Inhibins and Activins
Hello bloggers, The last blog of mine will be regarding Inhibins and Activins. These Inhibins are the growth factors which are synthesized in the gonads. They are members of TGF family of proteins. Function: They show their effect directly on gonadal and extragonadal tissue. Apart from targeting the pituitary gland they also play a role as paracrine/autocrine regulators of gonadal function They induce responses in tissues other than gonads. Chemical nature: * Inhibins are heterodimer with alpha and beta polypeptide subunits and Activins are dimmers with only beta subunits . * A mature form of subunit has 134 amino acids. Inhibins and Activins are named along with the polypeptide composition as Inhibin A(alpha and beta A), Inhibin B(alpha and beta B), Activin A(2 beta A units), Activin AB ( beta A and Beta B). The important thing is that these gonadal derived proteins are capable of either inhibiting (Inhibins) or stimulating (Activins) the pituitary FSH production. Site of synthesis: The major gonadal sites of Inhibin synthesis are Sertoli cells in males and granulose cells in females. In adults Inhibins are also synthesized in adrenal glands, spleen and nervous system. Recent studies were done in which mice with Inhibin deficiency was studied. These mice in which Inhibin gene was missing developed normally but finally showed gonadal stromal tumors. Reference: http://ebm.rsmjournals.com/content/231/5/534.long dated December 1, 2011.