Objective> To study the effect of pesticide
YE KU NING on the levels of serum FT4 and TSH in rats,and their time effect
relationship.
YE KU NING dimethylsulfoxide solution was administered to rats by gavage at a dose of 50 mg/kg body weight for 5,6,10,20 days,respectively. The rats in the control group were given solvent dimethylsulfoxide by oral gavage at the same volume. All animals were sacrificed after the last dosage and the levels of FT4 and TSH in serum were measured by radioimmunoassay. The histological changes of thyroid gland were observed too. A significant decrease in FT4 level but significant increase in TSH level ( P <0 05) was found in rats given YE KU NING for 5 days as compared with the control rats. Histological observation of thyroid gland showed proliferation of follicular epithelium on 5 th and 6 th day of experiment group,formation of solid bud on 10 th day,and formation of sequential follicles in the solid bud on 20 th day. The effect of YE KU NING on the level of serum FT4 and TSH in rats occurs within 5 days and may be followed by the consequent hyperplasia of thyroid gland. This in vivo experiment provides a foundation for screening methods for thyroid hormone disruptors.