THE EFFECT OF NICOTINIC ACID ON THE DEPRESSANT ACTION OF ETHANOL AND PENTOBARBITAL

The effect of nicotinic acid (NA) on sleeping time induced bya single dose of ethanol or pentobarbital was studied in rats.It was found that sleeping time was markedly reduced by NA ina dose-dependent manner. The effect was observed when NA wasadministered 10 min before or after ethanol or pentobarbital,but not when given 60 min in advance. NA did not affect therate of ethanol elimination measured up to 5 hr after ethanoladministration. Rats pretreated with NA 60 min before ethanolslept longer than controls. This latter effect was not observedwith pentobarbital. These observations, together with the knownlack of effect of high liver NAD⁺ levels on ethanol metabolismand the rather stable NAD⁺ concentration in brain cells, suggestthat the effect of NA on sleeping time is not mediated by anincrease in ethanol metabolism in liver or by NAD⁺ or NAD⁺-dependentreactions in brain. Our results are consistent with a directaction of NA, or some rapidly formed derivative, on a structureor process associated with brain cell functions or membranes.