Dopamine and serotonin neurotransmission in the reinforcing effects of alchol and apomorphine

To determine the role of dopamine and 5-hydroxytryptamine [5-HT; serotonin] in the reinforcing effects of alcohol and apomorphine. Experimental study. Department of Biochemistry, University of Karachi from September to November 2004. The study was conducted on 24 male albino Wistar rats. Reinforcing effects were monitored in a conditioned place preference [CPP] paradigm using a light-dark activity box. Slicing and punching method was used to collect dorsal and ventral striatum. Neurochemical estimations were done by HPLC-EC. Withdrawal from repeated administration of ethanol [1g/kg/day] as well as apomorphine [1 mg/kg/day] elicited reinforcement that could be monitored in a CPP paradigm. CNS depressant effects of ethanol were not altered on repeated administration but CNS stimulatory effects of apomorphine increased. Reinforcing effects of ethanol but not apomorphine were associated with a decrease in dopamine metabolism in the ventral striatum. A decrease in the activity of dopaminergic neurons following withdrawal from repeated administration is involved in the compulsive use of abused drugs

Decrease of ethanol intake following repeated injection of serotonin-1A agonist in rats: relationship with receptor responsiveness

To monitor pre and postsynaptic receptor responsiveness and consumption of ethanol following the repeated administration of a selective serotonin-1A receptor agonist, 8-hydroxy-2-di-n-propylaminotetralin [8-OH-DPAT], to ethanol treated rats. Design: The experimental protocol was designed to administer ethanol orally to rats for three weeks and 8-OH-DPAT during the 3rd week. Place and Duration of Study: The experiments were performed in the department of Biochemistry, Karachi University. Samples collected after three weeks of treatment were analyzed within a week. Subjects and The study was conducted on 24 males albino Wistar rats treated with ethanol for three weeks. 8-OH-DPAT at a dose of 1mg/kg or saline was injected to ethanol treated rats from day 1 to day 5 during the 3rd week to monitor the effects on ethanol consumption. Pre and postsynaptic responses to 8-OH-DPAT were monitored by injecting the drug on the 6th day to a group of 5-day saline and a group of 5-day 8-OH-DPAT injected animals. Control animals of the two groups were injected with saline. Before the injection of 8-OH-DPAT, weekly intakes of ethanol were highly comparable in the two groups. Administration of 8-OH-DPAT, from day 1 to day 5, decreased ethanol intake. Pre and postsynaptic serotonin-1A receptor dependent responses monitored on the 6th day were higher in 5-day saline than 5-day 8-OH-DPAT injected animals. A decrease in the effectiveness of negative feedback control over the synaptic availability of serotonin following 5-day administration of 8-OH-DPAT is involved in the decreases of ethanol consumption