Pyrithiamin shortens ethanol-induced narcosis and increases voluntary ethanol drinking in rats.

To investigate the role of thiamin deficiency in increasing voluntary ethanol intake in rats the effect of ethanol on the central nervous system was studied by measuring the duration of ethanol narcosis in pyrithiamin-treated rats. The duration of ethanol-induced narcosis was significantly shorter and blood ethanol concentration at the moment of righting reflex recovery was higher in pyrithiamin-treated rats than in controls. Thus, the shorter ethanol narcosis of pyrithiamin-treated rats was not a result of a change in ethanol metabolism but rather suggests changes in the central effects of ethanol. Treatment with thiamin increased the duration of ethanol narcosis to the initial level in rats pretreated with pyrithiamin. During the same pyrithiamin treatment as used for the narcosis test voluntary ethanol intake of rats was higher than during optimal treatment by thiamin. The results suggest that there might be a decrease in central sensitivity to ethanol in pyrithiamin treated rats, which may have a role in increasing their voluntary ethanol drinking.