New targets for old hormones: inhibins clinical role revisited

Inhibins are gonadal peptide hormones belonging to the transforming growth factor-β (TGF-β) superfamily that regulate the pituitary follicle stimulating hormone (FSH) secretion by negative feedback mechanisms. It is evident that the understanding of inhibins function in the hypothalamic-pituitary-gonadal axis will provide insights into physiology and pathology of the gonadal function. In recent years, a great deal of attention has been focussed on clinical relevance of measuring circulating inhibins in normal and disease state. The past few years also have witnessed the emergence and discovery of extra pituitary action of inhibins that might provide further insights into the underlying diseases like cancer especially in the reproductive axis and various other new endocrine target organs. In this review after systematic analysis of literature, we discuss briefly the known and recent advances in function of these hormones highlighting also its structure, production and mechanisms of signal transduction. Also this review discusses about the physiological relevance of inhibin association in the normal function to the development of reproductive cancers. Finally, we describe evidence from various emerging studies that inhibins make an important contribution to other physiological functions apart from reproduction which reveals new endocrine target organs of inhibins. The emerging view is inhibin participates in multiple ways to regulate the function in different cell types and still complete repertoire of its actions is under investigation.