7-NITRO-INDAZOLE, A SELECTIVE INHIBITOR OF NEURONAL NITRIC-OXIDE SYNTHASE, REDUCES FORMALIN EVOKED C-FOS EXPRESSION IN DORSAL HORN NEURONS OF THE RAT SPINAL-CORD

The effect of intravenous 7-nitro-indazole (7NI), a selective inhibitor of neuronal nitric oxide synthase, on intraplantar formalin evoked spinal expression of c-Fos was studied. The spinal expression of c-Fos in the superficial laminae of the dorsal horn was not significantly altered by 7NI. In contrast formalin evoked c-Fos expression in the deep laminae was reduced by 15 mg/kg of 7NI (42 +/- 8% reduction of control P < 0.05). Formalin evoked inflammation was not influenced by 7NI. Our results implicate a functional relationship between c-Fos expression and nitric oxide, at the spinal level, under inflammatory conditions.