Kisspeptin and its Effect on Mammalian Spermatogensis

Background: Kisspeptin and its receptor, GPR54, are regarded as key regulators of and catalysts for male puberty onset, and also fundamental gatekeepers of spermatogenesis in mammals. Consequently, the loss function of kisspeptin or GPR54 leads to a symptom of Hypogonadotropic Hypogonadism (HH) in human and HH accompanied by lower gonadotrophic hormone levels, smaller testes, impaired spermatogenesis and abnormal sexual maturation in mice. Besides its well-recognized functions in hypothalamus before and during puberty, accumulating data strongly support kisspeptin production in testis, and participation in somatic and germ cell development and sperm functions as well. This review aims to summarize recent findings regarding kisspeptin activity in the testes and sperm function. Methods: We undertook a keyword search of peer-reviewed research literature including data from in vivo and in vitro studies in humans and genetically modified animal models to identify the roles of kisspeptins in male reproduction. Results: A plethora of studies detail the role of kisspeptins and GPR54 in mammalian spermatogenesis in vivo and in vitro. This review identified recent findings regarding the kisspeptin system in male gonads, and regulation of kisspeptin in testicular physiology and male reproductive defects and disorders. Conclusion: The findings of this review confirm the importance role of kisspeptins in male fertility. Understanding their biphasic roles in testis may help to consider kisspeptins as potential pharmacological targets for treating human infertility.