BETA-ADRENOCEPTOR BLOCKADE MIMICS EFFECTS OF STRESS ON MOTOR-ACTIVITYIN MICE

Reduced central noradrenergic function has been implicated as a factor in reduced behavioral activity after stress. The present studies exam ined the role of reduced beta adrenergic neurotransmission in mediatin g this effect. This was done by testing the ability of beta receptor a ntagonists to mimic the behavioral actions of stress. Mice were subjec ted to stress or given various beta antagonists and tested for swimmin g behavior, locomotor activity, or grooming behavior. As previously re ported, stress reduced swimming and locomotor activity and increased g rooming. Both the nonselective antagonist, l-propranolol, and the beta -1 selective antagonist, betaxolol, produced the same effects as stres s on all three measures. A beta-2 selective antagonist, ICI 118,551, w as effective only on swimming, whereas a membrane stabilizing agent, d -propranolol, was effective only on grooming behavior. The peripherall y active beta-1 antagonist, atenolol, was not effective on any measure . The nonspecific dopaminergic receptor blocker, fluphenazine, reduced locomotion but tended also to reduce grooming. The results indicate t hat blockade of beta-1 receptors in the CNS selectively mimics the act ion of stress on gross motor activity in mice and, along with previous data, suggest that stress leads to a relative deficiency in central b eta-1 noradrenergic neurotransmission in these animals.