The antianxiety effect of beta-blockers on punished responding.

Clinically effective anxiolytic drugs generally increase responding that is suppressed by punishment. Although beta-adrenergic antagonists have been reported to reduce anxiety in humans, such effects have not been reported reliably in animal punishment procedures. In the present study, three pigeons were trained to key peck under a multiple schedule. In the presence of a white light every thirtieth response produced grain. In the presence of a red light every thirtieth response produced grain and electric shock which suppressed responding to approximately 10 percent of that occurring in the alternate component. Propranolol (1.0-5.6 mg/kg) and, less reliably, atenolol significantly increased punished responding in a dose-related manner; propranolol effects were approximately twice as large as those of atenolol. Both drugs no more than weakly increased unpunished response rates at doses that increased punished responding. These results suggest that beta-blockers have an antianxiety effect on punished behavior, and that peripheral beta-blockade, the predominant action of beta-blockers regardless of whether they readily penetrate the brain, is likely to be involved in this effect.