NITRIC-OXIDE PRODUCING NEURONS IN THE HUMAN COLON - AN IMMUNOHISTOCHEMICAL AND HISTOENZYMATICAL STUDY

The nitric oxide producing neurons of the human colonic myenteric plex us have been studied by using antibodies against cerebellar NO synthas e type I (NOS-IR) and NADPH-diaphorase (NAPDH-d) histoenzymatic reacti on. The majority of the stained neurons were both NOS-IR and NADPH-d-p ositive, while a few others were either NADPH-d-positive or NOS-IR onl y. Among the co-stained neurons, four subpopulations sharing various d egrees of staining intensities have been identified. These findings in dicate that in the human colon a one-to-one correlation between NOS-IR and NADPH-d positivity does not exist and thus the NAPDH-d reaction d oes not delineate with certainty all NO-producing neurons. The degree of staining intensity might account for different intracellular amount s of these two enzymes.