Effect of Carbimazole on the Structure of the Ovary of the Adult Albino Rat

Abstract

Thyroid hormones are the key regulators for a variety of biological processes, including growth, metabolism, development and differentiation in different tissues and organs including the ovary. The present study aimed at investigating the hypothesis that hypothyroidism in females impairs fertility by direct and indirect effects on ovaries. To confirm the current hypothesis, the anti-thyroid drug Carbimazole was used to induce a state of hypothyroidism and examined the outcome of its application. For this purpose, 45 adult female albino rats each weighing 180-220 grams, were used and were classified into three equal groups: Group I (Euthyroid, Control group): was composed of 15 rats, they received 0.5 ml of distilled water every day orally by gastric tube for three months, Group II (Hypothyroid group): was composed of 15 rats, each of which received Carbimazole at a dose of 5mg dissolved in distilled water every day orally by gastric tube for three months to induce hypothyroidism and Group III (Recovery Group): was composed of 15 rats and they ceased to receive Carbimazole for three months to examine the changes after the stoppage of the treatment. The changes that occurred after the use of Carbimazole, were tested by laboratory studies: measuring the serum levels of thyroid stimulating hormone, total thyroxine, total tri-iodothyronine, follicular stimulating hormone, Luteinizing hormone, estradiol and prolactin. Moreover, the effects on the structure of the ovary were investigated via histological and immuno-histochemical studies at the end of the experiment, using light microscopy and analyzed by image and statistical analyses. After sacrifice of the rats, their ovaries were separated and processed for histological examination using Hematoxylin and Eosin, Periodic Acid Schiff and Masson’s Trichrome. In addition, semithin preparations were made and stained by Toluidine Blue. Furthermore, the ovarian sections were processed for immuno-histochemial staining using Vimentin, thyroid receptor alpha 1 and α- smooth muscle actin stains. The studied histological and semithin preparations revealed a change in the normal architecture of the ovary, where the ovarian cortex showed an apparent decrease in the number of growing follicles with large fluid-filled cystic follicles and multiple atretic follicles. Marked condensation of the interstitial cells among the follicular component of the cortex was identified with engorged blood vessels which was reversed upon stoppage of the intake of the drug.