Voluntary ethanol drinking in mice and ethanol concentrations in the nucleus accumbens

The present study determined ethanol concentrations in the nucleus accumbens (NAcc) of C57BL/6J (B6) mice voluntarily drinking ethanol using an established limited access paradigm. Lickometer circuits were employed to monitor the temporal pattern of consummatory behavior, and serial samples were collected from the NAcc using in vivo microdialysis techniques. Ethanol in the dialysate was measured by gas chromatography with flame ionization detection. During dialysis, mice preferentially consumed sufficient amounts of sweetened ethanol (∼ 3 g/kg ethanol) to produce low millimolar levels of ethanol in dialysates from the NAcc; water intake was negligible. Overall, there was a positive relationship between total amount of ethanol consumed during the 2 h drinking session and cumulative (as well as peak) ethanol levels in NAcc. Additionally, and the total number of licking responses was positively correlated with the total amount of ethanol consumed. Moreover, the change in NAcc ethanol levels was temporally linked to the pattern of ethanol drinking, with periods of high licking responses on the ethanol tube preceding peak brain ethanol levels. The results indicate that the voluntary consumption of ethanol by B6 mice in a limited access time frame elevates ethanol concentration in NAcc dialysates in a manner consistent with the pattern of ethanol consumption.