Cocaine and anabolic-androgenic steroids are among the more commonly abused substances in selected populations. These agents, when used alone or in combination, have been reported to cause aggressive tendencies in both laboratory-based animal models and in human clinical situations. This project, using a resident-intruder paradigm, examined the effects of co-administration of cocaine and a typical anabolic-androgenic steroid, nandrolone decanoate, on the development of aggression in male Sprague-Dawley rats. 2. Dose response studies demonstrated that low dose cocaine (1 mg/kg) produced more aggression in a greater percentage of animals than for either the controls or groups receiving higher doses (up to 20 mg/kg). Initially, high intermittent doses of nandrolone (20 mg twice weekly) produced more aggression; however, low daily doses of nandrolone (2 mg) produced greater levels of aggression following 4 weeks of treatment. 3. Optimal doses of cocaine and nandrolone, when administered together, resulted in aggression scores that were not significantly different from controls or either drug singly. However, a greater percentage of animals receiving both drugs exhibited aggression than did rats receiving either drug alone. 4. These results support the interpretation that the drugs interact to produce unique effects in the development of aggression. However, the complexity and extent of the interactions is great and remains to be fully elucidated.
