Comparison of the behavioral effects of bupropion and psychostimulants

Anxiolytic and antidepressant-like effects of monoterpene tetrahydrolinalool and in silico approach of new potential targets

INTRODUCTION- The drugs currently available for treatment of anxiety and depression act through modulation of the neurotransmission systems involved in the neurobiology of the disorder, yet they of-ten present side effects, which can impair patient adherence to treatment. METHOD- This, has driven the search for new molecules with anxiolytic and antidepressant potential. Aromatic plants are rich in essential oils, and their chemical constituents, such as monoterpenes, are be-ing studied for these disorders. This study aims to evaluate the anxiolytic and antidepressant-like poten-tial of the monoterpene tetrahydrolinalool in in vivo animal models, and review pharmacological targets with validation through molecular docking. Male Swiss mice (Mus musculus) were treated with THL (37.5-600 mg kg-1 p.o.) and submitted to the elevated plus maze, open field, rota rod, and forced swim tests. In the elevated plus-maze, THL at doses of 37.5 and 75 mg kg-1 induced a significant increase in the percentage of entries (72.7 and 64.3% respectively), and lengths of stay (80.3 and 76.8% respective-ly) in the open arms tests. RESULT- These doses did not compromise locomotor activity or motor coordination in the animals. In the open field, rota rod tests, and the forced swimming model, treatment with THL significantly reduced immobility times at doses of 150, 300, and 600 mg kg-1, and by respective percentages of 69.3, 60.9 and 68.7%. CONCLUSION- In molecular docking assay, which investigated potential targets, THL presented sat-isfactory energy values for: nNOs, SGC, IL-6, 5-HT1A, NMDAr, and D1. These demonstrate the po-tential of THL (a derivative of natural origin) in in vivo and in silico models, making it a drug candidate.

Energizing effects of bupropion on effortful behaviors in mice under positive and negative test conditions: modulation of DARPP-32 phosphorylation patterns

Motivational symptoms such as anergia, fatigue, and reduced exertion of effort are seen in depressed people. To model this, nucleus accumbens (Nacb) dopamine (DA) depletions are used to induce a low-effort bias in rodents tested on effort-based decision-making. We evaluated the effect of the catecholamine uptake blocker bupropion on its own, and after administration of tetrabenazine (TBZ), which blocks vesicular storage, depletes DA, and induces depressive symptoms in humans. Male CD1 mice were tested on a 3-choice-T-maze task that assessed preference between a reinforcer involving voluntary physical activity (running wheel, RW) vs. sedentary activities (sweet food pellet intake or a neutral non-social odor). Mice also were tested on the forced swim test (FST), two anxiety-related measures (dark-light box (DL), and elevated plus maze (EPM)). Expression of phosphorylated DARPP-32 (Thr34 and Thr75) was evaluated by immunohistochemistry as a marker of DA-related signal transduction. Bupropion increased selection of RW activity on the T-maze. TBZ reduced time running, but increased time-consuming sucrose, indicating an induction of a low-effort bias, but not an effect on primary sucrose motivation. In the FST, bupropion reduced immobility, increasing swimming and climbing, and TBZ produced the opposite effects. Bupropion reversed the effects of TBZ on the T-maze and the FST, and also on pDARPP32-Thr34 expression in Nacb core. None of these manipulations affected anxiety-related parameters. Thus, bupropion improved active behaviors, which were negatively motivated in the FST, and active behaviors that were positively motivated in the T-maze task, which has implications for using catecholamine uptake inhibitors for treating anergia and fatigue-like symptoms.

Sex-specific sensitivity to methamphetamine-induced schizophrenia-relevant behaviours in neuregulin 1 type III overexpressing mice

BACKGROUND

Gene-environment interactions contribute to schizophrenia aetiology. Neuregulin 1 is a well-established genetic risk factor for schizophrenia, and elevated expression of type III neuregulin 1 mRNA in the dorsolateral prefrontal cortex is observed in patients with a core risk haplotype. A mouse model of type III Nrg1 overexpression (Nrg1 III tg) possesses face and construct validity for schizophrenia; however, the sensitivity of these transgenic mice to environmental risk factors relevant to schizophrenia is unknown.

AIMS

To determine sensitivity of Nrg1 III tg mice to the psychostimulant methamphetamine (METH) in schizophrenia and addiction-relevant behavioural tests.

METHODS

We examined behavioural responses of adult male and female Nrg1 III tg mice METH (1-3 mg/kg) in schizophrenia-relevant paradigms (drug-induced locomotion, sensorimotor gating) and drug reward (conditioned place preference).

RESULTS

Male Nrg1 III tg mice were less sensitive to METH-induced stereotypies, yet showed a greater negative impact of METH on prepulse inhibition compared with wild type-like males. In contrast, female Nrg1 III tg mice were less sensitive to METH-induced locomotion than wild type-like females, while sensorimotor gating was similarly impaired by METH between the genotypes. There were no genotype differences for METH reward, or anxiety-like and exploratory behaviours.

CONCLUSIONS

These results indicate that overexpression of Nrg1 type III modulates schizophrenia-relevant behaviours, and may help to explain increased sensitivity to the psychoactive effects of METH in patients with schizophrenia.

Effects of chronic treatment with bupropion on self-administration of nicotine + cocaine mixtures in nonhuman primates

Chronic health problems associated with long-term nicotine use are the leading cause of preventable death in the United States. The use of tobacco products is 3-4 times greater among individuals with cocaine use disorder than that observed in the general population. This may reflect the propensity of nicotine to augment the reinforcing effects of cocaine. However, the mechanism of action of nicotine differs from that of cocaine, which presents a significant challenge for the development of pharmacotherapeutic interventions for the management of nicotine + cocaine polydrug abuse. Bupropion, an FDA-approved smoking cessation aid, has pharmacological actions at both monoamine transporters and nicotinic receptors, suggesting that it may be effective at decreasing nicotine + cocaine coabuse. Here, rhesus monkeys (n = 4) responded for food pellets and, separately, intravenous injections of nicotine, cocaine, or nicotine + cocaine mixtures under a second-order FR2(VR16:S) schedule of reinforcement during 7- to 10-day continuous treatment with saline or bupropion (1.0 and 1.8 mg/kg/hr). Results show that bupropion treatment dose-dependently decreased self-administration of nicotine combined with a low dose of cocaine (0.0032 mg/kg/inj); however, when the dose of cocaine in the mixture was higher (i.e., 0.01 mg/kg/inj), bupropion attenuated self-administration in only a subset of subjects. The effective dosage of bupropion increased responding for cocaine alone, nicotine alone, and for saline injections and significantly increased measures of daily activity. The apparent stimulant-like effects of bupropion at the dosage required to decrease cocaine + nicotine self-administration does not support its clinical use for the management of nicotine + cocaine polydrug abuse. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Enhancement of the rewarding effects of 3,4-methylenedioxymethamphetamine in orexin knockout mice

Orexinergic neurons, which are closely associated with narcolepsy, regulate arousal and reward circuits through the activation of monoaminergic neurons. Psychostimulants as well as 5-HT-related compounds have potential in the treatment of human narcolepsy. Previous studies have demonstrated that orexin receptor antagonists as well as orexin deficiencies affect the pharmacological effects of psychostimulants. However, little information is available on the consequences of psychostimulant use under orexin deficiency. Therefore, the present study was designed to investigate the abuse liability of psychostimulants in orexin knockout (KO) mice. In the present study, conditioned place preferences induced by methamphetamine and methylphenidate were not altered in orexin KO mice. Interestingly, we found that MDMA induced a conditioned place preference in orexin KO mice, but not in wild type (WT) mice. In addition, MDMA produced methylphenidate/methamphetamine-like discriminative stimulus effects in orexin KO mice, but not WT mice. Increases in 5-HT and dopamine release in the nucleus accumbens induced by MDMA were not altered by knockout of orexin; the steady-state level of G protein activation was higher in the limbic forebrain of orexin KO mice. In substitution tests using a drug discrimination procedure, substitution of 5-HT_1A receptor agonist for the discriminative stimulus effects of methylphenidate was enhanced in orexin KO mice. These findings indicate that the orexinergic system is involved the rewarding effects of psychostimulants. However, there is a risk of establishing rewarding effects of psychostimulants even under orexin deficiency. On the other hand, deficiencies in orexin may enhance the abuse liability of MDMA by changing a postsynaptic signal transduction accompanied by changes in discriminative stimulus effects themselves.

An Examination of Psychomotor Disturbance in Current and Remitted MDD: An RDoC Study

Major depressive disorder (MDD) is a serious public health problem that has, at best, modest treatment response—potentially due to its heterogeneous clinical presentation. One way to parse the heterogeneity is to investigate the role of particular features of MDD, an endeavor that can also help identify novel and focal targets for treatment and prevention efforts. Our R01 focuses on the feature of psychomotor disturbance (e.g., psychomotor agitation (PmA) and retardation (PmR)), a particularly pernicious feature of MDD, that has not been examined extensively in MDD. Aim 1 is comparing three groups of individuals—those with current MDD (n = 100), remitted MDD (n = 100), and controls (n = 50)—on multiple measures of PmR and PmA (assessed both in the lab and in the subjects’ natural environment). Aim 2 is examining the structural (diffusion MRI) and functional (resting state fMRI) connectivity of motor circuitry of the three groups as well as the relation between motor circuitry and the proposed indicators of PmR and PmA. Aim 3 is following up with subjects three times over 18 months to evaluate whether motor symptoms change in tandem with overall depressive symptoms and functioning over time and/or whether baseline PmR/PmA predicts course of depression and functioning. Aim 3 is particularly clinically significant. Finding that motor functioning and overall depression severity co-vary over time, or that motor variables predict subsequent change in overall depression severity, would support the potential clinical utility of these novel, reliable, and easily administered motor assessments.

Involvement of monoaminergic targets in the antidepressant- and anxiolytic-like effects of the synthetic alkamide riparin IV: Elucidation of further mechanisms through pharmacological, neurochemistry and computational approaches

Despite recent advances, current antidepressants have considerable limitations: late onset of action and the high profile of refractoriness. Biomedical research with natural products has gained growing interest in the last years, and had provide useful candidates for new antidepressants. Riparins are a group of natural alkamides obtained from Aniba riparia, which had marked neuroactive effects, mainly as antidepressant and antinociceptive agents. We made modifications of the basic structure of riparins, originating a synthetic alkamide, also known as riparin IV (RipIV). RipIV demonstrated a superior analgesic effect than its congeners and a marked antidepressant-like effect. However, the basic mechanism for the central effects of RipIV remains unknown. Here, we aimed to investigate the participation of monoaminergic neurotransmission targets in the antidepressant-like effects of RipIV. To do this, we applied a combined approach of experimental (classical pharmacology and neurochemistry) and computer-aided techniques. Our results demonstrated that RipIV presented antidepressant- and anxiolytic-like effects without modifying locomotion and motor coordination of mice. Also, RipIV increased brain monoamines and their metabolite levels. At the higher dose (100 mg/kg), RipIV increased serotonin concentrations in all studied brain areas, while at the lower one (50 mg/kg), it increased mainly dopamine and noradrenaline levels. When tested with selective receptor antagonists, RipIV antidepressant effect showed dependence of the activation of multiple targets, including D1 and D2 dopamine receptors, 5-HT2A/2, 5-HT3 receptors and α2 adrenergic receptors. Molecular docking demonstrated favorable binding conformation and affinity of RipIV to monoamine oxidase B (MAO-B), serotonin transporter (SERT), α1 receptor, D2 receptor, dopamine transporter (DAT) and at some extent GABA-A receptor. RipIV also presented a computationally predicted favorable pharmacokinetic profile. Therefore, this study demonstrated the involvement of monoaminergic targets in the mechanism of RipIV antidepressant-like action, and provide evidence of it as a promising new antidepressant.

Bupropion increases activation in nucleus accumbens during anticipation of monetary reward

RATIONALE

Bupropion is used for major depressive disorder, smoking cessation aid, and obesity. It blocks reuptake of dopamine and noradrenaline and antagonizes nicotinic acetylcholine receptor. Animal studies showed that bupropion enhanced rewarding effects. In addition, bupropion has the potential to treat patients with reward processing dysfunction. However, neural substrates underlying the bupropion effects on reward function in human subjects are not fully understood.

OBJECTIVES

We investigated single-dose administration of bupropion on neural response of reward anticipation in healthy subjects using a monetary incentive delay (MID) task by functional magnetic resonance imaging (fMRI), especially focusing on nucleus accumbens (NAc) activity to non-drug reward stimuli under bupropion treatment.

METHODS

We used a randomized placebo-controlled within-subject crossover design. Fifteen healthy adults participated in two series of an fMRI study, taking either placebo or bupropion. The participants performed the MID task during the fMRI scanning. The effects of bupropion on behavioral performance and blood oxygenation level-dependent (BOLD) signal in NAc during anticipation of monetary gain were analyzed.

RESULTS

We found that bupropion significantly increased BOLD responses in NAc during monetary reward anticipation. The increased BOLD responses in NAc were observed with both low and high reward incentive cues. There was no significant difference between placebo and bupropion in behavioral performance.

CONCLUSIONS

Our findings provide support for the notion that bupropion enhances non-drug rewarding effects, suggesting a possible mechanism underlying therapeutic effects for patients with motivational deficit.

Effects of monoamine uptake inhibitors on pain-related depression of nesting in mice

Pain is a significant public health problem, and assessment of pain-related impairment of behavior is a key clinical indicator and treatment target. Similar to opioids and NSAIDs, dopamine (DA) transporter inhibitors block pain-related depression of intracranial self-stimulation (ICSS) in rats. The primary goal of the present study was to determine if the effects of monoamine uptake inhibitors on pain-related depression of ICSS in rats extend to an assay of pain-related depression of nesting in mice. We hypothesized that the DA transporter-selective uptake inhibitor bupropion would block depression of nesting behavior produced by intraperitoneal injection of lactic acid, whereas selective serotonin transporter-selective citalopram, norepinephrine transporter-selective nisoxetine, and the mixed action selective serotonin transporter/norepinephrine transporter inhibitor milnacipran would be ineffective. Effects of the NSAID ketoprofen were also obtained to facilitate interpretation of the effects of the monoamine uptake inhibitors. Consistent with previous findings, ketoprofen blocked pain-related depression of nesting. In contrast, none of the monoamine uptake inhibitors blocked pain-related depression of nesting, although they all blocked pain-related stimulation of stretching. Unlike findings from studies of pain-related depression of ICSS, these results do not support consideration of DA uptake inhibitors for treatment of pain-related depression of behavior.

Systematic review of preclinical, clinical, and post-marketing evidence of bupropion misuse potential

Background: Bupropion is a substituted cathinone compound widely used as a first line or add-on treatment for depression, smoking cessation, and more recently in combination with naltrexone for weight loss. As abuse of synthetic cathinone compounds has received more attention in recent years, concern about the misuse potential of bupropion has grown as well. Objectives: We review bupropion pharmacology and assessments of misuse potential including preclinical evidence, human studies, and post-marketing surveillance of bupropion misuse. Methods: This review reports the results of a systematic review of publications evaluating the potential for bupropion to be misused. Publications were identified using PubMed and Medline through Ovid® as well as iterative bibliographic searches. A summary of data from informal sources of information including substance-user experience from online forum entries is included. Results: Preclinical evidence demonstrates some potential for misuse based on psychomotor, discrimination, self-administration, and conditioned place preference tasks. However, this potential is less than that of commonly misused stimulants. Studies in human populations similarly indicate that bupropion shares interoceptive effects with other stimulants, but lacks some key reinforcing effects of other stimulants. In the real-world setting, misuse of bupropion occurs, but is uncommon. Adverse effects of bupropion misuse are frequently cited as significant barriers to obtaining any desired interoceptive effect. Conclusions: While bupropion demonstrates some potential for misuse, pharmacological differences from other structurally-related stimulants limit bupropion's reinforcing effects. Without additional data indicating susceptibility of specific populations to bupropion misuse, there is no empirical data suggesting a need to modify bupropion prescribing patterns.

The effect of N-acetylcysteine or bupropion on methamphetamine self-administration and methamphetamine-triggered reinstatement of female rats

N-acetylcysteine and bupropion are two promising candidate medications for treatment of substance use disorder. The effects of N-acetylcysteine or bupropion on methamphetamine self-administration of female rats are not well understood. To fill this gap, this study assessed the effects of N-acetylcysteine (0, 30, 60, or 120 mg/kg) and bupropion (0, 10, 30, and 60 mg/kg) on methamphetamine self-administration of female rats across the natural estrous cycle. Following a completed dose-response curve, responding for methamphetamine self-administration was extinguished and the effects of N-acetylcysteine or bupropion on methamphetamine-triggered reinstatement was evaluated in separate experiments. N-acetylcysteine did not decrease responding maintained by methamphetamine or methamphetamine-triggered reinstatement. Bupropion significantly decreased methamphetamine self-administration and methamphetamine-triggered reinstatement in female rats with highest dose (60 mg/kg) also significantly decreasing general chamber activity. In a companion experiment, testing the effect of bupropion on responding maintained by sucrose, we confirmed non-specificity of bupropion's effects as bupropion also decreased responding for sucrose. Considered together, our findings suggest that while N-acetylcysteine has considerable promise for treatment of cocaine dependence it may not generalize to other stimulants like methamphetamine. Furthermore, although bupropion has been shown to effectively decrease methamphetamine self-administration, and presently methamphetamine-triggered reinstatement, its locomotor and reward suppressing effects warrant further investigation including both sexes.

[Underlying Mechanisms of Methamphetamine-Induced Self-Injurious Behavior and Lethal Effects in Mice]

Relatively high doses of psychostimulants induce neurotoxicity on the dopaminergic system and self-injurious behavior (SIB) in rodents. However the underlying neuronal mechanisms of SIB remains unclear. Dopamine receptor antagonists, N-methyl-D-aspartic acid (NMDA) receptor antagonists, Nitric Oxide Synthase (NOS) inhibitors and free radical scavengers significantly attenuate methamphetamine-induced SIB. These findings indicate that activation of dopamine as well as NMDA receptors followed by radical formation and oxidative stress, especially when mediated by NOS activation, is associated with methamphetamine-induced SIB. On the other hand, an increase in the incidence of polydrug abuse is a major problem worldwide. Coadministered methamphetamine and morphine induced lethality in more than 80% in mice, accompanied by an increase in the number of poly (ADP-ribose) polymerase (PARP)-immunoreactive cells in the heart, kidney and liver. The lethal effect and the increase in the incidence of rupture or PARP-immunoreactive cells induced by the coadministration of methamphetamine and morphine were significantly attenuated by pretreatment with a phospholipase A2 inhibitor or a radical scavenger, or by cooling of body from 30 to 90 min after drug administration. These results suggest that free radicals play an important role in the increased lethality induced by the coadministration of methamphetamine and morphine. Therefore, free radical scavengers and cooling are beneficial for preventing death that is induced by the coadministration of methamphetamine and morphine. These findings may help us better understand for masochistic behavior, which is a clinical phenomenon on SIB, as well as polydrug-abuse-induced acute toxicity.

Assessing the Value of the Zebrafish Conditioned Place Preference Model for Predicting Human Abuse Potential

Regulatory agencies recommend that centrally active drugs are tested for abuse potential before approval. Standard preclinical assessments are conducted in rats or non-human primates (NHPs). This study evaluated the ability of the zebrafish conditioned place preference (CPP) model to predict human abuse outcomes. Twenty-seven compounds from a variety of pharmacological classes were tested in zebrafish CPP, categorized as positive or negative, and analyzed using standard diagnostic tests of binary classification to determine the likelihood that zebrafish correctly predict robust positive signals in human subjective effects studies (+HSE) and/or Drug Enforcement Administration drug scheduling. Results were then compared with those generated for rat self-administration and CPP, as well as NHP self-administration, using this same set of compounds. The findings reveal that zebrafish concordance and sensitivity values were not significantly different from chance for both +HSE and scheduling. Although significant improvements in specificity and negative predictive values were observed for zebrafish relative to +HSE, specificity without sensitivity provides limited predictive value. Moreover, assessments in zebrafish provided no added value for predicting scheduling. By contrast, rat and NHP models generally possessed significantly improved concordance, sensitivity, and positive predictive values for both clinical measures. Although there may be predictive value with compounds from specific pharmacological classes (e.g., µ-opioid receptor agonists, psychostimulants) for zebrafish CPP, altogether these data highlight that using the current methodology, the zebrafish CPP model does not add value to the preclinical assessment of abuse potential.

Pharmacotherapeutic agents in the treatment of methamphetamine dependence

INTRODUCTION

Methamphetamine use is a serious public health concern in many countries and is second to cannabis as the most widely abused illicit drug in the world. Effective management for methamphetamine dependence remains elusive and the large majority of methamphetamine users relapse following treatment. Areas covered: Progression in the understanding of the pharmacological basis of methamphetamine use has provided us with innovative opportunities to develop agents to treat dependence. The current review summarizes relevant literature on the neurobiological and clinical correlates associated with methamphetamine use. We then outline agents that have been explored for potential treatments in preclinical studies, human laboratory phase I and phase II trials over the last ten years. Expert opinion: No agent has demonstrated a broad and strong effect in achieving MA abstinence in Phase II trials. Agents with novel therapeutic targets appear promising. Advancement in MA treatment, including translation into practice, faces several clinical challenges.

A dopamine and noradrenaline reuptake inhibitor (bupropion) does not alter exercise performance of bank voles

Physical performance is determined both by biophysical and physiological limitations and behavioral characteristic, specifically motivation. We applied an experimental evolution approach combined with pharmacological manipulation to test the hypothesis that evolution of increased aerobic exercise performance can be triggered by evolution of motivation to undertake physical activity. We used a unique model system: bank voles from A lines, selected for high swim-induced aerobic metabolism (VO₂swim), which achieved a 61% higher mass-adjusted VO₂swim than those from unselected C lines. Because the voles could float on the water surface with only a minimum activity, the maximum rate of metabolism achieved in that test depended not only on their aerobic capacity, but also on motivation to undertake intensive activity. Therefore, we hypothesized that signaling of neurotransmitters putatively involved in regulating physical activity (dopamine and noradrenaline) had changed in response to selection. We measured VO₂swim after intraperitoneal injections of saline or the norepinephrine and dopamine reuptake inhibitor bupropion (20 mg/kg or 30 mg/kg). Additionally, we measured forced-exercise VO₂ (VO₂max). In C lines, VO₂swim (mass-adjusted mean ± standard error (SE): 4.0 ± 0.1 mLO₂/min) was lower than VO₂max (5.0 ± 0.1 mLO₂/min), but in A lines VO2swim (6.0 ± 0.1 mLO₂/min) was as high as VO₂max (6.0 ± 0.1 mLO₂/min). Thus, the selection effectively changed both the physiological-physical performance limit and mechanisms responsible for the willingness to undertake vigorous locomotor activity. Surprisingly, the drug had no effect on the achieved level of VO₂swim. Thus, the results did not allow firm conclusions concerning involvement of these neurotransmitters in evolution of increased aerobic exercise performance in the experimental evolution model system.

Stimulants for the Control of Hedonic Appetite

The focus of this paper is treatment of obesity in relation to the management of hedonic appetite. Obesity is a complex condition which may be potentiated by excessive reward seeking in combination with executive functioning deficits that impair cognitive control of behavior. Stimulant medications address both reward deficiency and enhance motivation, as well as suppressing appetite. They have long been recognized to be effective for treating obesity. However, stimulants can be abused for their euphoric effect. They induce euphoria via the same neural pathway that underlies their therapeutic effect in obesity. For this reason they have generally not been endorsed for use in obesity. Among the stimulants, only phentermine (either alone or in combination with topiramate) and bupropion (which has stimulant-like properties and is used in combination with naltrexone), are approved by the United States Food and Drug Administration (FDA) for obesity, although dexamphetamine and methylpenidate are approved and widely used for treating attention deficit hyperactivity disorder (ADHD) in adults and children. Experience gained over many years in the treatment of ADHD demonstrates that with careful dose titration, stimulants can be used safely. In obesity, improvement in mood and executive functioning could assist with the lifestyle changes necessary for weight control, acting synergistically with appetite suppression. The obesity crisis has reached the stage that strong consideration should be given to adequate utilization of this effective and inexpensive class of drug.