Adolescent chemogenetic activation of dopaminergic neurons leads to reversible decreases in amphetamine-induced stereotypic behavior.

Chronic perturbations of neuronal activity can evoke homeostatic and new setpoints for neurotransmission. Using chemogenetics to probe the relationship between neuronal cell types and behavior, we recently found reversible decreases in dopamine (DA) transmission, basal behavior, and amphetamine (AMPH) response following repeated stimulation of DA neurons in adult mice. It is unclear, however, whether altering DA neuronal activity via chemogenetics early in development leads to behavioral phenotypes that are reversible, as alterations of neuronal activity during developmentally sensitive periods might be expected to induce persistent effects on behavior. To examine the impact of developmental perturbation of DA neuron activity on basal and AMPH behavior, we expressed excitatory hM3D(Gq) in postnatal DA neurons in TH-Cre and WT mice. Basal and CNO- or AMPH-induced locomotion and stereotypy was evaluated in a longitudinal design, with clozapine N-oxide (CNO, 1.0 mg/kg) administered across adolescence (postnatal days 15-47). Repeated CNO administration did not impact basal behavior and only minimally reduced AMPH-induced hyperlocomotor response in adolescent TH-CrehM3Dq mice relative to WThM3Dq littermate controls. Following repeated CNO administration, however, AMPH-induced stereotypic behavior robustly decreased in adolescent TH-CrehM3Dq mice relative to controls. A two-month CNO washout period rescued the diminished AMPH-induced stereotypic behavior. Our findings indicate that the homeostatic compensations that take place in response to chronic hM3D(Gq) stimulation during adolescence are temporary and are dependent on ongoing chemogenetic stimulation.

Enantiomer-specific analysis of amphetamine in urine, oral fluid and blood.

Illegal amphetamine is usually composed of a racemic mixture of the two enantiomers (S)- and (R)-amphetamine. However, when amphetamine is used in medical treatment, the more potent (S)-amphetamine enantiomer is used. Enantiomer-specific analysis of (S)- and (R)-amphetamine is therefore used to separate legal medical use from illegal recreational use. The aim of the present study was to describe our experience with enantiomer-specific analysis of amphetamine in urine and oral fluid, as well as blood, and examine whether the distribution of the two enantiomers seems to be the same in different matrices. We investigated 1,722 urine samples and 1,977 oral fluid samples from prison inmates, and 652 blood samples from suspected drugged drivers, where prescription of amphetamine was reported. Analyses were performed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS). The enantiomer separation was achieved by using a chiral column, and results from the method validation are reported. Samples containing <60% (S)-amphetamine were interpreted as representing illegal use of amphetamine. The distribution of the two enantiomers was compared between different matrices. In urine and oral fluid, the mean amount of (S)-amphetamine was 45.2 and 43.7%, respectively, while in blood, the mean amount of (S)-amphetamine was 45.8%. There was no statistically significant difference in the amount of (S)-amphetamine between urine and oral fluid samples and between urine and blood samples, but the difference was significant in blood compared to oral fluid samples (P < 0.001). Comparison of urine and oral fluid between similar populations indicated that enantiomers of amphetamine can be interpreted in the same way, although marginally higher amounts of (R)-amphetamine may occur in oral fluid. Oral fluid, having several advantages, especially during collection, could be a preferred matrix in testing for illegal amphetamine intake in users of medical amphetamine.

Evaluation of the immune system status and hematological dyscrasias, among amphetamine and cannabis abusers at Eradah Hospital in Qassim, Saudi Arabia.

This cross-sectional study aims to evaluate the immune system status and hematological disturbances among individuals who abuse amphetamines and cannabis. Substance abuse, particularly of amphetamines and cannabis, has been associated with various adverse effects on the body, including potential impacts on the immune system and hematological parameters. However, limited research has been conducted to comprehensively assess these effects in a cross-sectional design. Additionally, fungal infections are on the rise internationally, and immune-compromised people are particularly susceptible. The study will recruit a sample of amphetamine and cannabis abusers (n = 50) at the Eradah Hospital in the Qassim Region of Buraydah and assess their sociodemographic and biochemical variables, including blood indices and differential WBC indices, liver, and kidney profiles. Additionally, 50 sputum samples in total were cultured for testing for fungus infections. To obtain the descriptive statistics, the data was imported into Microsoft Excel and subjected to statistical analysis using SPSS 22.0. Amphetamine and cannabis abuser's sociodemographic variables analysis observed that the majority (52%) were aged 18-30, with 56% in secondary school. Unemployment was a significant issue, and most had no other health issues. The majority (50%) had 5-10 years of abuse, while 32% had less than 5 years, and only 18% had been drug abusers for more than 10 years. There were significant changes (p < 0.001) in all different leukocyte blood cells, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Furthermore, a microscopic examination of blood films from individuals who misuse the combination of the medications "amphetamine and cannabis" reveals hazardous alterations in Neutrophils. Out of 50, 35 sputum samples showed positive growth on Sabouraud dextrose agar (SDA) with chloramphenicol antibiotic, indicating a unicellular fungal growth. The present study explores the immune system and hematological disturbances linked to amphetamine and cannabis abuse, providing insights into health risks and targeted interventions. The findings complement previous research on drug users' hematological abnormalities, particularly in white blood cells. Routine hematological tests help identify alterations in homeostatic conditions, improving patient knowledge and preventing major issues. Further research is needed on multi-drug abuse prevention, early detection, and intervention. The cross-sectional design allows for a snapshot of the immune system and hematological status among abusers, laying the groundwork for future longitudinal studies. Key Words: Drug Effect, Immunity, Epidemiology, Oxidative Stress, Inflammation.

Amphetamine Exposure during Embryogenesis Alters Expression and Function of Tyrosine Hydroxylase and the Vesicular Monoamine Transporter in Adult C. elegans.

Amphetamines (Amph) are psychostimulants broadly used as physical and cognitive enhancers. However, the long-term effects of prenatal exposure to Amph have been poorly investigated. Here, we show that continuous exposure to Amph during early development induces long-lasting changes in histone methylation at the C. elegans tyrosine hydroxylase (TH) homolog cat-2 and the vesicular monoamine transporter (VMAT) homologue cat-1 genes. These Amph-induced histone modifications are correlated with enhanced expression and function of CAT-2/TH and higher levels of dopamine, but decreased expression of CAT-1/VMAT in adult animals. Moreover, while adult animals pre-exposed to Amph do not show obvious behavioral defects, when challenged with Amph they exhibit Amph hypersensitivity, which is associated with a rapid increase in cat-2/TH mRNA. Because C. elegans has helped reveal neuronal and epigenetic mechanisms that are shared among animals as diverse as roundworms and humans, and because of the evolutionary conservation of the dopaminergic response to psychostimulants, data collected in this study could help us to identify the mechanisms through which Amph induces long-lasting physiological and behavioral changes in mammals.

A critical review of the dextroamphetamine transdermal system for the treatment of ADHD in adults and pediatric patients.

INTRODUCTION: The dextroamphetamine transdermal system (d-ATS) is a stimulant patch recently approved by the United States (U.S.) Food and Drug Administration for the treatment of attention-deficit/hyperactivity disorder (ADHD). AREAS COVERED: The composition of the d-ATS, pharmacokinetics, and metabolism are presented along with data from dermal trials evaluating the tolerability of patch application at various skin sites. Efficacy and safety data from a laboratory classroom study in children and adolescents including effect sizes are assessed. Pharmacokinetic-pharmacodynamic modeling of variable wear times is also discussed. EXPERT OPINION: Although stimulants are recommended as first-line treatment for ADHD in the U.S. some patients may have difficulty swallowing intact tablets and capsules, or dislike the taste or texture of chewable, oral disintegrating, or liquid formulations. The d-ATS fills an unmet need for those with ADHD who are unable or prefer not to take medication orally. Varying wear time of the d-ATS also gives flexibility in length of stimulant effect which may be useful for patients with changing schedules. However, dermal discomfort must be considered in addition to the usual amphetamine side effects when prescribing the d-ATS. Patient and provider experience will determine how frequent the use of d-ATS becomes.

Psychosis with use of amphetamine drugs, methylphenidate and atomoxetine in adolescent and adults.

BACKGROUND: Use of psychostimulants and relative drugs has increased worldwide in treatment of attention-deficit hyperactivity disorder (ADHD) in adolescents and adults. Recent studies suggest a potential association between use of psychostimulants and psychotic symptoms. The risk may not be the same between different psychostimulants. OBJECTIVE: To assess whether amphetamine or atomoxetine use is associated with a higher risk of reporting symptoms of psychosis than methylphenidate use in adolescents and adults, particularly in patients with ADHD. METHODS: Using VigiBase, the WHO's pharmacovigilance database, disproportionality of psychotic symptoms reporting was assessed among adverse drug reactions related to methylphenidate, atomoxetine and amphetamines, from January 2004 to December 2018, in patients aged 13-25 years. The association between psychotic symptoms and psychostimulants was estimated through the calculation of reporting OR (ROR). FINDINGS: Among 13 863 reports with at least one drug of interest, we found 221 cases of psychosis with methylphenidate use, 115 with atomoxetine use and 169 with a prescription of an amphetamine drug. Compared with methylphenidate use, amphetamine use was associated with an increased risk of reporting psychotic symptoms (ROR 1.61 (95% CI 1.26 to 2.06)]. When we restricted the analysis to ADHD indication, we found a close estimate (ROR 1.94 (95% CI 1.43 to 2.64)). No association was found for atomoxetine. CONCLUSION: Our study suggests that amphetamine use is associated with a higher reporting of psychotic symptoms, compared with methylphenidate use. CLINICAL IMPLICATIONS: The prescription of psychostimulants should consider this potential adverse effect when assessing the benefit-risk balance.

Neither Amphetamine nor Sub-Anesthetic Ketamine Treatment during Adolescence Impairs Devaluation in Rats Tested during Adulthood.

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.

Chiral analysis of amphetamine, methamphetamine, MDMA and MDA enantiomers in human hair samples.

A novel analytical method was developed for the simultaneous quantification of the R/S-enantiomers of amphetamine, methamphetamine, MDA and MDMA in hair samples using liquid chromatography-tandem mass spectrometry (LC-MS-MS). This method involved a straightforward derivatization step with dansyl chloride and the use of a chiral column, enabling the separation and quantification of all eight enantiomers in a single analysis. The method exhibited excellent linearity across a concentration range of 0.03-3.00 ng/mg for each enantiomer. Precision and accuracy were within acceptable limits, with bias and relative standard deviation (RSD) values consistently below 6% and 9%, respectively. Selectivity and specificity assessments confirmed the absence of any interference from contaminants or co-extracted drugs. The method demonstrated high sensitivity, with limits of detection (LOD) below 8 pg/mg and limits of quantification (LOQ) below 19 pg/mg for all analytes. Extraction recovery exceeded 79%, and matrix effects were minimal for all analytes. Processed sample stability evaluations revealed consistent results with deviations below 11% for all analytes. Application of the method to 32 authentic human hair samples provided valuable insights into amphetamine use patterns, allowing differentiation between medical amphetamine consumption and illicit use based on enantiomeric composition. Additionally, the method detected co-use of methamphetamine, MDA or MDMA in some samples, highlighting its applicability in drug monitoring and real-life case scenarios within a forensic institute. This innovative analytical approach offers a sensitive and selective method for enantiomeric differentiation of amphetamine, methamphetamine, MDA and MDMA in human hair samples, providing a valuable tool for forensic and clinical investigations.

Long-term disruption of tissue levels of glutamate and glutamatergic neurotransmission neuromodulators, taurine and kynurenic acid induced by amphetamine.

RATIONALE: Chronic amphetamine (AMPH) use leading to addiction results in adaptive changes within the central nervous system that persist well beyond the drug's elimination from the body and can precipitate relapse. Notably, alterations in glutamatergic neurotransmission play a crucial role in drug-associated behaviours. OBJECTIVES: This study aimed to identify changes induced by amphetamine in glutamate levels and the neuromodulators of glutamatergic neurotransmission (taurine and kynurenic acid) observable after 14 and 28 days of abstinence in key brain regions implicated in addiction: the cortex (Cx), nucleus accumbens (Acb), and dorsolateral striatum (CPu-L). METHODS: The rats were administered 12 doses of amphetamine (AMPH) intraperitoneally (i.p.) at 1.5 mg/kg. The behavioural response was evaluated through ultrasonic vocalizations (USV). High-performance liquid chromatography (HPLC) was used to measure the levels of glutamate, taurine, and kynurenic acid in the Cx, Acb, and CPu-L after 14 and 28 days of abstinence. RESULTS: AMPH administration led to sensitisation towards AMPH's rewarding effects, as evidenced by changes in USV. There was a noticeable decrease in kynurenic acid levels and an increase in both taurine and glutamate in the CPu-L, along with an increase in glutamate levels in the Cx, 28 days following the final AMPH injection. CONCLUSIONS: The most significant changes in the tissue levels of glutamate, taurine, and kynurenic acid were seen in the CPu-L 28 days after the last dose of AMPH. The emergence of these changes exclusively after 28 days suggests that the processes initiated by AMPH use and subsequent abstinence take time to become apparent and may be enduring. This could contribute to the incubation of craving and the risk of relapse. Developing pharmacological strategies to counteract the reduction in kynurenic acid induced by psychostimulants may provide new avenues for therapy development.

Efficacy of probiotic supplements in improving the symptoms of psychosis, anxiety, insomnia, and anorexia due to amphetamine and methamphetamine use: a randomized clinical trial.

RATIONALE: Changes in the density and diversity of gut microbiota in chronic use of methamphetamine have been mentioned as contributors to psychotic and anxiety symptoms, sleep problems, and loss of appetite. OBJECTIVE: In this placebo-controlled clinical trial, we investigated the effect of the probiotic Lactobacillus Acidophilus in improving psychiatric symptoms among hospitalized patients with chronic methamphetamine use along with psychotic symptoms. METHODS: 60 inpatients with a history of more than 3 years of methamphetamine use, were randomly assigned to one of two groups receiving either a probiotic capsule or placebo along with risperidone for 8 weeks based on a simple randomization method. In weeks 0, 4, and 8, patients were evaluated using the Brief Psychiatric Rating Scale (BPRS), Beck Anxiety Inventory (BAI), Pittsburgh Sleep Quality Index (PSQI), Simple Appetite Nutritional Questionnaire (SANQ), and Body Mass Index (BMI). RESULTS: Compared to the control group, patients receiving probiotics had better sleep quality, greater appetite, and higher body mass index (there were significant interaction effects of group and time at Week 8 in these variables (t = -3.32, B = -1.83, p = .001, d = 0.89), (t = 10.50, B = 2.65, p <.001, d = 1.25) and (t = 3.40, B = 0.76, p <.001, d = 0.30), respectively. In terms of the improvement of psychotic and anxiety symptoms, there was no statistically significant difference between the two groups. CONCLUSIONS: The use of probiotics was associated with improved sleep quality, increased appetite, and increased body mass index in patients with chronic methamphetamine use. Conducting more definitive clinical trials with larger sample sizes and longer-term follow-up of cases is recommended.

Maternal immune activation and estrogen receptor modulation induce sex-specific dopamine-related behavioural and molecular alterations in adult rat offspring.

Dopamine dysregulation contributes to psychosis and cognitive deficits in schizophrenia that can be modelled in rodents by inducing maternal immune activation (MIA). The selective estrogen receptor (ER) modulator, raloxifene, can improve psychosis and cognition in men and women with schizophrenia. However, few studies have examined how raloxifene may exert its therapeutic effects in mammalian brain in both sexes during young adulthood (age relevant to most prevalent age at diagnosis). Here, we tested the extent to which raloxifene alters dopamine-related behaviours and brain transcripts in young adult rats, both control and MIA-exposed females and males. We found that raloxifene increased amphetamine (AMPH)-induced locomotor activity in female controls, and in contrast, raloxifene reduced AMPH-induced locomotor activity in male MIA offspring. We did not detect overt prepulse inhibition (PPI) deficits in female or male MIA offspring, yet raloxifene enhanced PPI in male MIA offspring. Whereas, raloxifene ameliorated increased startle responsivity in female MIA offspring. In the substantia nigra (SN), we found reduced Drd2s mRNA in raloxifene-treated female offspring with or without MIA, and increased Comt mRNA in placebo-treated male MIA offspring relative to placebo-treated controls. These data demonstrate an underlying dopamine dysregulation in MIA animals that can become more apparent with raloxifene treatment, and may involve selective alterations in dopamine receptor levels and dopamine breakdown processes in the SN. Our findings support sex-specific, differential behavioural responses to ER modulation in MIA compared to control offspring, with beneficial effects of raloxifene treatment on dopamine-related behaviours relevant to schizophrenia found in male MIA offspring only.

The Influence of Genetic Polymorphic Variability of the Catechol-O-methyltransferase Gene in a Group of Patients with a Diagnosis of Behavioural Addiction, including Personality Traits.

Gambling Disorder (GD) is characterised by a harmful, enduring, and recurrent involvement in betting-related behaviours. Therefore, GD shares similar biological mechanisms and symptoms to substance use disorders (SUD). Therefore, in this study, we chose the behavioural addictions group. During the examination and recruitment to the study, it turned out that all the people undergoing treatment for gambling addiction were also addicted to amphetamines, which is consistent with the biological mechanism related to cerebral neurotransmission. The aim of the study was to investigate the association of the COMT gene polymorphism with behavioral addiction. The study group consisted of 307 participants: 107 men with gambling disorder and amphetamine dependency (mean age = 27.51, SD = 5.25) and 200 non-addicted, nor dependent, free from neuro-psychiatric disorders control group men (mean age = 20.20, SD = 4.51). Both groups were subjected to psychometric evaluation using the State-Trait Anxiety Inventory and the NEO Five-Factor Personality Inventory. Genomic DNA was extracted from venous blood following standard protocols. Determination of the rs4680 polymorphism in the COMT gene was performed using the real-time PCR technique. Statistically significant differences in the frequency of rs4680 genotypes were found in the tested sample of subjects compared with the control group (p = 0.03543). Subjects with gambling disorder and amphetamine use disorder compared to the control group obtained higher scores in the assessment of the STAI trait scale (p = 0.0019), state scale (p < 0.0000), and NEO-FFI Neuroticism scale (p < 0.0000). Significantly lower results were obtained for the NEO-FFI Agreeability scale (p < 0.0000). Additionally, a significant statistical impact of gambling disorder and amphetamine use disorder, and the COMT rs4680 genotype was demonstrated for the score of the STAI trait (p = 0.0351) and state (p = 0.0343) and the NEO-FFI Conscientiousness scale (p = 0.0018). We conclude that COMT and its polymorphic variant influence the development of addiction. Still, considering its multifactorial and polygenic nature, it should be combined with other factors such as personality.

Structural insights into vesicular monoamine storage and drug interactions.

Biogenic monoamines-vital transmitters orchestrating neurological, endocrinal and immunological functions1-5-are stored in secretory vesicles by vesicular monoamine transporters (VMATs) for controlled quantal release6,7. Harnessing proton antiport, VMATs enrich monoamines around 10,000-fold and sequester neurotoxicants to protect neurons8-10. VMATs are targeted by an arsenal of therapeutic drugs and imaging agents to treat and monitor neurodegenerative disorders, hypertension and drug addiction1,8,11-16. However, the structural mechanisms underlying these actions remain unclear. Here we report eight cryo-electron microscopy structures of human VMAT1 in unbound form and in complex with four monoamines (dopamine, noradrenaline, serotonin and histamine), the Parkinsonism-inducing MPP+, the psychostimulant amphetamine and the antihypertensive drug reserpine. Reserpine binding captures a cytoplasmic-open conformation, whereas the other structures show a lumenal-open conformation stabilized by extensive gating interactions. The favoured transition to this lumenal-open state contributes to monoamine accumulation, while protonation facilitates the cytoplasmic-open transition and concurrently prevents monoamine binding to avoid unintended depletion. Monoamines and neurotoxicants share a binding pocket that possesses polar sites for specificity and a wrist-and-fist shape for versatility. Variations in this pocket explain substrate preferences across the SLC18 family. Overall, these structural insights and supporting functional studies elucidate the mechanism of vesicular monoamine transport and provide the basis to develop therapeutics for neurodegenerative diseases and substance abuse.

Forebrain EAAT3 Overexpression Increases Susceptibility to Amphetamine-Induced Repetitive Behaviors.

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder characterized by intrusive obsessive thoughts and compulsive behaviors. Multiple studies have shown the association of polymorphisms in the SLC1A1 gene with OCD. The most common of these OCD-associated polymorphisms increases the expression of the encoded protein, excitatory amino acid transporter 3 (EAAT3), a neuronal glutamate transporter. Previous work has shown that increased EAAT3 expression results in OCD-relevant behavioral phenotypes in rodent models. In this study, we created a novel mouse model with targeted, reversible overexpression of Slc1a1 in forebrain neurons. The mice do not have a baseline difference in repetitive behavior but show increased hyperlocomotion following a low dose of amphetamine (3 mg/kg) and increased stereotypy following a high dose of amphetamine (8 mg/kg). We next characterized the effect of amphetamine on striatal cFos response and found that amphetamine increased cFos throughout the striatum in both control and Slc1a1-overexpressing (OE) mice, but Slc1a1-OE mice had increased cFos expression in the ventral striatum relative to controls. We used an unbiased machine classifier to robustly characterize the behavioral response to different doses of amphetamine and found a unique response to amphetamine in Slc1a1-OE mice, relative to controls. Lastly, we found that the differences in striatal cFos expression in Slc1a1-OE mice were driven by cFos expression specifically in D1 neurons, as Slc1a1-OE mice had increased cFos in D1 ventral medial striatal neurons, implicating this region in the exaggerated behavioral response to amphetamine in Slc1a1-OE mice.

Angiotensin II involvement in the development and persistence of amphetamine-induced sensitization: Striatal dopamine reuptake implications.

Amphetamine (AMPH) exposure induces behavioural and neurochemical sensitization observed in rodents as hyperlocomotion and increased dopamine release in response to a subsequent dose. Brain Angiotensin II modulates dopaminergic neurotransmission through its AT1 receptors (AT1-R), positively regulating striatal dopamine synthesis and release. This work aims to evaluate the AT1-R role in the development and maintenance of AMPH-induced sensitization. Also, the AT1-R involvement in striatal dopamine reuptake was analysed. The sensitization protocol consisted of daily AMPH administration for 5 days and tested 21 days after withdrawal. An AT1-R antagonist, candesartan, was administered before or after AMPH exposure to evaluate the participation of AT1-R in the development and maintenance of sensitization, respectively. Sensitization was evaluated by locomotor activity and c-Fos immunostaining. Changes in dopamine reuptake kinetics were evaluated 1 day after AT1-R blockade withdrawal treatment, with or without the addition of AMPH in vitro. The social interaction test was performed as another behavioural output. Repeated AMPH exposure induced behavioural and neurochemical sensitization, which was prevented and reversed by candesartan. The AT1-R blockade increased the dopamine reuptake kinetics. Neither the AMPH administration nor the AT1-R blockade altered the performance of social interaction. Our results highlight the AT1-R's crucial role in AMPH sensitization. The enhancement of dopamine reuptake kinetics induced by the AT1-R blockade might attenuate the neuroadaptive changes that lead to AMPH sensitization and its self-perpetuation. Therefore, AT1-R is a prominent candidate as a target for pharmacological treatment of pathologies related to dopamine imbalance, including drug addiction and schizophrenia.

Post-translational mechanisms in psychostimulant-induced neurotransmitter efflux.

The availability of monoamine neurotransmitters in the brain is under the control of dopamine, norepinephrine, and serotonin transporters expressed on the plasma membrane of monoaminergic neurons. By regulating transmitter levels these proteins mediate crucial functions including cognition, attention, and reward, and dysregulation of their activity is linked to mood and psychiatric disorders of these systems. Amphetamine-based transporter substrates stimulate non-exocytotic transmitter efflux that induces psychomotor stimulation, addiction, altered mood, hallucinations, and psychosis, thus constituting a major component of drug neurochemical and behavioral outcomes. Efflux is under the control of transporter post-translational modifications that synergize with other regulatory events, and this review will summarize our knowledge of these processes and their role in drug mechanisms.

The role of sex and drug use during adolescence in determining the risk for adverse consequences of amphetamines.

Use of amphetamines during adolescence, a critical period of brain development and reorganization, may lead to particularly adverse outcomes that are long-lasting. Similarly, female users may be uniquely vulnerable to certain aspects of drug use. A recognition of the role of use during adolescence and sex on outcomes of amphetamine and methamphetamine exposure are of critical importance in understanding and treating substance use disorders. This chapter highlights what human research, which has been largely epidemiological, suggests about sex and age differences in drug use patterns and outcomes. We also discuss work in laboratory animals that has typically utilized rats or mice exposed to drugs in a non-contingent manner (i.e., involuntarily) or through volitional self-administration. Lastly, we draw attention to the fact that advancing our understanding of the effects of amphetamine and methamphetamine use, the development of problematic drug taking, and the mechanisms that contribute to relapse will require an emphasis on inclusion of age and sex as moderating factors in future studies.

Cholesterol modulation of interactions between psychostimulants and dopamine transporters.

The dopamine transporter (DAT) is a key site of action for cocaine and amphetamines. Dysfunctional DAT is associated with aberrant synaptic dopamine transmission and enhanced drug-seeking and taking behavior. Studies in cultured cells and ex vivo suggest that DAT function is sensitive to membrane cholesterol content. Although it is largely unknown whether psychostimulants alter cholesterol metabolism in the brain, emerging evidence indicates that peripheral cholesterol metabolism is altered in patients with psychostimulant use disorder and circulating cholesterol levels are associated with vulnerability to relapse. Cholesterol interacts with sphingolipids forming lipid raft microdomains on the membrane. These cholesterol-rich lipid raft microdomains serve to recruit and assemble other lipids and proteins to initiate signal transduction. There are two spatially and functionally distinct populations of the DAT segregated by cholesterol-rich lipid raft microdomains and cholesterol-scarce non-raft microdomains on the plasma membrane. These two DAT populations are differentially regulated by DAT blockers (e.g. cocaine), substrates (e.g. amphetamine), and protein kinase C providing distinct cholesterol-dependent modulation of dopamine uptake and efflux. In this chapter, we summarize the impact of depletion and addition of membrane cholesterol on DAT conformational changes between the outward-facing and the inward-facing states, lipid raft-associated DAT localization, basal and induced DAT internalization, and DAT function. In particular, we focus on how the interactions of the DAT with cocaine and amphetamine are influenced by membrane cholesterol. Lastly, we discuss the therapeutic potential of cholesterol-modifying drugs as a new avenue to normalize DAT function and dopamine transmission in patients with psychostimulant use disorder.

The pharmacology and neurotoxicology of synthetic cathinones.

The synthetic cathinones are man-made compounds derived from the naturally occurring drug cathinone, which is found in the khat plant. The drugs in this pharmacological class that will be the focus of this chapter include mephedrone, MDPV, methcathinone and methylone. These drugs are colloquially known as "bath salts". This misnomer suggests that these drugs are used for health improvement or that they have legitimate medical uses. The synthetic cathinones are dangerous drugs with powerful pharmacological effects that include high abuse potential, hyperthermia and hyperlocomotion. These drugs also share many of the pharmacological effects of the amphetamine class of drugs including methamphetamine, amphetamine and MDMA and therefore have high potential to cause damage to the central nervous system. The synthetic cathinones are frequently taken in combination with other psychoactive drugs such as alcohol, marijuana and the amphetamine-like stimulants, creating a situation where heightened pharmacological and neurotoxicological effects are likely to occur. Despite the structural features shared by the synthetic cathinones and amphetamine-like stimulants, including their actions at monoamine transporters and receptors, the effects of the synthetic cathinones do not always match those of the amphetamines. In particular, the synthetic cathinones are far less neurotoxic than their amphetamine counterparts, they produce a weaker hyperthermia, and they cause less glial activation. This chapter will briefly review the pharmacology and neurotoxicology of selected synthetic cathinones with the aim of delineating key areas of agreement and disagreement in the literature particularly as it relates to neurotoxicological outcomes.

Adicciones y enfermedades neurodegenerativas: Dianas comunes en la búsqueda de nuevas terapias / Addictions and neurodegenerative diseases: Common targets in the search for new therapies

La Pleiotrofina (PTN) es un factor neurotrófico para las neuronas dopaminérgicas cuya expresión se encuentra aumentada en el cerebro de pacientes alcohólicos, en roedores tras la administración de anfetamina y en pacientes con distintas enfermedades neurodegenerativas. La PTN limita los efectos neurotóxicos de las anfetaminas en el circuito nigroestriatal, que en el ser humano pueden llevar a causar la enfermedad de Parkinson. Además, la PTN limita los efectos reforzadores del alcohol.La PTN es un inhibidor endógeno del receptor de membrana Proteína Fosfatasa de Tirosinas Z1 (PTPRZ1, también conocido como RPTPβ/ζ o Fosfacano). Hemos demostrado que se pueden reproducir los efectos de la PTN con inhibidores selectivos del receptor RPTPβ/ζ que obtuvimos a través de un programa de diseño racional de fármacos. El compuesto líder inhibidor de RPTPβ/ζ, MY10, disminuye significativamente el consumo de alcohol en modelos animales y regula la respuesta neuroinmune a esta droga, logrando bloquear la disminución de la neurogénesis hipocampal producida por el alcohol, poniendo de manifiesto importantes diferencias entre sexos.Se ha demostrado que RPTPβ/ζ es un punto de anclaje clave para las redes perineuronales (PNNs) en la superficie celular, las cuales desempeñan un papel importante en la adicción al alcohol. En el hipocampo juegan un papel fundamental en la neurogénesis y el aprendizaje, lo que sugiere que los efectos de MY10 sobre el consumo de alcohol y la disminución de la neurogénesis hipocampal inducida por esta droga, podrían estar mediados por las acciones de la inhibición de RPTPβ/ζ sobre las PNNs.(AU)

Pleiotrophin (PTN) is a neurotrophic factor for dopaminergic neurons whose levels of expression are increased in the brain of alcoholic patients, in rodents after the administration of amphetamine and in patients with different neurodegenerative diseases. PTN limits the neurotoxic effects of amphetamines in the nigrostriatal pathway which, in humans, can lead to Parkinson’s disease. Additionally, PTN limits the rewarding effects of alcohol.PTN is an endogenous inhibitor of the Receptor Protein Tyrosine Phosphatase Z1 (PTPRZ1, also known as RPTPβ/ζ or Phosphacan). We have shown that the effects of PTN can be reproduced with selective inhibitors of RPTPβ/ζ that we obtained through a rational drug design program. The leading RPTPβ/ζ inhibitory compound, MY10, significantly reduces alcohol consumption in animal models and regulates the neuroimmune response to this drug, blocking as a result the decrease in hippocampal neurogenesis produced by alcohol, revealing important differences between sexes.RPTPβ/ζ has been shown to be a key anchor for cell surface perineuronal nets (PNNs), which play an important role in alcohol addiction. In the hippocampus PNNs play a fundamental role in neurogenesis and learning, suggesting that the effects of MY10 on alcohol consumption and the decrease in hippocampal neurogenesis induced by this drug could be mediated by the actions of RPTPβ/ζ inhibition on the PNNs.(AU)