The effect of the leucopyrokinin analogue: [2-8]-leucopyrokinin on central opioid receptors in rats.
The antinociceptive effect of intracerebroventricular injections of [2-8]-leucopyrokinin (LPK), a truncated leucopyrokinin analogue, was determined in rats, by means of a tail immersion test. We found a significant antinociceptive effect of three i.c.v. doses of [2-8]-LPK: 1, 5 and 10 nmol. Pre-treating animals with naloxone hydrochloride (1 mg/kg i.p.) completely blocked the effect of two high doses of [2-8]-LPK. To determine the sub-types of opioid receptors involved in [2-8]-leucopyrokinin-induced analgesia we injected specific blockers of mu-, delta- and kappa-receptors namely, beta-funaltrexamine hydrochloride, naltrindole hydrochloride and nor-binaltorphimine dihydrochloride, respectively, prior to [2-8]-leucopyrokinin at equimolar doses. We conclude that the antinociceptive effect of [2-8]-leucopyrokinin is mediated mainly by central mu- and delta-opioid receptors.
Rykaczewska-Czerwińska
M
M
Department of Pharmacology Medical Faculty in Zabrze of the Medical University of Silesia, H. Jordana 38, PL 41-808, Zabrze, Poland.
Konopińska
D
D
Plech
A
A
D000698:Analgesia; D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists; D009619:Nociceptors / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000502:physiology*; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000502:physiology; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000502:physiology; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000502:physiology; D013623:Tail; D013997:Time Factors
C448479:(2-8)-leucopyrokinin; D000700:Analgesics; D009292:Narcotic Antagonists; D009842:Oligopeptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D009270:Naloxone; C051844:norbinaltorphimine; D009271:Naltrexone; C024524:beta-funaltrexamine; C055382:naltrindole