Antibodies to fragments of provasoactive intestinal peptide reveal subpopulations of vasoactive intestinal peptide containing neurons in the rat gut

The cellular origin of peptides derived from preprovasoactive intestinal peptide has been studied in rat stomach and ileum. Antisera specific for the C-terminal regions of the N-terminal flanking peptide (preprovasoactive intestinal peptide 22-80), bridging peptide (preprovasoactive intestinal peptide 111-124), C-terminal flanking peptide (preprovasoactive intestinal peptide 156-170) and vasoactive intestinal peptide were used in immunohistochemical studies on sections and whole mounts. All four antisera stained nerve fibres and cell bodies in the stomach and intestine. However, there were distinct differences in the pattern of colocalization of peptides derived from provasoactive intestinal peptide. In the sub-mucous plexus of the ileum virtually 100% of neurons reacting with vasoactive intestinal peptide antibodies also reacted with antibodies to the other three peptides. In contrast, in the stomach, while all vasoactive intestinal peptide-immunoreactive neurons of the myenteric plexus contained C-terminal flanking peptide- and bridging peptide-like immunoreactivity, only 50% of these cells reacted with the antiserum to N-terminal flanking peptide. The data indicate that in a population of neurons in the myenteric plexus of the rat stomach, preprovasoactive intestinal peptide is processed in such a way that the antigenic determinant of the N-terminal flanking peptide is not produced. In a second population of enteric neurons in the stomach, and in the intestine, it appears that processing of preprovasoactive intestinal peptide results in the production of peptides reacting with antibodies to vasoactive intestinal peptide, the flanking and bridging peptides.