Effects of propranolol, buspirone, pCPA, reserpine, and chlordiazepoxide on open-field behavior.

The study examined the possibility that propranolol, buspirone, pCPA, and reserpine have antianxiety effects by comparing their effects with those of chlordiazepoxide on an open-field test of emotionality in rats. The effects of intraperitoneal injections of d,l, propranolol (5, 10, 20 mg/kg), buspirone (1.25, 2.5, 5 mg/kg), reserpine (0.5 mg/kg), parachlorophenylalanine (pCPA) (100 mg/kg), and chlordiazepoxide (CDP) (2.5, 5, 10 mg/kg) were compared with performance of rats under saline or water using an open-field test on 5 successive days. Significant effects were found on peripheral movements, rearing, grooming, immobility, and defecation. The patterns of effects of high doses of propranolol and buspirone resembled those of CDP, while pCPA had some of the effects of CDP, and reserpine produced few effects. With propranolol, buspirone, and CDP, there was evidence of dose sensitivity. The effects of repeated testing across 5 days were different from these of CDP or other drugs. The results are consistent with the hypothesis that the effects of propranolol and buspirone on open-field behavior are anxiolytic, and may be mediated by action on the same brain systems.