Effect of Methanol Soy Extracts on TSH, T3and T4 Serum Concentrations in Ovariectomized Rats

Foods including soy and dietary supplements are widely used for health benefits، particularly by menopausal women. Serum levels of T3 and T4 decrease in ovariectomized animals and on the other hand، Estradiol can increase levels of thyroid hormones. Therefore، the aim of this study was to examine the effects of soy extract on the thyroid hormones in ovariectomized rats. Forty female wistar rats were randomly divided into four groups (ten animals in each): Sham–operated (surgery without remove of ovaries)، ovariectomized، treated (OVX+soy extract) and control-gavages (intact animals with soy extract). Animals in sham - operated and ovariectomized (OVX) groups received 0/5 ml normal saline by gavages. Animals of treated and control-gavages groups were treated with soy extracts 60mg/kg/day in drinking water for 28 days by gavages. The results showed that TSH serum level increased and serum levels of T3 and T4 decreased significantly in OVX group compared to the sham group (p0. 000). Furthurmore، serum levels of T3 and T4 increased and TSH levels decreased significantly in the treated group compared to the OVX group (p0. 000). Soy extract administration has a positive effect on serum concentrations of thyroid hormones in ovariectomized rats.