ORIGINS OF NERVE-FIBERS CONTAINING NITRIC-OXIDE SYNTHASE IN THE RAT CELIAC-SUPERIOR MESENTERIC GANGLION

The origin of nitric oxide synthase-containing nerve fibers in rat cel iac-superior mesenteric ganglion was examined using retrograde tracing techniques combined with the immunofluorescence method. Fluoro-Gold w as injected into the celiac-superior mesenteric ganglion. Neuronal cel l bodies retrogradely labeled with Fluoro-Gold in the thoracic spinal cord, the dorsal root ganglia at the thoracic level, the nodose gangli on, and the intestine from the duodenum to the proximal colon were exa mined for nitric oxide synthase immunoreactivity. About 60% of sympath etic preganglionic neurons in the intermediolateral nucleus projecting to the celiac-superior mesenteric ganglion were immunoreactive for ni tric oxide synthase, as were approximately 27% of nodose ganglion neur ons and about 65% of dorsal root ganglion neurons projecting to the ce liac-superior mesenteric ganglion. Neurons projecting to the celiac-su perior mesenteric ganglion were found in the myenteric plexus of the s mall and large intestine. In the proximal colon, about 23% of such neu rons were immunoreactive for nitric oxide synthase. However, in the sm all intestine, no immunoreactivity was found in these neurons.