Studies of the Vegetable Components on Menopausal Obesity and the Associated Mechanisms

Menopause is always associated with overweight and obesity, especially abdominal fat accumulation, leading to increased risk of various metabolic diseases. Although the reasons are not clear, depletion of estrogen is thought to be an important factor. Estrogen deficiency or estrogen receptor knockout has been indicated to enhance lipid accumulation in adipocytes, and administration of estrogen may inhibit lipid accumulation in white adipocyte but enhance the functions of brown adipocytes. On the other hand, excess lipid accumulated in white adipose tissue (WAT) is positively associated with increased expression of aromatase, a key enzyme in estrogen biosynthesis, and thus increased estrogen concentrations in both blood and local tissues resulting in increased risks of estrogen-associated cancers. Therefore, a complicated interaction between estrogen and WAT exists. Different concentrations of estrogen had differential effects on various types of adipocytes, including preadipocytes, white adipocytes, and possibly brite adipocytes, is proposed. Although estrogen replacement therapy can decrease body weight of postmenopausal women, a high breast cancer risk is also observed. Therefore, foods or food components which have phytoestrogenic activities have been suggested for women to relief the menopausal symptoms. Among these, onions and indole-3-carbinol (I3C) have been shown to be able to modulate estrogen activities and to decrease body weight in diet-induced obese animals, and such effect is associated with modulated expressions of factors that are associated with white, brown, and brite adipocytes. However, their effects on menopausal obesity have not been investigated. This 3-year study is then aimed at investigating the effects of onion, I3C, and the combination on menopause-induced obesity, and the effects of their bioactive components or derivatives, including quercetin, (S-methyl-L-cysteine sulfoxide) SMC, and 3,35-diindolylmethane (DIM), on the adipocyte differentiation and mitochondria functions will be also investigated. In the first year, the ovariectomy rats will be used, and the factors related to obesity, adipocyte differentiation, and estrogen will be determined. In the second year, 3T3L-1 adipocyes will be applied, and different concentrations of estrogen in the presence of the treatments on preadipocyes or adipocytes will be studied. In the third year, the effects of these food components on brite adipocyte differentiation and mitochondria functions will be explored. Results obtained from this study may help us to understand the roles and mechanisms of these foods or food components on obesity caused by menopause, and help to provide dietary recommendations for menopausal women.