Effects of some beta-adrenoceptor blockers on avoidance learning in rats

In experiments on male Wistar rats, we studied the effects of some beta-adrenoceptor blockers: nonselective-propranolol, pindolol and 3b (a new aminotetraline derivative); and cardioselective (beta 1)-acebutolol and talinolol, on avoidance learning. The nonselective beta-adrenoceptor blockers failed to deteriorate and in some cases even facilitated learning, estimated by the number of avoidance responses and their latencies, while the cardioselective blockers significantly impaired learning process. A significant learning-impairing effect was shown by the beta 2-adrenoceptor agonist salbutamol. Similar was the effect of the mixed alpha- and beta-adrenoceptor blocker labetalol. The results are interpreted in connection with the functional role of beta 1- and beta 2- adrenoceptors in the CNS and with the importance of their balance for learning process.