Inhibin in Male Reproduction and its Clinical Relevance

Inhibins have been implicated in the control of spermatogenesis by exerting negative feedback regulation of pituitary FSH release. In addition, locally produced inhibins play an important role in paracrine regulation of testicular function. The recent availability of speciflc and sensitive assays for different types of inhibin and activin heralds a new phase in our understanding of physiology and pathophysiology of these proteins. The identification and cloning of the inhibin receptor(s) are actively pursued, but the understanding of mechanism of inhibin action has been relatively incomplete. In recent years a number of male reproductive functions have been correlated with circulating inhibin B level. At the same time, several reports are also described questioning the importance of inhibin B as a reliable marker of male fertility. This report summarizes the physiological roles of inhibin in male reproduction, focusing on clinical relevance of these roles and possible future application in clinical practice.