Effects Of Hypothyroidism And Hyperthyroidism On Oxidative Stress In The Ovary And Uterus Of Young Adult Rats

Thyroid hormones and oxidative stress play significant roles in the normal functioning of the female reproductive system.Nitric oxide(NO),a free radical synthesized by nitric oxide synthases(NOS),participates in the regulation of thyroid functions and is also a good biomarker for assessment of the oxidative stress status.Therefore,the purpose of this study was to investigate effects of thyroid hormones on ovarian and uterine antioxidative status in young adult rats.Thirty immature female Sprague-Dawley rats were randomly divided into three groups:control,hypothyroid(hypo-T)and hyperthyroid(hyper-T).We used propylthiouracil(PTU)and thyronine(T4)to induce the rat models of hypo-and hyperthyroidism,respectively.The results showed that the body and ovarian weights decreased significantly in both the hypo-T and hyper-T groups,and that uterine weights were decreased significantly in the hypo-T group.The number of ovarian follicles decreased significantly in both the hypo-T and hyper-T groups.Serum concentrations of total triiodothyronine(T3)and thyroxine(T4),as well as estradiol(E2),were significantly decreased in the hypo-T group,but increased in the hyper-T group.The progesterone(P4)concentrations in the hypo-and hyperthyroid rats markedly decreased.Immunohistochemical staining provided evidences that thyroid hormone nuclear receptor ?/?(TRa?/?)and three NOS isoforms were located in different cell types of rat ovaries and uteri,indicating that these receptors were involved in ovarian and uterine development and function.The NO content,total NOS activity and inducible NOS(iNOS)activity of the ovary and uterus were significantly decreased in the hypo-T group,whereas they were increased in hyper-T rats.The ovarian constitutive NOS(cNOS)activity in the hypo-T group was significantly lower,while almost no significant difference was observed between the hyper-T and control groups.In addition,the uterine cNOS activity in the hypo-T group was significantly lower than that in the hyper-T group,while neither the hypo-T nor hyper-T group differed significantly from the control group.Moreover,the results showed that the ovarian and uterine malondialdehyde(MDA)contents in both the hypo-T and hyper-T groups were consistently higher than those in the control group and showed significant differences.The activities of both glutathione peroxidase(GSH-Px)and catalase(CAT)of the ovary and uterus exhibited significant decreases and increases in the hypo-T and hyper-T groups,respectively.Additionally,ovarian total superoxide dismutase(T-SOD)activity in the hyper-T group was significantly higher,while almost no significant difference was observed between the hypo-T and control groups.The uterine T-SOD activity in both the hypo-T and hyper-T groups showed a decrease compared with the control rats,whereas there was almost no significant 'difference between the hypo-T and hyper-T groups.In conclusion,the results of the present study using hypo-T and hyper-T rat models provide the evidence that thyroid hormones have an important influence on the modulation of ovarian and uterine antioxidative status in the young adult rat.Nevertheless,the roles of NOS signaling and oxidative stress in thyroid hormone-induced reproductive problems still needs further researches.Clearly,there might be significant relationships between thyroid hormones and antioxidative status in the female reproductive system,and these findings would be helpful in clarifying the effects of thyroid dysfunction on female reproduction overall.