Immunohistochemical properties of nerve fibres supplying accessory male genital glands in the pig. A colocalisation study

Immunohistochemical studies have been performed to investigate the occurrence and coexistence of two catecholamine-synthesising enzymes, tyrosine hydroxylase and dopamine-beta-hydroxylase, and several neuropeptides, including neuropeptide Y, vasoactive intestinal polypeptide, Leu(5)-enkephalin, somatostatin, calcitonin gene-related peptide and substance P, in nerve fibres supplying porcine accessory genital glands, the seminal vesicles, prostate (body and the disseminated part) and bulbourethral glands. Three major populations of nerve fibres supplying non-vascular elements of the glands have been distinguished (from the largest to the smallest one): (1) noradrenergic fibres, the majority of which contain Leu(5)-enkephalin, neuropeptide Y or, to a lesser extent, somatostatin, (2) non-noradrenergic, putative cholinergic fibres containing vasoactive intestinal polypeptide, neuropeptide Y and/or somatostatin and, (3) nonnoradrenergic, presumably sensory fibres, containing calcitonin gene-related peptide and substance P. Whilst the coexistence patterns within nerves supplying particular glands are similar, the density of innervation varies between the organs. The innervation of the seminal vesicles and prostatic body is more developed than that of the disseminated part of the prostate and bulbourethral glands. The majority of noradrenergic fibres related to blood vessels contain neuropeptide Y only, while the non-noradrenergic nerves contain mainly vasoactive intestinal polypeptide. The possible function and origin of particular nerve fibre populations are discussed.