An antibody inactivating inhibin in female animals would most likely lead to what change in hormone levels?

• A. Increased serum follicle-stimulating hormone concentration
• B. Decreased serum gonadotropin-releasing hormone concentration
• C. Increased serum estrogen concentration
• D. Decreased serum luteinizing hormone concentration

Answer: (A)

Inhibin is a hormone produced by the ovaries that primarily functions to inhibit the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. When inhibin levels are reduced, whether through antibody-mediated inactivation or other means, FSH secretion is no longer inhibited, leading to an increase in its concentration in the serum.

In the context of female reproductive physiology, when there is an increase in serum follicle-stimulating hormone due to the inactivation of inhibin, the stimulation of ovarian follicles may lead to higher production of estrogen as well. However, the primary and immediate effect of antagonizing inhibin is the rise in FSH levels. Therefore, the most direct consequence of inactivating inhibin is an increased concentration of serum follicle-stimulating hormone, as the usual inhibitory feedback is disrupted, allowing for greater secretion from the pituitary.