Differential taurine responsiveness to ethanol in high- and low-alcohol sensitive rats: a brain microdialysis study

Abstract

Several microdialysis studies have investigated the effects of acute ethanol on extracellular amino acids in various rat brain regions. However, these studies led to conflicting results, suggesting that individual differences between rat strains and lines may play an important role. In the present study, high-alcohol sensitive (HAS) and low-alcohol sensitive (LAS) rats were used to investigate the possible relationship between ethanol sensitivity and the concentrations of extracellular amino acids in the nucleus accumbens. Several groups of HAS and LAS rats were injected with either saline or ethanol (1.0, 2.0 or 3.0 g/kg, i.p.) and the concentrations of amino acids in the nucleus accumbens microdialysates were assayed by electrochemical detection. Acute ethanol induced a dose-dependent increase in extracellular taurine concentrations. However, this increase was significantly reduced at 2.0 and 3.0 g/kg ethanol in HAS rats relative to LAS rats. Since the biological functions of taurine suggest its implication in the reduction of ethanol adverse effects, a higher increase in taurine concentrations may contribute to the lower ethanol sensitivity of LAS rats. Although 2.0 and 3.0 g/kg ethanol did not affect extracellular glutamate concentrations, a significant increase in glutamate was observed after 1.0 g/kg ethanol to HAS rats but not to LAS rats. Such an effect remains unexplained but suggests that discrepancies between the results of previous microdialysate studies may be related to differences in the ethanol sensitivities of various rat strains.