Immunolocalisation of ghrelin and obestatin in human testis, seminal vesicles, prostate and spermatozoa

Abstract

The role of ghrelin and obestatin in male reproduction has not completely been clarified. We explored ghrelin and obestatin localisation in the male reproductive system. Polyclonal antibodies anti-ghrelin and anti-obestatin were used to detect the expression of these hormones in human testis, prostate and seminal vesicles by immunocytochemistry, while in ejaculated and swim up selected spermatozoa by immunofluorescence. Sertoli cells were positive for both peptides and Leydig cells for ghrelin; germ cells were negative for both hormones. Mild signals for ghrelin and obestatin were observed in rete testis; efferent ductules were the most immune reactive region for both peptides. Epididymis was moderately positive for ghrelin; vas deferens and seminal vesicles showed intense obestatin and moderate ghrelin labelling; prostate tissue expressed obestatin alone. Ejaculated and selected spermatozoa were positive for both peptides in different head and tail regions. This study confirms ghrelin localisation in Leydig and Sertoli cells; the finding that ghrelin is expressed in rete testis, epididymis, vas deferens and seminal vesicles is novel, as well as the localisation of obestatin in almost all tracts of the male reproductive system. This research could offer insights for stimulating other studies, particularly on the role of obestatin in sperm physiology, which is still obscure.

The effects of streptozotocin-induced diabetes on ghrelin expression in rat testis: biochemical and immunohistochemical study

“…Ghrelin was observed by immunohistochemistry to be moderately expressed in Leydig cells. Observed expression of ghrelin only in Leydig cells is in accordance with previous studies [11,27].…”

Regulation and roles of Ca2+ stores in human sperm

“…Ghrelin, another peptide hormone that also acts through mobilisation of stored Ca 2 + ( Camina et al . 2003 ), has also been detected in human sperm ( Moretti et al . 2014 ).…”

Exogenous obestatin affects pancreatic enzyme secretion in rat through two opposite mechanisms, direct inhibition and vagally-mediated stimulation

“…This widely expressed in the body a 23-amino acid peptide is encoded on preproghrelin gene region. Obestatin has been found in the small intestine, colon, spleen, cerebral cortex, skeletal muscle, adipose tissue, lung, liver and many other tissues, but the major production of obestatin in rats takes place in the fundic region of gastric mucosa (Zhang et al, 2005;Zhao et al, 2008;Grönberg et al, 2010;Moretti et al, 2014). In the pancreas, obestatin-immunoreactive cells are mainly present in the peripheral region of the islets and do not co-localize with glucagon, pancreatic polypeptide Y or insulin secreting cells .…”