Differential responsiveness to cocaine in C57BL/6J and DBA/2J mice

• Published in: Psychopharmacologia Vol. 138; no. 1; pp. 82 - 88
• Main Authors: ROCHA, B. A, ODOM, L. A, BARRON, B. A, ATOR, R, WILD, S. A, FORSTER, M. J
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.07.1998; Springer Nature B.V
• Subjects: Animals; Biological and medical sciences; Brain - drug effects; Brain - metabolism; Cocaine; Cocaine - metabolism; Cocaine - pharmacology; Conditioning, Operant; Drug addictions; Drug self-administration; Injection; Locomotor activity; Male; Medical sciences; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Motor Activity - drug effects; Narcotics - pharmacology; Operant conditioning; Reinforcement; Self Administration; Toxicology; Intraperitoneal administration; Intravenous administration; Toxicity; Rodentia; Self administration; Locomotion; Vertebrata; Mammalia; Acquisition process; Mouse; Animal; Toxicogenetics; Reinforcement; Genetics; Cocaine; Drug of abuse
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s002130050648

The present study compared cocaine-induced hyperlocomotion and cocaine i.v. self-administration in DBA/2J and C57BL/6J mice. In the locomotor activity experiment, these strains were tested for hyperlocomotion after i.p. cocaine injection (0-60.0 mg/kg), using a Digiscan Animal Activity Monitoring System. In the cocaine i.v. self-administration experiment, they were compared for their ability to acquire and maintain cocaine self-administration in operant chambers with levers as the manipulanda. Animals were first trained to respond for food as a reinforcer (condensed milk solution); they were then submitted to surgical i.v. insertion of an in-dwelling catheter, and required to respond for i.v. cocaine (0.25-4.0 mg/kg per injection) as a reinforcer. DBA/2J mice showed significantly higher maximal cocaine-induced hyperlocomotion, more rapid acquisition of cocaine self-administration, and significantly lower rates of cocaine self-administration. Cocaine concentration in the brains of DBA/2J and C57BL/6J mice failed to differ following i.p. injection, suggesting that distribution factors were not involved in the differential responses to cocaine. Although not conclusive, this pattern of effects may suggest that cocaine has greater reinforcing efficacy in DBA/2J mice, confirming genetic make-up as a determinant factor in cocaine taking behavior.