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The cannabinoid 1 receptor (CB1) is highly expressed in the central nervous system, where its physiological functions include the regulation of energy balance, pain, and addiction. Herein, we develop and validate a technique to use magnetic resonance imaging (MRI) to investigate the distribution of CB1 across mouse brains with high spatial resolution, expanding previously described in vitro studies and in vivo studies with positron emission tomography (PET). To support the MRI investigations, we developed a ligand that is specific for in vivo neuroimaging of CB1. By chemically conjugating the CB1 antagonist rimonabant acid to a gadolinium chelator, we obtained the paramagnetic probe Rimota-Gd. The specificity of binding of rimonabant acid to CB1 and the relaxation enhancement by the paramagnetic gadolinium permit MRI-based localization of CB1. We used Rimota-Gd to investigate the spatial distribution of CB1 across the mouse brain and compared the results with an investigation using the PET radioligand [ 18 F]MK-9470. Rimota-Gd opens the door for in vivo MRI imaging of CB1 and provides a roadmap for the study of other receptors by whole-brain images with high spatial and temporal resolution.

Purpose: We have shown that cannabinoid CB1 receptors regulate both salivation and tearing, but for tearing, this regulation is sex dependent with opposing effects by sex. We investigated a potential interplay of circadian and cannabinoid regulation of tearing., Methods: We measured cannabinoid and circadian regulation of tearing in CD1 strain mice as well as CB1 receptor protein expression using immunohistochemistry., Results: We now report that CD1 strain mice have a circadian variation in basal tearing, differing by sex in terms of phase and amplitude. The amplitude of circadian variation in females is substantially dampened relative to males. Male CB1 receptor knockout mice do not differ from strain controls, but in female CB1 knockouts, the amplitude is enhanced and resembles that of WT males. This increased tearing is mimicked by the CB1 antagonist SR141716 (4 mg/kg, intraperitoneally [IP]), suggesting that tonic CB1 activation dampens female circadian tearing. Consistent with this, the cannabinoid receptor agonist CP55940 (0.5 mg/kg, IP) decreases tearing during the rest phase but increases tearing during the active phase in females. CB1 protein expression also differs by sex. While both males and females have CB1 receptors in parasympathetic inputs to the lacrimal gland, in female lacrimal glands, CB1 is also detected in myoepithethial cells., Conclusions: Mice have a sex-dependent circadian cycle of tearing. The endogenous cannabinoid signaling system appears to mediate some circadian effects, albeit in a sex-dependent manner and via distinct cellular targets.

The endocannabinoid system plays a crucial role in metabolic regulation, prompting the investigation of cannabinoid type 1 receptor (CB1R) antagonists for obesity and its complications like non-alcoholic fatty liver disease (NAFLD). Concerns over psychiatric side effects led to the development of peripheral CB1R antagonists that circumvent the blood-brain barrier (BBB). In this study, we synthesized PMG-505-010 and PMG-505-013 as peripherally restricted CB1 receptor antagonists by modifying rimonabant to minimize BBB penetration. Physicochemical analysis confirmed their reduced lipophilicity and increased polarity compared to rimonabant, indicating limited brain exposure. Molecular docking studies revealed similar binding modes to rimonabant at CB1R, characterized by robust hydrophobic interactions. Functionally, they acted as CB1R antagonists and inverse agonists, effectively reversing CP55,940-induced cAMP inhibition. In a murine model of obesity-related NAFLD, PMG-505-010 and -013 improved metabolic profiles, including fasting blood glucose levels and dyslipidemia. They also ameliorated hepatic injury, steatosis, and inflammation, evidenced by reduced liver enzymes, lipid peroxidation, hepatic lipid levels, and inflammatory cytokine levels. Notably, these compounds inhibited hepatic fibrosis by reducing extracellular matrix (ECM) deposition and altering fibrosis-related gene and protein expressions. In conclusion, PMG-505-010 and PMG-505-013 hold promise for treating obesity-related liver diseases, including NAFLD and fibrosis, through selective peripheral CB1R targeting, potentially avoiding CNS-related side effects seen with earlier CB1R antagonists., 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 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Anxiety disorder is one of the most common neuropsychiatric disorders, and affects many people's daily activities. Although the pathogenesis and treatments of anxiety disorder have been studied for several decades, the underlying mechanisms remain elusive. Here, we provide evidence that olfactory stimuli with inhaled linalool or 2-phenylethanol decreased mouse anxiety-like behaviors and increased the activities of hippocampal dentate granule cells (DGCs). RNA-sequencing analysis identified retrograde endocannabinoid signaling, which is a critical pathway for mood regulation and neuron activation, is altered in the hippocampus of both linalool- and 2-phenylethanol-exposed mice. Further studies found that selective inhibition of endocannabinoid signaling by injecting rimonabant abolished the activation of DGCs and the anxiolytic effect induced by linalool or 2-phenylethanol. Together, these results uncovered a novel mechanism by which linalool or 2-phenylethanol decreases mouse anxiety-like behaviors and increases DG activity likely through activating hippocampal retrograde endocannabinoid signaling.

Stress-related disorders are becoming increasingly common and are often associated with cognitive impairments. Within this context, the endocannabinoid (ECB) system, particularly the type 1 cannabinoid (CB1) receptor, seems to play a decisive role in restoring body homeostasis. There is consistent evidence in the literature that disrupted CB1-mediated neurotransmission can ultimately contribute to stress-related diseases. Therefore, the present study aimed to evaluate the participation of CB1 receptors in the integrity of stress-induced peripheral and behavioral responses. For this purpose, male adult Wistar rats underwent physical restraint (1 h/day, for 7 days), followed by a single administration of rimonabant (CB1 receptor antagonist, 3 mg/Kg, intraperitonial) at the end of stress protocol. Animals were then subjected to evaluation of neuroendocrine responses, behavioral tests and quantification of Iba-1 (microglial) immunoreactivity in the parvocellular subdivisions of the paraventricular nucleus of the hypothalamus (PVN). No effects of restraint stress or rimonabant administration were detected on body mass variation. However, stress significantly increased adrenal relative mass and corticosterone secretion, and reduced thymus relative size. The stress effects on adrenal size and corticosterone plasma levels were absent in rimonabant-treated rats, but the thymus size was further reduced in the restraint-rimonabant group. Restraint stress also induced anhedonia, a depression-like behavior, and reduced object recognition index, indicating memory recovery impairment. Treatment with the CB1 antagonist significantly reversed stress-induced anhedonia and memory deficit. In the PVN, restraint stress reduced the number of Iba-1 positive cells in the medial parvocellular region of vehicle- but not rimonabant-treated animals. Taken together, these results indicate that the acute inhibition of the CB1-mediated endogenous pathway restores stress-induced depression-like behaviors and memory loss, suggesting a role for endocannabinoids in the neuro-immune-endocrine interplay at both peripheral and hypothalamic levels., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Addiction can be viewed as a state of compulsive engagement in drug use. It is believed that drug-associated memories maintain compulsive drug-seeking behavior. Therefore, disrupting drug-associated memories may reduce drug-seeking behavior. In the present study, a conditioned place preference (CPP) apparatus was conducted to evaluate the effect of cannabinoid receptor type 1 (CB1R) agonist and antagonist on the acquisition of CPP induced by methamphetamine (METH). Anxiety behaviors and memory retrieval were assessed using elevated plus maze (EPM) and step-through passive avoidance tasks. In this study using a 5-day schedule of CPP, exposure to METH increased the time spent in the drug-paired compartment, and CB1Rs agonist (WIN 55,212-2, WIN) disrupted the METH-induced CPP. In the EPM experiment, METH significantly decreased the ratio of times spent in the open arms to total times spent in any arms (OAT) and the ratio of entries into open arms to total entries (OAE), indicating that METH increases anxiety-like behaviors. However, the CB1Rs antagonist (SR141716A, SR) reversed METH-induced anxiety behaviors. The results obtained in the passive avoidance experiment showed that blockade of brain CB1Rs by SR improves METH-induced amnesia. In summary, CB1Rs appear to modulate METH-associated memories, and antagonists of CB1Rs may serve as a therapeutic target for METH-induced anxiety behaviors., 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 B.V. All rights reserved.)

Background: Defective mitochondria and aberrant brain mitochondrial bioenergetics are consistent features in syndromic intellectual disability disorders, such as Rett syndrome (RTT), a rare neurologic disorder that severely affects mainly females carrying mutations in the X-linked MECP2 gene. A pool of CB1 cannabinoid receptors (CB1R), the primary receptor subtype of the endocannabinoid system in the brain, is located on brain mitochondrial membranes (mtCB1R), where it can locally regulate energy production, synaptic transmission and memory abilities through the inhibition of the intra-mitochondrial protein kinase A (mtPKA). In the present study, we asked whether an overactive mtCB1R-mtPKA signaling might underlie the brain mitochondrial alterations in RTT and whether its modulation by systemic administration of the CB1R inverse agonist rimonabant might improve bioenergetics and cognitive defects in mice modeling RTT., Methods: Rimonabant (0.3 mg/kg/day, intraperitoneal injections) was administered daily to symptomatic female mice carrying a truncating mutation of the Mecp2 gene and its effects on brain mitochondria functionality, systemic oxidative status, and memory function were assessed., Results: mtCB1R is overexpressed in the RTT mouse brain. Subchronic treatment with rimonabant normalizes mtCB1R expression in RTT mouse brains, boosts mtPKA signaling, and restores the defective brain mitochondrial bioenergetics, abnormal peripheral redox homeostasis, and impaired cognitive abilities in RTT mice., Limitations: The lack of selectivity of the rimonabant treatment towards mtCB1R does not allow us to exclude that the beneficial effects exerted by the treatment in the RTT mouse model may be ascribed more broadly to the modulation of CB1R activity and distribution among intracellular compartments, rather than to a selective effect on mtCB1R-mediated signaling. The low sample size of few experiments is a further limitation that has been addressed replicating the main findings under different experimental conditions., Conclusions: The present data identify mtCB1R overexpression as a novel molecular alteration in the RTT mouse brain that may underlie defective brain mitochondrial bioenergetics and cognitive dysfunction., (© 2024. The Author(s).)

Background & Purpose: The constant emergence and broad toxicological effects of synthetic cannabinoids create a discernible public health threat. The synthetic cannabinoid AMB-FUBINACA (AMB-FUB) is a potent agonist at the CB 1 receptor and has been associated with numerous fatalities. Synthetic cannabinoids are commonly abused alongside other drugs and medications, including a "party pill" drug, para-fluorophenylpiperazine (pFPP), and the antipsychotic risperidone. This research aimed to investigate the mechanisms underpinning AMB-FUB toxicity and the impact of clinically relevant co-exposures in vivo., Experimental Approach: Male and female C57Bl/6 mice received a single dose of AMB-FUB (3 or 6 mg kg -1 ), pFPP (10 or 20 mg kg -1 ) or vehicle intraperitoneally. Mice were co-exposed to AMB-FUB (3 mg kg -1 ) and pFPP (10 mg kg -1 ) or risperidone (0.5 mg kg -1 ) to investigate these drug combinations. To study receptor-dependency and potential rescue of AMB-FUB toxicity, rimonabant (3 mg kg -1 ) was administered both pre- and post-AMB-FUB. Adverse effects caused by drug administration, including hypothermia and convulsions, were recorded., Key Results: AMB-FUB induced CB 1 -dependent hypothermia and convulsions in mice. The combination of AMB-FUB and pFPP significantly potentiated hypothermia, as did risperidone pre-treatment. Interestingly, risperidone provided significant protection from AMB-FUB-induced convulsions in female mice. Pre- and post-treatment with rimonabant was able to significantly attenuate both hypothermia and convulsions in mice administered AMB-FUB., Conclusion & Implications: Factors such as dose, CB 1 signalling, and substance co-exposure significantly contribute to the toxicity of AMB-FUBINACA. Mechanistic understanding of synthetic cannabinoid toxicity and fatality can help inform overdose treatment strategies and identify vulnerable populations of synthetic cannabinoid users., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The addictive use of nicotine contained in tobacco is associated with stressor-like emotional and cognitive effects such as anxiety and working memory impairment, and the involvement of epigenetic mechanisms such as histone acetylation has recently been reported. Although the precise nature of behavioural plasticity remains unclear, both anxiogenic- and working memory impairment-like effects were observed in the present experimental model of mice treated with repeated subcutaneous nicotine and/or immobilization stress, and these effects were commonly attenuated by the histone deacetylase (HDAC) inhibitors that induce histone acetylation. Such HDAC inhibitor-induced resilience was mimicked by ligands for the endocannabinoid (ECB) system, a neurotransmitter system that is closely associated with nicotine-induced addiction-related behaviours: the anxiogenic-like effects were mitigated by the cannabinoid type 1 (CB1) agonist arachidonylcyclopropylamide (ACPA), whereas the working memory impairment-like effects were mitigated by the CB1 antagonist SR 141716A. Moreover, the effects of the HDAC inhibitors were also mimicked by ligands for the endovanilloid (transient receptor potential vanilloid 1 [TRPV1]) system, a system that shares common characteristics with the ECB system: the anxiogenic-like effects were mitigated by the TRPV1 antagonist capsazepine, whereas the working memory impairment-like effects were mitigated by the TRPV1 agonist olvanil. Notably, the HDAC inhibitor-induced anxiolytic-like effects were attenuated by SR 141716A, which were further counteracted by capsazepine, whereas the working memory improvement-like effects were attenuated by capsazepine, which were further counteracted by SR 141716A. These results suggest the contribution of interrelated control of the ECB/TRPV1 systems and epigenetic processes such as histone acetylation to novel therapeutic approaches., (© 2024 The Author(s). Addiction Biology published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.)

The cannabinoid receptor 1 (CB 1 ) is famous as the target of Δ 9 -tetrahydrocannabinol (THC), which is the active ingredient of marijuana. Suppression of CB 1 is frequently suggested as a drug target or gene therapy for many conditions (e.g., obesity, Parkinson's disease). However, brain networks affected by CB 1 remain elusive, and unanticipated psychological effects in a clinical trial had dire consequences. To better understand the whole brain effects of CB 1 suppression we performed in vivo imaging on mice under complete knockout of the gene for CB 1 ( cnr1 -/- ) and also under the CB 1 inverse agonist rimonabant. We examined white matter structural changes and brain function (network activity and directional uniformity) in cnr1 -/- mice. In cnr1 -/- mice, white matter (in both sexes) and functional directional uniformity (in male mice) were altered across the brain but network activity was largely unaltered. Conversely, under rimonabant, functional directional uniformity was not altered but network activity was altered in cortical regions, primarily in networks known to be altered by THC (e.g., neocortex, hippocampal formation). However, rimonabant did not alter many brain regions found in both our cnr1 -/- results and previous behavioral studies of cnr1 -/- mice (e.g., thalamus, infralimbic area). This suggests that chronic loss of cnr1 is substantially different from short-term suppression, subtly rewiring the brain but largely maintaining the network activity. Our results help explain why pathological mutations in CB 1 (e.g., chronic pain) do not always provide insight into the side effects of CB 1 suppression (e.g., clinical depression), and thus urge more preclinical studies for any drugs that suppress CB 1 .

Synthetic cannabinoids are associated with higher risk of dependence and more intense withdrawal symptoms than plant-derived Δ9-tetrahydrocannabinol (THC). Avoidance of withdrawal symptoms, including anxiogenic effects, can contribute to continued cannabinoid use. Adult male and female Long-Evans rats were given escalating doses of WIN 55,212-2 (WIN) via twice daily intrajugular infusions. Precipitated withdrawal was elicited with SR 141716 (rimonabant) 4 h after the final infusion. Global withdrawal scores (GWS) were compiled by summing z-scores of observed somatic behaviors over a 30-min period with locomotor activity simultaneously collected via beam breaks. Rimonabant precipitated withdrawal in female and male rats at 3 or 10 mg/kg, respectively, but the individual behaviors contributing to GWS were not identical. 3 mg/kg rimonabant did not impact locomotor behavior in females, but 10 mg/kg decreased locomotion in male controls. Spontaneous withdrawal observed between 6 and 96 h after the final infusion was quantifiable up to 24 h following WIN administration. Individual behaviors contributing to GWS varied by sex and time point. Males undergoing spontaneous withdrawal engaged in more locomotion than females undergoing withdrawal. Separate groups of rats were subjected to a battery of anxiety-like behavioral tests (elevated plus maze, open field test, and marble burying test) one or two weeks after WIN or vehicle infusions. At one week abstinence, sex-related effects were noted in marble burying and the open field test but were unrelated to drug treatment. At two weeks abstinence, females undergoing withdrawal spent more time grooming during marble burying and performed more marble manipulations than their male counterparts. WIN infusions did not impact estrous cycling, and GWS scores were not correlated with estrous at withdrawal. Collectively, these results show qualitative sex differences in behaviors contributing to the behavioral experience of cannabinoid withdrawal supporting clinical findings from THC., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Eclampsia, new-onset seizures in pregnancy, can complicate preeclampsia, a hypertensive pregnancy disorder. The mechanisms contributing to increased risk of seizures in preeclampsia are not fully known. One mechanism could be abnormal endocannabinoid system (ECS) activity and impaired neuromodulation. Indeed, increased placental cannabinoid receptor 1 (CB1R) expression and reduced serum anandamide, a CB1R ligand, have been reported in preeclampsia patients. We hypothesized that reduced uterine perfusion pressure (RUPP), used to mimic preeclampsia, leads to changes in hippocampal CB1R expression, and that manipulating CB1R activity will change seizure severity in RUPP mice. Pregnant mice underwent sham or RUPP surgery on gestational day (GD)13.5. On GD18.5, mice received: no drug treatment, pentylenetetrazol (PTZ, 40 mg/kg), Rimonabant (10 mg/kg) + PTZ, or 2-AG (1 mg/kg) + PTZ. Behaviors were video recorded (15 min for Rimonabant and 2-AG, followed by 30 min for PTZ), and the hippocampus was harvested. The expression of CB1R and ECS proteins was measured in hippocampal homogenates, synaptosomes, and cytosol. Hippocampal CB1R increased in homogenates and cytosolic fraction, and was unchanged in synaptosomes of RUPP mice. Increased CB1R colocalization on glutamate-releasing neurons within hippocampal CA1 was observed in RUPP mice. Rimonabant modestly increased seizure scores over time in RUPP mice. PTZ after rimonabant pretreatment increased seizure scores and duration, while reducing latency in sham mice, with little to no change in RUPP mice. Furthermore, RUPP mice had lower seizure scores over time than sham following CB1R blockade and activation. These data suggest that RUPP modifies CB1R activity prior to seizure induction, which protects mice from worse seizure outcomes., (© 2023 Wiley Periodicals LLC.)

Objective: Incretin receptor agonists are now standard of care in treating obesity. Their efficacy and tolerability might be further improved by combining them with compounds that offer orthogonal mechanisms of action. The cannabinoid type 1 receptor (CB1R) is a clinically validated therapeutic target in obesity, and several experimental CB1R inverse agonists have been shown to induce weight loss., Methods: This study characterizes a novel CB1R inverse agonist (CRB-913) with similar preclinical potency to rimonabant but markedly reduced brain penetration. CRB-913 was tested as monotherapy and in combination with tirzepatide, semaglutide, or liraglutide in the diet-induced obesity (DIO) mouse model for body weight reduction., Results: CRB-913 demonstrated enhanced plasma exposure (3.8-fold larger area under the curve last ) and reduced brain levels (9.5-fold lower area under the curve last ) than rimonabant. CRB-913 monotherapy yielded a dose-dependent decrease in body weight in DIO mice reaching -22% within 18 days. In further DIO studies in combination with tirzepatide, semaglutide, or liraglutide, CRB-913 (2.5 mg/kg) resulted in -32.6%, -28.8%, and -16.8% decreases in body weight on Day 18, respectively, with concomitant improvements in body fat content, liver triglycerides, and liver fat deposits., Conclusions: CRB-913 in combination with incretin analogues could deliver meaningful improvements over current standards of care for obesity and related conditions., (© 2023 The Obesity Society.)

Introduction: Male reproduction is under the control of the hypothalamus-pituitary-gonadal (HPG) axis. The endocannabinoid system (ECS) and the kisspeptin system (KS) are two major signaling systems in the central and peripheral control of reproduction, but their possible interaction has been poorly investigated in mammals. This manuscript analyzes their possible reciprocal modulation in the control of the HPG axis., Materials and Methods: Adolescent male rats were treated with kisspeptin-10 (Kp10) and endocannabinoid anandamide (AEA), the latter alone or in combination with the type 1 cannabinoid receptor (CB1) antagonist rimonabant (SR141716A). The hypothalamic KS system and GnRH expression, circulating sex steroids and kisspeptin (Kiss1) levels, and intratesticular KS and ECS were evaluated by immunohistochemical and molecular methods. Non-coding RNAs (i.e., miR145-5p , miR-132-3p , let7a-5p , let7b-5p ) were also considered., Results: Circulating hormonal values were not significantly affected by Kp10 or AEA; in the hypothalamus, Kp10 significantly increased GnRH mRNA and aromatase Cyp19, Kiss1, and Kiss1 receptor (Kiss1R) proteins. By contrast, AEA treatment affected the hypothalamic KS at the protein levels, with opposite effects on the ligand and receptor, and SR141716A was capable of attenuating the AEA effects. Among the considered non-coding RNA, only the expression of miR145-5p was positively affected by AEA but not by Kp10 treatment. Localization of Kiss1+/Kiss1R+ neurons in the arcuate nucleus revealed an increase of Kiss1R-expressing neurons in Kp10- and AEA-treated animals associated with enlargement of the lateral ventricles in Kp10-treated animals. In the brain and testis, the selected non-coding RNA was differently modulated by Kp10 or AEA. Lastly, in the testis, AEA treatment affected the KS at the protein levels, whereas Kp10 affected the intragonadal levels of CB1 and FAAH, the main modulator of the AEA tone. Changes in pubertal transition-related miRNAs and the intratesticular distribution of Kiss1, Kiss1R, CB1, and CB2 following KP and AEA treatment corroborate the KS-ECS crosstalk also showing that the CB1 receptor is involved in this interplay., Conclusion: For the first time in mammals, we report the modulation of the KS in both the hypothalamus and testis by AEA and revealed the KP-dependent modulation of CB1 and FAAH in the testis. KP involvement in the progression of spermatogenesis is also suggested., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Marino, D’Auria, Mele, Pastorino, Di Pietro, D’Angelo, Della Rocca, Operto, Vecchione, Fasano, Pierantoni, Viggiano, Meccariello and Santoro.)

Lujo virus (LUJV), which belongs to Mammarenavirus, family Arenaviridae, has emerged as a pathogen causing severe hemorrhagic fever with high mortality. Currently, there are no effective treatments for arenaviruses, including LUJV. Here, we screened chemical compound libraries of Food and Drug Administration (FDA)-approved drugs and G protein-coupled receptor-associated drugs to identify effective antivirals against LUJV targeting cell entry using a vesicular stomatitis virus-based pseudotyped virus bearing the LUJV envelope glycoprotein (GP). Cannabinoid receptor 1 (CB1) antagonists, such as rimonabant, AM251 and AM281, have been identified as robust inhibitors of LUJV entry. The IC 50 of rimonabant was 0.26 and 0.53 μM in Vero and Huh7 cells, respectively. Analysis of the cell fusion activity of the LUJV GP in the presence of CB1 inhibitors revealed that these inhibitors suppressed the fusion activity of the LUJV GP. Moreover, rimonabant, AM251 and AM281 reduced the infectivity of authentic LUJV in vitro, suggesting that the antiviral activity of CB1 antagonists against LUJV is mediated, at least in part, by inhibition of the viral entry, especially, membrane fusion. These findings suggest promising candidates for developing new therapies against LUJV infections., 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 © 2023 Elsevier Inc. All rights reserved.)

Introduction: The antidepressant properties of ketamine have been extensively demonstrated in experimental and clinical settings. However, the psychotomimetic side effects still limit its wider use as an antidepressant. It was recently observed that endocannabinoids are inolved in ketamine induced reward properties. As an increase in endocannabinoid signaling induces antidepressant effects, this study aimed to investigate the involvement of cannabinoid type 1 receptors (CB 1 R) in the antidepressant and psychostimulant effects induced by ketamine. Methods: We tested the effects of genetic and pharmacological inhibition of CB 1 R in the hyperlocomotion and antidepressant-like properties of ketamine. The effects of ketamine (10-20 mg/kg) were assessed in the open-field and the forced swim tests (FSTs) in CB 1 R knockout (KO) and wild-type (WT) mice (male and female), and mice pre-treated with rimonabant (CB 1 R antagonist, 3-10 mg/kg). Results: We found that the motor hyperactivity elicited by ketamine was impaired in CB 1 R male and female KO mice. A similar effect was observed upon pharmacological blockade of CB 1 R in WT mice. However, genetic CB 1 R deletion did not modify the antidepressant effect of ketamine in male mice submitted to the FST. Surprisingly, pharmacological blockade of CB 1 R induced an antidepressant-like effect in both male and female mice, which was not further potentiated by ketamine. Conclusions: Our results support the hypothesis that CB 1 R mediate the psychostimulant side effects induced by ketamine, but not its antidepressant properties.

Physical exercise benefits Parkinson's disease (PD) patients but the mechanism is unclear. Cannabinoid receptor type 1 (CB1R) is known to be reduced in PD patients and animal models. We test the hypothesis that binding of the CB1R inverse agonist, [ 3 H]SR141716A, is normalized by treadmill exercise in the toxin-induced 6-hydroxydopamine (6-OHDA) model of PD. Male rats had unilateral striatal injections of 6-OHDA or saline. After 15 days, half were submitted to treadmill exercise and half remained sedentary. [ 3 H]SR141716A autoradiography was performed in postmortem tissue from striatum, substantia nigra (SN) and hippocampus. There was a 41% decrease of [ 3 H]SR141716A specific binding in the ipsilateral SN of 6-OHDA-injected sedentary animals which was attenuated to 15% by exercise, when compared to saline-injected animals. No striatal differences were observed. A 30% bilateral hippocampal increase was observed in both healthy and 6-OHDA exercised groups. In addition, a positive correlation between nigral [ 3 H]SR141716A binding and nociceptive threshold was observed in PD-exercised animals (p = 0.0008), suggesting a beneficial effect of exercise in the pain associated with the model. Chronic exercise can reduce the detrimental effects of PD on nigral [ 3 H]SR141716A binding, similar to the reported reduction after dopamine replacement therapy, so should be considered as an adjunct therapy for PD., 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 © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

The spread of breast cancer to distant sites is the major cause of death in breast cancer patients. Increasing evidence supports the role of the tumor microenvironment (TME) in breast cancers, and its pathologic assessment has become a diagnostic and therapeutic tool. In the TME, a bidirectional interplay between tumor and stromal cells occurs, both at the primary and metastatic site. Hundreds of molecules, including cytokines, chemokines, and growth factors, contribute to this fine interaction to promote tumor spreading. Here, we investigated the effects of Rimonabant and Cannabidiol, known for their antitumor activity, on reprogramming the breast TME. Both compounds directly affect the activity of several pathways involved in breast cancer progression. To mimic tumor-stroma interactions during breast-to-lung metastasis, we investigated the effect of the compounds on growth factor secretion from metastatic breast cancer cells and normal and activated lung fibroblasts. In this setting, we demonstrated the anti-metastatic potential of the two compounds, and the membrane array analyses highlighted their ability to alter the release of factors involved in the autocrine and paracrine regulation of tumor proliferation, angiogenesis, and immune reprogramming. The results enforce the antitumor potential of Rimonabant and Cannabidiol, providing a novel potential tool for breast cancer TME management.

Aims: Acute and chronic Δ 9 -THC exposure paradigms affect the body differently. More must be known about the impact of chronic Δ 9 -THC on cannabinoid-1 (CB1R) and mu-opioid (MOR) receptor levels in the brain. The present study examined chronic Δ 9 -THC's effects on CB1R and MOR levels and locomotor activity., Main Methods: Adolescent Sprague-Dawley rats were given daily intraperitoneal injections of Δ 9 -THC [0.75mg/kg (low dose or LD) or 2.0 mg/kg (high dose or HD)] or vehicle for 24 days, and locomotion in the open field was tested after the first and fourth weeks of chronic Δ 9 -THC exposure. Brains were harvested at the end of treatment. [ 3 H] SR141716A and [ 3 H] DAMGO autoradiography assessed CB1R and MOR levels, respectively., Key Findings: Relative to each other, chronic HD rats showed reduced vertical plane (VP) entries and time, while LD rats had increased VP entries and time for locomotion, as assessed by open-field testing; no effects were found relative to the control. Autoradiography analyses showed that HD Δ 9 -THC significantly decreased CB1R binding relative to LD Δ 9 -THC in the cingulate (33%), primary motor (42%), secondary motor (33%) somatosensory (38%), rhinal (38%), and auditory (50%) cortices; LD Δ 9 -THC rats displayed elevated binding in the primary motor (33% increase) and hypothalamic (33% increase) regions compared with controls. No significant differences were observed in MOR binding for the LD or HD compared to the control., Significance: These results demonstrate that chronic Δ 9 -THC dose-dependently altered CB1R levels throughout the brain and locomotor activity in the open field., 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 © 2023 Elsevier Inc. All rights reserved.)

Sign-tracking (ST) rats show enhanced cue sensitivity before drug experience that predicts greater discrete cue-induced drug seeking compared with goal-tracking or intermediate rats. Cue-evoked dopamine in the nucleus accumbens (NAc) is a neurobiological signature of sign-tracking behaviors. Here, we examine a critical regulator of the dopamine system, endocannabinoids, which bind the cannabinoid receptor-1 (CB1R) in the ventral tegmental area (VTA) to control cue-evoked striatal dopamine levels. We use cell type-specific optogenetics, intra-VTA pharmacology, and fiber photometry to test the hypothesis that VTA CB1R receptor signaling regulates NAc dopamine levels to control sign tracking. We trained male and female rats in a Pavlovian lever autoshaping (PLA) task to determine their tracking groups before testing the effect of VTA → NAc dopamine inhibition. We found that this circuit is critical for mediating the vigor of the ST response. Upstream of this circuit, intra-VTA infusions of rimonabant, a CB1R inverse agonist, during PLA decrease lever and increase food cup approach in sign-trackers. Using fiber photometry to measure fluorescent signals from a dopamine sensor, GRAB DA (AAV9-hSyn-DA2m), we tested the effects of intra-VTA rimonabant on NAc dopamine dynamics during autoshaping in female rats. We found that intra-VTA rimonabant decreased sign-tracking behaviors, which was associated with increases in NAc shell, but not core, dopamine levels during reward delivery [unconditioned stimulus (US)]. Our results suggest that CB1R signaling in the VTA influences the balance between the conditioned stimulus-evoked and US-evoked dopamine responses in the NAc shell and biases behavioral responding to cues in sign-tracking rats. SIGNIFICANCE STATEMENT Substance use disorder (SUD) is a chronically relapsing psychological disorder that affects a subset of individuals who engage in drug use. Recent research suggests that there are individual behavioral and neurobiological differences before drug experience that predict SUD and relapse vulnerabilities. Here, we investigate how midbrain endocannabinoids regulate a brain pathway that is exclusively involved in driving cue-motivated behaviors of sign-tracking rats. This work contributes to our mechanistic understanding of individual vulnerabilities to cue-triggered natural reward seeking that have relevance for drug-motivated behaviors., (Copyright © 2023 the authors.)

Introduction: treatment of HIV infection with Protease Inhibitors (PIs) and Nucleoside Reverse Transcriptase Inhibitors (NRTIs) can lead to insulin resistance and changes in body fat distribution. Overactivity of the endogenous cannabinoid system produces similar disturbances in metabolic syndrome within the general population. However, Cannabinoid receptor type 1 antagonism, in both human and animal studies, reverses many of these biochemical and physical derangements observed in the metabolic syndrome., Methods: using an experimental study design, fifteen adult male Sprague-Dawley rats housed under standard conditions were randomized into three groups; Control, combined Anti-Retroviral Therapy (cART) only and cART + rimonabant. Drugs were administered daily by oral gavage for four weeks. After four weeks, insulin tolerance tests were conducted, the rats were euthanised and fat depots were excised and weighed. Experimental data were analysed using STATA 16.0 with the significance level set at p<0.05. The Shapiro-Wilk test determined normalcy. In cases of significance, post hoc analysis was performed by either the Dunn test or the Tukey HSD test., Results: Sprague Dawley rats treated with cART + rimonabant demonstrated better insulin sensitivity (p = 0.0239) and lower body weight (p = 0.044) than rats treated with cART alone. They had leaner body composition with 58% less adiposity than cART-only rats., Conclusion: the study results suggest a role for the endogenous cannabinoid system in cART induced metabolic derangements and physical changes. Future studies can directly assay ECS activity in cART associated metabolic syndrome., Competing Interests: The authors declare no competing interests., (Copyright: Brian Lishenga Makamu et al.)

Objective We aimed to investigate whether antagonism of the cannabinoid CB 1 receptor (CB 1 R) could affect novel object recognition (NOR) memory in chronically rapid eye movement sleep-deprived (RSD) rats.Methods The animals were examined for recognition memory following a 7-day chronic partial RSD paradigm using the multiple platform technique. The CB 1 R antagonist rimonabant (1 or 3 mg/kg, i.p.) was administered either at one hour prior to the sample phase for acquisition, or immediately after the sample phase for consolidation, or at one hour before the test phase for retrieval of NOR memory. For the reconsolidation task, rimonabant was administered immediately after the second sample phase.Results The RSD episode impaired acquisition, consolidation, and retrieval, but it did not affect the reconsolidation of NOR memory. Rimonabant administration did not affect acquisition, consolidation, and reconsolidation; however, it attenuated impairment of the retrieval of NOR memory induced by chronic RSD.Conclusions These findings, along with our previous report, would seem to suggest that RSD may affect different phases of recognition memory based on its duration. Importantly, it seems that the CB 1 R may, at least in part, be involved in the adverse effects of chronic RSD on the retrieval, but not in the acquisition, consolidation, and reconsolidation, of NOR memory.

Cannabis use is a worldwide issue with the development of legalization. Prenatal exposure to Δ9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis, is related to affect fetal nervous system development. In our present study, we administered THC to pregnant mice from gestational day 5.5-12.5. Differences in neuronal cell composition and organization between the two groups were found by staining sections of the offspring hippocampus at PND21. In addition, RNA-seq of hippocampal tissue also suggested differences in gene expression due to THC treatment, especially significant enrichment to neurogenesis and neural differentiation. Subsequently, the effect of THC treatment on the proliferation and differentiation capacity of neural stem cells (NSCs) was confirmed. Based on the RNA-seq results, we selected the differentially expressed transcription factor MEF2C for validation. The effect of THC treatment on NSCs differentiation was found to be regulated by knocking down the expression of MEF2C in NSCs. Considering that THC is an agonist of cannabinoid receptor (CB1R), the differentiation outcome of NSC after THC treatment was significantly rescued, by pretreating with the CB1R inhibitor Rimonabant. Notably, pretreatment with Rimonabant restored the expression of MEF2C. Taken together, the present results suggested that THC regulated the MEF2C pathway through CB1R and had an impact on hippocampal neurodevelopment., 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 © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Sarcopenia, the age-related loss of skeletal muscle mass, is associated with lipid accumulation and anabolic resistance; phenomena also observed in obesity and worsen when obesity and aging are combined. The endocannabinoid system (ECS) is overactivated in obesity, but its role in aging obesity-related muscle dysfunction is unknown. The aims of this study were to evaluate the effect of inhibition of the ECS by rimonabant (RIM) on the metabolic alterations induced by a high-fat high-sucrose diet and on skeletal muscle mass/function in aged mice. Eighteen-month-old male mice were subjected to a control (CTL) or a high-fat high-sucrose (HFHS) diet for 24 weeks. Mice were administered with saline or RIM (10 mg/kg/day) for the last 4 weeks of the diet. Skeletal muscle function was evaluated by open-field, rotarod, and grip strength tests. Metabolic alterations in liver, adipose tissue, and skeletal muscle were investigated by quantitative RT-PCR. Body mass was higher in HFHS mice compared to CTL mice (48.0 ± 1.5 vs. 33.5 ± 0.7 g, P < 0.01), as a result of fat accumulation (34.8 ± 1.0 vs. 16.7 ± 0.8%, P < 0.01). RIM reduced body fat mass in both CTL (-16%, P < 0.05) and HFHS conditions (-40%, P < 0.01), without affecting hindlimb skeletal muscle mass. In HFHS mice, grip strength evolution was improved (-0.29 ± 0.06 vs. -0.49 ± 0.06 g/g lean mass, P < 0.05), and rotarod activity was increased by ≈60% in response to RIM (45.9 ± 6.3 vs. 28.5 ± 4.6 cm, P < 0.05). Lipolysis and β-oxidation genes were upregulated in the liver as well as genes involved in adipose tissue browning. These results demonstrate that inhibition of the ECS induces metabolic changes in liver and adipose tissue associated with a reversion of the obese phenotype and that RIM is able to improve motor coordination and muscle strength in aged mice, without affecting skeletal muscle mass. NEW & NOTEWORTHY In 24-month-old mice submitted to high-fat high-sucrose-induced obesity, inhibition of the endocannabinoid system by rimonabant reversed the obese phenotype by promoting adipose tissue browning and β-oxidation in the liver but not in skeletal muscle. These metabolism modifications are associated with improved skeletal muscle function.

A series of rimonabant analogues, where the N-aminopiperidine moiety was replaced by various amines and an additional carbonyl group, were synthesized and their inhibition of nitric oxide (NO) production was evaluated in lipopolysaccharide (LPS)-induced BV2 microglial cells. Among the synthesized compounds, the morpholine analogue 7y (IC 50  = 4.71 ± 0.11 μM) showed significantly higher inhibitory activity than rimonabant (IC 50  = 16.17 ± 0.56 μM), and suppressed NO production dose-dependently without cytotoxicity. In addition, 7y inhibited the expression of iNOS, COX-2 and pro-inflammatory cytokines and attenuated LPS-induced activation of nuclear factor-kappa B (NF-κB) and ERK MAPK phosphorylation in BV2 cells. These results demonstrated that 7y exerted anti-inflammatory effects by ERK pathway in BV2 cells, which can be used for the prevention and treatment of neuroinflammatory diseases., 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 © 2022 Elsevier Ltd. All rights reserved.)

In this work we strived to determine whether endocannabinoid system activity could account for the differences in acute inflammatory pain sensitivity in mouse lines selected for high (HA) and low (LA) swim-stress-induced analgesia (SSIA). Mice received intraplantar injections of 5% formalin and the intensity of nocifensive behaviours was scored. To assess the contribution of the endocannabinoid system, mice were intraperitoneally (i.p.) injected with rimonabant (0.3-3 mg/kg) prior to formalin. Minocycline (45 and 100 mg/kg, i.p.) was administered to investigate microglial activation. The possible involvement of the endogenous opioid system was investigated with naloxone (1 mg/kg, i.p.). Cannabinoid receptor types 1 and 2 ( Cnr1 , Cnr2 ) and opioid receptor subtype ( Oprm1 , Oprd1 , Oprk1 ) mRNA levels were quantified by qPCR in the structures of the central nociceptive circuit. Levels of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) were measured by liquid chromatography coupled with the mass spectrometry method (LC-MS/MS). In the interphase, higher pain thresholds in the HA mice correlated with increased spinal anandamide and 2-AG release and higher Cnr1 transcription. Downregulation of Oprd1 and Oprm1 mRNA was noted in HA and LA mice, respectively, however no differences in naloxone sensitivity were observed in either line. As opposed to the LA mice, inflammatory pain sensitivity in the HA mice in the tonic phase was attributed to enhanced microglial activation, as evidenced by enhanced Aif1 and Il-1β mRNA levels. To conclude, Cnr1 inhibitory signaling is one mechanism responsible for decreased pain sensitivity in HA mice in the interphase, while increased microglial activation corresponds to decreased pain thresholds in the tonic inflammatory phase.

Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer that displays highly aggressive with poor prognosis. Owing to the limited targets and drugs for TNBC clinical therapy, it is necessary to investigate the factors regulating cancer progression and develop novel therapies for cancer treatment. Ferroptosis, a nonapoptotic form of programmed cell death characterized by accumulation of iron-dependent peroxidation of phospholipids, is regulated by cellular metabolism, redox homeostasis, and various cancer-related signaling pathways. Recently, considerable progress has been made in demonstrating the critical role of lipid metabolism in regulating ferroptosis, indicating potential combinational therapeutic strategies for cancer treatment. In this study, by drug combination screen of lipid metabolism compounds with ferroptosis inducers in decreasing TNBC cell viability, we found potent synergy of the CB1 antagonist rimonabant with erastin/(1 S, 3 R)-RSL3 (RSL3) in inhibiting TNBC cell growth both in vitro and in vivo via promoting the levels of lipid peroxides, malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) and cytosolic reactive oxygen species (ROS) production, enhancing intracellular glutathione (GSH) depletion and inducing G1 cell cycle arrest. We identified that inhibition of CB1 promoted the effect of erastin/RSL3 on inducing ferroptosis and enhanced their inhibitory effect on tumor growth. Using RNA-Seq, fatty acid analyses and functional assays, we found that CB1 regulated stearoyl-CoA desaturase 1 (SCD1)- and fatty acyl desaturase 2 (FADS2)-dependent fatty acid metabolism via phosphatidylinositol 3 kinase (PI3K)-AKT and mitogen-activated protein kinase (MAPK) signaling pathways to modulate ferroptosis sensitivity in TNBC cells. These data demonstrate that dual targeting of CB1 and ferroptosis could be a promising therapeutic strategy for TNBC., (© 2022. The Author(s).)

The dynamics of neuronal microtubules are essential for brain plasticity. Vesicular transport and synaptic transmission, additionally, requires acetylation of α-tubulin, and aberrant tubulin acetylation and neurobiological deficits are associated. Prolonged exposure to a stressor or consumption of drugs of abuse, like marihuana, lead to neurological changes and psychotic disorders. Here, we studied the effect of psychosocial stress and the administration of cannabinoid receptor type 1 drugs on α-tubulin acetylation in different brain regions of mice. We found significantly decreased tubulin acetylation in the prefrontal cortex in stressed mice. The impact of cannabinoid drugs on stress-induced microtubule disturbance was investigated by administration of the cannabinoid receptor agonist WIN55,212-2 and/or antagonist rimonabant. In both, control and stressed mice, the administration of WIN55,212-2 slightly increased the tubulin acetylation in the prefrontal cortex whereas administration of rimonabant acted antagonistically indicating a cannabinoid receptor type 1 mediated effect. The analysis of gene expression in the prefrontal cortex showed a consistent expression of ApoE attributable to either psychosocial stress or administration of the cannabinoid agonist. Additionally, ApoE expression inversely correlated with acetylated tubulin levels when comparing controls and stressed mice treated with WIN55,212-2 whereas rimonabant treatment showed the opposite., Competing Interests: The authors declare no competing interests.

Δ 9 -Tetrahydrocannabinol (Δ 9 -THC) inhibits tics in individuals with Tourette syndrome (TS). Δ 9 -THC has similar affinities for CB 1 /CB 2 cannabinoid receptors. However, the effect of HU-308, a selective CB 2 receptor agonist, on repetitive behaviors has not been investigated. The effects of 2,5-dimethoxy-4-iodoamphetamine (DOI)-induced motor-like tics and Δ 9 -THC were studied with gene analysis. The effects of HU-308 on head twitch response (HTR), ear scratch response (ESR), and grooming behavior were compared between wildtype and CB 2 receptor knockout (CB 2 -/- ) mice, and in the presence/absence of DOI or SR141716A, a CB 1 receptor antagonist/inverse agonist. The frequency of DOI-induced repetitive behaviors was higher in CB 2 -/- than in wildtype mice. HU-308 increased DOI-induced ESR and grooming behavior in adult CB 2 -/- mice. In juveniles, HU-308 inhibited HTR and ESR in the presence of DOI and SR141716A. HU-308 and beta-caryophyllene significantly increased HTR. In the left prefrontal cortex, DOI increased transcript expression of the CB 2 receptor and GPR55, but reduced fatty acid amide hydrolase (FAAH) and α/β-hydrolase domain-containing 6 (ABHD6) expression levels. CB 2 receptors are required to reduce 5-HT 2A/2C -induced tics in adults. HU-308 has an off-target effect which increases 5-HT 2A/2C -induced motor-like tics in adult female mice. The increased HTR in juveniles induced by selective CB 2 receptor agonists suggests that stimulation of the CB 2 receptor may generate motor tics in children. Sex differences suggest that the CB 2 receptor may contribute to the prevalence of TS in boys. The 5-HT 2A/2C -induced reduction in endocannabinoid catabolic enzyme expression level may explain the increased endocannabinoids' levels in patients with TS., (© 2022. The Author(s).)

Oleoylethanolamide (OEA) is an endogenous N-acylethanolamine that reduces both food and alcohol intake through the activation of peripheral sensory nerves in the gut. These effects are opposite to those of anandamide, a main endogenous cannabinoid type 1 receptor (CB 1 R) agonist. The present study aims to characterize the impact of intermittent and voluntary alcohol intoxications (using the two-bottle choice paradigm) during adolescence on inhibitory actions of OEA and the CB 1 R antagonist/inverse agonist SR141716A on voluntary alcohol intake in adulthood. In the present study we show that both OEA (5 mg/kg) and SR141716A (3 mg/kg) reduce alcohol drinking in adult rats using a two-bottle choice paradigm. These effects lasted for 24 h and were not additive when both compounds were co-administered. However, when OEA and SR141716A were administered to adult rats with a history of intermittent alcohol exposure during adolescence (from postnatal day 31 to 55), the effects of OEA were attenuated. Moreover, the co-administration of OEA and SR141716A was not as effective as the administration of SR141716A alone. These data suggest that adolescent exposure to alcohol alters the inhibitory actions of OEA on alcohol drinking, which results in the loss of a protective mechanism that might account for the long-term effects of alcohol exposure in the adolescence. The implications for the vulnerability to alcohol addiction is discussed., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Rationale: In human beings and experimental animals, maladaptive impulsivity is manifested by the acute injection of psychostimulants, such as amphetamine. Cannabinoid CB1 receptors have been implicated in the regulation of stimulant-induced impulsive action, but the role of CB1 receptors in timing-related impulsive action by amphetamine remains unknown., Methods: Male rats were used in evaluating the effects of CB1 receptor antagonist and agonist (SR141716A and WIN55,212-2, respectively) systemically administered individually and combined with d-amphetamine on a differential reinforcement of low-rate response (DRL) task, an operant behavioral test of timing and behavioral inhibition characterized as a type of timing impulsive action., Results: A distinct pattern of DRL behavioral changes was produced by acute d-amphetamine (0, 0.5, 1.0, and 1.5 mg/kg) treatment in a dose-dependent fashion, whereas no significant dose effect was detected for acute SR141716A (0, 0.3, 1, and 3 mg/kg) or WIN55,212-2 (0, 0.5, 1, and 2 mg/kg) treatment. Furthermore, DRL behavior altered by 1.5 mg/kg d-amphetamine was reversed by a noneffective dose of SR141716A (3 mg/kg) pretreatment. The minimally influenced DRL behavior by 0.5 mg/kg d-amphetamine was affected by pretreatment with a noneffective dose of WIN55,212-2 (1 mg/kg)., Conclusion: These findings reveal that the activation and blockade of CB1 receptors can differentially modulate the timing impulsive action of DRL behavior induced by acute amphetamine treatment. Characterizing how CB1 receptors modulate impulsive behavior will deepen our understanding of the cannabinoid psychopharmacology of impulsivity and may be helpful in developing an optimal pharmacotherapy for reducing maladaptive impulsivity in patients with some psychiatric disorders., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The prevalence of post-traumatic stress disorder (PTSD) is higher in women than in men. Among both humans and mice, females exhibit higher resistance to fear extinction than males, suggesting that differences between sexes in fear-extinction processes are involved in the pathophysiology of such fear-related diseases. Sex differences in molecular mechanisms underlying fear memory and extinction are unclear. The cannabinoid (CB) system is well known to be involved in fear memory and extinction, but this involvement is based mainly on experiments using male rodents. It is not known whether there are sex differences in the role of the CB system in fear memory and extinction. To explore this possibility, we investigated the effects of pharmacological manipulations of the CB system on the retrieval and extinction of contextual fear memory in male and female mice. WIN55,212-2, a CB receptor (CBR) agonist, augmented the retrieval of fear memory in both sexes, but SR141716 (a CB1R antagonist) did not affect it in either sex. An enhancement of 2-arachidonylglycerol (2-AG, one of the two major endocannabinoids) via JZL184 (an inhibitor of the 2-AG hydrolase monoacylglycerol lipase [MAGL]), augmented the retrieval of fear memory through the activation of CB1R but not CB2R in female mice. In contrast, the enhancement of N-arachidonylethanolamine (AEA, the other major endocannabinoid) via URB597, an inhibitor of an AEA hydrolase (fatty acid amide hydrolase-1) did not show any effects on the retrieval of fear memory in either sex. WIN55,212-2, SR141716, and JZL184 inhibited fear extinction irrespective of sex. URB enhanced fear extinction in females that were in diestrus phase at the first extinction session, but not in males. These results suggest that although the role of CB1R in the retrieval and extinction of contextual fear memory is common among males and females, the effects of an increase in endocannabinoid levels on the retrieval or extinction of contextual fear memory differ between the sexes., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Calcitonin gene-related peptide (CGRP), substance P and dural mast cells are main contributors in neurogenic inflammation underlying migraine pathophysiology. Modulation of endocannabinoid system attenuates migraine pain, but its mechanisms of action remain unclear. We investigated receptor mechanisms mediating anti-neuroinflammatory effects of endocannabinoid system modulation in in vivo migraine model and ex vivo hemiskull preparations in rats. To induce acute model of migraine, a single dose of nitroglycerin was intraperitoneally administered to male rats. Moreover, isolated ex vivo rat hemiskulls were prepared to study CGRP and substance P release from meningeal trigeminal afferents. We used methanandamide (cannabinoid agonist), rimonabant (cannabinoid receptor-1 CB1 antagonist), SR144528 (CB2 antagonist) and capsazepine (transient receptor potential vanilloid-1 TRPV1 antagonist) to explore effects of endocannabinoid system modulation on the neurogenic inflammation, and possible involvement of CB1, CB2 and TRPV1 receptors during endocannabinoid effects. Methanandamide attenuated nitroglycerin-induced CGRP increments in in vivo plasma, trigeminal ganglia and brainstem and also in ex vivo hemiskull preparations. Methanandamide also alleviated enhanced number and degranulation of dural mast cells induced by nitroglycerin. Rimonabant, but not capsazepine or SR144528, reversed the attenuating effects of methanandamide on CGRP release in both in vivo and ex vivo experiments. Additionally, SR144528, but not rimonabant or capsazepine, reversed the attenuating effects of methanandamide on dural mast cells. However, neither nitroglycerin nor methanandamide changed substance P levels in both in vivo and ex vivo experiments. Methanandamide modulates CGRP release in migraine-related structures via CB1 receptors and inhibits the degranulation of dural mast cells through CB2 receptors. Selective ligands targeting CB1 and CB2 receptors may provide novel and effective treatment strategies against migraine., (© 2020 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Assessing the role of cannabinoid (CB) receptors in behavior is relevant given the trend toward the legalization of medicinal and recreational marijuana. The present research aims at bridging a gap in our understanding of CB-receptor function in animal models of frustrative nonreward. These experiments were designed to (1) determine the effects of chronic administration of the nonselective CB1-receptor agonist WIN 55,212-2 (WIN) on reward downshift in rats and (2) determine whether the effects of chronic WIN were reducible to acute effects. In Experiment 1, chronic WIN (7 daily injections, 10 mg/kg, ip) accelerated the recovery of consummatory behavior after a 32-to-4% sucrose downshift relative to vehicle controls. In addition, chronic WIN eliminated the preference for an unshifted lever when the other lever was subject to a 12-to-2 pellet downshift in free-choice trials, but only in animals with previous experience with a sucrose downshift. In Experiment 2, acute WIN (1 mg/kg, ip) reduced consummatory behavior, but did not affect recovery from a 32-to-4% sucrose downshift. The antagonist SR 141716A (3 mg/kg, ip) also failed to interfere with recovery after the sucrose downshift. In Experiment 3, acute WIN administration (1 mg/kg, ip) did not affect free-choice behavior after a pellet downshift, although it reduced lever pressing and increased magazine entries relative to vehicle controls. The effects of chronic WIN on frustrative nonreward were not reducible to acute effects of the drug. Chronic WIN treatment in rats, like chronic marijuana use in humans, seems to increase resistance to the effects of frustrative nonreward., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Cannabinoid use has increased among aging individuals. However, little information on age-related differences in the behavioral effects of these agents is available. To explore potential differences in the behavioral effects of cannabinoids, we determined effects of Δ 9 -tetrahydrocannabinol (THC, 1-10 mg/kg) or rimonabant (0.3-3.2 mg/kg) on operant fixed-ratio responding (FR10) for food in young adult (6 months) and aged (29 months) rats. THC dose-dependently decreased responding for food. Rimonabant alone had little or no effect on responding up to 1.0 mg/kg, but disrupted responding following a 3.2 mg/kg dose. Rimonabant (1.0 mg/kg) partially antagonized response disruption by THC. These effects were similar in young adult and aged rats. However, aging has been reported to change the neurobiology of cannabinoid CB1 receptors. To confirm our rats exhibited such differences, we assessed CB1 receptor binding sites and function in six subcortical (caudate, nucleus accumbens CA1, and CA2/CA3), and three cortical regions (medial prefrontal, temporal, entorhinal) in young adult (6 months) or aged (26 months) male Lewis rats using quantitative autoradiography. CB1 receptor binding sites were reduced in cortical, but not subcortical brain regions of aged rats. CB1 receptor function, at the level of receptor-G protein interaction, was not different in any region studied. Results indicate that down-regulation of CB1 receptor binding sites observed in cortical regions of aged rats was not accompanied by a commensurate decrease in CB1 receptor-stimulated [ 35 S]GTPγS binding, suggesting a compensatory increase in receptor function in cortical areas. Together, our results provide additional evidence of age-related changes in central CB1 receptor populations. However, the functional compensation for decreased CB1 receptor binding may mitigate changes in behavioral effects of cannabinoids. With the rising use of cannabinoid-based therapeutics among aging populations, further evaluation of age-related changes in the cannabinoid system and the impact of these changes on effects of this class of drugs is warranted., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Enteroendocrine (EE) cells are the most abundant hormone-producing cells in humans and are critical regulators of energy homeostasis and gastrointestinal function. Challenges in converting human intestinal stem cells (ISCs) into functional EE cells, ex vivo, have limited progress in elucidating their role in disease pathogenesis and in harnessing their therapeutic potential. To address this, we employed small molecule targeting of the endocannabinoid receptor signaling pathway, JNK, and FOXO1, known to mediate endodermal development and/or hormone production, together with directed differentiation of human ISCs from the duodenum and rectum. We observed marked induction of EE cell differentiation and gut-derived expression and secretion of SST, 5HT, GIP, CCK, GLP-1 and PYY upon treatment with various combinations of three small molecules: rimonabant, SP600125 and AS1842856. Robust differentiation strategies capable of driving human EE cell differentiation is a critical step towards understanding these essential cells and the development of cell-based therapeutics., (© 2022. The Author(s).)

Background & Aims: The endocannabinoid system is involved in the modulation of inflammatory, fibrotic, metabolic, and carcinogenesis-associated signaling pathways via cannabinoid receptor (CB)1 and CB2. We hypothesized that the pharmacologic antagonization of CB1 receptor improves cholestasis in Abcb4 -/- mice., Methods: After weaning, male Abcb4 -/- mice were treated orally with rimonabant (a specific antagonist of CB1) or ACEA (an agonist of CB1) until up to 16 weeks of age. Liver tissue and serum were isolated and examined by means of serum analysis, quantitative real time polymerase chain reaction, Western blot, immunohistochemistry, and enzyme function. Untreated Abcb4 -/- and Bagg Albino Mouse/c wild-type mice served as controls., Results: Cholestasis-induced symptoms such as liver damage, bile duct proliferation, and enhanced circulating bile acids were improved by CB1 antagonization. Rimonabant treatment also improved Phosphoenolpyruvat-Carboxykinase expression and reduced inflammation and the acute-phase response. The carcinogenesis-associated cellular-Jun N-terminal kinase/cellular-JUN and signal transducer and activator of transcription 3 signaling pathways activated in Abcb4 -/- mice were reduced to wild-type level by CB1 antagonization., Conclusions: We showed a protective effect of oral CB1 antagonization in chronic cholestasis using the established Abcb4 -/- model. Our results suggest that pharmacologic antagonization of the CB1 receptor could have a therapeutic benefit in cholestasis-associated metabolic changes, liver damage, inflammation, and carcinogenesis., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The generation of functional regulatory T cells (Tregs) is essential to keep tissue homeostasis and restore healthy immune responses in many biological and inflammatory contexts. Cannabinoids have been pointed out as potential therapeutic tools for several diseases. Dendritic cells (DCs) express the endocannabinoid system, including the cannabinoid receptors CB1 and CB2. However, how cannabinoids might regulate functional properties of DCs is not completely understood. We uncover that the triggering of cannabinoid receptors promote human tolerogenic DCs that are able to prime functional FOXP3 + Tregs in the context of different inflammatory diseases. Mechanistically, cannabinoids imprint tolerogenicity in human DCs by inhibiting NF-κB, MAPK and mTOR signalling pathways while inducing AMPK and functional autophagy flux via CB1- and PPARα-mediated activation, which drives metabolic rewiring towards increased mitochondrial activity and oxidative phosphorylation. Cannabinoids exhibit in vivo protective and anti-inflammatory effects in LPS-induced sepsis and also promote the generation of FOXP3 + Tregs. In addition, immediate anaphylactic reactions are decreased in peanut allergic mice and the generation of allergen-specific FOXP3 + Tregs are promoted, demonstrating that these immunomodulatory effects take place in both type 1- and type 2-mediated inflammatory diseases. Our findings might open new avenues for novel cannabinoid-based interventions in different inflammatory and immune-mediated diseases., (© 2021. The Author(s).)

We know surprisingly little about the sex differences in the neurobiology of cocaine addiction, except females are more susceptible to the rewarding effects of cocaine than their male counterparts. Only a handful of recent studies have examined the neurobiology of cocaine-induced conditioned place preference (CPP) memory among female rodents. We contribute to this emerging line of research by documenting sex differences in cocaine-associated memory and illustrating the underlying signaling pathways in five experiments. Rimonabant (Rim), a cannabinoid CB 1 antagonist and inverse agonist, exerted a facilitating effect for low-dose cocaine and an impairing effect for high-dose cocaine CPP memory in male mice, as in our previous study, but not in female mice. Nor did we observe the effect exist among CB 1 knockout male mice, which indicated that the CB 1 receptors played a mediating role. We also found that the metabotropic glutamate receptor 5 (mGluR5) was located in the same signaling pathway as CB 1 in male mice. To clarify the mechanisms behind the sex differences, we used ovariectomized (OVX) female mice with estradiol benzoate (EB) replacement. In the OVX female mice, we showed that Rim-alone and EB-alone, but not Rim-and-EB-combined, facilitated the low-dose cocaine CPP memory. Moreover, 4-hydroxytamoxifen (4-OHT), an estrogen receptor (ER) antagonist, blocked Rim's and EB's facilitating effect. Finally, 2-methyl-6-(phenylethynyl)pyridine (MPEP), an mGluR5 antagonist, partially blocked EB's facilitating effect. In sum, we identified sex-specific effects of Rim on cocaine-induced CPP memory and the respective signaling pathways: mGluR5-CB 1 for male mice and ER-mGluR5-CB 1 for female mice. These findings may have merits for the development of sex-specific treatment for cocaine addiction., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Hepatic ischemia/reperfusion (HIR), which can result in severe liver injury and dysfunction, is usually associated with autophagy and endocannabinoid system derangements. Whether or not the modulation of the autophagic response following HIR injury is involved in the hepatoprotective effect of the cannabinoid receptor 1(CB1R) antagonist rimonabant remains elusive and is the aim of the current study. Rats pre-treated with rimonabant (3 mg/kg) or vehicle underwent 30 min hepatic ischemia followed by 6 hrs. reperfusion. Liver injury was evaluated by serum ALT, AST, bilirubin (total and direct levels) and histopathological examination. The inflammatory, profibrotic and oxidative responses were investigated by assessing hepatic tumor necrosis factor α (TNFα), nuclear factor kappa B (NF-κB), transforming growth factor (TGF-β), lipid peroxidation and reduced glutathione. The hepatic levels of CB1R and autophagic markers p62, Beclin-1, and LC3 as well as the autophagic signaling inhibitors ERK1/2, PI3K, Akt and mTOR were also determined. Rimonabant significantly attenuated HIR-induced increases in hepatic injury, inflammation, profibrotic responses and oxidative stress and improved the associated pathological features. Rimonabant modulated the expression of p62, Beclin-1, and LC3, down-regulated CB1R, and dcreased pERK1/2, PI3K, Akt, and mTOR activities. The current study suggests that rimonabant can protect the liver from IR injury at least in part by inducing autophagy, probably by modulating ERK- and/or PI3K/AKT-mTOR signaling., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cannabidiol is increasingly considered for treatment of a wide range of medical conditions. Binding studies suggest that cannabidiol binds to CB 1 receptors. In the rat isolated vas deferens bioassay, a single electrical pulse causes a biphasic contraction from nerve-released ATP and noradrenaline. WIN 55,212-2 acts on prejunctional CB 1 receptors to inhibit release of these transmitters. In this bioassay, we tested whether cannabidiol and SR141716 were acting as competitive antagonists of this receptor. Monophasic contractions mediated by ATP or noradrenaline in the presence of prazosin or NF449 (P2X1 inhibitor), respectively, were measured to a single electrical pulse delivered every 30 min. Following treatment with cannabidiol (10-100 μM) or SR141716 (0.003-10 μM), cumulative concentrations of WIN 55,212-2 (0.001-30 μM) were applied followed by a single electrical pulse. The WIN 55,212-2 concentration-contraction curve EC 50 values were applied to global regression analysis to determine the pK B . The antagonist potency of cannabidiol at the CB 1 receptor in the rat vas deferens bioassay matched the reported receptor binding affinity. Cannabidiol was a competitive antagonist of WIN 55,212-2 with pK B values of 5.90 when ATP was the effector transmitter and 5.29 when it was noradrenaline. Similarly, SR141716 was a competitive antagonist with pK B values of 8.39 for ATP and 7.67 for noradrenaline as the active transmitter. Cannabidiol's low micromolar CB 1 antagonist pK B values suggest that at clinical blood levels (1-3 μM) it may act as a CB 1 antagonist at prejunctional neuronal sites with more potency when ATP is the effector than for noradrenaline., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Alcohol consumption is associated with gut dysbiosis, increased intestinal permeability, endotoxemia, and a cascade that leads to persistent systemic inflammation, alcoholic liver disease, and other ailments. Craving for alcohol and its consequences depends, among other things, on the endocannabinoid system. We have analyzed the relative role of central vs. peripheral cannabinoid CB1 receptors (CB1R) using a "two-bottle" as well as a "drinking in the dark" paradigm in mice. The globally acting CB1R antagonist rimonabant and the non-brain penetrant CB1R antagonist JD5037 inhibited voluntary alcohol intake upon systemic but not upon intracerebroventricular administration in doses that elicited anxiogenic-like behavior and blocked CB1R-induced hypothermia and catalepsy. The peripherally restricted hybrid CB1R antagonist/iNOS inhibitor S -MRI-1867 was also effective in reducing alcohol consumption after oral gavage, while its R enantiomer (CB1R inactive/iNOS inhibitor) was not. The two MRI-1867 enantiomers were equally effective in inhibiting an alcohol-induced increase in portal blood endotoxin concentration that was caused by increased gut permeability. We conclude that (i) activation of peripheral CB1R plays a dominant role in promoting alcohol intake and (ii) the iNOS inhibitory function of MRI-1867 helps in mitigating the alcohol-induced increase in endotoxemia.

A wide body of evidence supports an integral role for mesolimbic dopamine (DA) in motivated behavior. In brief, drugs that increase DA in mesolimbic terminal regions, like cocaine, enhance motivation, while drugs that decrease DA concentration reduce motivation. Data from our laboratory and others shows that phasic activation of mesolimbic DA requires signaling at cannabinoid type-1 (CB1) receptors in the ventral tegmental area (VTA), and systemic delivery of CB1 receptor antagonists reduces DA cell activity and attenuates motivated behaviors. Recent findings demonstrate that cocaine mobilizes the endocannabinoid 2-arachidonoylglycerol (2-AG) in the VTA to cause phasic activation of DA neurons and terminal DA release. It remains unclear, however, if cocaine-induced midbrain 2-AG signaling contributes to the motivation-enhancing effects of cocaine. To examine this, we trained male and female rats on a progressive ratio (PR) task for a food reinforcer. Each rat underwent a series of tests in which they were pretreated with cocaine alone or in combination with systemic or intra-VTA administration of the CB1 receptor antagonist rimonabant or the 2-AG synthesis inhibitor tetrahydrolipstatin (THL). Cocaine increased motivation, measured by augmented PR breakpoints, while rimonabant dose-dependently decreased motivation. Importantly, intra-VTA administration of rimonabant or THL, at doses that did not decrease breakpoints on their own, blocked systemic cocaine administration from increasing breakpoints in male and female rats. These data suggest that cocaine-induced increases in motivation require 2-AG signaling at CB1 receptors in the VTA and may provide critical insight into cannabinoid-based pharmacotherapeutic targets for the successful treatment of substance abuse., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Osteoporosis is an increasing burden on public health as the world-wide population ages and effective therapeutics are severely needed. Two pathways with high potential for osteoporosis treatment are the retinoic acid (RA) and endocannabinoid system (ECS) signaling pathways. We sought to elucidate the roles that these pathways play in bone development and maturation. Here, we use chemical treatments to modulate the RA and ECS pathways at distinct early, intermediate, and late times bone development in zebrafish. We further assessed osteoclast activity later in zebrafish and medaka. Finally, by combining sub-optimal doses of AR and ECS modulators, we show that enhancing RA signaling or reducing the ECS promote bone formation and decrease osteoclast abundance and activity. These data demonstrate that RA signaling and the ECS can be combined as sub-optimal doses to influence bone growth and may be key targets for potential therapeutics., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cannabis is the most frequently used federally illicit substance in the United States. However, there are currently no FDA-approved pharmacotherapies to mitigate the withdrawal symptoms associated with cessation in heavy users. A promising, readily available, non-cannabinoid therapy are the gabapentinoids. Although currently approved for epilepsy and neuropathic pain, gabapentinoids are increasingly used for their "off-label" efficacy in treating various psychiatric conditions and substance abuse. Gabapentin (GBP) synergizes with cannabinoid agonism in neuropathic pain models, substitutes for Δ 9 -tetrahydrocannabinol (THC) in drug discrimination procedures, and reduced withdrawal symptoms in an outpatient clinical trial. However, there are limited data on the biological plausibility of the therapeutic action of gabapentinoids in cannabinoid withdrawal in preclinical models. The purpose of the current study was to determine the efficacy of GBP on attenuating THC withdrawal in mice, using an array of tests targeting withdrawal-induced and withdrawal-suppressed behaviors. Separate cohorts of male and female mice were administered THC (10 mg/kg, s.c.) or vehicle for 5.5 days, and withdrawal was precipitated by the CB 1 antagonist rimonabant (2 or 3 mg/kg, i.p.) on the sixth day. GBP (≥10 mg/kg) reduced somatic signs of withdrawal (i.e., paw tremors and head twitches), but had no effect in locomotor activity or conditioned place preference. GBP (50 mg/kg) also restored withdrawal-suppressed responding on a progressive ratio reinforcement schedule. However, GBP (50 mg/kg) had no effect in withdrawal-suppressed marble burying or tail suspension struggling and did not normalize the stress response induced by THC withdrawal, as indicated by plasma corticosterone. These data suggest gabapentin may be effective at treating cannabinoid withdrawal symptoms including somatic and affective symptoms but may act independently of endocrine stress activation., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The endocannabinoid system (ECS) plays a complex role in the development of neural circuitry during fetal brain development. The cannabinoid receptor type 1 (CB 1 ) controls synaptic strength at both excitatory and inhibitory synapses and thus contributes to the balance of excitatory and inhibitory signaling. Imbalances in the ratio of excitatory to inhibitory synapses have been implicated in various neuropsychiatric disorders associated with dysregulated central nervous system development including autism spectrum disorder, epilepsy, and schizophrenia. The role of CB 1 in human brain development has been difficult to study but advances in induced pluripotent stem cell technology have allowed us to model the fetal brain environment. Cortical spheroids resemble the cortex of the dorsal telencephalon during mid-fetal gestation and possess functional synapses, spontaneous activity, an astrocyte population, and pseudo-laminar organization. We first characterized the ECS using STORM microscopy and observed synaptic localization of components similar to that which is observed in the fetal brain. Next, using the CB 1 -selective antagonist SR141716A, we observed an increase in excitatory, and to a lesser extent, inhibitory synaptogenesis as measured by confocal image analysis. Further, CB 1 antagonism increased the variability of spontaneous activity within developing neural networks, as measured by microelectrode array. Overall, we have established that cortical spheroids express ECS components and are thus a useful model for exploring endocannabinoid mediation of childhood neuropsychiatric disease.

Amphotericin B (AmB) is a very effective antifungal agent, and resistance in clinical isolates is rare. However, clinical treatment with AmB is often associated with severe side effects. Reducing the administration dose of AmB by combining it with other agents is a promising strategy to minimize this toxicity. In this study, we screened a small compound library and observed that the anti-obesity drug rimonabant exhibited synergistic antifungal action with AmB against Candida species and Cryptococcus neoformans. Moreover, the combination of AmB and rimonabant exhibited synergistic or additive effects against Candida albicans biofilm formation and cell viability in preformed biofilms. The effects of this combination were further confirmed in vivo using a murine systemic infection model. Exploration of the mechanism of synergy revealed that rimonabant enhances the fungicidal activity of AmB by increasing cellular oxidative stress and cell membrane permeability. These findings provide a foundation for the possible development of AmB-rimonabant polytherapies for fungal infections., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

Across many species, endocannabinoids play an important role in regulating social play, reward, and anxiety. These processes are mediated through at least two distinct cannabinoid receptors (CB), CB1 and CB2. CB1 expression is found in appreciable densities across regions of the brain that integrate memory with socio-spatial information; many of these regions have been directly linked to the neurobiology of pair bonding in monogamous species. Using receptor autoradiography, we provide the first distributional map of CB1 within the brains of closely related monogamous prairie voles and promiscuous meadow voles, and compare receptor densities across sexes and species in limbic regions. We observe CB1-specific signal using [3H] CP-55,940 and [3H] SR141716A, though the latter exhibited a lower signal to noise ratio. We confirmed the presence of CB2 in prairie vole spleen tissue using [3H] CP-55,940. However, we found no evidence of CB2 in the brain using either [3H] CP-55,940 or [3H] A-836,339. The overall distribution of putative CB1 in the brain was similar across vole species and followed the pattern of CB1 expression observed in other species-high intensity binding within the telencephalon, moderate binding within the diencephalon, and mild binding within the mesencephalon and metencephalon (aside from the cerebellar cortex). However, we found profound differences in CB1 densities across species, with prairie voles having higher CB1 binding in regions implicated in social attachment and spatial memory (e.g., periaqueductal gray, hippocampus). These findings suggest that CB1 densities, but not distribution, correlate with the social systems of vole species., (© 2020 Wiley Periodicals LLC.)

Sarcopenia is an age-related loss of muscle mass associated with changes in skeletal muscle protein homeostasis due to lipid accumulation and anabolic resistance; changes that are also commonly described in obesity. Activation of the endocannabinoid system is associated with the development of obesity and insulin resistance, and with the perturbed skeletal muscle development. Taken together this suggests that endocannabinoids could be regulators of skeletal muscle protein homeostasis. Here we report that rimonabant, an antagonist for the CB1 receptor, can prevent dexamethasone-induced C2C12 myotube atrophy without affecting the mRNA expression of atrogin-1/MAFbx (a marker of proteolysis), which suggests it is involved in the control of protein synthesis. Rimonabant alone stimulates protein synthesis in a time- and dose-dependent manner through mTOR- and intracellular calcium-dependent mechanisms. CB1 agonists are unable to modulate protein synthesis or prevent the effect of rimonabant. Using C2C12 cells stably expressing an shRNA directed against CB1, or HEK293 cells overexpressing HA-tagged CB1, we demonstrated that the effect of rimonabant is unaffected by CB1 expression level. In summary, rimonabant can stimulate protein synthesis in C2C12 myotubes through a CB1-independent mechanism. These results highlight the need to identify non-CB1 receptor(s) mediating the pro-anabolic effect of rimonabant as potential targets for the treatment of sarcopenia, and to design new side-effect-free molecules that consolidate the effect of rimonabant on skeletal muscle protein synthesis., (© 2020 Wiley Periodicals LLC.)

Rationale: The emergence of the consumption of highly potent synthetic cannabinoid receptor agonists (spice drugs) that produce important neurological symptoms has prompted the research on the consequences of acute and chronic use of these new psychoactive substances. Most studies on cannabinoid dependence have been performed in male animals, and there is a need of studies using female subjects., Objectives: In the present study, we evaluated only in female animals the role of dopamine D1 receptors in the behavioral responses induced by acute and repeated stimulation of cannabinoid CB1 receptors, including the development of physical dependence, since cannabinoid CB1 receptors are co-localized with dopamine D1 receptors on GABAergic neurons projecting to the substantia nigra., Methods: To this end, female dopamine D1 receptor-deficient mice and wild-type littermates were treated with HU-210, a potent synthetic cannabinoid agonist., Results: Mutant mice displayed an enhanced response to acute motor and hypothermic effects to HU-210 when compared with wild-type females. The administration of SR141716A precipitated behavioral signs of withdrawal in mice treated subchronically with HU-210. Severity of cannabinoid withdrawal syndrome was potentiated in dopamine D1-deficient female mice. Indeed, 4 of 6 abstinence signs were increased in mutant mice., Conclusions: These results support for a role of dopamine D1 receptors in the acute, chronic, and withdrawal actions of spice drugs.