title: Antinociceptive effects induced by intra-periaqueductal grey injection of the galanin receptor 1 agonist M617 in rats with morphine tolerance.
abstract: The present study was performed to investigate the antinociceptive effects of M617, a selective galanin receptor 1 agonist, and M1145, a selective galanin receptor 2 agonist, in the periaqueductal grey (PAG) in rats with morphine tolerance. Intra-PAG injection of 0.1 nmol, 0.5 nmol and 1 nmol of M617 induced dose-dependent increases in hindpaw withdrawal latencies (HWLs) to noxious thermal and mechanical stimulations in rats with morphine tolerance. Nevertheless, intra-PAG injection of 5 nmol of the selective galanin receptor 2 agonist M1145 showed no significant influences on HWLs to noxious thermal and mechanical stimulations in rats with morphine tolerance. The results demonstrated that it is the selective galanin receptor 1 agonist M617, not the selective galanin receptor 2 agonist M1145, induced significant antinociceptive effects in morphine-tolerant rats, indicating that galanin receptor 1 is involved in nociceptive modulation in the PAG of morphine-tolerant rats.
authors.affiliation: Neurobiology Laboratory, School of Life Sciences, Peking University, Beijing 100871, PR China.
authors.forename: Qingyao
authors.initials: Q
authors.lastname: Kong
authors.forename: Long-Chuan
authors.initials: LC
authors.lastname: Yu
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D004361:Drug Tolerance; D019004:Galanin / Q000494:pharmacology / Q000627:therapeutic use* / Q000031:analogs & derivatives; D008297:Male; D009020:Morphine / Q000494:pharmacology / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement; D010446:Peptide Fragments / Q000494:pharmacology / Q000627:therapeutic use*; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044091:Receptor, Galanin, Type 1 / Q000819:agonists
chemical_list: C000614145:M617 peptide; D010446:Peptide Fragments; D044091:Receptor, Galanin, Type 1; D009020:Morphine; D019004:Galanin; D001920:Bradykinin
keywords: Antinociceptive effect; Galanin; Galanin receptor 1; Hindpaw withdrawal latency; Morphine tolerance; Periaqueductal grey