Immunohistochemical studies on enteric substance P of extrinsic origin in the cat

The origin of substance P (SP)-like immunoreactivity in the Auerbach's plexuses of the esophagus, stomach duodenum was examined in the cat. The intensity of the fluorescence and the area of distribution of SP-like immunoreactivity in the Auerbach's plexuses of the cardiac part of the esophagus and the corpus of the stomach were markedly reduced by bilateral ligation of the abdominal vagus nerve, while little change occurred in the antrum of the stomach and the duodenum. After splanchnic nerve ligation or celiac ganglionectomy, the SP-like immunoreactivity in the Auerbach's plexuses of the antrum of the stomach and the duodenum was markedly reduced, whereas that in the esophagus and the corpus of the stomach was only slightly attenuated. Intense SP-like immunoreactivity was observed in the portions of the abdominal vagus and splanchnic nerve cranial to the ligation. This the Auerbach's plexuses of the esophagus, stomach and duodenum were considered to contain SP transported through the vagus and splanchnic nerve. It was also indicated experimentally that the SP-like immunoreactive fibers in the auerbach's plexus arose from the nodose and spinal ganglia as well as from the dorsal vagus nucleus in the medulla oblongata.