alpha-melanotropin and beta-endorphin-like immunoreactivities are contained within neurons and nerve fibers of the rat duodenum.

Both alpha-melanotropin and beta-endorphin were revealed by immunofluorescence microscopy studies within neurons and nerve fibers of the rat duodenum. An immunohistochemical staining for alpha-melanotropin was seen within neuronal cell bodies and nerve fibers bundles of the myenteric and submucous plexus. A beta-endorphin immunofluorescence was visualized within perikarya and nerve fibers of both the myenteric and submucous plexus. alpha-Melanotropin as well as beta-endorphin immunoreactivities were strictly localized to structures of the enteric nervous system. In crypts and epithelial cells only a non-specific staining was observed.