Abstract
Hormone replacement therapy (HRT) can alleviate estrogen deficiency symptoms especially during menopause. The present study aimed at investigating the effect of soy isoflavones as HRT on immunological and bone health-related parameters with a special focus on the interactions between immunological status and metabolism. Thirty healthy cyclic female Wistar rats were used in this experiment. Ten females were sham-operated, and 20 females were subjected to ovariectomy. Overiectomized (OVX) female rats were randomly divided into 2 groups: the control group (G1, OVX/casein) was fed a casein-based diet, and the second group (G2, OVX/soy) was fed a high soy isoflavone diet. Both groups were compared to a sham-operated group (G3, sham/casein). Treatments continued for 7 weeks. Feed intake, weight gain, and lymphoid organ relative weights were recorded. Some metabolic, immunological, and bone health-related parameters were measured. Moreover, nitric oxide (NO), malondialdehyde (MDA), and total antioxidant capacity (TAC) were determined. Bone histopathology and immunohistochemistry to estrogen receptor alpha (ERα) were done. Feeding soy to OVX females reduced feed intake, weight gain, relative lymphoid organ weight, and T-lymphocytes transformation. Soy isoflavone administration normalized nearly all metabolic and immunological parameters to a level comparable to the sham group via oxidative stress amelioration and bone ERα promotion. Soy isoflavones seemed to be good HRT in estrogen deprivation which modulated the appetite, weight gain, lipid profile, proinflammation, and bone turnover.
Highlights
The estrogen hormone contributes a substantial role in different aspects of body homeostasis and anabolism [1]
It exerts these effects via unexpected regulatory roles on oxidative stress [2], immune function [3], and several metabolic aspects including bone cells as well as adipose tissue [4]
Dietary isoflavone analysis by High-Performance Liquid Chromatography (HPLC) in the current study revealed 800 μg/g daidzein and 1500 μg/g genistein that were together equal to the Asian people intake which was estimated to be about 20 to 80 mg of phytoestrogens/day [50]
Summary
The estrogen hormone contributes a substantial role in different aspects of body homeostasis and anabolism [1]. The estrogen hormone gives signals through two main distinguished receptors: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) [5] These receptors are widely spread all over the different body tissues such as reproductive [6], nervous [7], fat [8], liver [9], immune [10], cardiovascular [11], and bone tissues [12]. Estrogen hormone deficiency or depletion has been associated with several metabolic [13] and immunological alterations [14] These alterations include dyslipidemia, Oxidative Medicine and Cellular Longevity increased appetite, and bone loss [13] that predispose metabolic syndrome along with predisposing autoimmunity and proinflammation [14]. Homeostatic alterations due to estrogen depletion and menopause led researchers to suggest hormone replacement therapy (HRT) to combat their adverse effects
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