Ghrelin and male reproduction

Abstract

Ghrelin is a multifunctional peptide hormone, conventionally known to be secreted by the stomach. The synthesis of ghrelin by the reproductive organs signifies its autocrine and/or paracrine actions upon the gonads. Expression of the functional ghrelin receptor is observed in different levels of the hypothalamic-pituitary-gonadal axis, suggesting its action on hypothalamic secretion of gonadotropin-releasing hormone and the pulsatile secretion of pituitary gonadotropins. It mainly acts to inhibit the secretion of the luteinizing hormone and thereby may also hinder proper testicular functions. This review article aims to provide a concise concept on (a) the characteristics, secretion and mode of actions of ghrelin, and (b) the role of ghrelin as a potential regulator of male reproductive functions. It may act upon the hypothalamic-pituitary-gonadal axis as well as directly regulate key testicular functions such as testosterone secretion, Leydig cell proliferation and expressions of prime functional proteins in the seminiferous tubule. These actions of ghrelin on testicular functions appear to be species-specific. Ghrelin and its versatile biological functions bring to a consensus that further research on ghrelin may establish one of the associations between body energy status with alterations in male reproductive functions.

Keywords

• Ghrelin
• Male infertility
• Testosterone
• Spermatogenesis