Effects of ethanol on the accumbal output of dopamine,GABA and glutamate in alcohol-tolerant and alcohol-nontolerant rats

Effects of ethanol on the accumbal extracellular concentrations of dopamine, as well as of the amino acid transmitters gamma-amino butyric acid (GABA), glutamate and taurine, were studied in the alcohol-insensitive (alcohol-tolerant, AT) and alcohol-sensitive (alcohol-nontolerant, ANT) rats selected for low and high sensitivity to ethanol-induced motor impairment. Ethanol (2 or 3 g/kg ip) enhanced the output of dopamine and its metabolites in freely moving rats of both lines as measured by in vivo microdialysis. The effect of ethanol on the metabolites of dopamine tended to be stronger in the ANT rats. The smaller dose of ethanol decreased the output of GABA only in the AT rats, whereas the larger dose of ethanol decreased the output of GABA in rats of both lines to a similar degree. Ethanol at the dose of 2 g/kg slightly, but statistically, significantly decreased the output of glutamate in rats of both lines, but the larger dose of ethanol decreased the output of glutamate only in the AT rats. Ethanol at the dose of 2 g/kg induced a small transient increase in the output of taurine within 2 h after its administration in rats of both lines, but the larger dose of ethanol was without significant effect. These results confirm the previous findings that ethanol suppresses the release of GABA more in the AT than ANT rats. Thus, among the neurotransmitter systems we studied, the effects of ethanol might be the most relevant on GABAergic transmission regarding the sensitivity towards ethanol. However, our findings suggest that glutamate is also involved in this respect.