title: Cocaine-induced behavioral sensitization in mice: effects of microinjection of dopamine d2 receptor antagonist into the nucleus accumbens.
abstract: To determine the role of dopamine D2 receptor (D2R) in the nucleus accumbens (NAc) core in cocaine-induced behavioral sensitization, D2R antagonist, raclopride was bilaterally microinjected (2.5 or 5 nmol) into the NAc core of WT and D2R(-/-) mice and the initiation and expression phase of cocaine-mediated locomotor sensitization were analyzed. WT and D2R knockout (D2R(-/-)) mice received bilateral injections of either saline, or raclopride at the NAc core 30 min before each of five daily repeated injections of saline or cocaine (15 mg/kg i.p.). Following 2 weeks of withdrawal after repeated exposure to cocaine, the animals were pre-treated with an intra-accumbal injection of vehicle or raclopride before receiving a systemic cocaine challenge for the expression of sensitization. Animals which had been microinjected raclopride into NAc core displayed the enhancement of cocaine-induced behavioral response for the initiation but also for the expression of sensitization in WT as well as in D2R(-/-) mice, which was thus unaltered as compared to vehicle-injected control group. These results suggest that D2R in NAc core is not involved in cocaine-induced behavioral sensitization.
authors.affiliation: Molecular Neurobiology Laboratory, College of Life Sciences and Biotechnology, Department of Life Sciences, Korea University, Seoul 136-701, Korea.
authors.forename: Eun-Sol
authors.initials: ES
authors.lastname: Jung
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Lee
authors.forename: Hye-Ri
authors.initials: HR
authors.lastname: Sim
authors.forename: Ja-Hyun
authors.initials: JH
authors.lastname: Baik
keywords: addiction; behavioral sensitization; cocaine; dopamine receptor; nucleus accumbens