Peptidergic not monoaminergic fibers profusely innervate the young adult human testis

Abstract

Numerous studies have reported that intratesticular nerves exert important regulatory effects on the functions of the male gonad; however, as yet little is known about their distribution in the young adult human testis. The purpose of this study was to explore whether peptidergic and adrenergic nerves occur in the male gonad of this age, and, if present, to depict their distribution further. Thirty testes were collected from 15 reproductively healthy donors aged 21-32 years. Antibodies against protein gene product 9.5 (PGP 9.5), neuropeptide Y (NPY), C-terminal flanking peptide of NPY (CPON) and vasoactive intestinal peptide (VIP) were employed for immunohistochemical detection of intratesticular peptidergic nerves, and those against dopamine-beta-hydroxylase (DBH) and 5-hydroxytryptamine (5-HT) for monoaminergic ones. The testicular parenchyma exhibited a rich innervation by PGP 9.5-positive fibers, mainly associated with Leydig cell nests, blood vessels, and seminiferous tubules. Numerous NPY-and CPON-immunoreactive (IR) nerves also appeared in the gonads, but the vast majority were confined to blood vessels. A small number of VIP-IR fibers were detected in some arterioles. By contrast, however, no fibers displaying DBH or 5-HT immunoreactivity were observed within the testis. Additionally, expression of PGP-9.5, NPY, CPON, VIP, DBH and 5-HT was found in Leydig cells, PGP 9.5 in spermatogonia, and NPY and CPON in peritubular myoid cells. Our results suggest that the young adult human testis is devoid of monoaminergic nerves but profusely innervated by peptidergic fibers, which may serve as major neuronal regulators for testicular functions at this age.

Pituitary adenylate cyclase‐activating polypeptide in the testis of the quailCoturnix coturnix: Expression, localization, and phylogenetic analysis

“…Our immunohistochemical investigation highlights that the PACAP/receptors system is well represented in the Coturnix testis. Indeed, PACAP is evident in Leydig and vascular endothelial cells, as well as in peritubular cells and in interstitial nervous fibers, as other neuropeptides previously described (Gong et al, ); by contrast, germ and Sertoli cells are lacking in PACAP. Furthermore, in Leydig cells, PAC 1 , VPAC 1 , and VPAC 2 are well represented too, in germ and Sertoli cells only VPAC 2 is recognizable.…”

“…In mammals, it is well known that circulating PACAP contributes to the intratesticular pool (Banks, Kastin, Komaki, & Arimura, ; Thomas et al, ) and that PACAP is expressed, even if transiently, in the seminiferous tubules during rat spermatogenesis (Kononen, Paavola, Penttilä, Parvinen, & Pelto‐Huikko, ). So, one can hypothesize that in Coturnix PACAP could be partly synthesized within vascular endothelial cells and then transferred to the Leydig cells and partly may be transported in the testis via nervous fibers, as occurs with VIP and NPY neuropeptides in human testis (Gong et al, ).…”

Cisatracurium stimulates testosterone synthesis in rat and mouse Leydig cells via nicotinic acetylcholine receptor

“…In addition to the hypothalamic‐pituitary‐gonadal axis, the nervous system may play a key role in Leydig cell function. Previous studies have shown that some nerve fibres reach the rat and human testes and may have an effect on Leydig cells 1,2 . The destruction of testicular innervation led to Leydig cell apoptosis and impaired Leydig cell function 1 .…”

Perspectives in Pediatric Pathology, Chapter 4. Pubertal and Adult Testis

“…These nerves extend throughout the tunica vasculosa, follow the interlobular septa, and end in the testicular interstitium. Most of the nerve fibers are peptidergic [99], 4.33,4.34).…”