Effects of endomorphins-1 and -2, endogenous mu-opioid receptor agonists, on spontaneous alternation performance in mice.
The effects of intracerebroventricular (i.c.v.) administration of endomorphins-1 and -2, endogenous mu-opioid receptor agonists, on the spontaneous alternation performance associated with spatial working memory were investigated in mice. Endomorphin-1 (10 and 17.5 microg) and endomorphin-2 (10 microg) produced a significant decrease in percent alternation without affecting total arm entries. beta-Funaltrexamine (5 microg) almost completely reversed the endomorphin-1 (10 microg)- and endomorphin-2 (10 microg)-induced decrease in percent alternation, although neither naltrindole (4 ng) nor nor-binaltorphimine (4 microg) produced any significant effects on alternation performance. These results suggest that endomorphins impair spatial working memory through the mediation of mu-opioid receptors.
Ukai
M
M
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan. ukai@meijo-u.ac.jp
Watanabe
Y
Y
Kameyama
T
T
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects*; D017450:Receptors, Opioid, mu / Q000819:agonists
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; C051844:norbinaltorphimine; C105294:endomorphin 2; D009271:Naltrexone; C024524:beta-funaltrexamine