ADHD pharmacotherapy uses methylphenidate (MPH), D-amphetamine (D- amph), two psychostimulants targeting dopamine transporters, or atomoxetine (ATX), specifically targeting norepinephrine transporters. We have assessed the pharmacological mechanisms of these three drugs on the in vitro efflux of neurotransmitters in rat prefrontal cortex (PFC) and striatal slices as well as on the in vivo electrical activities of PFC pyramidal neurons, striatal medium spiny neurons, ventral tegmental area dopamine neurons or dorsal raphe nucleus serotonin neurons, using single cell extracellular electrophysiological recording techniques. We have also tested whether chronic methylphenidate treatment, during either adolescence or adulthood, could have long-lasting consequences on body growth, depression and neuronal functions. Release experiments showed that all ADHD drugs induce dose-dependent dopamine efflux in both the PFC and striatum, with different efficacies, while only D- amph induced cortical norepinephrine efflux. Atomoxetine induced an unexpected massive dopamine outflow in striatal regions, by mechanisms that depend on physiological parameters. Our electrophysiological studies indicate that all three drugs equally stimulate the excitability of PFC pyramidal neurons, in basal and NMDA-evoked conditions, when administered acutely (3 mg/kg). While the electrophysiological effects elicited by psychostimulants may be dependent on D1 receptor activation, those induced by atomoxetine relied on different mechanisms. In the ventral tegmental area (VTA), methylphenidate (2 mg/kg), but not atomoxetine, induced firing and burst activity reductions, through dopamine D2 autoreceptor activation. Reversal of such effects (eticlopride 0.2 mg/kg) revealed an excitatory effect of methylphenidate on midbrain dopamine neurons that appear to be dependent on glutamate pathways and the combination of D1 and alpha-1 receptors. Finally, acute intraperitoneal psychostimulant injections increased vertical locomotor activity as well as NMDA2B protein expression in the striatum. Some animals chronically treated with intraperitoneal administrations (methylphenidate 4 mg/kg/day or saline 1.2 ml/kg/day) showed decreased body weight gain. Voluntary oral methylphenidate intake induces desensitisation to subsequent intravenous methylphenidate challenges, without altering dopamine D2 receptor plasticity. Significant decreases in striatal NMDA2B protein expression were observed in animals chronically treated. After adolescent MPH treatment, midbrain dopaminergic neurons do not display either desensitisation or sensitisation to intravenous methylphenidate re-challenges. However, partial dopamine D2 receptor desensitisation was observed in midbrain dopamine neurons. Using behavioural experiments, cross-sensitisation between adolescent methylphenidate exposure and later-life D-amphetamine challenge was observed. Significant decreases in striatal NMDA2B protein expression were observed in animals chronically treated, while striatal medium spiny neurons showed decreased sensitivities to locally applied NMDA and dopamine. While caffeine is devoid of action on baseline spike generation and burst activity of dopamine neurons, nicotine induces either firing rate enhancement, firing rate reduction, or has no consequences. Adolescent methylphenidate treatment leads to decreased neuronal sensitivities to the combination of nicotine, MPH and eticlopride, compared to controls. Finally, nicotine partially prevented D-amphetamine-induced increase of rearing activities. Our results show that increases in the excitability of PFC neurons in basal conditions and via NMDA receptor activation may be involved in the therapeutic response to ADHD drugs. Long-term consequences were observed after psychostimulant exposure. Such novel findings strengthen the mixed hypothesis in ADHD, whereby both dopamine and glutamate neurotransmissions are dysregulated. Therefore, ADHD therapy may now focus on adequate balancing between glutamate and dopamine.

Introduction : La douleur est un phénomène complexe dont la neurophysiologie est encore mal caractérisée chez les enfants. De nombreux neurotransmetteurs sont impliqués, dont plusieurs jouent également un rôle dans le trouble déficitaire de l’attention avec ou sans hyperactivité (TDA/H), un diagnostic très fréquent dans la population pédiatrique. Notre étude avait comme objectif de mieux caractériser les mécanismes de la douleur chez les enfants. En second lieu, nous avons décrits ces mêmes mécanismes dans un groupe de jeunes atteints du TDA/H. Méthode : 54 participants sains de 7 à 17 ans ont été recrutés, dont 25 enfants (7-11 ans) et 29 adolescents (11-17 ans). 25 autres sujets (17 garçons) avec un diagnostic de TDA/H ont constitué un second groupe. Deux visites avaient lieu pour ce groupe : l’une avec prise régulière de médication psychostimulante et l’autre après un arrêt thérapeutique. Chaque sujet avec TDA/H a été apparié avec un sujet sans ce diagnostic selon l’âge et le sexe. La douleur était mesurée grâce à une stimulation thermique appliquée sur l’avant-bras droit et l’immersion de l’avant-bras gauche un bain d’eau froide (10,0 °C). La modulation conditionnée de la douleur (MCD) était calculée par la différence de la douleur perçue pendant une stimulation thermique de 120 secondes (stimulus test) avant et après le bain d’eau froide (stimulus conditionnant). La sommation temporelle (ST) était calculée en observant l’augmentation de la douleur au cours de la stimulation thermique. Résultats : Chez sujets sans TDA/H, aucune réduction de la douleur par la MCD n’était observable pour les 7-11 ans. À l’opposé, la MCD était efficace sur une courte durée pour les garçons adolescents, tandis qu’elle avait un effet plus soutenu chez les adolescentes. La MCD était inefficace chez les enfants sains appariés et les enfants avec TDA/H. La ST n’était pas influencée par le sexe, l’âge ou le statut TDA/H. En comparant les enfants sains et ceux avec TDA/H, le seuil de douleur était similaire. Toutefois, le seuil de tolérance thermique était plus faible chez les enfants avec TDA/H lors de la visite sans médication. La tolérance au bain d’eau froide était également plus faible pour les enfants atteints du TDA/H, peu importe la prise de psychostimulants. Conclusion : La MCD était absente chez les enfants prépubères mais très efficace chez les adolescentes, ce qui suggère un effet important de la maturation neurophysiologique et hormonale dans le développement de la MCD. Les jeunes avec TDA/H ont une moins bonne tolérance à la douleur, ce que les psychostimulants semblent corriger partiellement. Toutefois, notre étude ne permet pas de conclure sur l’effet du TDA/H sur la MCD.

Cathinones are psychostimulant compounds heavily implicated as drugs of abuse. They exert their physiological actions at the monoamine transporters, which are responsible for maintaining synaptic neurotransmitter homeostasis. Monoamine transporters produce currents during transport and have been shown to depolarize cell membranes and activate voltage-gated calcium channels in mammalian expression systems. This phenomenon is harnessed in an assay which measures these induced calcium transients, allowing for quantification of pharmacodynamic effects of compounds at monoamine transporters. It is unknown if this electrical coupling occurs in neurons, but the implications if it does are significant. In the current work, fluorescent resonance energy transfer studies of HEK cells expressing hDAT suggest that a subpopulation of monoamine transporters and calcium channels may be interacting directly. Additionally, this work presents calcium assay data comparing several novel methcathinone analogs. Of the compounds tested, a single α-methyl substituent at the α-carbon yields the greatest potency at hDAT. The implications of these results shed light on future psychostimulant studies and further define the physiological relationship of the components of a system used to study these compounds.

Psychostimulant dependence is a major public health issue in many parts of the world associated with a wide range of psychological, medical and social problems. Psychosocial interventions are the mainstay of treatment for psychostimulant problems, although their effectiveness is compromised by poor uptake and compliance. Despite increasing knowledge of the neurobiological consequences of psychostimulant use, no medications to date have been any more successful than placebo in reducing psychostimulant use in dependent patients. Modafinil is a non-amphetamine type psychostimulant that may have potential as an agonist pharmacotherapy for psychostimulant dependence. The aim of this thesis was to examine the safety, efficacy and cost-effectiveness of modafinil 200 mg/day over ten weeks plus a four session brief CBT intervention for methamphetamine and cocaine dependence through two concurrent randomised placebo controlled trials. There were no statistically significant differences between modafinil and placebo in treatment retention, medication adherence, psychostimulant abstinence, psychostimulant craving or severity of psychostimulant dependence. Methamphetamine-dependent subjects tended to provide more illicit psychostimulant negative urine samples while in treatment than those who received placebo. There appeared to be a reduction in self-reported days of psychostimulant use among methamphetamine-dependent subjects who received modafinil compared to placebo, but the effect size was too small to be statistically significant in this sample. The reduction in self-reported psychostimulant use did reach statistical significance in methamphetamine-dependent subjects with no other substance dependence. Uptake of counselling was the most significant predictor of reduced psychostimulant use post treatment, and the addition of counselling improved the cost-effectiveness of modafinil relative to placebo. Modafinil appeared to be safe, well-tolerated, and non-reinforcing in this treatment population. Compared to placebo, there was a significant increase in weight in subjects who completed the 10-week course of treatment, and a significant decrease in systolic blood pressure in methamphetamine-dependent subjects who received modafinil. The results support further trials of modafinil in methamphetamine-dependent patients, although future trials in cocaine-dependent patients from this treatment population were not likely to be viable. Modafinil appeared to be modestly effective in reducing, but not stopping, methamphetamine use in selected patients. Multi-centre trials with larger sample sizes, and measures sensitive enough to detect quantitative changes in psychostimulant use would be needed to confirm the findings. Blood pressure and weight may be important indicators of clinical outcome, and warrant particular attention in future trials, particularly given the cardio-toxicity of both methamphetamine and cocaine. Strategies to enhance medication adherence including a higher dose and counselling adherence are recommended to improve outcomes. Given the predominance of behavioural and psychosocial factors in psychostimulant dependence, it is likely that the role of medications such as modafinil will be as an adjunct to psychosocial therapy.

Psychostimulant dependence is a major public health issue in many parts of the world associated with a wide range of psychological, medical and social problems. Psychosocial interventions are the mainstay of treatment for psychostimulant problems, although their effectiveness is compromised by poor uptake and compliance. Despite increasing knowledge of the neurobiological consequences of psychostimulant use, no medications to date have been any more successful than placebo in reducing psychostimulant use in dependent patients. Modafinil is a non-amphetamine type psychostimulant that may have potential as an agonist pharmacotherapy for psychostimulant dependence. The aim of this thesis was to examine the safety, efficacy and cost-effectiveness of modafinil 200 mg/day over ten weeks plus a four session brief CBT intervention for methamphetamine and cocaine dependence through two concurrent randomised placebo controlled trials. There were no statistically significant differences between modafinil and placebo in treatment retention, medication adherence, psychostimulant abstinence, psychostimulant craving or severity of psychostimulant dependence. Methamphetamine-dependent subjects tended to provide more illicit psychostimulant negative urine samples while in treatment than those who received placebo. There appeared to be a reduction in self-reported days of psychostimulant use among methamphetamine-dependent subjects who received modafinil compared to placebo, but the effect size was too small to be statistically significant in this sample. The reduction in self-reported psychostimulant use did reach statistical significance in methamphetamine-dependent subjects with no other substance dependence. Uptake of counselling was the most significant predictor of reduced psychostimulant use post treatment, and the addition of counselling improved the cost-effectiveness of modafinil relative to placebo. Modafinil appeared to be safe, well-tolerated, and non-reinforcing in this treatment population. Compared to placebo, there was a significant increase in weight in subjects who completed the 10-week course of treatment, and a significant decrease in systolic blood pressure in methamphetamine-dependent subjects who received modafinil. The results support further trials of modafinil in methamphetamine-dependent patients, although future trials in cocaine-dependent patients from this treatment population were not likely to be viable. Modafinil appeared to be modestly effective in reducing, but not stopping, methamphetamine use in selected patients. Multi-centre trials with larger sample sizes, and measures sensitive enough to detect quantitative changes in psychostimulant use would be needed to confirm the findings. Blood pressure and weight may be important indicators of clinical outcome, and warrant particular attention in future trials, particularly given the cardio-toxicity of both methamphetamine and cocaine. Strategies to enhance medication adherence including a higher dose and counselling adherence are recommended to improve outcomes. Given the predominance of behavioural and psychosocial factors in psychostimulant dependence, it is likely that the role of medications such as modafinil will be as an adjunct to psychosocial therapy.

Psychostimulant abuse is a major public health concern yet no FDA-approved medications exist. Synthetic cathinones (“bath salts”) are a class of psychostimulants that have emerged relatively recently worldwide. One synthetic cathinone, MDPV (3,4-methylenedioxypyrovalerone) is mechanistically similar to cocaine but is over ten times more potent, possesses high abuse potential, and is relatively understudied. Recent studies have revealed involvement of inflammatory proteins called chemokines in the rewarding effects of MDPV and the mechanistically similar drug, cocaine. We and others have shown that the chemokine-receptor ligand pair CXCL12-CXCR4 is recruited in the rewarding effects of cocaine and MDPV. Humans and animal models of cocaine addiction have dysregulated CXCL12 and the commercially-available CXCR4 antagonist, AMD3100, can reverse cocaine use and relapse in preclinical models of addiction. Specifically, AMD3100 reduces self-administration and reinstatement to cocaine-seeking with concomitant alterations in CXCL12 gene expression in the midbrain. Here, I employ several complementary methods to demonstrate that AMD3100 also reverses MDPV-elicited behaviors. I demonstrate that (i) AMD3100 reverses MDPV-induced hyperlocomotion, conditioned place preference (preclinical model of drug reward), self-administration and reinstatement to MDPV-seeking behavior; (ii) AMD3100 can rescue MDPV-induced deficits in measures of anxiety and recognition memory shortly after a binge; and (iii) repeated MDPV exposure upregulates CXCL12 gene expression in the nucleus accumbens with concomitant downregulation of dendrite morphometrics and a related synapse scaffolding protein gene expression. These findings implicate CXCR4-CXCL12 signaling in the modulation of MDPV-elicited behaviors, suggesting that AMD3100 is a viable therapeutic option for the effects of this synthetic cathinone. / Psychology

A series of rigid azetidenyl-based methamphetamine analogs were synthesized from commercially available N-Boc-azetidinone. The benzylideneazetidine analogs were prepared via a Wittig olefination via the ylides generated from the corresponding triphenylphosphonium benzylhalide salts. The substituted benzylazetidine analogs were synthesized from the corresponding benzylideneazetidienes via hydrogention over palladium and platinum catalysts. The benzylideneazetidine and benzyliazetidine analogs were evaluated at monoamine transporters as a part of preliminary structure-activity study for the development of novel monoamine transporter ligands. The binding affinities of the azetidine analogs were determined at dopamine (DAT) and serotonin (SERT) transporters in rat brain tissue preparations. The preliminary in vitro binding studies revealed that the rigid scaffold of the azetidine ring system was an effective substitution for the 2-aminopropyl group of methamphetamine and led to compounds with nanomolar binding affinity at dopamine and serotonin. In general, the benzylideneazetidine analogs were more potent than the corresponding benzylazetidine analogs. In addition, the azetidine analogs were more selective for the serotonin transporter than the dopamine transporter. The 3-(3,4-dichlorobenzylidene)azetidine (24m) was the most potent analog of the series with Ki values of 139 nM for SERT and 531 nM for DAT (DAT/SERT = 3.8).

Previous research has shown that cannabidiol (CBD), a non-psychoactive compound in the hemp plant Cannabis sativa, may be useful in treating drug craving, one of the hallmarks of drug addiction. However, the neural mechanism by which CBD attenuates craving is poorly understood. Studies from other laboratories have shown that neuroplastic changes associated with brain NMDA glutamate systems may at least partially serve as a neural mechanism for craving. In the current study, the noncompetitive NMDA receptor antagonist MK-801 maleate was used to induce locomotor sensitization, a form of NMDA glutamate-mediated neuroplasticity, in mice to test the sensitization-attenuating potential of CBD. Separate groups of mice (N=8) received either CBD (1.0 mg/kg, i.p.) or saline thirty minutes prior to an intraperitoneal injection of MK-801 (0.5 mg/kg, i.p.) or saline and tested for locomotor performance in an open field (Induction Trial). Seventy-two hours later all mice, regardless of drug pretreatment, were tested for locomotor activity following a second administration (0.5 mg/kg, i.p.) of MK-801 (Sensitization Trial). Results revealed a significant difference across groups for the Induction Trial, with groups receiving SAL-MK801 and CBD-MK801 significantly more active than SAL-SAL and CBD-SAL groups. Pretreatment with CBD had no effect on the locomotor activating effects of MK-801 during the Sensitization Trial with similar levels of locomotor performance across drug groups. Possibilities for the lack of CBD effects are discussed, as well as implications and future research directions.

No description available.

Introduction: Attention deficit hyperactivity disorder (ADHD) is a common disease in childhood and adolescence. In about 60% of pediatric patients, the symptoms persist into adulthood. Treatment guidelines for adult ADHD patients suggestmultimodal therapy consisting of psychostimulants and psychotherapy.Many adult ADHD patients also suffer frompsychiatric comorbidities, among others obsessive–compulsive disorder (OCD). The treatment of the comorbidity of ADHD and OCD remains challenging as the literature is sparse. Moreover, the impact of psychostimulants on obsessive–compulsive symptoms is still unclear. Case Presentation: Here, we report on a 33-year-old patient with an OCD who was unable to achieve sufficient remission under long-term guideline-based treatment for OCD. The re-examination of the psychological symptoms revealed the presence of adult ADHD as a comorbid disorder. The patient has already been treated with paroxetine and quetiapine for the OCD. Due to the newly established diagnosis of ADHD, extendedrelease methylphenidate (ER MPH) was administered in addition to a serotonin reuptake inhibitor. After a dose of 30mg ER MPH, the patient reported an improvement in both the ADHD and the obsessive–compulsive symptoms. After discharge, the patient reduced ER MPH without consultation with a physician due to subjectively described side effects. The discontinuation of medication led to a renewed increase in ADHD and obsessive– compulsive symptoms. The readjustment to ER MPH in combination with sertraline and quetiapine thereafter led to a significant improvement in the compulsive symptoms again. Conclusion: The present case shows that in ADHD and comorbid obsessive–compulsive disorder, treatment with psychostimulants can improve the obsessive–compulsive symptoms in addition to the ADHD-specific symptoms. To our knowledge, this is only the second case report describing a treatment with ER MPH for an adult patient with OCD and ADHD comorbidity in the literature. Further research, especially randomized controlled trials, is needed to standardize treatment options.