GnRH is secreted in a pulsatile fashion from the hypothalamus. A patient is being treated with continuous (non-pulsatile) GnRH administration. What effect is expected on LH and FSH?

• A Sustained stimulation of LH and FSH throughout treatment
• B Selective suppression of FSH with preservation of LH
• C Initial surge followed by sustained down-regulation and suppression of LH and FSH ✓
• D No change because GnRH receptors are not regulated by agonist exposure

Explanation

Continuous GnRH exposure causes receptor down-regulation on gonadotrophs (desensitization), resulting in an initial LH/FSH surge followed by profound suppression — the basis for GnRH agonist therapy in endometriosis, prostate cancer, and precocious puberty. Normal pulsatile GnRH (every 60–90 min) maintains receptor sensitivity and sustains gonadotropin production. This pharmacological principle is clinically exploited with leuprolide, buserelin, and goserelin.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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