Effects of chronic cocaine administration on aggressive behavior in virginrats

1. Virgin Sprague-Dawley rats received subcutaneous injections of saline, 3 .5, 7.5 or 15 mg/kg of cocaine, twice daily, for 20 consecutive days. 2. Females were videotaped for 10 minutes in the presence of a male rat for assessment of ag. agression towards the intruder 2, 3, and 5 days followin g cessation of cocaine or saline administration. Oxytocin levels in discret e brain areas were assayed following behavioral testing, 5 days following c essation of cocaine or saline administration. 3. The 30 mg/kg-dose group tended to have a lower frequency of fight attack s and aggressive postures compared to saline-treated controls across sessio ns. 4. The frequency of most of the behaviors analyzed were represented by quad ratic functions across time, such that the highest frequency of behavior oc curred 2 days following the final injection with relatively less activity 3 and 5 days following cessation of saline or cocaine administration. 5. The 30 mg/kg cocaine-treated group had significantly lower hippocampal O T levels than the 15 mg/kg group 5 days following cessation of cocaine or s aline administration.