Which hormone, produced by the ovaries, inhibits the secretion of FSH and LH?

GMCH Chandigarh - 2022

Obstetrics & Gynaecology

Easy

Appeared in: GMCH Chandigarh - 2022

Explanation

Inhibin is a peptide hormone produced by the granulosa cells within the ovarian follicles.
Its primary function is to selectively inhibit the synthesis and secretion of Follicle-Stimulating Hormone (FSH) from the anterior pituitary gland.
Some evidence suggests it also has a minor inhibitory effect on Luteinizing Hormone (LH).
This negative feedback is essential for selecting a single dominant follicle for ovulation each cycle.

Option A: Progesterone primarily inhibits the release of GnRH from the hypothalamus, which then indirectly reduces FSH and LH secretion. Its main role is to prepare the endometrium for pregnancy.
Option B: Oestrogen has a complex, dual-feedback role. At low and moderate concentrations, it inhibits FSH and LH. However, at sustained high levels, it triggers a positive feedback loop, causing the LH surge that leads to ovulation.
Option D: Gonadotropin-releasing hormone (GnRH) is produced by the hypothalamus, not the ovaries. Furthermore, its function is to stimulate the pituitary to release FSH and LH, not inhibit it.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of the female reproductive cycle as background academic context rather than a clinical decision trigger.
Assessing hormone levels, including FSH, LH, oestradiol, and Inhibin B, is a key part of evaluating a woman's ovarian reserve and diagnosing causes of infertility.
Abnormally high FSH levels, often seen with low Inhibin B levels, can indicate diminished ovarian reserve, a condition common with advancing maternal age.
What if? If a patient had a granulosa cell tumor of the ovary, her Inhibin levels would likely be extremely high. This would lead to a profound suppression of FSH from the pituitary gland.

How to Approach the Question

First, analyze the question to identify the key criteria: the hormone must be 1) produced by the ovaries and 2) inhibit FSH and LH.
Evaluate Option A (Progesterone): It's from the ovary and is inhibitory, but indirectly via GnRH. Keep as a possibility.
Evaluate Option B (Oestrogen): It's from the ovary but has both inhibitory and stimulatory effects, making it a less precise answer.
Evaluate Option C (Inhibin): It's from the ovary and its specific, named function is to inhibit gonadotropins, primarily FSH. This is a very strong candidate.
Evaluate Option D (GnRH): Immediately eliminate this option. It is not produced by the ovaries, and it stimulates, not inhibits.
Compare the remaining options. Inhibin is the hormone whose primary and most direct role is the inhibition of gonadotropins from the pituitary, making it the best answer.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 1032-1034

E6 Physiology Guyton 4SAE Part 3 p. 37-39