Intravenous and intragastric self-administration of chlordiazepoxide in the rat

Rats were implanted with intravenous (IV) or intragastric (IG) cannulas and allowed access, by lever-pressing on a CRF schedule, to chlordiazepoxide solution in 10-h sessions at doses of 0.1, 0.25, 0.5 and 1.0 mg/kg/injection. Self-administration behavior was acquired by both routes and for all doses of the drug by 60-70% of subjects tested. Subjects given access by the IV route showed more pronounced responding at the lower 2 doses and greater drug intake with the higher 2 doses than the IG group. A 2-lever study, controlling for possible motor effects of chlordiazepoxide, supports the interpretation that responding was indeed the result of reinforcing effects of chlordiazepoxide rather than an artifact.