Search results for "Dopamine"
showing 10 items of 660 documents
Dual motor responses elicited by ethanol in the posterior VTA: Consequences of the blockade of μ-opioid receptors
2015
A recent hypothesis, based on electrophysiological and behavioural findings, suggests that ethanol simultaneously exerts opposed effects on the activity of dopamine (DA) neurons in the ventral tegmental area (VTA) through two parallel mechanisms, one promoting and the other reducing the GABA release onto VTA DA neurons. In this sense, the activating effects are mediated by salsolinol, a metabolite of ethanol, acting on the μ-opioid receptors (MORs) located in VTA GABA neurons. The inhibitory effects are, however, triggered by the non-metabolized fraction of ethanol which would cause the GABAA receptors-mediated inhibition of VTA DA neurons. Since both trends tend to offset each other, only…
Effects of bupropion, alone or coadministered with nicotine, on social behavior in mice
2008
Bupropion, administered alone or combined with nicotine, is presently used to treat nicotine dependence. Despite experimental evidence of the complex behavioral actions of this drug, there have been little data reported about its effects on social behavior. Our main aim was to investigate the effects of acute administration of bupropion, alone or plus nicotine, on social interaction in mice. OF1 group-housed male mice were confronted in a neutral cage with an anosmic opponent during a 10 minutes encounter. Time allocated to body care and digging was reduced by administration of bupropion (40 mg/kg) both when administered alone and with nicotine (1 and 0.5 mg/kg). The lowest dose of bupropio…
Gamma-hydroxybutyric acid affects the acquisition and reinstatement of cocaine-induced conditioned place preference in mice
2006
Cocaine addicts very often use different combinations of cocaine and other drugs of abuse such as gamma-hydroxybutyric acid. The objective of the present work was to evaluate the impact of gamma-hydroxybutyric acid administration on the rewarding actions of cocaine, using the conditioned place preference procedure. Cocaine-induced conditioned place preference (50 mg/kg) was studied after pairing this drug with different gamma-hydroxybutyric acid doses (6.25, 12.5, 25, 50 and 100 mg/kg) during either the acquisition or the expression phase of the procedure. After conditioned place preference had been established, and the preference was extinguished, a reinstatement was induced by a dose of c…
rTMS of supplementary motor area modulates therapy-induced dyskinesias in Parkinson disease
2005
The neural mechanisms and circuitry involved in levodopa-induced dyskinesia are unclear. Using repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) in a group of patients with advanced Parkinson disease, the authors investigated whether modulation of SMA excitability may result in a modification of a dyskinetic state induced by continuous apomorphine infusion. rTMS at 1 Hz was observed to markedly reduce drug-induced dyskinesias, whereas 5-Hz rTMS induced a slight but not significant increase.
Alterations in striatal neuropeptide mRNA produced by repeated administration of L-DOPA, ropinirole or bromocriptine correlate with dyskinesia induct…
2002
Chronic administration of L-DOPA to MPTP-treated common marmosets induces marked dyskinesia while repeated administration of equivalent antiparkisonian doses of ropinirole and bromocriptine produces only mild involuntary movements. The occurrence of dyskinesia has been associated with an altered balance between the direct and indirect striatal output pathways. Using in situ hybridisation histochemistry, we now compare the effects of these drug treatments on striatal preproenkephalin-A (PPE-A) and adenosine A(2a) receptor mRNA expression as markers of the indirect pathway and striatal preprotachykinin (PPT) mRNA and preproenkephalin-B (PPE-B, prodynorphin) mRNA expression as markers of the d…
Assessment of the abuse potential of MDMA in the conditioned place preference paradigm: Role of CB1 receptors
2013
Numerous reports have highlighted the role of the endocannabinoid system in the addictive potential of MDMA (3,4-methylenedioxy-methamphetamine). A previous report showed that CB1 knockout (KOCB1) mice do not acquire MDMA self-administration, despite developing conditioned place preference (CPP). This contradiction could be due to the particular procedure of place conditioning used. The present work compares MDMA-induced CPP in KOCB1 mice using unbiased and biased procedures of place conditioning. In the unbiased procedure, MDMA induced CPP and reinstatement of the extinguished preference in wild type (WT) mice, but not in KOCB1 mice. In contrast, in a biased protocol of CPP, MDMA produced …
Sex differences in behavioral traits related with high sensitivity to the reinforcing effects of cocaine
2021
Cocaine is the most prevalent illegal stimulant drug in Europe among the adult population. Its abuse is characterized by a faster substance abuse disorder (SUD) development than other drugs, with high vulnerability to relapse. However, there does not exist an effective treatment for cocaine dependence. Sex differences have been reported in psychological disorders including SUD. For this reason, it is essential to identify risk factors that predict susceptibility or resilience to cocaine addiction for the development of effective prevention strategies considering sex differences. In the present study, the main objective was to determine more sensitive phenotypes to the conditioned reinforcin…
Effects of co-administration of bupropion and nicotinic agonists on the elevated plus-maze test in mice
2005
There is evidence that the cholinergic nicotinic system is involved in the modulation of anxiety. Anxiolytic and anxiogenic effects of nicotine agonists have been reported in mice. Bupropion is an antidepressant drug which may alleviate some symptoms of nicotine withdrawal, although its effects on anxiety are not clear. It has been suggested that the interaction between bupropion and nicotinic mechanisms could be complex. The aim of the present study was to investigate acute effects of co-administration of bupropion and nicotinic agonists on the elevated plus-maze test in NMRI mice. Effects of nicotine, lobeline, and cytisine (0.35 and 0.175 mg/kg), administered alone or combined with bupro…
γ1- and γ2-melanocyte stimulating hormones induce central anxiogenic effects and potentiate ethanol withdrawal responses in the elevated plus-maze te…
2008
Little is known about the endogenous functions of gamma1- and gamma2-melanocyte stimulating hormones (gamma1- and gamma2-MSH). Although gamma-MSHs bind to melanocortin receptor subtypes 3 and 4, we have previously shown that these peptides also influence non-melanocortinergic processes, such as dopaminergic and GABAergic. The aim of this study was to determine the effects of gamma1- and gamma2-MSH (at doses 0.3, 1 and 2 nmol/mouse/5 microl) on the anxiety levels in mice in elevated plus maze. Three experimental paradigms were performed to assess the effects of peptides on: a) ethanol withdrawal; b) acute ethanol-induced anxiolytic action; c) peptides per se. We used ethanol as the model sub…
Peripheral and central CB1 cannabinoid receptors control stress-induced impairment of memory consolidation
2016
Stressful events can generate emotional memories linked to the traumatic incident, but they also can impair the formation of nonemotional memories. Although the impact of stress on emotional memories is well studied, much less is known about the influence of the emotional state on the formation of nonemotional memories. We used the novel object-recognition task as a model of nonemotional memory in mice to investigate the underlying mechanism of the deleterious effect of stress on memory consolidation. Systemic, hippocampal, and peripheral blockade of cannabinoid type-1 (CB1) receptors abolished the stress-induced memory impairment. Genetic deletion and rescue of CB1 receptors in specific ce…