Dose-related effects of chronic gestational cocaine treatment on maternal aggression in rats on postpartum days 2, 3, and 5

1. Gravid Sprague-Dawley rats received subcutaneous injections of saline, 3 .5, 7.5 or 15 mg/kg of cocaine, twice daily, throughout gestation. 2. On postpartum days 2, 3, and 5, dams and their litters (surrogate or nat ural) were videotaped for 10 minutes in the presence of a male rat for asse ssment of aggression towards the intruder. Oxytocin levels in discrete brai n areas were assayed on postpartum day 5. 3. The 30 mg/kg dose group had a significantly greater increase in the freq uency of threats from postpartum day2 through postpartum day 5 than the 7.5 mg/kg cocaine and the non-yoke-fed saline control groups. 4. Dams with natural litters exhibited a significantly greater frequency of receptive behavior compared to dams with surrogate litters. 5. There were no significant differences in oxytocin levels between the 30 mg/kg cocaine-treated group and the other treatment or control groups on po stpartum day 5. 6 There are very few statistically significant cocaine-induced increases in maternal aggressive behavior and no dose-dependent decreases in amygdaloid OT levels in the early postpartum period.