Ascending choline acetyltransferase and descending nitric oxide synthase immunoreactive neurones of the myenteric plexus project to the mucosa of the guinea pig gastric corpus.

The aim of this study was to reveal mucosal projections of myenteric neurones in the stomach by using the neuronal tracer DiI (1,1'-didodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorat) in combination with immunohistochemical detection of choline acetyltransferase (ChAT) and nitric oxide synthase (NOS). The mucosal application of one DiI coated glass bead (diameter 50-100 microm) labelled on average 167 +/- 58 neurones in the myenteric plexus (n = 9 preparations). Most labelled cells were ChAT-positive (74%), the remaining cells were NOS-positive (n = 6). The vast majority of ascending DiI-labelled neurones were ChAT-positive (94%), whereas most descending neurones were NOS-positive (75%). ChAT- and NOS-positive fibers were demonstrated in the mucosa. Results suggest that ascending and descending myenteric neuronal pathways releasing acetylcholine and nitric oxide, respectively, are involved in control of mucosal functions in the stomach.