Dose-response effects of alcohol upon rat strains bred for differences in reactivity to alcohol.

Two rat strains, designated LA and MA, selectively bred for differential impairment of motor activity following an injection of alcohol, were tested in stabilmeters and compared over a range of ethanol doses. As expected, increasing doses of ethanol produced progressively greater activity decrements in both strains; however, the same dose of ethanol induced a more pronounced decrement in the MA strain than in LA strain at all doses. At the highest alcohol dose (2.25 g/kg), the LA animals were twice as active as were the MA strain at the 1.5 g/kg dose. This strain difference in impairment was evident within 3 min postinjection and remained throughout the 30 min test session. The results are discussed in terms of differential neural and behavioral toelrance to ethanol in the two strains.