Voluntary consumption of ethanol and its consequences in C57 mice treated with 4-methylpyrazole

Abstract

Daily injections of the alcohol dehydrogenase inhibitor 4-methylpyrazole (4MP) were administered to C57BL/6J mice offered continuous free access to food, water and 10% v/v ethanol. There was a significant correlation (r=−0.82) between the rate of ethanol consumption during pretreatment and the effect of 4MP on subsequent intake. Mice drinking more than 2.5 g/kg per day decreased their intake, while subjects drinking less than this amount increased the quantity of ethanol self-administered. The elevated concentrations of plasma ethanol which resulted from voluntary consumption were sufficient to produce intoxication but did not induce physical dependence. Presenting mice with 10% ethanol as their only fluid or offering them a choice of water and saccharin-sweetened ethanol increased intake but failed to raise plasma ethanol to the concentrations observed in mice offered unflavored ethanol and water, and treated with 4MP. The evidence suggests that plasma ethanol does not limit voluntary drinking in untreated mice and that concentrations of 135 to 250 mg/dl are not avoided by C57 mice in a free-choise situation.