What primary effect does inhibin have on the anterior pituitary gland?

Inhibin is a hormone produced primarily by the Sertoli cells in the testes and the granulosa cells in the ovaries. Its primary role is to regulate the feedback mechanism involving the anterior pituitary gland, specifically targeting follicle-stimulating hormone (FSH) production.

When inhibin is released into the bloodstream, it selectively inhibits the secretion of FSH. This is crucial in maintaining the balance of reproductive hormones and ensuring that the gametogenesis processes (spermatogenesis in males and oogenesis in females) occur at proper rates. By reducing FSH production, inhibin helps fine-tune the stimulation of the growth and maturation of the follicles in females and the stimulation of spermatogenesis in males.

The other options are less relevant to the primary action of inhibin on the anterior pituitary. While inhibin does not affect LH (luteinizing hormone) production directly, it has no role in increasing testosterone levels or specifically reducing estrogen levels. Instead, those processes are regulated by other hormones and feedback mechanisms involving the action of gonadotropins and the sex steroids. Thus, inhibin’s primary action within the anterior pituitary is focused on the inhibition of FSH production.