Immunohistochemical and enzyme histochemical localization of peptidergic, aminergic and cholinergic nerve fibers in the rat seminal vesicle.

The distribution of the autonomic nervous system in the rat seminal vesicle was studied with immuno- and enzyme-histochemistry. In the smooth muscle layer, a large number of neuropeptide Y (NPY)- and tyrosine hydroxylase (TH)-immunoreactive nerve fibers were observed, while few fibers were distributed in the mucosal layer. A small number of substance P-immunoreactive fibers were present only in the smooth muscular layer, but vasoactive intestinal polypeptide (VIP)-immunoreactive fibers were abundantly distributed in both layers. In the mucosal layer, the VIP-fibers ran attached to blood vessels and encircled the glandular cavities. Acetylcholinesterase-positive fibers were also observed in the mucosal and muscular layers. Electron-microscopic studies revealed that NPY- and TH-containing nerve terminals were in apposition to smooth muscle cells, and VIP-fibers terminated at blood vessels. These results suggest different modes of action of NPY-, TH- and VIP-containing nerve fibers in the seminal vesicle.