Release of [Met5]enkephalin from the spinal cord by intraventricularly administered endomorphin-2, but not endomorphin-1 in the anesthetized rat.
Effects of intraventricular injection of endomorphin-1, endomorphin-2 and beta-endorphin on the release of immunoreactive [Met(5)]enkephalin from the spinal cord were studied in pentobarbital anesthetized rats. Intraventricular injection of endomorphin-2, but not endomorphin-1, caused an increased release of immunoreactive [Met(5)]enkephalin in the spinal perfusates. Beta-endorphin given intraventricularly also increased the release of immunoreactive [Met(5)]enkephalin in an amount 15-fold higher than that produced by endomorphin-2. The increase of the release of immunoreactive [Met(5)]enkephalin induced by endomorphin-2 was blocked by mu-opioid receptor antagonist CTOP. Our result suggests that endomorphin-2 stimulates another subtype of mu-opioid receptor different from that acted by endomorphin-1 at the supraspinal site and subsequently increases the release of [Met(5)]enkephalin from the spinal cord.
Ohsawa
M
M
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Shiraki
M
M
Mizoguchi
H
H
Narita
M
M
Kawai
K
K
Nagase
H
H
Cheng
E Y
EY
Narita
M
M
Tseng
L F
LF
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D004744:Enkephalin, Methionine / Q000378:metabolism*; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage* / Q000494:pharmacology*; D010424:Pentobarbital / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism*; D001615:beta-Endorphin / Q000494:pharmacology
D000701:Analgesics, Opioid; D000777:Anesthetics; D006993:Hypnotics and Sedatives; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; C049352:phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide; C105294:endomorphin 2; D013004:Somatostatin; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; D010424:Pentobarbital