Tolerance to ethanol and cross-tolerance to pentobarbital and barbital in four rat strains.

Chronic ethanol treatment by gastric intubation conferred tolerance to ethanol-induced motor impairment and hypnosis in four different rat strains: Fischer 344, Long-Evans, Sprague-Dawley, and Wistar. Cross-tolerance to barbital was also observed in all strains after chronic treatment with ethanol. However, chronic ethanol treatment failed to produce cross-tolerance to pentobarbital-induced motor impairment and hypnosis in any of the four strains. The demonstration of cross-tolerance to barbital and the lack of it to pentobarbital after chronic ethanol treatment confirms and extends recent observations on the specificity of the site and/or mechanism of action of sedative-hypnotic drugs that differ in lipid solubility.