title: Evidence for the involvement of the nitric oxide-cGMP pathway in the antinociception of morphine in the formalin test.
abstract: The effect of inhibition of nitric oxide synthesis and guanylate cyclase on the peripheral antinociceptive effect of morphine was assessed by using the formalin test in the rat. Saline, N(G)-monomethyl-L-arginine, a nitric oxide synthesis inhibitor (50 microg) and methylene blue, a guanylate cyclase inhibitor (500 microg), did not exhibit any antinociceptive activity. However, morphine (10 microg) produced a significant antinociceptive effect in phases 2a and 2b, which was reduced by pretreatment with either N(G)-monomethyl-L-arginine or methylene blue. These results suggest that the local administration of morphine induces antinociception by the activation of the L-arginine-nitric oxide-cGMP pathway.
authors.affiliation: Departamento de Farmacología y Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, DF, Mexico.
authors.forename: V
authors.initials: V
authors.lastname: Granados-Soto
authors.forename: M O
authors.initials: MO
authors.lastname: Rufino
authors.forename: L D
authors.initials: LD
authors.lastname: Gomes Lopes
authors.forename: S H
authors.initials: SH
authors.lastname: Ferreira
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D000242:Cyclic AMP / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005557:Formaldehyde; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010147:Pain Measurement / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D005557:Formaldehyde; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D009020:Morphine; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D008751:Methylene Blue