| Objective To observe the continuous changes of iodine metabolism, the structure and function of the thyroid and immune function in each trimester of pregnancy and lactation in Wistar rats. The changes of TPO and TG mRNA and protein expression will be researched as well. The experimental results will provide experimental data and the theoretical basis for the intervention of maternal thyroid disease.Methods According to the body weight and period, wistar rats were divided into 7 groups: control group, early pregnancy group, mid pregnancy group, late pregnancy group, early lactation group, mid lactation group and late lactation group. Female rats of the last 7 groups were mated with male rats. Urine of female rats were collected and blood samples were collected by exsanguination from femoral artery at the 7th, 14 th and 21 th day of their pregnancy and lactation respectively. Structure under the microscope of thyroid gland was observed by HE staining.UIC was determined by As3+-Ce4+ catalytic spectrophotometry using ammonium persulfate digestion. TT3 and TT4, FT3 and FT4, TSH were measured by CLIA. Serum rat estrogen, progesterone, Tg, TgAb and TPOAb were determined by RIA. The mRNA expression level of TPO and TG was detected by quantitative real-time PCR, and the protein expression level of TPO and TG was detected by Western blotting.Results1.The thyroid weight of late pregnancy and early lactation were higher than control group. Compared with control group, structure under the microscope in pregnancy and lactation showed mild hyperplasia phenomenon.2.There were no significant differences of UIC between pregnancy groups and control group. The late lactation group was lower than control group.3.TT3, TT4 level in early pregnancy were higher than control group; TT3 level of postpartum rats reduced, in the late lactation it was lower than control group, TT4 level in lactation gradually recoved to pre pregnancy level. With the development of pregnancy, the levels of FT4 and FT3 decreased and TSH increased gradually. TSH continued to rise to the highest value in early lactation, and decreased to the level of control group. FT3, FT4 in lactation have increasing trends, FT3 of late lactation compared with control group has no difference; while FT4 has not recoved to pre pregnancy levels.4.The estrogen level of rat was increased, and reached the peak in late pregnancy,in early lactation it decreased to pre pregnancy level. Progesterone of early pregnancy was higher than control group, it reached the highest value in the late pregnancy. Progesterone decreased after childbirth, and recoved to pre pregnancy levels in late lactation.5.Compared with control group, there was no difference of Tg in pregnancy. Tg in late lactation group was higher than control group.6.There was no difference of TgAb between pregnancy groups and control group, while TgAb in all lactation groups were decreased. TPOAb has no difference with control group.7.Tg mRNA of pregnancy and postpartum were higher than control group. Tg protein levels in pregnancy and lactation were coincided with the level of serum Tg changes. TPO mRNA in pregnancy and lactation were higher than control group. The protein levels and genetic changes were the same.Conclusion1.Thyroid weight,microscopic structure,UIC, thyroid hormone and TG, TPO mRNA and protein expression of rat showed that there was a relative lack of maternal thyroid hormone in pregnancy and lactation. Thyroid function showed mild low performance.2.Thyroid function of rats have continuous changes in different stages of pregnancy and lactation, which coincided with the rules of human. Wistar rats can consider as the animal model to research thyroid function.3.There were differences of thyroid autoantibodies in pregnancy and lactation between Wistar rats and human. Wistar rats can not be considered as the animal model to research autoimmune thyroid disease. |
