Peptidergic Innervation of the Human Male Genital Tract

Abstract

Four peptides--vasoactive intestinal polypeptide, substance P, somatostatin and a peptide-like avian pancreatic polypeptide--have been found in nerves of the human male genitalia using highly sensitive and specific methods of immunocytochemistry and radioimmunoassay. Five other peptides (met-enkephalin, leu-enkephalin, neurotensin, bombesin and cholecystokinin-8) were absent. Vasoactive intestinal polypeptide was the most abundant peptide, its highest concentration being in the proximal corpus cavernosum. Immunoelectron microscopy localized this peptide to large (97 +/- 20 nm), round, electron-dense granules of p-type nerve terminals. Vasoactive intestinal polypeptide-immunoreactive neuronal cell bodies were found in the prostate gland and the root of the corpus cavernosum. Substance P immunoreactive material was present in smaller concentration and was mainly localized in nerves around the corpuscular receptors of the glans penis. Somatostatin immunoreactive nerves were associated mainly with the smooth muscle of the seminal vesicle and the vas deferens. When antiserum to avian pancreatic polypeptide was applied, certain nerves were stained, particularly in the vas deferens, the prostate gland and the seminal vesicle. However, chromatography detected no pure avian pancreatic polypeptide suggesting the presence of a structurally related substance, possibly neuropeptide Y, which cross-reacts with the avian pancreatic polypeptide antiserum. Similar distributions between vasoactive intestinal polypeptide-immunoreactive and acetylcholinesterase-positive nerves and between avian pancreatic polypeptide-immunoreactive and adrenergic nerves were observed. A general neuronal marker, neuron-specific enolase, was used to investigate the general pattern of the organ's innervation. The abundance and distribution patterns of these peptide-immunoreactive nerves indicate that they may play important roles in the male sexual physiology.

Noradrenergic and cholinergic innervation of the accessory sexual glands in male sheep

“…The simultaneous presence of these two catecholamine-synthesising enzymes justifies naming these nerve fibres the noradrenergic ones. A more or less equal density of noradrenergic nerve fibres was found in the mucosa and muscular layer of the BU and SV, which is consistent with the results previously obtained in humans (Gu et al, 1983;Chapple et al, 1991;Hedlund et al, 1997) and pigs (Kaleczyc et al, 1999). It must be mentioned that in other studies of the SV of humans (Gosling and Dixon, 1994; as well as rats (Owman and Sjöstrand, 1965;Moss et al, 1987;Yuri, 1990) and guinea pigs (Owman and Sjöstrand, 1965;Wakade and Kirpekar, 1971;Al-Zuchair et al, 1975) noradrenergic nerve fibres were found only in the muscular layer.…”

“…The ovine prostate contained VIP-IR nerve fibres in a frequency comparable to the one found in the SV and BU but the abundance of NPY-IR nerve fibres was very low. Previously, numerous VIPand NPY-containing nerve fibres were found in the human ASG (Gu et al, 1983;Adrian et al, 1984;Higgins and Gosling, 1989;Lange and Unger, 1990;Chapple et al, 1991;Tainio, 1995;Hedlund et al, 1997;Dixon et al, 2000) and in the ASG of many other animal species (Alm et al, 1977(Alm et al, , 1980Stjernquist et al, 1983;Lamano-Carvalho et al, 1986;Moss et al, 1987;Yuri, 1990;Properzi et al, 1992;Iravani and Zar, 1994;Pinho et al, 1994;Ottesen et al, 1995;Domeneghini, 1997, 1998;Chow et al, 1997;Kaleczyc et al, 1999;Czaja et al, 2000;Majewski et al, 2001;Mirabella et al, 2003). The results of the previously mentioned studies can be summarised as follows: in all species the vast majority of VIP-IR nerve fibres were localised in the mucosal layer of the SV, BU and prostate, whereas only sparse VIP-IR nerve fibres were found within the smooth muscle layer.…”

“…The general opinion is that the development and function of the ASG are influenced both by the endocrine and the nervous system. The application of histochemical and immunohistochemical techniques has revealed autonomic nerve fibres (noradrenergic and cholinergic) Acta Veterinaria Hungarica 54, 2006 in all (or specific) ASG of man (Baumgarten et al, 1968;Dunzendorfer et al, 1976;Vaalasti and Hervonen, 1980;Gu et al, 1983;Higgins and Gosling, 1989;Chapple et al, 1991;Hedlund et al, 1997;Dixon et al, 2000), rat (Owman and Sjöstrand, 1965;Sjöstrand, 1965;Vaalasti and Hervonen, 1979;Moss et al, 1987;Yuri, 1990), hamster (Chow et al, 1997), guinea pig (Owman and Sjöstrand, 1965;Sjöstrand, 1965;Al-Zuchair et al, 1975;Lamano-Carvalho et al, 1986;Sjöstrand et al, 1998), rabbit, dog, cat (Owman and Sjöstrand, 1965;Sjöstrand, 1965), pig (Kaleczyc et al, 1999;Czaja et al, 2000;Majewski et al, 2001) and even in those of the water buffalo (Mirabella et al, 2003). It is known that nerve fibres may contain substances of peptide character, which act as neurotransmitters and/or neuromodulators.…”

Immunohistochemical characterisation of cholinergic nerve fibres supplying accessory genital glands in the pig

“…It is therefore possible, that VIP plays a role in the regulation of the secretory function of epithelial cells in this and other AGG. Immunoreactivity to SOM was found in a few nerve fibres supplying the human seminal vesicle and prostate (Gu et al, 1983;Chapple et al, 1991;Crowe et al, 1991;Tainio, 1995). Mirabella et al (2003) revealed SOM-IR nerve fibres innervating the prostate in the water buffalo.…”

“…VIP has been demonstrated in nerve fibres supplying the prostate and seminal vesicles in the guinea-pig, rat, cat, rabbit, mouse and humans. VIP-immunoreactive nerve fibres have been mainly associated with the basis of the glandular epithelium and, in smaller proportion, with the smooth muscle coat and blood vessels (Alm et al, 1980;Vaalasti et al, 1980Vaalasti et al, , 1986Larsen et al, 1981;Gu et al, 1983;Stjernquist et al, 1983;Polak and Bloom, 1984;Lamano Carvalho et al, 1986;Higgins and Gosling, 1989;Lange and Unger, 1990;Properzi et al, 1992;Jen et al 1995;Kepper and Keast, 1995;Tainio, 1995). Very little is known about the physiological role of VIP in AGG.…”