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Exposure to environmental microplastics has been demonstrated to impact health. However, its effect on development remains unclear. This study investigated whether consumption of nanoplastics (NPx) during development affects social and cognitive functions in rodents. In this study, we utilized male Institute of Cancer Research mice; they were divided into five subgroups based on the duration of NPx administration. NPx (100 nm) was orally administered via gavage for 6 days from gestational day (GTD) 7, representing the mid-gestation period, and for 5-6 days from GTD13 to birth, representing the late-gestation period; the male offspring were used for experiments. NPx was orally administered for 15 days starting at postnatal day (PND) 21 as the juvenile, PND38 as the adolescent, and PND56 as adulthood. On PND77, offspring were assessed for locomotion, social behavior, and nest-building tests. We observed that NPx administration altered dopamine system responses in GTD13 and PND56 groups. Social behavior was similarly affected by NPx treatment, with GTD13 and PND56 groups displaying decreased familiarity. Additionally, NPx treatment enhanced local field potentials in the prefrontal cortex, nucleus accumbens, and amygdala of GTD7 group and in the striatum of GTD13 group, while amphetamine treatment induced changes of local field potentials compared to saline treatment in the prefrontal cortex and the ventral tegmental area of CTR, GTD7, PND21, and PND56 groups. Taken together, these results showed that NPx treatment induced changes in social behavior partly depending on developmental stage, and these changes are associated with neural circuits innervated by the dopamine system., 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 International Brain Research Organization (IBRO). Published by Elsevier Inc. All rights reserved.)

Objective: To determine if treatment of co-occurring adult ADHD and Cannabis Use Disorder (CUD) with extended-release mixed amphetamine salts (MAS-ER) would be effective at improving ADHD symptoms and promoting abstinence., Method: A 12-week randomized, double-blind, two-arm pilot feasibility trial of adults with comorbid ADHD and CUD ( n  = 28) comparing MAS-ER (80 mg) to placebo. Main outcomes: ADHD: ≥30% symptom reduction, measured by the Adult ADHD Investigator Symptom Rating Scale (AISRS). CUD: Abstinence during last 2 observed weeks of maintenance phase., Results: Overall, medication was well-tolerated. There was no significant difference in ADHD symptom reduction (MAS-ER: 83.3%; placebo: 71.4%; p  = .65) or cannabis abstinence (MAS-ER: 15.4%; placebo: 0%; p  = .27). MAS-ER group showed a significant decrease in weekly cannabis use days over time compared to placebo ( p  < .0001)., Conclusions: MAS-ER was generally well-tolerated. The small sample size precluded a determination of MAS-ER's superiority reducing ADHD symptoms or promoting abstinence. Notably, MAS-ER significantly reduced weekly days of use over time., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Frances R. Levin receives research support from NCATS, SAMHSA, US World Meds, and Aelis Pharmaceuticals. She also receives medication from Indivior for research and royalties from APA publishing. In addition, Dr. Levin served as a nonpaid member of a Scientific Advisory Board for Alkermes, Indivior, Novartis, Teva, and US WorldMeds and is a consultant to Major League Baseball. John J Mariani has served as a consultant to Indivior, Inc. Martina Pavlicova has no conflicts to report. C. Jean Choi has no conflicts to report. Cale Basaraba has no conflicts to report. Amy L. Mahony has no conflicts to report. Daniel J. Brooks has no conflicts to report. Christina A. Brezing has no conflicts to report. Nasir Naqvi has no conflicts to report.

Introduction: In the dopamine system, the mesolimbic pathway, including the dorsal striatum, underlies the reinforcing properties of tobacco smoking, and the mesocortical pathway, including the dorsolateral prefrontal cortex (dlPFC), is critical for cognitive functioning. Dysregulated dopamine signaling has been linked to drug-seeking behaviors and cognitive deficits. The dorsal striatum and dlPFC are structurally and functionally connected and are key regions for cognitive functioning. We recently showed that people who smoke have lower dlPFC dopamine (D2/3R) receptor availability than people who do not, which is related to poorer cognitive function., Aims and Methods: The goal of this study was to examine the same brain-behavior relationship in the dorsal striatum. Twenty-nine (18 males) recently abstinent people who smoke and 29 sex-matched healthy controls participated in 2 same-day [11C]-(+)-PHNO positron emission tomography scans before and after amphetamine administration to provoke dopamine release. D2/3R availability (binding potential; BPND) and amphetamine-induced dopamine release (%ΔBPND) were calculated. Cognition (verbal learning and memory) was assessed with the CogState computerized battery., Results: There were no group differences in baseline BPND. People who smoke have a smaller magnitude %ΔBPND in dorsal putamen than healthy controls (p = .022). People who smoke perform worse on immediate (p = .035) and delayed (p = .011) recall than healthy controls. In all people, lower dorsal putamen BPND was associated with worse immediate (p = .006) and delayed recall (p = .049), and lower %ΔBPND was related to worse delayed recall (p = .022)., Conclusions: Lower dorsal putamen D2/3R availability and function are associated with disruptions in cognitive function that may underlie difficulty with resisting smoking., Implications: This study directly relates dopamine imaging outcomes in the dorsal striatum to cognitive function in recently abstinent people who smoke cigarettes and healthy controls. The current work included a well-characterized subject sample in terms of demographics, smoking characteristics, and a validated neurocognitive test of verbal learning and memory. The findings of this study extend previous literature relating dopamine imaging outcomes to cognition in recently abstinent people who smoke and people who do not smoke, expanding our understanding of brain-behavior relationships., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Recent epidemiological data has shown a sharp increase in stimulant use among older adults, which is notable as older adults may be especially vulnerable to their cardiovascular effects. Results of recent studies have shown an increase in cardiovascular events among older adults using stimulants; however, little data exists comparing cardiovascular safety of these agents head-to-head. Objective: To determine if the incidence of serious cardiovascular events, including myocardial infarction (MI), stroke/transient ischemic attack (TIA), or arrhythmia, are different in patients taking amphetamine/dextroamphetamine compared with patients taking methylphenidate. Methods: Retrospective chart review of veterans 50 years and older at the Veterans Affairs North Texas Health Care System (VANTHCS) who were first prescribed a stimulant between 2015 and 2021. The primary outcome was the difference in composite cardiovascular events between amphetamine/dextroamphetamine and methylphenidate. Secondary outcomes were the composite cardiovascular endpoints compared individually (MI, stroke/TIA, or arrhythmia). Hazard ratios were calculated based off of a time-to-event analysis displayed using a Kaplan-Meier curve for primary and secondary outcomes. Results: 466 veterans were screened for inclusion, 30 were excluded, and 436 were included. There was no difference found in composite cardiovascular events between the 241 veterans in the amphetamine/dextroamphetamine group and the 195 veterans in the methylphenidate group with 12 (5%) vs 8 (4.1%) events respectively ( P = .6635). There was also no difference in time-to-event analysis ( P = .4966). Conclusion: In elderly veterans, there was no difference found in incidence of major cardiovascular events with the use of amphetamine/dextroamphetamine compared with methylphenidate., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

With more than 30 available stimulant medications, choosing among therapeutic options for attention-deficit/hyperactivity disorder (ADHD) has become increasingly complex and patient specific. All ADHD stimulants owe their action to variants of either amphetamine or methylphenidate, yet formulation and delivery system differences create unique pharmacokinetic and clinical profiles for each medication. A benefit of the diversity within ADHD pharmacotherapy is that it facilitates tailoring treatment to meet patient needs. Historically, there has been a constant among long-acting stimulant options, regardless of formulation, which was morning dosing. The introduction of delayed-release and extended-release methylphenidate (DR/ER-MPH) is the first long-acting stimulant that patients take in the evening, with the clinical effect delayed until awakening in the morning. This paradigm shift has generated questions among clinicians and continued interest in real-world experience and data. This review used available clinical data, real-world evidence, emerging analyses, and clinical experience to evaluate the characteristics of DR/ER-MPH and its clinical utility within the greater context of ADHD medications and to provide clinicians with practical guidance on the use of DR/ER-MPH in children, adolescents, and adults with ADHD.

Background: Non-medical use of amphetamine and other stimulants prescribed for treatment of attention deficit/hyperactivity disorder (ADHD) is of special concern when combined with alcohol consumption. In a previous study, we modeled chronic ethanol-amphetamine co-use in adolescent Long-Evans (LE) rats and provided evidence that amphetamine attenuates alcohol withdrawal symptoms. Objectives: This project modeled co-use of amphetamine with alcohol in adolescents with ADHD-like symptoms by examining ethanol-amphetamine administration in adolescent Spontaneously Hypertensive Rats (SHR), an experimental model for the study of ADHD. Withdrawal symptoms were compared among SHR and two control rat strains, LE and Wistar Kyoto (WKY). Methods: At postnatal day 32, parallel groups of 12-24 male SHR, WKY and LE rats were administered a liquid diet containing ethanol (3.6%) and/or amphetamine (20 mg/L). Following administration periods up to 26 days, rats were withdrawn from their treatment and tested for overall severity of alcohol withdrawal symptoms, general locomotor activity, and anxiety-like behavior. Results: Overall withdrawal severity was lower for SHR than for LE ( p  < .001) or WKY ( p  = .027). Co-consumption of amphetamine decreased withdrawal severity for LE ( p  = .033) and WKY ( p  = .011) but not SHR ( p  = .600). Only WKY showed increased anxiety-like behavior during withdrawal ( p  = .031), but not after amphetamine co-administration ( p  = .832). Conclusion: Alcohol withdrawal severity may be attenuated when co-used with amphetamine. However, as a model for ADHD, SHR adolescents appeared resistant to developing significant signs of alcohol withdrawal following alcohol consumption. Whether alcohol withdrawal symptoms are attenuated or absent, potential consequences could include a decreased awareness of an emerging problem with alcohol use.

Background: Much of the existing animal literature on the devaluation task suggests that prior repeated exposure to drugs of abuse during adulthood can impair goal-directed action, but the literature on human drug users is mixed. Also, the initiation of drug use often occurs during adolescence, but examinations of the effects of drug exposure during adolescence on behavior in the devaluation task are lacking., Methods: We examined whether repeated exposure during adolescence to amphetamine (3 mg/kg injections every-other day from post-natal day 27-45) or ketamine (twice daily 30 mg/kg injections from post-natal day 35-44) would impair behavior in a devaluation test when tested drug-free in adulthood. Rats were trained to press a left lever with a steady cue-light above it for one reinforcer and a right lever with a flashing cue-light above it for a different reinforcer. We tested whether any impairments in goal-directed action could be overcome by compensation between strategies by giving rats information based on lever-location and cue-lights during the test that was either congruent (allowing compensation) or incongruent (preventing compensation between strategies) with the configurations during training., Results: Our results provided no evidence for impairment of goal-directed action during adulthood after adolescent amphetamine or ketamine exposure., Conclusions: We discuss possible reasons for this discrepancy with the prior literature, including (1) the age of exposure and (2) the pattern in the previous literature that most previous demonstrations of drug exposure impairing devaluation in laboratory animals may be attributed to either drug-associated cues present in the testing environment and/or accelerated habit learning in tasks that predispose laboratory animals towards habit formation with extended training (with training procedures that should resist the formation of habits in the current experiment). However, additional research is needed to examine the effects of these factors, as well a potential role for the particular doses and washout periods to determine the cause of our finding of no devaluation impairment after drug exposure., Competing Interests: The authors declare no conflict of interest. Charles L. Pickens is serving as one of the Editorial Board members of this journal. We declare that Charles L. Pickens had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Gernot Riedel., (© 2024 The Author(s). Published by IMR Press.)

The rapid serial visual presentation (RSVP) task and continuous performance tasks (CPT) are used to assess attentional impairments in patients with psychiatric and neurological conditions. This study developed a novel touchscreen task for rats based on the structure of a human RSVP task and used pharmacological manipulations to investigate their effects on different performance measures. Normal animals were trained to respond to a target image and withhold responding to distractor images presented within a continuous sequence. In a second version of the task, a false-alarm image was included, so performance could be assessed relative to two types of nontarget distractors. The effects of acute administration of stimulant and nonstimulant treatments for ADHD (amphetamine and atomoxetine) were tested in both tasks. Methylphenidate, ketamine, and nicotine were tested in the first task only. Amphetamine made animals more impulsive and decreased overall accuracy but increased accuracy when the target was presented early in the image sequence. Atomoxetine improved accuracy overall with a specific reduction in false-alarm responses and a shift in the attentional curve reflecting improved accuracy for targets later in the image sequence. However, atomoxetine also slowed responding and increased omissions. Ketamine, nicotine, and methylphenidate had no specific effects at the doses tested. These results suggest that stimulant versus nonstimulant treatments have different effects on attention and impulsive behaviour in this rat version of an RSVP task. These results also suggest that RSVP-like tasks have the potential to be used to study attention in rodents., (© 2024. The Author(s).)

Chronic opioid use disorder patients often also use other substances such as amphetamines. The gene-based analysis method was applied in the genomic database obtained from our previous study with 343 methadone maintenance treatment (MMT) patients. We found that the gene encoding gamma-aminobutyric acid type A receptors (GABA-A receptor) delta subunit isoforms ( GABRD ) was associated with amphetamine use in heroin dependent patients under MMT in Taiwan. A total of 15% of the 343 MMT patients tested positive for amphetamine in the urine toxicology test. Two genetic variants in the GABRD , rs2889475 and rs2376805, were found to be associated with the positive urine amphetamine test. They are located in the exon 1 of the splice variant and altered amino acid compositions (T126I, C/T, for rs2889475, and R252Q, G/A, for rs2376805). The CC genotype carriers of rs2889475 showed a four times higher risk of amphetamine use than those with TT genotype. The GG genotype carriers of rs2376805 showed a three times higher risk of amphetamine use than the AA genotype carriers. To our knowledge, this is the first report that demonstrated an association of the delta splice variant isoform in the GABA-A receptor with an increased risk of amphetamine use in MMT patients. Our results suggest that rs2889475 and rs2376805 may be indicators for the functional role and risk of amphetamine use in MMT patients.

Locomotor hyperactivity induced by psychotomimetic drugs, such as amphetamine and phencyclidine, is widely used as an animal model of psychosis-like behaviour and is commonly attributed to an interaction with dopamine release and N-methyl-D-aspartate (NMDA) receptors, respectively. However, what is often not sufficiently taken into account is that the pharmacological profile of these drugs is complex and may involve other neurotransmitter/receptor systems. Therefore, this study aimed to assess the effect of three antagonists targeting different monoamine pathways on amphetamine- and phencyclidine-induced locomotor hyperactivity. A total of 32 rats were pre-treated with antagonists affecting dopaminergic, noradrenergic and serotonergic transmission: haloperidol (0.05 mg/kg), prazosin (2 mg/kg) and ritanserin (1 mg/kg), respectively. After 30 min of spontaneous activity, rats were injected with amphetamine (0.5 mg/kg) or phencyclidine (2.5 mg/kg) and distance travelled, stereotypy and rearing recorded in photocell cages over 90 min. Pre-treatment with haloperidol or prazosin both reduced amphetamine-induced hyperactivity although pre-treatment with ritanserin had only a partial effect. None of the pre-treatments significantly altered the hyperlocomotion effects of phencyclidine. These findings suggest that noradrenergic as well as dopaminergic neurotransmission is critical for amphetamine-induced locomotor hyperactivity. Hyperlocomotion effects of phencyclidine are dependent on other factors, most likely NMDA receptor antagonism. These results help to interpret psychotomimetic drug-induced locomotor hyperactivity as an experimental model of psychosis., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

Background: Given the limited treatment options for younger children with attention-deficit/hyperactivity disorder (ADHD), a clinical study for SHP465 treatment was warranted., Objectives: We aimed to evaluate the pharmacokinetics, safety, and tolerability of SHP465 mixed amphetamine salts (MAS) 6.25 mg after multiple once-daily doses in children aged 4-5 years with ADHD., Methods: In this open-label multicenter study, SHP465 MAS 6.25 mg once daily was administered for 28 days to children aged 4-5 years with ADHD; baseline ADHD Rating Scale-5 total score ≥ 28 (boys) or ≥ 24 (girls) and Clinical Global Impression-Severity scale score ≥ 4. Blood samples were collected in the pharmacokinetic-rich group predose on day 1 week 1 and day 7 week 4 (predose, postdose at 2, 5, 8, 12, 16, 24, and 48 hours); and in the pharmacokinetic-sparse group predose on day 1 weeks 1, 2, and 3 and 24 hours postdose on day 7 week 4 . Key pharmacokinetic parameters included maximum plasma drug concentration (C max ), plasma trough drug concentration, time to C max during a dosing interval (t max ), area under the concentration-time curve from time 0 to time of last collected sample, area under the concentration-time curve over the dosing interval (24 h) at steady state (AUC tau,ss ), first-order rate constant associated with the terminal phase of elimination, terminal half-life (t 1/2 ), total clearance of drug from plasma after oral administration, and apparent volume of distribution at steady state. Safety endpoints included treatment-emergent adverse events and vital signs., Results: Mean ± standard deviation age and body mass index of 24 participants (66.7% male) were 4.8 ± 0.41 years and 17.2 ± 3.18 kg/m 2 , respectively. The most common ADHD was the combined presentation (91.7%); ratings were 50% markedly ill and 45.8% moderately ill on the Clinical Global Impression-Severity scale. Plasma d-amphetamine and l-amphetamine steady state was attained by predose on treatment day 8, consistent with the half-life. Peak steady-state plasma concentration (median t max ) for both d-amphetamine and l-amphetamine occurred at 7.92 h postdose on day 7 week 4 and thereafter declined monoexponentially, with a geometric mean t 1/2 of 10.4 and 12.3 h for d-amphetamine and l-amphetamine, respectively. For both d-amphetamine and l-amphetamine, C max and AUC tau,ss were comparable between children aged 4 years (n = 3) and children aged 5 years (n = 8) regardless of sex. In total, 14 treatment-emergent adverse events were reported by 45.8% (11/24) of participants. Five treatment-emergent adverse events, reported for four (16.7%) participants, were considered treatment related; affect lability occurred in two (8.3%) participants, and insomnia, accidental overdose, and increased blood pressure each occurred in one (4.2%) participant., Conclusions: In children aged 4-5 years with ADHD, following multiple once-daily administrations of SHP465 MAS 6.25 mg, the pharmacokinetic profile of plasma d-amphetamine and l-amphetamine was generally consistent among participants. Between-individual variability of plasma d-amphetamine and l-amphetamine steady-state exposure was low to moderate. SHP465 MAS was generally well tolerated in this study., Trial Registration: ClinicalTrials.gov, NCT03327402 (31 October, 2017)., (© 2021. The Author(s).)

Described as amphetamine-like due to their structural and stimulant similarities, clobenzorex is one of the five most-commonly used drugs in Mexico for the treatment of obesity. Various studies have shown that amphetamines induce dopaminergic neurotoxicity and neuroinflammation in the striatum, symptoms which are associated with motor damage. For this reason, the present study aimed to evaluate the effect of chronic clobenzorex administration on motor behaviors, TH immunoreactivity, gliosis, and the neurodegenerative process in the striatum and substantia nigra pars compacta (SNpc). The present research was conducted on three experimental groups of male Wistar rats: the vehicle group, the amphetamine group (2 mg/kg), and the clobenzorex group (30 mg/kg). All groups were subject to oral administration every 24 h for 31 days. Motor activity and motor coordination were evaluated in the open field test and the beam walking test, respectively. The animals were euthanized after the last day of treatment to enable the extraction of their brains for the evaluation of tyrosine hydroxylase (TH) levels, the immunoreactivity of the glial cells, and the neurodegeneration of both the striatum and SNpc via amino-cupric-silver stain. The results obtained show that amphetamine and clobenzorex administration decrease motor activity and motor coordination in the beam walking test and cause increased gliosis in the striatum, while no significant changes were observed in terms of immunoreactivity to TH and neurodegeneration in both the striatum and SNpc. These results suggest that the chronic administration of clobenzorex may decrease motor function in a manner similar to amphetamine, via the neuroadaptive and non-neurotoxic changes caused to the striatum under this administration scheme., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

As drug addiction may result from pathological usurpations of learning and memory's neural mechanisms, we focused on the amphetamine-induced time-dependent neurochemical changes associated with neural plasticity. We used juvenile rats as the risk for drug abuse is higher during adolescence. Experiment 1 served to define the appropriate amphetamine dose and the neurochemical effects of a single administration. In experiment 2, rats received seven amphetamine or saline injections in the open-field test throughout a twelve-day period. We measured the mRNA levels of the brain-derived neurotrophic factor (BDNF), its tropomyosin receptor kinase B (TrkB), the cAMP response element-binding protein (CREB), the microRNA-132, the Rho GTPase-activating protein 32 (p250GAP), the corticotropin-releasing factor (CRF), and monoamines and amino-acids contents in the nucleus accumbens and the dorsal striatum 45, 90, and 180 min after the last injection. We found that amphetamine changed gene expression only at certain time points and in a dose and region-dependent manner. Repeated but not single administrations upregulated accumbal and striatal BDNF (180 min) and striatal pri-miR-132 (90 min) expression, while downregulated accumbal CREB levels (90 min). As only some drug users develop addiction, we compared brain parameters between low and high amphetamine responders. Prone subjects characterized by having reduced striatal 5-HT metabolism, higher accumbal BDNF and TrkB expression, and lower levels of CREB in the dorsal striatum and p250GAP in both regions. Thus, individual differences in drug-induced changes in neurotransmission and gene expression in nigrostriatal and mesolimbic dopaminergic pathways may underlie the plasticity adaptations associated with behavioral sensitization to amphetamine., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The alkaloid ephedrine derived from Ephedra vulgaris is at the origin of psychostimulant-drugs as amphetamine. These drugs have been principally utilized for medical treatments in the past, while their utilization has been largely reduced from the 1970s when the high risk of addiction and abuse has been recognized. The first reported treatments were as anti-asthmatics and to contrast narcolepsy until their recreational stimulant and anorexic effects were reported. Benzedrine and Pervitin use were of great importance during the Second World War due to their abundant utilization among military troops. Nowadays the use of selective amphetamine-like drugs is limited to ADHD treatment., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Introduction/objective: ADHD is, for many people, a lifelong disease that requires chronic medication use. Stimulant therapy is often recommended as first-line treatment for ADHD. Adherence to stimulant treatment among patients diagnosed with ADHD is poor. Major regulatory agencies have recommended measurement of palatability for new tablet formulations. A new amphetamine extended-release tablet (AMPH ER TAB) for the treatment of attention-deficit/hyperactivity disorder (ADHD) was developed. The AMPH ER TAB has a bubblegum flavor and can be chewed or swallowed whole. In 2016, the FDA developed a draft guidance document on the topic of chewable drug tablet formulation palatability., Methods: A palatability study of the AMPH ER TAB using the 2016 FDA guidance was conducted. Subjects were asked to assess the taste, aftertaste, and mouthfeel of the tablet formulation using a short questionnaire. Scores from the questionnaire were rated and presented., Results: The substudy assessed 35 subjects with a mean age of 38 (±11) years. Subjects were predominantly male, non-Hispanic, and White. Most subjects rated the oral sensation/mouth feel and taste of the tablet as positive (pleasant to very pleasant) (70.1% and 83.6%, respectively). Additionally, 86.6% of the subjects rated the strength of the taste as neutral (moderate taste) or positive (mild to no taste). Finally, 82.1% of all subjects rated the aftertaste as positive (pleasant to very pleasant) and 92.5% of subjects rated the strength of the aftertaste as neutral or positive (mild to no taste). The trends in evaluation scores for each question were similar regardless of whether the ER chewable tablet was administered under fasted or fed conditions., Conclusion: The positive palatability data presented here will be useful for future "real-world" assessments of adherence to treatment with the AMPH ER TAB. Enhanced adherence may bolster the argument that taste, mouthfeel, and aftertaste are critical determinants of treatment adherence., Competing Interests: AP, ER, and JCK are compensated employees of Tris Pharma, Inc., the developer and manufacturer of the product that is the subject of this work. JCK owns stock from Johnson and Johnson and Takeda. TRK was an employee of Tris Pharma, Inc. at the time the study was conducted. The authors report no other conflicts of interest in this work., (© 2021 Pardo et al.)

Background: Dopamine transporter (DAT) and serotonin transporter (SERT) are targets for many psychoactive substances. Functional assays including uptake inhibition and release assays often involve radiolabeled compounds like [ 3 H]-dopamine and [ 3 H]-serotonin to assess drug activity at transporters, which have high requirements on handling radioactive samples., Aims: The aim of this study was to establish a label-free method to assess drug activity at DAT and SERT., Methods: A liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was established using transporter-transfected human embryonic kidney 293T (HEK293T) cells. This method was evaluated by testing the effects of amphetamine and cocaine in the assay procedure., Results: The limits of detection of this method were 0.2 nM for both dopamine (DA) and serotonin (5-HT), with good linearities in the range of 0.5-160 nM. Amphetamine and cocaine's IC 50 and EC 50 on DAT and SERT determined by this method were consistent with previous reports., Conclusions: A rapid, reliable and label-free LC-MS/MS method for assessing drug activity was established, which affords an attractive alternative for those laboratories that do not have a radiation license or capabilities.

Objective: The purpose of this study was to retrospectively investigate the abuse characteristics of amphetamine-type stimulants (ATS) in patients receiving methadone maintenance treatment (MMT) and buprenorphine maintenance treatment (BMT)., Methods: A total of 58 MMT and 51 BMT patients abusing ATS were recruited from the drug maintenance treatment clinic of Ningbo Addiction Research and Treatment Center from January 2018 to December 2019. They were assessed using the amphetamine abuse questionnaire (AAQ), addiction severity index (ASI) and Barratt impulsiveness scale (BIS). Moreover, 40 MMT control patients, 40 BMT control patients and 20 healthy controls were also assessed using the BIS. All information was collected using the amphetamine abuse questionnaire (AAQ), Chinese version of addiction severity index (ASI-C) and Chinese version of Barratt impulsiveness scale (BIS-C) conducted by qualified psychologists., Results: The interval of amphetamine use in the MMT group was shorter than the BMT group ( P < 0.05). The drug use subscale score of ASI was higher in the MMT group than the BMT group ( P < 0.05). The respective and total scores of attentional impulsiveness, motor impulsiveness and non-planning impulsiveness in BIS in the MMT group were all higher than the MMT control group ( P < 0.05). The scores of motor impulsiveness and non-planning impulsiveness in the BMT group were higher than the BMT control group ( P < 0.05). The respective and total scores in BIS in the MMT control group and the BMT control group were all higher than those in the healthy controls., Conclusion: The patients showing amphetamine abuse in maintenance therapy had a greater impulsiveness than those having other simple maintenance treatments, and patients under MMT may be more addicted to amphetamines in comparison with those having BMT., Competing Interests: The authors declare that they have no conflicts of interest., (© 2021 Liu et al.)

This study evaluated a battery of pain-stimulated, pain-depressed, and pain-independent behaviors for preclinical pharmacological assessment of candidate analgesics in mice. Intraperitoneal injection of dilute lactic acid (IP acid) served as an acute visceral noxious stimulus to produce four pain-related behaviors in male and female ICR mice: stimulation of 1) stretching, 2) facial grimace, 3) depression of rearing, and 4) depression of nesting. Additionally, nesting and locomotion in the absence of the noxious stimulus were used to assess pain-independent drug effects. These six behaviors were used to compare effects of two mechanistically distinct but clinically effective positive controls (ketoprofen and oxycodone) and two negative controls that are not clinically approved as analgesics but produce either general motor depression (diazepam) or motor stimulation (amphetamine). We predicted that analgesics would alleviate all IP acid effects at doses that did not alter pain-independent behaviors, whereas negative controls would not. Consistent with this prediction, ketoprofen (0.1-32 mg/kg) produced the expected analgesic profile, whereas oxycodone (0.32-3.2 mg/kg) alleviated all IP acid effects except depression of rearing at doses lower than those that altered pain-independent behaviors. For the negative controls, diazepam (1-10 mg/kg) failed to block IP acid-induced depression of either rearing or nesting and only decreased IP acid-stimulated behaviors at doses that also decreased pain-independent behaviors. Amphetamine (0.32-3.2 mg/kg) alleviated all IP acid effects but only at doses that also stimulated locomotion. These results support utility of this model as a framework to evaluate candidate-analgesic effects in a battery of complementary pain-stimulated, pain-depressed, and pain-independent behavioral endpoints. SIGNIFICANCE STATEMENT: Preclinical assays of pain and analgesia often yield false-positive effects with candidate analgesics. This study used two positive-control analgesics (ketoprofen, oxycodone) and two active negative controls (diazepam, amphetamine) to validate a strategy for distinguishing analgesics from nonanalgesics by profiling drug effects in a battery of complementary pain-stimulated, pain-depressed, and pain-independent behaviors in male and female mice., (Copyright © 2021 by The American Society for Pharmacology and Experimental Therapeutics.)

Physical exercise, which can be addictogenic on its own, is considered a therapeutic alternative for drug craving. Exercise might thus share with drugs the ability to strengthen excitatory synapses onto ventral tegmental area (VTA) dopaminergic neurones, as assessed by the ratio of AMPA receptor (AMPAR)-mediated excitatory postsynaptic currents (EPSCs) to NMDA receptor (NMDAR)-mediated EPSCs. As did acute cocaine, amphetamine, or Δ 9 -tetrahydrocannabinol (THC) pretreatments, an acute 1-h wheel-running session increased the AMPAR/NMDAR ratio in VTA dopaminergic neurones. To dissect the respective influences of wheel-running seeking and performance, mice went through an operant protocol wherein wheel-running was conditioned by nose poking under fixed ratio schedules of reinforcement. Conditioned wheel-running increased the AMPAR/NMDAR ratio to a higher extent than free wheel-running, doing so although running performance was lower in the former paradigm than in the latter. Thus, the cue-reward association, rather than reward consumption, played a major role in this increase. The AMPAR/NMDAR ratio returned to baseline levels in mice that had extinguished the cued-running motivated task, but it increased after a cue-induced reinstatement session. The amplitude of this increase correlated with the intensity of exercise craving, as assessed by individual nose poke scores. Finally, cue-induced reinstatement of running seeking proved insensitive to acute cocaine or THC pretreatments. Our study reveals for the first time that the drive for exercise bears synaptic influences on VTA dopaminergic neurones which are reminiscent of drug actions. Whether these influences play a role in the therapeutic effects of exercise in human drug craving remains to be established., (© 2020 Society for the Study of Addiction.)

COR659 is a recently synthesized positive allosteric modulator (PAM) of the GABA B receptor. Similarly to all GABA B PAMs tested to date, COR659 has been reported to suppress different alcohol-related behaviors in rodents. The present study was designed to assess whether the anti-addictive properties of COR659 extend to drugs of abuse other than alcohol. Specifically, it investigated the effect of COR659 on cocaine-, amphetamine-, nicotine-, and morphine-induced locomotor hyperactivity in mice. To this aim, independent groups of CD1 mice were acutely pretreated with COR659 (0, 10, and 20 mg/kg; i.p.), then acutely treated with cocaine (0 and 10 mg/kg, s.c.), amphetamine (0 and 5 mg/kg; s.c.), nicotine (0 and 0.05 mg/kg; s.c.), or morphine (0 and 20 mg/kg; s.c.), and finally exposed for 60 min to a photocell-equipped motility cage. When given alone, both doses of COR659 were ineffective on spontaneous locomotor activity. Pretreatment with COR659 reduced, or even suppressed, the increase in motility counts induced by cocaine, amphetamine, nicotine, and morphine. Since locomotor hyperactivity is an attribute common to drugs of abuse, the results of the present study constitute the first line of evidence on the extension of the preclinical, anti-addictive profile of COR659 to cocaine, amphetamine, nicotine, and morphine., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the suited rat-models, we focused on the stable pentadecapeptide BPC 157, L-NAME, NOS-inhibitor, and L-arginine, NOS-substrate, relation, the effect on schizophrenia-like symptoms. Medication (mg/kg intraperitoneally) was L-NAME (5), L-arginine (100), BPC 157 (0.01), given alone and/or together, at 5 min before the challenge for the acutely disturbed motor activity (dopamine-indirect/direct agonists (amphetamine (3.0), apomorphine (2.5)), NMDA-receptor non-competitive antagonist (MK-801 (0.2)), or catalepsy, (dopamine-receptor antagonist haloperidol (2.0)). Alternatively, BPC 157 10 μg/kg was given immediately after L-NAME 40 mg/kg intraperitoneally. To induce or prevent sensitization, we used chronic methamphetamine administration, alternating 3 days during the first 3 weeks, and challenge after next 4 weeks, and described medication (L-NAME, L-arginine, BPC 157) at 5 min before the methamphetamine at the second and third week. Given alone, BPC 157 or L-arginine counteracted the amphetamine-, apomorphine-, and MK-801-induced effect, haloperidol-induced catalepsy and chronic methamphetamine-induced sensitization. L-NAME did not affect the apomorphine-, and MK-801-induced effects, haloperidol-induced catalepsy and chronic methamphetamine-induced sensitization, but counteracted the acute amphetamine-induced effect. In combinations (L-NAME + L-arginine), as NO-specific counteraction, L-NAME counteracts L-arginine-induced counteractions in the apomorphine-, MK-801-, haloperidol- and methamphetamine-rats, but not in amphetamine-rats. Unlike L-arginine, BPC 157 maintains its counteracting effect in the presence of the NOS-blockade (L-NAME + BPC 157) or NO-system-over-stimulation (L-arginine + BPC 157). Illustrating the BPC 157-L-arginine relationships, BPC 157 restored the antagonization (L-NAME + L-arginine + BPC 157) when it had been abolished by the co-administration of L-NAME with L-arginine (L-NAME + L-arginine). Finally, BPC 157 directly inhibits the L-NAME high dose-induced catalepsy. Further studies would determine precise BPC 157/dopamine/glutamate/NO-system relationships and clinical application., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: Evaluate the relative bioavailability of single-dose amphetamine extended-release tablet (AMPH ER TAB) 20 mg, swallowed whole or chewed, and amphetamine extended-release oral suspension (AMPH EROS) 2.5 mg/mL; evaluate food effect on AMPH ER TAB., Methods: Healthy volunteers (18-55 years) were randomized to 1 dose of AMPH ER TAB 20 mg swallowed (fasted), chewed (fed/fasted), or 20 mg AMPH EROS (fasted). A crossover study design was used. Plasma samples were collected each period predose and at time points to 60 hours postdose. d- and l-amphetamine were measured and pharmacokinetic (PK) was calculated (90% confidence intervals of the ratios of the plasma levels) for AUC0-t, AUC0-∞, and Cmax. Comparative relative bioavailability between formulations was determined when ratios were within 80% and 125%. Safety was also assessed., Results: Thirty-two subjects completed the study. AMPH ER TAB swallowed versus AMPH EROS (fasted): for d- and l-amphetamine, the total and peak exposure was similar: d: AUC0-t: 100.68% to 108.08%, AUC0-∞: 101.47% to 109.52%, Cmax: 98.10% to 103.17%; l: AUC0-t: 100.31% to 108.57%, AUC0-∞: 101.27% to 111.09%, Cmax: 98.2% to 103.37%. For d- and l-amphetamine when the tablet is swallowed whole, Tmax was 5.00 hours (with a range of 2.00-9.00 hours). AMPH ER TAB chewed versus AMPH EROS (fasted): for d- and l-amphetamine, the total and peak exposure was similar: d: AUC0-t: 99.23% to 106.62%, AUC0-∞: 99.58% to 107.59%, Cmax: 99.91% to 105.14%; l: AUC0-t: 98.16% to 106.35%, AUC0-∞: 98.44% to 108.11%, Cmax: 99.53% to 104.75%. For d- and l-amphetamine when the tablet has been chewed, Tmax was 5.00 hours (with a range of 3.00-7.00 hours). PK results were similar for patients in the fasted and fed groups, indicative of no presence of food effect. No serious adverse events (AEs) were reported, overall AE profiles between the tablet and oral suspension were comparable without any unanticipated safety concerns., Conclusions: Single doses of AMPH ER TAB for both d- and l-amphetamine demonstrated comparable bioavailability to a 20 mg dose of AMPH EROS, 2.5 mg/mL under fasted conditions when chewed and swallowed whole, and demonstrated equivalent peak and overall exposure without apparent food effect. AMPH ER TAB was well-tolerated and consistent with adverse events noted in other amphetamine formulations.

Risperidone is an atypical antipsychotic drug used increasingly in children to manage symptoms of ADHD and conduct disorder. In rats, developmental risperidone administration is accompanied by increased locomotor activity during adulthood, as well as heightened sensitivity to the locomotor stimulating effects of amphetamine. This study compared sensitivity to the rewarding effects of amphetamine, as measured by conditioned place preference (CPP), between groups of rats administered chronic risperidone (3.0 mg/kg, s.c.) during development (postnatal days 14-42) or adulthood (postnatal days 77-105). Locomotor activity in a novel test cage and amphetamine-induced CPP were measured beginning three and four weeks, respectively, after the final risperidone injection. Female rats administered risperidone early in life were more active than any other group tested. Previous risperidone administration enhanced amphetamine CPP regardless of sex, and this effect appeared more prominent in the developmentally treated group. The density of forebrain dopamine transporters, a primary target of amphetamine, was also quantified in rats administered risperidone early in life and found to be reduced in the medial anterior, posterior, and ventral caudate nucleus. These results suggest that chronic risperidone treatment modifies later locomotor activity and sensitivity to the reinforcing effects of amphetamine, perhaps via a mechanism related to decreased forebrain dopamine transporter density., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Introduction: The assessment of the abuse potential of CNS-active drugs is a regulatory requirement. Drug discrimination is one of the nonclinical tests that contribute to this assessment by providing information on a drug's potential to induce a discriminative stimulus comparable to that of a known drug of abuse., Aim: The objective was to validate drug discrimination in the rat for the purpose of supporting regulatory submissions for novel drugs with potential cannabinoid-like activity., Methods: Ten female Lister hooded rats were trained to discriminate no-drug from Δ 9 -THC (1.5 mg/kg, IP) under a FR10 schedule of reinforcement. Once trained, a Δ 9 -THC dose-response curve was obtained using doses of 0.25, 0.75, 1.5, and 3 mg/kg, IP. This was followed by evaluation of amphetamine (0.3 mg/kg, SC); morphine (3 mg/kg, IP); midazolam (2.5 mg/kg, PO); and the synthetic cannabinoids WIN55,212-2 (0.75 to 2 mg/kg, IP), CP-47,497 (0.5 to 2 mg/kg, IP), and JWH-018 (1 mg/kg, IP) for their discriminative stimulus similarity to Δ 9 -THC., Results: Pharmacological specificity was demonstrated by achieving the anticipated dose-response curve for Δ 9 -THC, and a vehicle-like response for the non-cannabinoid drugs. Although full generalisation was obtained for JWH-018, in contrast to published literature, WIN55,212-2 and CP-47,497 failed to generalise to Δ 9 -THC., Discussion: Based on the literature review performed in light of the results obtained, contrasting and unpredictable behavioural responses produced by cannabinoids in animals and humans raises the question of the reliability and relevance of including drug discrimination and self-administration studies within an abuse potential assessment for novel cannabinoid-like drugs., (Copyright © 2020 Elsevier Inc. All rights reserved.)

One characteristic feature of addictive drugs is their ability to induce, after a single exposure, a lasting sensitization to the next doses; the underlying neuroplastic changes supposedly involve the brain dopamine system. We aimed at identifying putative relationships between alterations in extracellular dorsal striatal dopamine, HVA and DOPAC levels and in frequency-modulated 50-kHz ultrasonic vocalizations rate response during repeated intraperitoneal amphetamine treatment. Measurements were performed before and after amphetamine doses 1, 2, 7 and 8 (Amph1, Amph2, Amph7 and Amph8; treatment days 1, 7, 12 and 23, respectively). Amphetamine was confirmed to induce sensitization of the vocalization response, but an extended recording time (180 instead of 20 min) revealed that sensitization of this response requires more time to develop than hitherto believed. Baseline extracellular dopamine level increased initially, declined after a series of daily amphetamine doses and showed some tendency for recovery after drug withdrawal. Baseline extracellular DOPAC (but not HVA) showed a continuous decline during the treatment. There was no significant change in the integrated short-term (3-h) extracellular dopamine response, whereas the respective DOPAC collection lowered significantly after repeated drug treatment. Extracellular DOPAC is believed to originate mostly from newly synthesized dopamine, hence the declines in its baseline and post-amphetamine levels suggest falling dopamine synthesis. These results indicate that sensitization of the appetitive vocalization response to amphetamine continues despite reduced dorsal striatal dopamine synthesis and involves no changes in amphetamine-induced dopamine release., Competing Interests: Declaration of Competing Interest The authors declare that they do not have any conflict of interest related to this work., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Parkinson's disease (PD) is a common neurodegenerative disease characterized by motor and cognitive deficits, the result of dopamine (DA)-depletion within the basal ganglia. Currently, DA replacement therapy in the form of Sinemet (L-DOPA plus Carbidopa) provides symptomatic motor benefits and remains the "gold standard" for treatment. Several pharmacological approaches can enhance DA neurotransmission including the administration of DA receptor agonists, the inhibition of DA metabolism, and enhancing pre-synaptic DA release. DA neurotransmission is regulated by several receptor subtypes including signaling through the purinergic system. P2 × 4 receptors (P2 × 4Rs) are a class of cation-permeable ligand-gated ion channels activated by the synaptic release of extracellular adenosine 5'-triphosphate (ATP). P2 × 4Rs are expressed throughout the central nervous system including the dopaminergic circuitry of the substantia nigra, basal ganglia, and related reward networks. Previous studies have demonstrated that P2 × 4Rs can modulate several DA-dependent characteristics including motor, cognitive, and reward behaviors. Ivermectin (IVM) and moxidectin (MOX) are two macrocyclic lactones that can potentiate P2 × 4Rs. In this study, we sought to investigate the role of P2 × 4Rs in mediating DA neurotransmission by exploring their impact on DA-dependent behavior, specifically rotation frequency in the unilateral 6-hydroxydopamine-lesioned mouse model of DA-depletion. While we did not observe any differences in the degree of lesioning based on immunostaining for tyrosine hydroxylase between sexes, male mice displayed a greater number of rotations with L-DOPA compared to female mice. In contrast, we observed that IVM plus L-DOPA increased the number of rotations (per 10 min) in female, but not male mice. These findings highlight the potential role of pharmacologically targeting the purinergic receptor system in modulating DA neurotransmission as well as the importance of sex differences impacting outcome measures., Competing Interests: Declaration of Competing Interest There are no declarations of interests to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Methamphetamine (MA) is a highly addictive central nervous system stimulant. Drug addiction is not a static condition but rather a chronically relapsing disorder. Hair is a valuable and stable specimen for chronic toxicological monitoring as it retains toxicants and metabolites. The primary focus of this study was to discover the metabolic effects encompassing diverse pathological symptoms of MA addiction. Therefore, metabolic alterations were investigated in human hair following heavy MA abuse using both targeted and untargeted mass spectrometry and through integrated network analysis. The statistical analyses ( t -test, variable importance on projection score, and receiver-operator characteristic curve) demonstrated that 32 metabolites (in targeted metabolomics) as well as 417 and 224 ion features (in positive and negative ionization modes of untargeted metabolomics, respectively) were critically dysregulated. The network analysis showed that the biosynthesis or metabolism of lipids, such as glycosphingolipids, sphingolipids, glycerophospholipids, and ether lipids, as well as the metabolism of amino acids (glycine, serine and threonine; cysteine and methionine) is affected by heavy MA abuse. These findings reveal crucial metabolic effects caused by MA addiction, with emphasis on the value of human hair as a diagnostic specimen for determining drug addiction, and will aid in identifying robust diagnostic markers and therapeutic targets.

Psychostimulants such as d-amphetamine (AMPH) often have behavioral effects that appear paradoxical within the framework of optimal choice theory. AMPH typically increases task engagement and the effort animals exert for reward, despite decreasing reward valuation. We investigated neural correlates of this phenomenon in the anterior cingulate cortex (ACC), a brain structure implicated in signaling cost-benefit utility. AMPH decreased signaling of reward, but not effort, in the ACC of freely-moving rats. Ensembles of simultaneously recorded neurons generated task-specific trajectories of neural activity encoding past, present, and future events. Low-dose AMPH contracted these trajectories and reduced their variance, whereas high-dose AMPH expanded both. We propose that under low-dose AMPH, increased network stability balances moderately increased excitability, which promotes accelerated unfolding of a neural 'script' for task execution, despite reduced reward valuation. Noise from excessive excitability at high doses overcomes stability enhancement to drive frequent deviation from the script, impairing task execution., Competing Interests: SH, DE, AG No competing interests declared, (© 2020, Hashemnia et al.)

Objective: To describe our experience with amphetamine/dextroamphetamine salts (AMP) as a treatment for delayed orgasm/anorgasmia (DO/AO)., Methods: We identified patients with DO/AO from September 2017 to September 2019. Baseline characteristics and patient-reported orgasmic latency time (OLT) were recorded. After extensive screening, patients were treated with AMP. Validated questionnaires were administered including International Index of Erectile Function, quantitative Androgen Deficiency in the Aging Male and Adult ADHD Self-Report Scale. OLT change, adverse effects, and patient satisfaction were assessed. Baseline characteristics were compared using chi-squared test. OLT changes were compared with one-way ANOVA. Multivariable logistic regression was performed to identify predictors of treatment success. P < 0.05 was statistically significant., Results: Seventeen men received AMP - 6 of 17 (35.3%) for AO and 11 of 17 (64.7%) for DO, with median follow-up 1.0 year (interquartile range [IQR] 1.0 year). Amongst responders, AMP improved subjective experience of sex in 8 of 17 (47.1%) patients (2/6 with AO). Of those, 6 of 17 (35.3%; 1/6 with AO) experienced reduced OLT or increased frequency of orgasm. Non-responders were older than responders, with median age 69.5 (IQR 4.3) vs 61.0 years (IQR 12.3; P = 0.024). There were no other significant differences in baseline characteristics among responders. Of note, 6 of 8 (75%) responders and 8 of 9 (88.9%) non-responders failed other treatment modalities prior to AMP. Among responders with DO and improved OLT, mean OLT decreased by 72.3% (40.7 to 11.1 minutes, P = 0.049) during intercourse. Minimal side effects were noted including insomnia and jitters, each in one patient respectively., Conclusion: AMP as a treatment for AO/DO merits further investigation. Measurable improvements in OLT or frequency of orgasm occurred in more than a third of patients. Larger prospective multicenter studies with strict inclusion and exclusion criteria are warranted., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Probability discounting is often measured with independent schedules. Independent schedules have several limitations, such as confounding preference for one alternative with frequency of reward presentation and generating ceiling/floor effects at certain probabilities. To address this potential caveat, a controlled reinforcer frequency schedule can be used, in which the manipulandum that leads to reinforcement is pseudo-randomly determined before each trial. This schedule ensures subjects receive equal presentations of the small and large magnitude reinforcers across each block of trials. A total of 24 pair-housed and 11 individually housed female Sprague Dawley rats were tested in a controlled reinforcer frequency procedure. For half of the rats, the odds against (OA) receiving the large magnitude reinforcer increased across the session (ascending schedule); the OA decreased across the session for half of the rats (descending schedule). Following training, rats received treatments of amphetamine (AMPH; 0, 0.25, 0.5, 1.0 mg/kg; s.c.). For pair-housed rats, AMPH (0.5 mg/kg) increased risky choice, regardless of probability presentation order, whereas a higher dose of AMPH (1.0 mg/kg) decreased discriminability of reinforcer magnitude for rats trained on the descending schedule only. For individually housed rats, probability presentation order modulated the effects of AMPH on probability discounting, as AMPH (0.25 and 0.5 mg/kg) increased risky choice in rats trained on the ascending schedule but not on the descending schedule. These results show that pair-housing animals, but not using a controlled reinforcer frequency procedure, attenuates the modulatory effects of probability presentation order on drug effects on risky choice., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The repeated administration of high doses of amphetamine has been shown to cause long-lasting depletions of striatal dopamine which, when substantial enough, have been shown to result in cognitive and motor impairment. These amphetamine-induced lesions are slightly larger in males than that in females and can be partially ameliorated by pretreatment with antioxidants. The objective of the present study was to replicate these two latter observations using an amphetamine dosing regimen that yields only minor depletions of dopamine. It was found that a low-dose treatment of amphetamine using only two subcutaneous injections caused a 57% depletion of striatal dopamine with males slightly more affected than females. Furthermore, pretreatment with ascorbic acid reduced the magnitude of this dopamine depletion with males exhibiting a slightly enhanced protection as compared to females. Compared to the traditionally used high-dose regimens, these effects were mild but in the same direction. The advantage of this regimen is that it better reflects amphetamine-induced depletions of dopamine in humans.

Background: Controlled drug challenge studies provide valuable information about the acute behavioral effects of drugs, including individual differences that may affect risk for abuse. One question that arises in such studies is whether a single administration of a drug (and placebo) provides an accurate measure of response to the drug., Methods: Here, we examined data from two studies, one with alcohol and one with amphetamine, in which participants received two administrations of the drug and placebo. In this analysis we assess the stability of acute subjective and cardiovascular responses to the drugs across the two administrations. We examine i) systematic increases or decreases to the drugs from the first to the second administration, ii) test-retest reliability within individuals and iii) the accuracy of the acute drug responses to predict drug choice in a later session., Results: Responses were largely stable across sessions, although on the second session amphetamine "liking" was higher, and subjective responses to placebo including "liking" and "want more" decreased in both studies. Test-retest reliability within individuals was high. Responses during the first drug administration were as accurate in predicting drug choice as responses during both administrations combined., Conclusions: Our findings indicate that a single administration of drug (and placebo) provides a good index of an individual's responses to alcohol or amphetamine, when participants are tested under controlled experimental conditions., Competing Interests: Declaration of Competing Interest None., (Published by Elsevier B.V.)

The guidance cue receptor DCC controls mesocortical dopamine development in adolescence. Repeated exposure to an amphetamine regimen of 4 mg/kg during early adolescence induces, in male mice, downregulation of DCC expression in dopamine neurons by recruiting the Dcc microRNA repressor, microRNA-218 (miR-218). This adolescent amphetamine regimen also disrupts mesocortical dopamine connectivity and behavioral control in adulthood. Whether low doses of amphetamine in adolescence induce similar molecular and developmental effects needs to be established. Here, we quantified plasma amphetamine concentrations in early adolescent mice following a 4 or 0.5 mg/kg dose and found peak levels corresponding to those seen in humans following recreational and therapeutic settings, respectively. In contrast to the high doses, the low amphetamine regimen does not alter Dcc mRNA or miR-218 expression; instead, it upregulates DCC protein levels. Furthermore, high, but not low, drug doses downregulate the expression of the DCC receptor ligand, Netrin-1, in the nucleus accumbens and prefrontal cortex. Exposure to the low-dose regimen did not alter the expanse of mesocortical dopamine axons or their number/density of presynaptic sites in adulthood. Strikingly, adolescent exposure to the low-dose drug regimen does not impair behavioral inhibition in adulthood; instead, it induces an overall increase in performance in a go/no-go task. These results show that developmental consequences of exposure to therapeutic- versus abused-like doses of amphetamine in adolescence have dissimilar molecular signatures and opposite behavioral effects. These findings have important clinical relevance since amphetamines are widely used for therapeutic purposes in youth., (© 2019 Society for the Study of Addiction.)

Amphetamine (AMPH) is a systemic stimulant used to treat a variety of diseases including Attention Deficit Hyperactive Disorder, narcolepsy and obesity. Previous data showed that by binding to catecholamine transporters, AMPH prevents the reuptake of the neurotransmitters dopamine (DA) and norepinephrine (NE). Because AMPH, either used therapeutically at final concentrations of 1-10 µM or abused as recreational drug (50-200 µM), is taken over long periods of time, we investigated the prolonged effects of this drug on the uptake of DA. We found that, in LLC-PK1 cells stably expressing the human DA transporter (hDAT), pretreatments with 1 or 50 µM AMPH caused significant reduction in DA uptake right after the 15-h pretreatment. Remarkably, after 50 but not 1 µM AMPH pretreatment, we observed a significant reduction in DA uptake also after one, two or three cell divisions. To test whether these long-term effects induced by AMPH where conserved in a model comparable to primordial neuronal cells and native neurons, we used the human neuroblastoma cell line SH-SY5Y cells, which were reported to endogenously express both hDAT and the NE transporter. Pretreatments with 50 µM AMPH caused a significant reduction of DA uptake both right after 15 h and 3 cell divisions followed by neuro-differentiation with retinoic acid (RA) for 5 days. Under these same conditions, AMPH did not change the intracellular concentrations of ATP, ROS and cell viability suggesting, therefore, that the reduction in DA uptake was not cause by AMPH-induced toxicity. Interestingly, while 1 µM AMPH did not cause long-term effects in the LLC-PK1 cells, in the SH-SY5Y cells, it decreased the DA uptake after one, two, but not three, cell divisions and 5-day RA differentiation. These data show that besides the well-known acute effects, AMPH can also produce long-term effects in vitro that are maintained during cell division and transmitted to the daughter cells.

Several studies have reported that low doses of the 5-HT 1A receptor agonist 8-OH-DPAT reduce cocaine-induced locomotor activity. However, it has also been reported that high doses of 8-OH-DPAT do not substitute for or alter the discriminative signal of cocaine (COC) or amphetamine (AMPH). This study aimed to evaluate the effects of low and high doses of the 5-HT 1A agonist 8-OH-DPAT on the discriminative signal of AMPH using conditioned taste aversion as a drug discrimination procedure. Additionally, to establish a correlation between the behavioral effects in drug discrimination and changes in dopamine (DA) and gamma-aminobutyric acid (GABA) concentrations, we evaluated the effect of systemic administration of low or high doses of the 5-HT 1A receptor agonist 8-OH-DPAT and of the 5-HT 1A receptor antagonist WAY100135 on DA and GABA extracellular concentrations in the nucleus accumbens (nAcc) and ventral tegmental area (VTA), respectively, using cerebral microdialysis. The behavioral results showed that low but not high doses of 8-OH-DPAT produced a reduction in the AMPH-induced discriminative signal, while WAY100135 administration prevented such effects. The microdialysis results showed that a low dose of 8-OH-DPAT decreased extracellular DA concentrations in the nAcc and increased GABA concentrations in the VTA. Pretreatment with WAY100135 prevented these effects. These data support the hypothesis that 5-HT 1A receptors modulate the behavioral effects of psychostimulant drugs, such as AMPH, through somatodendritic 5-HT 1A autoreceptors in the raphe nucleus indicating that 5-HT 1A receptors may be an important target for the development of pharmacological treatments for psychostimulant addiction., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A challenge for developing effective treatments for substance use disorders (SUDs) is understanding how environmental variables alter the efficacy of therapeutics. Environmental enrichment (EC) enhances brain development and protects against behaviors associated with drug abuse vulnerability when compared to rats reared in isolation (IC) or standard conditions (SC). EC rearing enhances the expression and function of metabotropic glutamate receptor 2/3 (mGlurR 2/3 ) and activating mGluR 2/3 reduces psychostimulant self-administration (SA). However, the ability for mGluR 2/3 activation to suppress amphetamine (AMP) SA in differentially reared rats is not determined. Therefore, we tested the hypothesis EC reduces AMP (SA) by augmenting mGluR 2/3 function. At postnatal day 21, male Sprague-Dawley rats were assigned to EC, IC, or SC environments for 30 days. Then, they acquired AMP SA and were moved to a progressive ratio (PR) schedule of reinforcement. EC, IC, and SC rats were pretreated with LY379268 (vehicle, 0.3 and 1 mg/kg), a selective mGluR 2/3 agonist, before PR behavioral sessions. Linear mixed effects analysis determined EC rats had reduced motivation for AMP SA when compared to IC or SC rats and that LY379268 dose-dependently suppressed AMP SA, but there was no evidence of an interaction. Cumming/Gardner-Altman estimation plots illustrate that the 0.3 mg/kg dose suppressed infusions in EC rats while the 1 mg/kg dose suppressed infusions in SC rats. LY379268 was incapable of suppressing the motivation for AMP SA in IC rats. Controlling for baseline differences in differentially reared rats remains a challenge. Normalizing to a baseline introduced error which is illustrated in the precision of the estimated effect size differences. The data indicate that environmental enrichment enhances the ability of a selective mGluR 2/3 agonist to suppress AMP SA and indicates the functional status of the mGluR 2/3 is formed during development. Therefore, environmental history must be considered when evaluating pharmacological therapeutics particularly those aimed at the mGluR 2/3 ., (Copyright © 2020 Elsevier Inc. All rights reserved.)

In an uncertain world, the ability to predict and update the relationships between environmental cues and outcomes is a fundamental element of adaptive behaviour. This type of learning is typically thought to depend on prediction error, the difference between expected and experienced events and in the reward domain that has been closely linked to mesolimbic dopamine. There is also increasing behavioural and neuroimaging evidence that disruption to this process may be a cross-diagnostic feature of several neuropsychiatric and neurological disorders in which dopamine is dysregulated. However, the precise relationship between haemodynamic measures, dopamine and reward-guided learning remains unclear. To help address this issue, we used a translational technique, oxygen amperometry, to record haemodynamic signals in the nucleus accumbens (NAc) and orbitofrontal cortex (OFC), while freely moving rats performed a probabilistic Pavlovian learning task. Using a model-based analysis approach to account for individual variations in learning, we found that the oxygen signal in the NAc correlated with a reward prediction error, whereas in the OFC it correlated with an unsigned prediction error or salience signal. Furthermore, an acute dose of amphetamine, creating a hyperdopaminergic state, disrupted rats' ability to discriminate between cues associated with either a high or a low probability of reward and concomitantly corrupted prediction error signalling. These results demonstrate parallel but distinct prediction error signals in NAc and OFC during learning, both of which are affected by psychostimulant administration. Furthermore, they establish the viability of tracking and manipulating haemodynamic signatures of reward-guided learning observed in human fMRI studies by using a proxy signal for BOLD in a freely behaving rodent.

Dysregulation in glucocorticoid stress and accumbal dopamine reward systems can alter reward salience to increase motivational drive in control conditions while contributing to relapse during drug withdrawal. Amphetamine withdrawal is associated with dysphoria and stress hypersensitivity that may be mediated, in part, by enhanced stress-induced corticosterone observed in the ventral hippocampus. Electrical stimulation of the ventral hippocampus enhances accumbal shell dopamine release, establishing a functional connection between these two regions. However, the effects of ventral hippocampal corticosterone on this system are unknown. To address this, a stress-relevant concentration of corticosterone (0.24ng/0.5 μL) or vehicle were infused into the ventral hippocampus of urethane-anesthetized adult male rats in control and amphetamine withdrawn conditions. Accumbal dopamine output was assessed with in vivo chronoamperometry. Corticosterone infused into the ventral hippocampus rapidly enhanced accumbal dopamine output in control conditions, but produced a biphasic reduction of accumbal dopamine output in amphetamine withdrawal. Selectively blocking glucocorticoid-, mineralocorticoid-, or cytosolic receptors prevented the effects of corticosterone. Overall, these results suggest that the ability of corticosterone to alter accumbal dopamine output requires cooperative activation of mineralocorticoid and glucocorticoid receptors in the cytosol, which is dysregulated during amphetamine withdrawal. These findings implicate ventral hippocampal corticosterone in playing an important role in driving neural systems involved in positive stress coping mechanisms in healthy conditions, whereas dysregulation of this system may contribute to relapse during withdrawal., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Compulsive eating behavior is hypothesized to be driven in part by reward deficits likely due to neuroadaptations to the mesolimbic dopamine (DA) system. Therefore, the aim of this study was to assess deficits in reward system functioning and mesolimbic DA after alternating a standard chow with palatable diet, a model of compulsive eating. In this model, rats in the control group (Chow/Chow) are provided a standard chow diet 7 days a week, while the experimental group (Chow/Palatable) is provided chow for 5 days a week ("C Phase"), followed by 2 days of access to a highly palatable sucrose diet ("P Phase"). We first tested the sensitivity to d-Amphetamine's stimulatory, reward-enhancing, and primary rewarding effects using a locomotor activity assay, an intracranial self-stimulation (ICSS) procedure, and a conditioned place preference test, respectively. We then quantified DA release in the nucleus accumbens (NAc) shell after treatment with d-Amphetamine using in vivo microdialysis, quantified levels of tyrosine hydroxylase (TH) and dopamine transporter (DAT) mRNA using quantitative polymerase chain reaction (qPCR), and lastly, quantified baseline extracellular DA and function of DAT in vivo using quantitative "no-net-flux" microdialysis. Chow/Palatable rats displayed blunted d-Amphetamine-induced locomotor activity, insensitivity to d-Amphetamine potentiation of ICSS threshold, and decreased place preference for d-Amphetamine during the P Phase. We found that Chow/Palatable rats had blunted DA efflux following d-Amphetamine treatment. Furthermore, DAT mRNA was increased in Chow/Palatable rats during the P Phase. Finally, quantitative "no-net-flux" microdialysis revealed reduced extracellular baseline DA and DAT function in Chow/Palatable rats. Altogether, these results provide evidence of reduced reward system functioning and related neuroadaptations in the DA and DAT systems in this model of compulsive eating. Reward deficits, resulting from repeated overeating, may in turn contribute to the perpetuation of compulsive eating behavior.

Objective: To examine medication prescribing patterns for preschool-aged children with diagnoses of attention-deficit/hyperactivity disorder (ADHD) and/or disruptive behavior disorder (DBD). Secondary objectives included determining if prescription patterns varied by gender, insurance type, or comorbid diagnosis of autism spectrum disorder (ASD). Methods: A retrospective, cross-sectional chart review was completed for children ages 2-5 years who were treated at an academic medical center between 2013 and 2016 with a diagnosis of ADHD and/or DBD. Data were analyzed by Fisher's exact and chi-square tests and Cochran-Armitage trend analysis. Results: Of the 966 children who met inclusion criteria, 343 (35.5%) were prescribed ADHD medications. For 2-, 3-, and 4-year olds, the most commonly prescribed medication was an alpha agonist (AA), while for 5-year olds, methylphenidate (MPH) was most commonly prescribed. With advancing age, an increasing number of children were prescribed a stimulant medication and a decreasing number of children were prescribed an AA ( p  < 0.001). Children were more often prescribed an MPH formulation (48.2%) compared with amphetamine-based stimulants (26.8%). Children without ASD were more likely to be prescribed a stimulant medication (72.1%) when compared with children with ASD (37.0%, p  < 0.0001). Children with private insurance were more likely to be prescribed an extended-release stimulant medication when compared with Medicaid patients (34.3% vs. 17.2%, p  = 0.004). Conclusion: Both stimulants and nonstimulants are being prescribed regularly in very young children, even before the age of four at an academic medical center. AAs were the most commonly prescribed medication for children 2, 3, and 4 years of age with diagnoses of ADHD, DBD, and ASD. Insurance type, comorbid diagnosis of ASD, and age of child were found to be significantly associated with prescribing a nonpreferred medication.

Objectives: We evaluated the pharmacokinetics (PK) of an investigational immediate-release amphetamine (AMP) sulfate formulation (AR19) designed to deter nonoral administration versus reference racemic amphetamine sulfate (RA-AMPH). We investigated AMP bioavailability from AR19, the effect of taking AR19 with food or sprinkling the capsules on food, and dose proportionality. Methods: Participants received AR19 (20 mg) or reference RA-AMPH (20 mg) (bioequivalence study) or AR19 5 or 30 mg (dose comparison study). Food effect study participants received AR19 (20 mg) as intact capsule while fasted or after high-fat/-calorie meal, or as pellets sprinkled on applesauce or yogurt (≥6-day washout). Blood samples were analyzed for dextroamphetamine ( d -AMP) and levoamphetamine ( l -AMP) PK: C max , AUC last , AUC inf , λ z , T ½ , and T max . Safety was assessed. Results: Bioequivalence, dose comparison, and food effect studies included 36, 24, and 36 participants. The 90% confidence intervals (CIs) of C max , AUC last , and AUC inf for AR19 20 mg versus reference RA-AMPH or AR19 with intact capsule and meal or sprinkled AR19 pellets on food versus fasted were between 80% and 125%. Dose-normalized C max /D, AUC last /D, and AUC inf /D for AR19 5 versus 30 mg had CIs within 80%-125%. Mean ± standard deviation (SD) T max was comparable for AMP ( d -AMP; l -AMP) following AR19 20 mg (2.84 ± 1.05; 3.05 ± 1.22) versus reference RA-AMPH (2.52 ± 0.75; 2.75 ± 1.00), and AR19 5 mg (2.48 ± 0.57; 2.65 ± 0.65) versus AR19 30 mg (2.55 ± 0.56; 2.72 ± 0.65). Mean ± SD T max for AMP ( d -AMP; l -AMP) was higher with intact capsule and meal (5.59 ± 1.57; 5.59 ± 1.59) versus fasted (2.85 ± 0.76; 2.97 ± 0.79). No serious adverse events were reported. Conclusion: AR19 was bioequivalent to reference RA-AMPH. Bioavailability was similar at doses between 5 and 30 mg and was not impacted by meal consumption or sprinkling on food. AR19 at tested doses was well tolerated.

Dopamine (DA) is a critical neurotransmitter involved in motivational processes. Tetrahydrobiopterin (BH4) is an essential cofactor for tyrosine hydroxylase, the rate-limiting enzyme in DA synthesis. Decreases in BH4 levels are observed in several DA-related neuropsychiatric diseases involving impairment in motivation. Yet, whether BH4 could be used to treat motivational deficits has not been comprehensively investigated. To investigate the effects of exogenous BH4 administration on the dopaminergic system and related behaviors, we acutely injected mice with BH4 (50 mg/kg). Passage of BH4 through the blood brain barrier and accumulation in brain was measured using the in situ brain perfusion technique. DA release was then recorded using in-vivo micro-dialysis and motivation was evaluated through operant conditioning paradigms in basal condition and after an amphetamine (AMPH) injection. First, we showed that BH4 crosses the blood-brain barrier and that an acute peripheral injection of BH4 is sufficient to increase the concentrations of biopterins in the brain, without affecting BH4- and DA-related protein expression. Second, we report that this increase in BH4 enhanced AMPH-stimulated DA release in the nucleus accumbens. Finally, we found that BH4-induced DA release led to improved performance of a motivational task. Altogether, these findings suggest that BH4, through its action on the dopaminergic tone, could be used as a motivational enhancer., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: In the U.S. ∼33% of children with attention-deficit/hyperactivity disorder (ADHD) are diagnosed during their preschool years (<6 years of age). The majority of these children are treated with a psychopharmacological treatment, despite limited data on pharmacokinetics (PKs), efficacy, or safety of these medications in this population. A phase 4, single-dose open-label study was conducted to assess the PK profile of amphetamine extended-release orally disintegrating tablets (AMP XR-ODT) under fasted conditions in preschool-aged children with ADHD. Methods: Preschool-aged children (aged 4 to <6 years) with a confirmed ADHD diagnosis were enrolled and administered AMP XR-ODT 3.1 mg under fasted conditions. Plasma samples were analyzed for d - and l -amphetamine (AMP) via liquid chromatography-tandem mass spectrometry. Area under the concentration-time curve from time 0 extrapolated to infinity (AUC 0-inf ), area under the concentration-time curve from time 0 to the last measurable plasma concentration (AUC 0-T ), maximum plasma concentration (C max ), time to maximum plasma concentration (T max ), terminal half-life (t 1/2 ), apparent volume of distribution (Vz/F), and apparent clearance (CL/F) for d - and l -AMP and safety were assessed. Results: The PK and safety analyses included 15 preschool-aged children (4 years old, n  = 6; 5 years old, n  = 9); 14 completed the study. Quantifiable plasma concentrations for d - and l -AMP were observed 1.5 hours postdose and throughout the 24-hour sampling period. For d - and l -AMP, mean AUC 0-inf was 315.2 and 104.4 h·ng/mL, AUC 0-T was 296.0 and 96.8 h·ng/mL, t 1/2 was 8.0 and 9.2 hours, C max was 23.0 and 7.0 ng/mL, T max was 3.9 and 4.0 hours, CL/F was 6996.3 and 6837.1 mL/h, and Vz/F was 75,874.5 and 84,140.0 mL, respectively. Adverse events included tachycardia ( n  = 2), neutropenia ( n  = 1), increased alanine aminotransferase ( n  = 1), and aspartate aminotransferase ( n  = 1). Conclusions: AMP XR-ODT 3.1 mg was well tolerated in preschool-aged children, with detectable plasma AMP concentrations over 24 hours, and a PK profile consistent with once-daily dosing.

Background: Amphetamine-type stimulants (ATS) are the second most commonly used illicit drugs in Europe and globally. However, there is limited understanding of what shapes patterns of ATS use over the life course. The ATTUNE project "Understanding Pathways to Stimulant Use: a mixed methods examination of the individual, social and cultural factors shaping illicit stimulant use across Europe" aims to fill this gap. Here we report initial findings from the life course chart exercise conducted as part of qualitative interviews with ATS users and nonusers., Methods: Two hundred seventy-nine in-depth qualitative interviews were conducted with five ATS user groups (current and former dependent users;current and former frequent users;non-frequent users) and one group of exposed non-ATS users in five European countries (Germany, UK, Poland, Netherlands and Czech Republic). As part of the interviews, we used life course charts to capture key life events and substance use histories. Life events were categorised as either positive, neutral or negative, and associated data were analysed systematically to identify differences between user groups. We applied statistical analysis of variance (ANOVA) and analysis of covariance (ANCOVA) to test for group differences., Results: Out of 3547 life events documented, 1523 life events were categorised as neutral, 1005 life events as positive and 1019 life events as negative. Current and formerly dependent ATS users showed more negative life events for the entire life course after age adjustment. Although some group differences could be attributed to the individuals' life course prior to first ATS use, most negative life events were associated with periods of ATS usage. A detailed analysis of the specific life domains reveals that dominantly, the social environment was affected by negative life events., Conclusions: For non-dependent, frequent and non-frequent ATS users, negative life events from the period of ATS use do not become obvious in our analysed data. Besides preventing a pathway into ATS dependency, the aim of an intervention should be to reduce the harm by for example drug testing which offers also the opportunity for interventions to prevent developing a substance use dependency. For the group of dependent ATS users, our study suggests holistic, tailored interventions and specialist treatment services are needed, as a single, simple intervention is unlikely to cover all the life domains affected.

Behavioural sensitization of locomotion and 50 kHz ultrasonic vocalizations (USVs) following repeated amphetamine (AMPH) injections in rats has been extensively demonstrated. These two behaviours appear dissociable in their sensitization patterns and are thought to be reflective of underlying emotional states of the organism. Although AMPH is often used to induce 50 kHz USVs there is little research to date on the extent of cortical and subcortical forebrain region involvement in 50 kHz call production associated with the drug. Nor has general ergometric activity (a measure that in addition to locomotor activity includes all major muscular activity of the body) been investigated in such a framework. The present study sought to address this by performing a minimal sensitization protocol, utilizing only two injections, to investigate expression of the inducible transcription factor Zif-268 (Zif) among brain regions thought to be associated with 50 kHz USV emission. It was found that animals that spent a longer time emitting 50 kHz calls after a second AMPH injection showed statistically significant correlative patterns of Zif expression in medial prefrontal and striatal regions. These associations were not significant in animals that spent a shorter period of time calling after AMPH. There was also no significant correlation between any ergometric activity and time spent calling. The results provide evidence that the medial prefrontal cortices (prelimbic and infralimbic regions) of the rat may be involved with 50 kHz USV emission induced by AMPH in association with medial portions of the ventral and dorsal striatum., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction: There is a frequent comorbidity of amphetamine-type stimulants (ATS) use disorders and attention-deficit/hyperactivity disorder (ADHD). The assumption that this patient group "self-medicate" suggests that there are different use motives for ATS addicted patients with and without ADHD., Objective: Our study investigates these potential differences in use motives., Methods: Within a mixed-method approach, we examined the use motives of adults with ATS use disorder with and without ADHD in the first and latest month of their use. For this purpose, we used the 12-item Amphetamine-Type Stimulants Motive Questionnaire (AMQ) and a mind mapping technique after verifying that these tools are applicable to adults with ADHD., Results: The mixed-method approach showed that enhancement motives were the most important motives in the first month of use (e.g., fun/kick/rush/desire, and curiosity/interest in the drug/appeal), and over time, the incidence of coping motives increased (e.g., repression and freeing the mind/not having to think/switching off). There were no differences between adults with and without ADHD in the AMQ data, while the qualitative data showed that adults with ADHD used ATS less often out of social motives. In particular, the results showed no differences in the coping dimension and, thus, did not suggest that self-medication is an important factor for patients with ADHD., Conclusions: Patients with and without ADHD show very similar motive patterns for ATS use. This indicates that ATS treatment programs addressing use motives do not necessarily have to be different for patients with and without ADHD., (© 2020 S. Karger AG, Basel.)

Background: Individual vulnerability to stress manifests in the interaction of innate properties and environment. There is a growing interest in the individual variability in vulnerability to stress and how it contributes to the development of psychiatric disorders. Intake of palatable substances is often measured in animal models. We have previously demonstrated that the consumption of sucrose solution is a stable trait in rats., Aims: The present study aimed to compare the sensitivity of rats with high vs low liquid sucrose consumption to chronic variable stress and the stress effect on behavioural sensitization to amphetamine., Methods: Male Wistar rats were subjected to a chronic stress regimen and subsequent repeated treatment with amphetamine (1 mg/kg, intraperitoneally). Fifty-kHz ultrasonic vocalizations, locomotor activity and stereotypies were measured., Results: In no-stress baseline conditions, the behavioural response to acute amphetamine was similar in rats with high vs low sucrose consumption. Prior chronic stress potentiated the effect of amphetamine only in rats with high sucrose consumption. Behavioural sensitization to repeated administration of amphetamine was observed in non-stressed rats with lower sucrose preference, but not in the respective stressed group that had increased monoamine turnover in the nucleus accumbens. In contrast, in rats with high sucrose preference the amphetamine sensitization effect was prevalent in stressed rats, but not in non-stressed animals., Interpretation: Chronic stress can change the psychostimulant effect but this depends on the inherent reward sensitivity of the animal. Trait-wise, sucrose intake reflects vulnerability to chronic stress and may interact with the development of addiction.

Small fluctuations in striatal glutamate and dopamine are required to establish goal-directed behaviors and motor learning, while large changes appear to underlie many neuropsychological disorders, including drug dependence and Parkinson's disease. A better understanding of how variations in neurotransmitter availability can modify striatal circuitry will lead to new therapeutic targets for these disorders. Here, we examined dopamine-induced plasticity in prefrontal cortical projections to the nucleus accumbens (NAc) core. We combined behavioral measures of male mice, presynaptic optical studies of glutamate release kinetics from prefrontal cortical projections, and postsynaptic electrophysiological recordings of spiny projection neurons within the NAc core. Our data show that repeated amphetamine promotes long-lasting but reversible changes along the corticoaccumbal pathway. In saline-treated mice, coincident cortical stimulation and dopamine release promoted presynaptic filtering by depressing exocytosis from glutamatergic boutons with a low-probability of release. The repeated use of amphetamine caused a frequency-dependent, progressive, and long-lasting depression in corticoaccumbal activity during withdrawal. This chronic presynaptic depression was relieved by a drug challenge which potentiated glutamate release from synapses with a low-probability of release. D1 receptors generated this synaptic potentiation, which corresponded with the degree of locomotor sensitization in individual mice. By reversing the synaptic depression, drug reinstatement may promote allostasis by returning corticoaccumbal activity to a more stable and normalized state. Therefore, dopamine-induced synaptic filtering of excitatory signals entering the NAc core in novice mice and paradoxical excitation of the corticoaccumbal pathway during drug reinstatement may encode motor learning, habit formation, and dependence., (© 2019 Wiley Periodicals, Inc.)