Repeated cocaine treatment activates flank marking in adolescent female hamsters

Cocaine abuse during adolescence represents a significant health risk due t o the potential for both acute and long-term negative physical and psycholo gical sequelae, including increased aggressive behavior. This study examine d the effect of adolescent cocaine treatment on flank marking (i.e., a ster cotypic motor behavior that is part of the response pattern of offensive ag gression) in female and male Syrian hamsters (Mesocricetus auratus). Adoles cent cocaine treatment activated flank marking in female hamsters when anim als were measured upon return to their home cage immediately following drug treatment. Sex differences were observed in cocaine-induced flank marking, as males failed to flank mark when returned to the home cage. In females, the behavioral response was most marked on Day 11 of cocaine treatment in a ll doses tested. Yet, animals treated with low-dose cocaine (0.5 mg/kg/day) showed the most significant increase in flank marking on and from Day 11 f orward as compared to medium- and high-dose cocaine-treated animals and con trols. In addition, the response of cocaine-treated animals was vigorous an d nearly immediate, as > 75% of the flank marks scored were performed withi n the first 2 min of the behavioral test in > 85% of animals examined. Meas ures of locomotion showed that cocaine had stimulatory effects on motor act ivity in adolescent female hamsters at all doses tested. Cocaine-treated an imals did not differ in body weight gain from controls, suggesting no drama tic physiological effects of adolescent cocaine exposure on body growth at the doses tested. (C) 2001 Elsevier Science Inc. All rights reserved.