Before menopause: estrogen keeps the KNDy cells small and their signal modest. The heat-loss centre idles, and everyday wanders in body heat pass unnoticed.

Before, after, or with a treatment · watch the cells at the base
KNDy cells and neurokinin BHeat-loss centre (MnPO)EstrogenDeep in the brain, just above the pituitary, a small cluster of nerve cells called KNDy neurons (for the kisspeptin, neurokinin B and dynorphin they make) also times the pulses of reproductive hormones, and sends neurokinin B to the brain's heat-loss centre, the median preoptic nucleus. Estrogen keeps these cells in check.After menopause they are larger (about twice the cross-section in a post-mortem study) and make more neurokinin B. The heat-loss centre then sits near its tipping point, so a tiny everyday rise in body heat sets off a full heat-loss response: flushing, sweating and a faster heart. In a study, neurokinin B given to women caused flushes.Treatment can act at either end. Hormone therapy replaces the estrogen that keeps these cells in check. Non-hormonal neurokinin-receptor blockers leave the cells signalling but stop the heat-loss centre receiving it. Neither is for everyone: each needs a safety review and has its own benefits and risks, and not treating is always an option.A typical pattern in women who have hot flashes; many women have few or none. How much a treatment helps varies from person to person; the drawing shows the mechanism, not an expected result. Time is compressed: the drawn bursts come seconds apart, while hot flashes come about an hour apart. Firing rates are drawn, not measured. Cell size from post-mortem studies of postmenopausal women.