Leptin and male reproduction

Abstract

The global scenario reveals that the recent trend of deterioration of male fertility parameters parallels the growing prevalence of obesity. Over the last few decades, substantial research evidence has surfaced that aid understanding of the mechanisms by which body energy homeostasis is associated with reproductive functions. In this regard, leptin, an adipocyte-derived hormone, finds utmost relevance for its versatile physiological functions especially in metabolism as well as in the regulation of reproductive functions. Since leptin receptors are found to be highly expressed in several structures, both centrally and peripherally, it has been hypothesized that leptin may affect reproductive functions either via the hypothalamic-pituitary-gonadal axis or may also directly act upon gonadal tissues. Its roles, particularly during puberty and reproduction, are well documented. However, the exact mechanisms of leptin actions upon the gonadotropin-releasing hormone neurons to induce physiological changes of puberty and reproduction need further research. Leptin is proven as an essential hormone required for normal reproductive functions, but when leptin levels exceed the physiological limit, it may adversely affect the testicular processes. Leptin can serve as a potential link between obesity and male infertility, as it has been shown that poor male reproductive parameters such as low sperm count, testicular oxidative stress, high rate of morphological abnormalities in sperm, positively correlate with increased levels of leptin in obese men. Therefore, the present review article aims to provide a better understanding of the updated views on the functions of leptin and mechanisms of leptin actions on male reproduction.