Experimental manipulation of hypothalamic GnRH pulse frequency alters pituitary gonadotrophin output. Which pattern correctly describes this relationship?

• A High pulse frequency favours FSH secretion, low frequency favours LH
• B Both LH and FSH increase proportionally with any rise in pulse frequency
• C High pulse frequency favours LH secretion, slow frequency favours FSH ✓
• D Continuous high-amplitude GnRH exposure maximises both gonadotrophins

Explanation

Rapid GnRH pulses preferentially upregulate LH beta-subunit expression, whereas slower pulses favour FSH beta-subunit expression, reflecting differential regulation by activin, inhibin and follistatin at the gonadotroph. Continuous non-pulsatile GnRH exposure causes receptor downregulation and suppresses both hormones, which is the basis for using long-acting GnRH agonists to achieve medical castration.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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