Potentiation by propranolol of stress-induced changes in passive avoidance and open-field emergence tests in mice

Noradrenergic and serotonergic systems are known to be stimulated during various forms of stress. The present study examined the effect of the beta-adrenergic serotonin1A receptor blocker propranolol on the ability of stress to elicit behavioral inhibition in mice. Mice were given the drug before immobilization or tube-restraint stress, and then were tested for either passive avoidance performance or time to emerge into an open field. Propranolol markedly potentiated stress-induced increases in latency in both of these tests, suggesting that it exacerbated reactions to stress. These results agree with previous data indicating that under certain conditions, propranolol can potentiate the effects of stress in rodents. The results support the hypothesis that the response of the noradrenergic and/or serotonergic systems to stress may have anxiolytic or antistress effects.