Behavioral effects of centrally administered dynorphin and [D-ala2-D-leu] enkephalin (DADLE) in rats.
Dynorphin and [D-ala2-D-leu]enkephalin (DADLE) were administered directly into the cerebrolateral ventricles of rats and effects on various indices of sensorimotor function and retention of a passive avoidance task were measured. Dynorphin markedly suppressed exploratory motor activity and decreased responsiveness to an acoustic stimulus. Although increases in latency to respond to a noxious thermal stimulus were seen in rats after dynorphin, these changes were always associated with alterations in motor capacity. Injection of dynorphin immediately after a passive avoidance training trial had no significant effect on retention 1 week later. The physiological effects of DADLE were clearly different than those of dynorphin. DADLE produced a biphasic decrease followed by an increase in motor activity and an increased acoustic startle reactivity. DADLE had no effect on reactivity to a noxious thermal stimulus. Posttrial administration of DADLE significantly impaired retention of a step-through passive avoidance task 1 week after training. These data indicate different neurobiological roles for kappa and delta opiate receptors in the central nervous system.
D000161:Acoustic Stimulation; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004399:Dynorphins / Q000008:administration & dosage / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D006358:Hot Temperature; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011916:Rats, Inbred F344; D013216:Reflex, Startle / Q000187:drug effects*
D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D004399:Dynorphins