Effects of propranolol and chlordiazepoxide on conflict behavior in rats

Abstract

Clinical reports have suggested that propranolol, a Β-adrenergic blocker, has antianxiety properties. In the present laboratory experiments, this suggestion was explored by testing propranolol and chlordiazepoxide in rat lever-pressing conflict procedures that selectively identify antianxiety compounds. Chlordiazepoxide produced anticonflict effects in such a procedure at doses from 1.25 to 40 mg/kg. Propranolol, tested at doses of 2.5 to 80 mg/kg, did not produce the anticonflict pattern typical of standard antianxiety agents, which is characterized by progressive dose-related increases in punished responding that frequently are several 100% above control levels. In contrast, the largest increases produced by propranolol, which occurred in the 10–40 mg/kg dose range, were 18–26% above control; only the 26% increase observed at the 20 mg/kg dose was statistically significant. In a different conflict test, a 40 mg/kg dose of propranolol was found to have a slight, but not significant, anticonflict effect. When this dose level was combined with doses of 2.5, 5, or 10 mg/kg of chlordiazepoxide p.o., the combined treatments produced greater anticonflict effects than did the corresponding individual doses of chlordiazepoxide.