Taurine blocks the glutamate increase in the nucleus accumbens microdialysate of ethanol-dependent rats

During ethanol withdrawal, dramatic changes in the concentration of many neurotransmitters may be responsible for many of the adverse effects. In the present study, the technique of microdialysis was used to assay the changes in excitatory and inhibitory amino acids after withdrawal from chronic ethanol intoxication. Rats were made physically dependent on ethanol by vapor inhalation for 4 weeks. The basal concentrations of both arginine and GABA were significantly decreased in ethanol-dependent rats, although there were no significant changes in any of the other amino acid basal concentration assayed (i.e.. glutamate and taurine). During the first 12 h after withdrawal from ethanol, only glutamate increased significantly (p < 0.05) at 6 h, and for the duration of the study period of 12 h. To investigate whether either taurine and ethanol interact with amino acids during ethanol withdrawal, two other ethanol-dependent groups were injected with a single intraperitoneal injection of either taurine or ethanol 5 h after commencement of ethanol withdrawal. The IP injection of ethanol (2 g/kg) significantly increased taurine microdialysate content, and although this dose of ethanol was not able to block completely the increase of glutamate release after ethanol withdrawal, a delayed decrease in glutamate content was observed by the end of the period of the study (i.e., 11-12 h). However, IP injection of taurine (45 mg/kg) significantly blocked the increased glutamate release during ethanol withdrawal. This latter finding suggests that taurine may interact with glutamate, possibly by inducing a blockade of glutamate release during ethanol withdrawal.