Beta-endorphin is behaviorally active in rats after chronic intravenous administration.
Male Sprague-Dawley rats received 14 daily intravenous injections of saline or human beta-endorphin (2.5 mg/kg). Animals were given one-way active avoidance training on the eleventh day, and analgesia testing on the twelfth (tail-flick) and thirteenth (hot-plate) days. Beta-endorphin had no effect on the number of trials needed to reach the avoidance criterion, but significantly lengthened response latencies. Beta-endorphin had no analgesic effect in either test procedure.
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D003216:Conditioning, Operant / Q000187:drug effects*; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D051381:Rats
D004723:Endorphins