title: Effect of melatonin on rat spinal cord nociceptive transmission.
abstract: Melatonin has been shown to exert potent antinociception but the sites and mechanisms of action underlying this effect have not yet been clarified. The effect of melatonin on spinal cord nociceptive transmission was studied in rats by assessing wid-up activity in a C-fiber reflex responses paradigm evoked by repetitive (0.6 Hz) electric stimulation. Intraperitoneal administration of 1.25, 2.5, 5.0 and 10.0 mg/kg melatonin induced a dose-dependent inhibition of spinal wind-up activity, the higher dose of the drug used being able to depress completely the C reflex gain. Results indicate that melatonin markedly depresses spinal wind-up in rats, probably through hyperpolarization of dorsal horn neurons consecutive to melatonin binding to membrane receptors, and/or via intracellular interference with a NMDA receptor-dependent nitric oxide generating pathway.
authors.affiliation: Department of Biological Sciences, Faculty of Chemistry and Biology, University of Santiago of Chile.
authors.forename: Claudio
authors.initials: C
authors.lastname: Laurido
authors.forename: Teresa
authors.initials: T
authors.lastname: Pelissie
authors.forename: Rubén
authors.initials: R
authors.lastname: Soto-Moyano
authors.forename: Luis
authors.initials: L
authors.lastname: Valladares
authors.forename: Francisco
authors.initials: F
authors.lastname: Flores
authors.forename: Alejandro
authors.initials: A
authors.lastname: Hernández
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D009412:Nerve Fibers / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D008550:Melatonin