Effects of Menopause and Diabetes on the Rat Thyroid Gland: A Histopathological and Stereological Examining

Objective: Menopause is described as the arrest of the menstruation cycle and ending of reproductive potential. Diabetes mellitus (DM) occurs with Type 1 diabetes that is originated from the absence of insulin and Type 2 diabetes depending on insulin resistance. It is one of the most common endocrine disorders encountered in clinical practice that can cause serious health complications. Therefore, the objective of the present thesis was to investigate the effects of menopause and diabetes upon the thyroid using a rat model. Materials and Methods: 24, 12 weeks old female Sprague-Dawley rats were divided randomly into; non-diabetic healthy control group (Group I, n = 6), diabetic group (Group II, n = 6), ovariectomy group (Group III, n = 6), and ovariectomy plus diabetic group (Group IV, n = 6), respectively. Results: In histopathological examinations, the thyroid gland of the diabetic group had large follicles with cuboidal or almost squamous epithelial lining surrounding wide lumen. There were areas of disorganized follicles with decreased colloid. In the ovariectomized (OVX) rats, there was hyperplasia of the thyroid follicles and disorganized follicles with complete obstruction of their lumina. Mitotic cells were available. Some parafollicular cells had lack of cytoplasm. Post ovariectomy diabetes-induced group (Group IV), there were some species between follicles and remarkable reduction of colloid. Hyperplasia of the thyroid follicles, solid cell nests, and mitotic cells were also seen increasingly in this group. Follicular lumen area of ovariectomy group is closer to the control group. The increase of the lumen area in the DM group was the largest, diabetes+ovariectomy group also had an increase in the follicular lumen area. Conclusion: Finally; postmenopausal aging and diabetes in rats, may cause thyroid degeneration. DM and menopause both cause oxidative stress. But their damages on thyroid tissue are different. It means they cause oxidative stress via different ways. DM + OVX group compared to other groups has the greatest damage.