Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion, and participates in the regulation of the menstrual cycle.

Structure

---

Inhibin contains an alpha and beta subunit linked by disulfide bonds. Two forms of inhibin differ in their beta subunits (A or B), while their alpha subunits are identical. Inhibin belongs to the transforming growth factor-β (TGF-β) family.

Action

---

In women, FSH stimulates the secretion of inhibin from the granulosa cells of the ovary. In turn, inhibin suppresses FSH. Inhibin secretion is diminished by GnRH, and enhanced by insulin-like growth factor-1 (IGF-1). Inhibin B reaches a peak in the early- to mid-follicular phase, and a second peak at ovulation, in contrast to inhibin A, which reaches its peak in the mid-luteal phase. Inhibin is produced in the gonads, pituitary gland, placenta and other organs.

In men, it is a hormone that inhibits FSH production. It is secreted from the sustentacular cell, located in the seminiferous tubule inside the testes.

Activin

---

Activin is a related peptide that counteracts inhibin.

External links

---

inhibin http://www.inhibin.com Reproductive system | Hormones of the ovary | Peptide hormones | TGFβ domain

Inhibin | Inhibine