The histochemical localization of nitric oxide synthase in the mouse intestine

The localization of nitric oxide synthase (NOS)in the mouse intestines(duodenum, jejunum, ileum and proximal segments of large intestine)was observed using NADPH-diaphorase (ND)histochemistry. The results showed that the NOS-positive reaction product was mainly located in the neuronal elements. Densely stained NOS-positive neuronal bodies and fibers were found in the myenteric plexus and dense NOS-positive fibers were distributed in the deep muscular plexus. Only a few of NOS-positive neuronal bodies and fibers were seen scattered in the submucosal laminae. NOS-positive reaction product was also seen in the endothelium of small arteries, cavity of the intestinal gland and on the mucosal epithelium. The results suggested that the NO might be involved in the modulation of motility and blood circulation of the intestines.