5/27/2023 0 Comments Exces d oestrogene![]() Increases in plasma osmolality are sensed by central osmo-Na + receptors, nerves responsible for detecting the concentration of the intravascular fluid. Arginine vasopressin is synthesized in the cell bodies of nuclei located in the anterior hypothalamus, and axons from these areas project into the posterior pituitary where AVP is stored and released in response to stimulation of central osmoreceptors. These systems are sensitive to stimuli that arise from fluid deficits in the ECF space or due to excess blood sodium, tonicity, or osmolality. Changes in 17 β-estradiol and progesterone during treatment with a gonadotropin-releasing hormone (GnRH) antagonist beginning on day 25 of a normal menstrual cycle, followed by treatment with two 17 β-estradiol patches (0.1 mg each), and oral progesterone (200 mg/d).īoth estradiol and progesterone can influence the complex and integrated neural and hormonal systems that have evolved to control thirst, fluid intake, sodium appetite, and renal fluid and sodium regulation ( Fig. This article will also address the potential impact of these sex hormones on plasma volume and fluid distribution within the extracellular fluid (ECF) space.Ĭhanges in 17 β-estradiol and progesterone across the menstrual cycle ( left). Despite these effects, however, water and sodium regulation seem only minimally effected by estradiol or progesterone (or both) administration, suggesting that in young and healthy women, these hormones alter the homeostatic set point around which these systems are regulated rather than induce excess fluid or sodium retention or loss. ![]() In general, our studies have shown that these hormones are associated with acute perturbations in body fluid regulation such as altering the threshold for osmotically induced arginine vasopressin (AVP, the primary hormone involved in the regulation of renal free water) release and thirst onset, as well as alterations in the sodium-regulation hormones atrial natriuretic peptide (ANP), renin, and aldosterone. By selectively administering estradiol and/or progesterone while the subjects were suppressed, we isolated the effects of these hormones on the fluid and sodium regulatory systems during acute fluid or osmotic challenges. The suppression is followed by controlled administration of estradiol, progesterone, or combined estradiol-progesterone to physiological levels. These protocols, in effect, pharmacologically “oophorectomize” subjects for a short easily reversible period. 1) to suppress reproductive function (and thus estrogens, progesterone, and gonadotropins). A series of studies described in this article used a newer paradigm to control the levels of sex hormones through the use of either a gonadotropin-releasing hormone (GnRH) agonist or antagonist ( Fig. However, when examining the interaction of these hormones and body fluid regulation under these study paradigms, estradiol or progesterone were elevated or suppressed simultaneously, so we did not isolate their individual effects. In our early studies, we determined reproductive hormone effects on body water regulation system in young women by examining responses to fluid perturbations either during the different phases of the menstrual cycle or during administration of oral contraceptives. The study of reproductive hormone effects on physiological systems is complex in young women because of hormonal fluctuations over the course of the menstrual cycle ( Fig. Moreover, the impact of sex hormones on body fluid and sodium regulation has important implications for a number of syndromes for which women are at risk, including orthostatic hypotension, insulin resistance, polycystic ovary syndrome, and neurological consequences from postoperative ( 8) and exercise-associated hyponatremia ( 1). Receptors for estrogens and progesterone are found in nonreproductive tissue involved in fluid regulation, such as the hypothalamus ( 10, 21), the cardiovascular system ( 6, 19), and the kidney tubules ( 6). One mechanism by which estrogens or progesterone may impact physiological systems is through regulation of body fluids and sodium content. For example, premenopausal women have delayed and less severe manifestation of cardiovascular diseases than do men ( 13), and although there continues to be some controversy surrounding hormone replacement in postmenopausal women, hormone replacement therapy is usually associated with improved cardiovascular function in perimenopausal and postmenopausal women ( 6, 19). There are clear sex differences in risk factors for a number of syndromes and diseases in addition to sex differences in the function of many physiological systems.
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