Thyroid hormones alter estrous cyclicity and antioxidative status in the ovaries of rats

Abstract

To expand our understanding of the roles of thyroid hormones on female reproduction, we induced hypo- and hyper-T rat models to investigate the roles of thyroid hormones on estrous cyclicity, as well as the antioxidative status in the ovaries of rats. In the current study, our data show that hypothyroidism (hypo-T) and hyperthyroidism (hyper-T) led to significantly reduced body weights and ovarain weights and delayed vaginal opening day. For hyper-T, thyroxine (T4), tri-iodothyronine (T3), progesterone (P4) and follicle-stimulating hormone (FSH) were significantly increased, while estradiol (E2) and luteinizing hormone (LH) were significantly decreased. For hypo-T rats, serum levels of total T4 and T3, E2, P4, FSH and LH were significantly increased, while concentrations of E2 and LH were significantly decreased. For ovary morphology, the numbers of secondary and antral follicles were significantly decreased with more atretic antral follicles and less corpora lutea in both hyper- and hypo-T groups. Both hyper-T and hypo-T treatment significantly decreased the expressions of thyroid hormone receptor α1 in the ovary. Hypo-T significantly reduced nitric oxide (NO), total NO synthase (tNOS), inducible NOS and constitutive NOS activities, but hyper-T increased them. For antioxidative parameters, hypo-T and hyper-T treatment significantly increased malondialdehyde (MDA) contents. The activities of both glutathione peroxidase (GSH-Px) and catalase (CAT) significantly decreased in the hypo-T group but increased in the hyper-T group. Total superoxide dismutase (T-SOD) activity was significantly increased in the hyper-T group. In summary, thyroid hormones alter estrous cyclicity and antioxidative status in the ovary of the rat may act through the NOS signaling pathway.

Bisphenol A attenuates thyroxine‐induced apoptosis in ovarian granulosa cells of pigs

“…We found that T4 diminished serum 17β‐estradiol accumulation (end product of synthesis, secretion and metabolism) by porcine granulosa cells. Our previous studies showed that the production of 17β‐estradiol was significantly decreased in both hypothyroid and hyperthyroid treatments (Wei et al, ). We hypothesized that thyroid hormone abnormalities would disturb sexual hormone secretion so as to affect reproductive performance in animals.…”

“…Our previous data also revealed that thyroxine (T4) plays important roles in follicular development in the ovaries of postnatal and immature rats (Fedail et al, ), and we therefore used T4 in the present study. In addition, this dose of T4 was chosen according to our previous study (Wei et al, ), where we measured total T3 and T4 levels and T3/T4 ratios in the serum of control, hyper‐T and hypo‐T rat on day 80. Furthermore, this dose range is similar to that used in previous studies (Asahara, Sato, Aljonaid, & Maruo, ; Chan & Tan, ).…”

“…One of our previous studies exhibited that TRα1 was expressed and localized in oocytes, granulosa cells and theca cells during follicular development (Zheng et al, ); thyroid hormones can alter the release of gonadotropins, further affecting the destiny of the ovarian follicle (Sun et al, ). It has been reported that the imbalance in thyroid hormones leads to a significant reduction in ovarian weight, which is related to a disorder of reproductive hormone synthesis and secretion, and further increases the risk of infertility (Ding et al, ; Hapon, Gamarra‐Luques, & Jahn, ; Wei et al, ). Moreover, other investigators have demonstrated that hyperthyroidism increased serum 17β‐estradiol concentrations, while hypothyroidism decreased serum 17β‐estradiol concentrations (Fedail et al, ).…”

Thyroid hormones in ovarian follicular fluid: Association with oocyte retrieval in women undergoing assisted fertilization procedures

“…Recent studies have revealed that thyroid hormones alter estrous cyclicity and antioxidative status in the ovary of the rat acting through the nitric oxide synthase signaling pathway ( Zheng et al, 2015 ; Wei et al ., 2018 ). It was also reported that ovarian follicles of the laying hen express mRNAs of thyroid hormone-nuclear receptors, as well as integrin (αVβ3) plasma membrane receptors, indicating a genomic and non-genomic action of thyroid hormones in the chicken ovary ( Sechman, 2013 ).…”

Oxidative Stress Produced by Hyperthyroidism Status Induces the Antioxidant Enzyme Transcription through the Activation of the Nrf-2 Factor in Lymphoid Tissues of Balb/c Mice

“…There are reports that the thyroid state modulates the expression of antioxidant enzymes in various tissues [14–16]. However, the effect of TH on the regulation of the expression of antioxidant enzymes and the cellular redox state in the lymphoid tissue has not yet been clarified.…”