Which mechanism best explains postmenopausal hot flushes?
- A Elevation of the core body temperature set point by oestrogen excess
- B Narrowing of the thermoneutral zone in the hypothalamus driven by oestrogen withdrawal and KNDy neuron signalling via neurokinin B ✓
- C Direct vasodilator action of rising FSH on cutaneous vessels
- D Loss of adrenal androgen production causing vasomotor instability
Correct answer: B. Narrowing of the thermoneutral zone in the hypothalamus driven by oestrogen withdrawal and KNDy neuron signalling via neurokinin B
Explanation
Oestrogen withdrawal widens the sensitivity of hypothalamic thermoregulatory neurons, narrowing the thermoneutral zone so small core temperature shifts trigger flushing and sweating. Kisspeptin-neurokinin-dynorphin (KNDy) neurons in the arcuate nucleus mediate this via neurokinin B signalling, which is why the NK3 receptor antagonist fezolinetant reduces flush frequency. FSH itself is not vasodilatory, and adrenal androgen loss is unrelated.
Reference: Williams Gynecology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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