title: Potentiation of cyclo (N-methyl-Tyr-Arg)-induced antinociceptive activity by thyrotropin-releasing hormone in mice.
abstract: The effect of thyrotropin-releasing hormone (TRH) and its metabolite, cyclo(His-Pro) (C.HP), on cyclo(N-methyl-Tyr-Arg) (C.NMTA)-induced antinociception as measured by the tail-pressure test in mice has been examined. C.NMTA-induced antinociception was significantly potentiated by simultaneously intracerebroventricular or intraperitoneal injection of TRH (approximately 20-50%) in a dose-dependent manner, whereas the effect of morphine was not influenced significantly by TRH. C.HP had no significant effect on the antinociceptive response induced by C.NMTA or morphine. It is concluded that the mechanism of C.NMTA-induced antinociception may be involved in TRH neuronal system in the brain.
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004357:Drug Synergism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
chemical_list: D000700:Analgesics; D010456:Peptides, Cyclic; D013973:Thyrotropin-Releasing Hormone; D009020:Morphine; C039517:cyclo(N-methyltyrosylarginyl)