Taurine : a novel approach to reducing the reinforcing properties of ethanol in adolescents.
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Helfand, Rebecca S.
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Adolescent ethanol use continues to be a societal problem with ethanol drinking beginning as early as 11 years old. Early initiation of drinking behavior is indicative of an increased risk for future substance abuse problems. This may stem from ethanol-induced changes in the brain that could potentially increase the rewarding properties of ethanol, making a person more likely to drink in the future. The neuroprotective amino acid taurine may attenuate ethanol-induced changes in the brain, potentially reducing the reinforcing properties of ethanol. In this study, three experiments were conducted using behavioral tests and tissue analysis to investigate the effects of taurine treatment on ethanol self-administration in C57BL/6J mice. Experiment 1 measured ethanol consumption in adolescent mice with the two-bottle choice test resulting in reduced ethanol preference, but not consumption. Experiment 2 utilized the drinking in the dark protocol, in adolescents, revealing a 20% decrease in ethanol intake in the taurine-treated group. This effect was ethanol specific, as consumption of a sucrose solution was not similarly decreased by taurine treatment. Upon completion of drinking in the dark testing, two tissues within the mesolimbic dopamine system, the VTA and NAc, were extracted and analyzed for amino acid and dopamine content. Amino acid analysis revealed that taurine treatment effectively increased taurine concentrations in both the VTA and NAc. Dopamine turnover in the NAc of the taurine-treated/ethanol exposed group was significantly lower than their water-treated counterparts. Turnover of dopamine in the NAc increases in response to reinforcing stimuli. A reduction in turnover therefore indicates a decrease in the reward associated with ethanol consumption. The reduction in ethanol consumption, in the taurine-treated group, can therefore be explained, at least in part, by the decrease in dopamine turnover in the NAc. Experiment 3 investigated the efficacy of taurine treatment in adults using the drinking in the dark procedure. Treatment did not significantly change ethanol intake, revealing the effect to be adolescent specific. Given the efficacy of taurine treatment in reducing ethanol consumption in an adolescent population, it may be a potential new direction for the investigation into therapeutic mechanisms to reduce drinking behavior.