Inhibin (specifically, "Inhibin A" or "Inhibin B" depending on subunit composition) (None universally accepted; sometimes INHA (inhibin alpha), INHBA (beta A), INHBB (beta B) used for gene/protein subunits)

Inhibin is a dimeric glycoprotein composed of one alpha and one beta subunit (either beta A or beta B), forming Inhibin A or Inhibin B. It is secreted primarily by ovarian granulosa cells and testicular Sertoli cells, but also detected in the placenta, brain, adrenal gland, and other tissues. Its main physiological role is to inhibit FSH synthesis and secretion, operating as a negative feedback regulator in the reproductive axis. Inhibin is part of the TGF-β family and has structural similarity to activin, but with opposing effects: inhibin decreases FSH, while activin stimulates it. Inhibin, especially its beta subunits (INHBB, INHBE), is now recognized to be abnormally expressed in certain cancers and metabolic states, where it may serve as a therapeutic target or biomarker. Diagnostic use of serum inhibin levels includes prenatal screening and assessment of gonadal cell function. Therapeutic strategies such as small molecule inhibitors, RNA interference, or molecular docking are under investigation for cancers expressing inhibin subunits.

Other names

Inhibin AInhibin BINHAINHBAINHBBTGF-β family hormone

Direct inhibition of activin signaling through competitive binding to activin type II receptor (ActRII, supported by coreceptor betaglycan). Feedback suppression of FSH release at pituitary. Potential interaction with cell migration and viability pathways in cancer. Downregulation via siRNA decreases fat mass and alters metabolic status.