Fatma Betül SİLİNMEZ, Hülya ÇETİN, İlknur LAFCI, Semih TAN, Saim ÖZDAMAR
Journal of Experimental and Clinical Medicine - 2026;43(1):37-45
Hypothyroidism causes a slowing of bodily functions as a result of insufficient production of thyroid hormones (T4 and T3). It also negatively affects reproductive health. Indeed, animal studies have shown that hypothyroidism inhibits follicular maturation and disrupts ovarian function. Epidermal growth factor (EGF) is a polypeptide that plays a vital role in cell growth and differentiation. This study aimed to investigate the effects of induced hypothyroidism in adult rats on ovarian follicles and changes in EGFR expression. Eighteen female Wistar rats were used in our study. Ten rats were randomly selected and given 10 mg/kg methimazole in their drinking water for 30 days, forming the hypothyroidism group. The remaining eight rats, which underwent no treatment, formed the control group. The effects of methimazole-induced experimental hypothyroidism on the ovary were investigated in terms of biochemical, histopathological, and mRNA expression changes. A significant decrease in serum T3 levels was observed in rats given methimazole. The mean body and ovary weights of rats in the hypothyroidism group, as well as the number of primary, secondary, and tertiary follicles, were found to be significantly reduced. Immunohistochemically, EGFR expression was also found to be reduced in rats in the hypothyroidism group. RT-PCR analysis revealed that, compared to the control group, the methimazole group rats had increased HB-EGF, EGFR, GPER1, and ESR1 gene expression, while RAF1 expression decreased. Methimazole causes severe impairments in rat ovarian follicular development and oocyte quality.
