Granados-Soto V, Rufino M O, Gomes Lopes L D, Ferreira S H
Departamento de Farmacología y Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, DF, Mexico.
Eur J Pharmacol. 1997 Dec 11;340(2-3):177-80. doi: 10.1016/s0014-2999(97)01399-x.
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.
