Pharmacologic response to pentobarbital in actively immunized mice

Mice were placed on an immunization schedule known to result in the production of antibodies directed against a variety of barbiturates (antibody binding capacity = 2.71 pmole 3H-phenobarbital bound/ml undiluted serum). The pharmacologic response to barbiturate in these actively immunized mice and suitably treated controls was investigates using rotarod apparatus for monitoring CNS depression. It was found that the response to pentobarbital in actively immunized mice was decreased, as reflected by an increase in the time the mice remained on the rotarod and a shift of the dose--response curve to the right. The decreased pharmacologic response to pentobarbital was not the result of changes in levels of the hepatic drug metabolism components. Furthermore, the alteration of pharmacologic response in actively immunized mice was selective for barbiturate and did not modify the ataxia produced by administration of another depressant agent, ethanol.