What causes hot flushes? The neuroendocrine origin of vasomotor symptoms in the menopause

Abstract

Vasomotor symptoms (VMS) such as hot flushes and night sweats are frequently encountered during menopause and can greatly reduce the quality of life. These symptoms are causally related to decreasing estradiol concentrations, mainly in the serum and subsequently also in the hypothalamic temperature regulating centre. The lack of estrogens alters neurotransmitter activity, especially in the serotonergic and noradrenergic pathways. Because sex steroids act as potent neuromodulators, the substitution of ovarian sex steroids by hormone replacement therapy is the most effective treatment option for VMS. When contraindications exist for the use of sex steroids, steroid-free drugs are a possible alternative. A better understanding of the physiology of thermoregulation, thermoregulatory dysfunction and adaptive processes of the brain may facilitate the development of new therapeutic approaches. Such drugs could then be used to treat vasomotor disorders even when the use of steroid hormones is contraindicated. This review article summarises our knowledge on the mechanisms of temperature regulation and describes deviations from this regulation during altered sex steroid conditions. Our current knowledge on neuroendocrinology of thermoregulation may serve as a basis for the use of steroid-free pharmacological intervention.

Los riesgos de no usar terapia hormonal de la menopausia: deterioro de la calidad de vida

“…En este sentido apunta la observación de Murphy, que relaciona altos niveles de temperatura corporal central, fenó-meno que precede a los bochornos, con pobre calidad de sueño; y vincula ambos síntomas con bajos niveles de estradiol y altos niveles de gonadotrofinas 13 . Además, la disminución de estradiol no sólo afecta al centro hipotalámico de regulación de la temperatura, implicado en la etiopatogenia de los bochornos, sino que también a las vías serotoninérgicas y noradrenérgicas 14 Por lo tanto, no es sorprendente que las mujeres con síntomas vasomotores tengan más trastornos psicológicos y que fármacos que modulan la neurotransmisión, como algunos antidepresivos, resulten útiles para tratar no sólo los bochornos, sino que también los trastornos del ánimo, disturbios del sueño y los síntomas somáticos del climaterio 15 . Por lo tanto, la presencia de síntomas vasomotores, por su asociación a otros síntomas climatéricos, son un fuerte indicador de mala calidad de vida 16 .…”

Vasomotor Symptoms: What is the Impact of Physical Exercise?

“…16 However, it is still unclear the exact mechanisms by which norepinephrine and serotonin cause VMS. The finding that selective serotonin reuptake inhibitor decreases skin blood flow implies that serotonin may play a role in hot flushes.…”

“…17 Decreasing estradiol levels during menopausal transition can alter the threshold for cutanoeus vasodilatation and low estrogen levels in postmenopausal women can reduce vascular elasticity, contributing to the impaired vascular reactivity. 16 Apart from estrogen levels, the reduction in estradiol, estrone ratio and estrogen function with regard to polymorphisms in sex steroid-metabolizing enzymes and estrogen receptors too are linked to VMS, contributing to ethnic differences in VMS.…”

Traitement des bouffées de chaleur après cancer du sein

“…L'hypothèse qui prévaut actuellement est celle d'une dysfonction des mécanismes de la thermorégulation qui comportent trois composants principaux : le système nerveux central, la température corporelle centrale (Tc) et le système vasculaire périphérique, tous en interaction [1,[19][20][21][22].…”

“…La thermorégulation est un mécanisme physiologique complexe dont l'objectif est de maintenir la Tc à l'intérieur de limites compatibles avec l'intégrité corporelle et un fonctionnement optimum quand l'environnement thermique change [22]. Ces limites sont représentées par deux seuils qui caractérisent la zone de neutralité thermique (ZNT), le seuil supérieur, qui est celui de l'apparition des sueurs qui permettent la dissipation de la chaleur, et le seuil inférieur, celui de l'apparition des frissons [1,20,22].…”