at DAT and hERG, which can be leveraged for rational optimization of lead atypical DAT inhibitors with desired pharmacological properties.
- Published
- 2021
- Full Text
- View/download PDF
49. Identifying dominant-negative actions of a dopamine transporter variant in patients with parkinsonism and neuropsychiatric disease.
- Author
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Herborg F, Jensen KL, Tolstoy S, Arends NV, Posselt LP, Shekar A, Aguilar JI, Lund VK, Erreger K, Rickhag M, Lycas MD, Lonsdale MN, Rahbek-Clemmensen T, Sørensen AT, Newman AH, Løkkegaard A, Kjærulff O, Werge T, Møller LB, Matthies HJ, Galli A, Hjermind LE, and Gether U
- Subjects
- Adult, Animals, Behavior, Animal, Biological Transport, Cells, Cultured, Databases, Genetic, Drosophila, Exome, Female, Humans, Hypokinesia diagnostic imaging, Hypokinesia genetics, Hypokinesia metabolism, Male, Mental Disorders metabolism, Mesencephalon metabolism, Mice, Middle Aged, Motor Activity genetics, Mutation, Parkinsonian Disorders diagnostic imaging, Parkinsonian Disorders metabolism, Phenotype, Synaptic Transmission, Tomography, Emission-Computed, Single-Photon, Transfection, Dopamine metabolism, Dopamine Plasma Membrane Transport Proteins genetics, Dopamine Plasma Membrane Transport Proteins metabolism, Mental Disorders genetics, Neurons metabolism, Parkinsonian Disorders genetics
- Abstract
Dysfunctional dopaminergic neurotransmission is central to movement disorders and mental diseases. The dopamine transporter (DAT) regulates extracellular dopamine levels, but the genetic and mechanistic link between DAT function and dopamine-related pathologies is not clear. Particularly, the pathophysiological significance of monoallelic missense mutations in DAT is unknown. Here, we use clinical information, neuroimaging, and large-scale exome-sequencing data to uncover the occurrence and phenotypic spectrum of a DAT coding variant, DAT-K619N, which localizes to the critical C-terminal PSD-95/Discs-large/ZO-1 homology-binding motif of human DAT (hDAT). We identified the rare but recurrent hDAT-K619N variant in exome-sequenced samples of patients with neuropsychiatric diseases and a patient with early-onset neurodegenerative parkinsonism and comorbid neuropsychiatric disease. In cell cultures, hDAT-K619N displayed reduced uptake capacity, decreased surface expression, and accelerated turnover. Unilateral expression in mouse nigrostriatal neurons revealed differential effects of hDAT-K619N and hDAT-WT on dopamine-directed behaviors, and hDAT-K619N expression in Drosophila led to impairments in dopamine transmission with accompanying hyperlocomotion and age-dependent disturbances of the negative geotactic response. Moreover, cellular studies and viral expression of hDAT-K619N in mice demonstrated a dominant-negative effect of the hDAT-K619N mutant. Summarized, our results suggest that hDAT-K619N can effectuate dopamine dysfunction of pathological relevance in a dominant-negative manner.
- Published
- 2021
- Full Text
- View/download PDF
50. The antidepressant drug vilazodone is an allosteric inhibitor of the serotonin transporter.
- Author
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Plenge P, Yang D, Salomon K, Laursen L, Kalenderoglou IE, Newman AH, Gouaux E, Coleman JA, and Loland CJ
- Subjects
- Allosteric Regulation drug effects, Animals, Binding Sites, COS Cells, Chlorocebus aethiops, Humans, Kinetics, Molecular Dynamics Simulation, Mutant Proteins metabolism, Mutation genetics, Serotonin metabolism, Serotonin Plasma Membrane Transport Proteins ultrastructure, Antidepressive Agents pharmacology, Serotonin Plasma Membrane Transport Proteins metabolism, Selective Serotonin Reuptake Inhibitors pharmacology, Vilazodone Hydrochloride pharmacology
- Abstract
Depression is a common mental disorder. The standard medical treatment is the selective serotonin reuptake inhibitors (SSRIs). All characterized SSRIs are competitive inhibitors of the serotonin transporter (SERT). A non-competitive inhibitor may produce a more favorable therapeutic profile. Vilazodone is an antidepressant with limited information on its molecular interactions with SERT. Here we use molecular pharmacology and cryo-EM structural elucidation to characterize vilazodone binding to SERT. We find that it exhibits non-competitive inhibition of serotonin uptake and impedes dissociation of [
3 H]imipramine at low nanomolar concentrations. Our SERT structure with bound imipramine and vilazodone reveals a unique binding pocket for vilazodone, expanding the boundaries of the extracellular vestibule. Characterization of the binding site is substantiated with molecular dynamics simulations and systematic mutagenesis of interacting residues resulting in decreased vilazodone binding to the allosteric site. Our findings underline the versatility of SERT allosteric ligands and describe the unique binding characteristics of vilazodone., (© 2021. The Author(s).)- Published
- 2021
- Full Text
- View/download PDF
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