Soy isoflavones reduce adiposity via increasing estrogen receptor beta expression in ovariectomized female rats.

Document Type : Original Article

Authors

1 Department of physiology, Faculty Veterinary Medicine, Suez Canal University

2 Department of Zoology, Faculty of Sciences, Suez Canal University

Abstract

Soy phytoestrogens have estrogenic activity and are used as a natural substitute for estrogen as a replacement therapy in case of estrogen deficiency. They have many useful activities in vitro and in vivo. However, Evidence is emerging that dietary phytoestrogens play a beneficial role in obesity and metabolic syndrome. The objectives of this study was to determine the effect of soy phytoestrogens on some metabolic parameters including energetic status (weekly food intake and body weight gain), abdominal and brown fat masses, adipocyte size, estradiol receptor beta (ERβ) expression in adipocytes, liver fatty changes, plasma high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TG), total cholesterol (TC) and oral glucose tolerance test (OGTT), insulin tolerance test (ITT), plasma leptin and adiponectin levels. A total of 30 ovariectomized female Albino rats were divided into two groups (15 females / group). Control group (C) received phytoestrogen-free casein-based diet and high soy phytoestrogens (HF) group received high phytoestrogens diet containing (27% soybeans) for 7 weeks. The results revealed that high phytoestrogens in diet decreased food intake and body weight gain significantly (P<0.05) than control group starting from 4th week and 5th week, respectively. Abdominal fat mass, brown fat masses and adipocytes size were significantly (P<0.05) lower in HF group than control. Adipocytes ERβ expression of in HF group was significantly (P<0.05) higher than control. The histopathological studies showed fatty infiltration in control group. The expression values of ERβ in adipocytes was significantly higher (P<0.05) in HF group than control. Levels of HDL was significantly (P<0.05) increased in HF group while LDL, TC and TG were significantly (p<0.05) decreased than control.  Oral glucose tolerance showed non significant change while insulin sensitivity was significantly improved in HF group. Plasma leptin levels were significantly (P<0.05) decreased, while adiponectin levels were increase in HF group than control group. These findings show the high dietary phytoestrogens interfere with adiposity and metabolic syndrome via increasing adipose ERβ expression with consequent reduction in leptin production and increase in adiponectin level that improves insulin sensitivity in ovariectomized female rats.

Keywords