Further evidence for the implication of a kappa-opioid receptor mechanism in the production of psychological stress-induced analgesia.
The analgesic effect induced by exposure to psychological stress, using a communication box (psychological stress-induced analgesia, PSY-SIA), was completely antagonized by 10 min pretreatment with 0.5, 1 and 2 mg/kg of nor-binaltorphimine and with 0.5 and 1 mg/kg of Mr2266, selective kappa-opioid receptor antagonists, in the tail pinch method. Neither footshock (FS)- nor forced swimming (SW)-SIA was affected by these antagonists. The selective delta-opioid receptor antagonist naltrindole, at doses up to 20 mg/kg, had no appreciable effect on PSY-SIA. Daily morphine treatment, 10 mg/kg, s.c., resulted in tolerance to the analgesic effect, and concurrent exposure to PSY-stress suppressed the development of morphine tolerance. The substitution of treatment with U-50,488H for PSY-stress still resulted in analgesia on the initial day; and likewise, the suppression by U-50,488H of the development of morphine tolerance was replicated by PSY-stress. Pretreatment with nor-binaltorphimine antagonized the suppressive effect of PSY-stress on the development of morphine tolerance without affecting the analgesic effect of morphine per se. These results provide further evidence that PSY-SIA involves the mediation by kappa-opioid receptor mechanisms.
Takahashi
M
M
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Nagasaki University, Japan.
Senda
T
T
Tokuyama
S
S
Kaneto
H
H
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000698:Analgesia; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology; D004361:Drug Tolerance; D004597:Electroshock; D007211:Indoles / Q000494:pharmacology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009019:Morphinans / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000502:physiology*; D017473:Receptors, Opioid, kappa; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming
D000700:Analgesics; D001575:Benzomorphans; D007211:Indoles; D009019:Morphinans; D009292:Narcotic Antagonists; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; C051843:binaltorphimine; C027247:MR 2266; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D009020:Morphine; C055382:naltrindole