Metabolic syndrome provides an insight into the possible physiologic mechanism(s) of climacteric hot flushes: A hypothesis of flush mechanism

Bahaeldin E. ELawad, Asim Alaa

Abstract

Climacteric is a more encompassing term that refers to the entire transition to the non-reproductive period of life. Hot flashes are one of the most common symptoms of climacteric and occur in the vast majority of postmenopausal women. Menopausal hot flashes manifest in form of peripheral vasodilatation and profuse perspiration. Although hot flashes clearly accompany estrogen withdrawal at menopause, the physiologic mechanisms for initiation of flushes and of transient physical changes during flush episodes remain elusive. Researchers targeted central-focus mechanisms in attempts to clarify the pathophysiology of hot flashes in postmenopausal women. In this article, we target a peripheral-focus mechanism. During data analysis of our unpublished work on “predictors and consequences of metabolic syndrome among postmenopausal Sudanese women”, we observed that 75.8% of postmenopausal women with metabolic syndrome have hot flushes and sweating compared to 42.6% in postmenopausal women without metabolic syndrome. We thought that metabolic syndrome in postmenopausal women might give an insight to elucidate the pathophysiology of hot flashes, in general. We propose a hypothesis, during normal female reproductive period, a vasomotor tone on peripheral blood vessels is brought about by synergistic action of estrogen and catecholamines. This vasomotor tone is modulated by vasodilator effect of insulin. In postmenopausal women without metabolic syndrome, lack of estrogen results in peripheral vasodilatation. In postmenopausal women with metabolic syndrome, vasodilator substances released as a result of associated endothelial dysfunction override the insulin resistance effect on blood vessels. In postmenopausal women without metabolic syndrome the normally produced endothelial vasodilators potentiate the effect of insulin on blood vessels.