Colitis generates remote antinociception in rats: the role of the L-arginine/NO/cGMP/PKG/KATP pathway and involvement of cannabinoid and opioid systems.

ABSTRACT

OBJECTIVE AND DESIGN: The aim of this study was to investigate the possible involvement of the NO/cGMP/PKG/KATP+ pathway, cannabinoids and opioids in remote antinociception associated with 2,4,6-trinitrobenzene sulph onic acid (TNBS)-induced colitis. METHODS: TNBS-induced colitis was induced by intracolonic administration of 20 mg of TNBS in 50% ethanol. After induction, carrageenan (500 µg/paw) or prostaglandin (PG) E2 (100 ng/paw) was injected in the rat's plantar surface and hypersensitivity was evaluated by the electronic von Frey test. Rats were pre-treated with L-Noarg one hour before carrageenan injection. L-Arginine was given 10 min before L-Noarg injections. ODQ, KT 5823, glibenclamide (Glib), naloxone and AM 251 or AM 630 were administered 30 min prior to carrageenan or PGE2 treatments. RESULTS: Colitis induction by TNBS reduced PGE2 or carrageenan-induced hypersensitivity. Antinociception produced by TNBS-induced colitis was reversed significantly (P<0.05) by L-Noarg, ODQ, KT 5823, glibenclamide, naloxone, AM251 and AM630 treatments. CONCLUSIONS: TNBS-induced colitis causes antinociception in the rat paw. This disorder appears to be mediated by activation of the NO/cGMP/PKG/KATP pathway, endocannabinoids and endogenous opioids. This information may contribute to a better understanding of peripheral neurological dysfunctions occurring in Crohn's disease.