Behavioral activation by enkephalins in mice.
Intraventricular injection of long lasting enkephalin analogues (D--Ala2Leu and Met enkephalin-amides) produced a sustained elevation of psychomotor activity in mice. The motor syndromes were characterized by continual stereotyped activity and were reversed by naloxone pretreatment. Naloxone administered to a separate group of mice reduced the initial activation seen after exposure to a novel environment. The present findings suggest one or more endogenous opiates normally facilitates behavioral excitation in mice.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology
D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone