EFFECTS OF THE BETA-ADRENERGIC BLOCKERS PROPRANOLOL AND ACEBUTOLOL ON STRESS-INDUCED LEARNED HELPLESSNESS BEHAVIOR OF RATS

The latency time and escape ability of rats with learned helplessness behavior were studied after 1, 6 and 14 days of oral treatment with beta-adrenergic blockers propranolol (1 and 3, mg/kg) and acebutolol (10 and 30 mg/kg). A dose-dependent significant decrease in latency time and increase in number of avoidances was established after single, 6 and 14 days propranolol treatment. The selective beta(1)-blocker acebutolol did not change the escape characteristics. These results suggest a greater impact of beta(1)- than beta(2)-adrenergic receptors for escape performance after unescapable foot shock, i.e., learned helplessness behavior.