Presynaptic opioid kappa-receptor and regulation of the release of Met-enkephalin in the rat brainstem.
Opioid kappa-agonists had much more potent inhibitory effects on the high K+-evoked Met-enkephalin release from rat brain slices than did the mu- or delta-agonists. The opioid kappa- antagonist, MR2266 enhanced the evoked release of Met-enkephalin to a greater extent than did mu- or delta-antagonists in vitro and had a potent analgesia in mice in vivo. These findings suggest that the release of Met-enkephalin may be regulated in vitro and in vivo, mainly by presynaptic kappa-receptor-mediated mechanisms.
Ueda
H
H
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Fukushima
N
N
Ge
M
M
Takagi
H
H
Satoh
M
M
D000200:Action Potentials / Q000187:drug effects; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology*; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D004723:Endorphins / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009019:Morphinans / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D017473:Receptors, Opioid, kappa
D000700:Analgesics; D001575:Benzomorphans; D004723:Endorphins; D009019:Morphinans; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D009270:Naloxone; C027247:MR 2266; D004744:Enkephalin, Methionine