Expression of ghrelin receptor (GHSR-1a) in rat epididymal spermatozoa and the effects of its activation

Signatures of metabolic diseases on spermatogenesis and testicular metabolism

Diets leading to caloric overload are linked to metabolic disorders and reproductive function impairment. Metabolic and hormonal abnormalities stand out as defining features of metabolic disorders, and substantially affect the functionality of the testis. Metabolic disorders induce testicular metabolic dysfunction, chronic inflammation and oxidative stress. The disruption of gastrointestinal, pancreatic, adipose tissue and testicular hormonal regulation induced by metabolic disorders can also contribute to a state of compromised fertility. In this Review, we will delve into the effects of high-fat diets and metabolic disorders on testicular metabolism and spermatogenesis, which are crucial elements for male reproductive function. Moreover, metabolic disorders have been shown to influence the epigenome of male gametes and might have a potential role in transmitting phenotype traits across generations. However, the existing evidence strongly underscores the unmet need to understand the mechanisms responsible for transgenerational paternal inheritance of male reproductive function impairment related to metabolic disorders. This knowledge could be useful for developing targeted interventions to prevent, counteract, and most of all break the perpetuation chain of male reproductive dysfunction associated with metabolic disorders across generations.

Regulation and roles of Ca2+ stores in human sperm

[Ca(2)(+)]i signalling is a key regulatory mechanism in sperm function. In mammalian sperm the Ca(2)(+)-permeable plasma membrane ion channel CatSper is central to [Ca(2)(+)]i signalling, but there is good evidence that Ca(2)(+) stored in intracellular organelles is also functionally important. Here we briefly review the current understanding of the diversity of Ca(2)(+) stores and the mechanisms for the regulation of their activity. We then consider the evidence for the involvement of these stores in [Ca(2)(+)]i signalling in mammalian (primarily human) sperm, the agonists that may activate these stores and their role in control of sperm function. Finally we consider the evidence that membrane Ca(2)(+) channels and stored Ca(2)(+) may play discrete roles in the regulation of sperm activities and propose a mechanism by which these different components of the sperm Ca(2)(+)-signalling apparatus may interact to generate complex and spatially diverse [Ca(2)(+)]i signals.

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

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.