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

Immunohistochemical studies have been performed to investigate the occurren ce and coexistence of two catecholamine-synthesising enzymes, tyrosine hydr oxylase and dopamine-beta-hydroxylase, and several neuropeptides, including neuropeptide Y, vasoactive intestinal polypeptide, Leu(5)-enkephalin, soma tostatin, 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 popu lations of nerve fibres supplying non-vascular elements of the glands have been distinguished (from the largest to the smallest one): (1) noradrenergi c fibres, the majority of which contain Leu(5)-enkephalin, neuropeptide Y o r, to a lesser extent, somatostatin, (2) non-noradrenergic, putative cholin ergic fibres containing vasoactive intestinal polypeptide, neuropeptide Y a nd/or somatostatin and, (3) nonnoradrenergic, presumably sensory fibres, co ntaining calcitonin gene-related peptide and substance P. Whilst the coexis tence patterns within nerves supplying particular glands are similar, the d ensity of innervation varies between the organs. The innervation of the sem inal vesicles and prostatic body is more developed than that of the dissemi nated part of the prostate and bulbourethral glands. The majority of noradr energic fibres related to blood vessels contain neuropeptide Y only, while the non-noradrenergic nerves contain mainly vasoactive intestinal polypepti de. The possible function and origin of particular nerve fibre populations are discussed.