Calbindin-D28K and the peptidergic neuroendocrine system in rat gut: an immunohistochemical study.

Calbindin-D28K was immunohistochemically localized in myenteric and submucosal plexuses throughout the rat intestine. Calbindin-D28K immunoreactivity was found in about half of myenteric neurons and in more than 90% of submucosal neurons. Calbindin-D28K was also observed in nerve processes running inside ganglia, muscle layers and lamina propria. No correlation could be established between the presence of calbindin-D28K and the distribution of neuropeptides localized in this study (VIP, enkephalin, somatostatin and substance P). In addition, some endocrine-like cells of the ileum were calbindin-D28K-positive. Half of these endocrine cells also contained neurotensin but none of the other neuropeptides investigated.