EC Gynaecology

An evolutionary-based explanation for menopausal hot flashes (VMS) is offered. Using mainly urinary assays for ovarian steroid, women in the early perimenopause were shown to experience VMS mainly in association with decreased progesterone metabolite excretion. Episodes of LH spikes were also prominent but the expected association with lowered estrogen excretion was absent. This hormonal scenario is most consistent with increased gonadotropin releasing hormone (GnRH) as a result of increased activity of the pulse generator. These events are consistent with the literature in terms of a GnRH-mediated alterations in the limbic system in lower mammalian species that exhibit the psychic manifestation of heat, a desire to mate and the optimal time for conception following the decline of progesterone from a previous non-conceptive luteal phase. The evolution of the menstrual cycle from the more ancient estrous cycle in which concealed ovulation replaces the demonstrated desire to mate (estrus) and the ability of a well-developed cerebral cortices in higher primates dampen most autonomic events. Higher brain functions in women modulate vestigial tendencies to stimulate the autonomic system until the ability of the ovary fails to produce sufficient progesterone. Declining progesterone allows the limbic system to be activated by the increased GnRH drive and menopausal symptoms can be the result.

Keywords: Progesterone; Menopausal Symptoms; Gonadotropin Releasing Hormone (GnRH)

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