α-Inhibin Gene Expression Occurs in the Ovine Adrenal Cortex, and is Regulated by Adrenocorticotropin

TLDR: Dot blot analysis showed that the level of alpha mRNA within the adrenal is influenced by ACTH, one of the major regulators of adrenal cortex function, implying that there are inhibin-related peptides not directly associated with the gonads.

Abstract: Inhibin is a glycoprotein hormone composed of two nonidentical subunits. It is produced by the ovary and testis and plays a vital role in gonadal function by inhibiting the secretion of FSH. More recently, additional activities associated with inhibin peptides have been identified. Inhibin heterodimers (α-β) are reported to act directly on ovarian granulosa cells and inhibit estrogen production induced by FSH. Furthermore, homodimers of β-inhibin subunits stimulate the secretion of FSH, an activity that is directly opposite to that of inhibin. Each of these inhibinrelated activities are concerned with the hypothalamic-pituitary-gonadal axis. We have investigated further the complexity of inhibin activity by determining whether inhibin genes are expressed in nongonadal tissue. RNA hybridization experiments demonstrate that the α-inhibin gene is expressed in the sheep adrenal cortex and hybridization histochemistry shows that this gene is expressed in each of the functional zones within the cortex. Dot blot...