Effect of cyproheptadine on bar-pressing for food reward in rats.

Lever pressing rate under a continuous reinforcement schedule for food reward in rats was reduced significantly by cyproheptadine in the dose of 5 and 10 mg/kg body weight. Under fixed ratio schedule of reinforcement, the responding was also suppressed significantly by 5 and 10 mg/kg body weight doses of cyproheptadine. However, high dose (20 mg/kg) of cyproheptadine administered subsequent to the low doses, failed to inhibit the bar pressing rate under either continuous or fixed ratio schedules.