The absence of Levallorphan-induced post-depressant hyperactivity following stress-reduction

ABSTRACT

Following the administration of levallorphan(100 mg/kg) rats' well-established avoidance behaviour is severly depressed for 30 minutes. During this period, animals are almost incessantly shocked. During saline trials, rats receive relatively few shocks. It is postulated that the rate enhancement observed after the drug-induced depressant period is probably due to the excessive stress which animals undergo during the depressive phase. Following drug treatment, rats were kept out of operant during the depressive phase. No rate enhancement was observed throughout the 120-minute experimental period. Response rate enhancement seems to depend on the level of stress during the depressant phase of the drug (AU)