Development of oxidative stress in different experimental models of hypothyroidism in immature rats

Abstract

Summary. Hypothyroidism is one of the common pathologies in the practice of endocrinologist. Autoimmune thyroiditis and alimentary iodine deficiency are the causes of hypothyroidism. Hypothyroidism is especially dangerous in children. An experiment study the pathology of the disease. Today there are several models of experimental hypothyroidism: surgical removal of the thyroid gland or thyrostatics using (thiourea derivatives – propylthiouracil, metamazole, mercazolyl, thyroperoxidase blockers – thiamazole), per os for 1–8 weeks.

The aim of the study – to investigate the processes of lipid peroxidation in immature rats in the simulation of hypothyroidism by thyroidectomy, mercazolyl using and a combination of both methods.

Materials and Methods. The experiments performed on 75 white sexually immature male rats aged 1.5–2.0 months of 3 groups. Group 1 – hypothyroidism was induced by mercazolyl (75 mg/kg of body weight for 14 days), group 2 – by thyroidectomy, group 3 – by the combination of the first two methods. Serum levels of diene conjugates (DC), TBA-active products, superoxide dismutase (SOD) and catalase activity were determined.

Results. The results of the examination of rats indicate that each of the proposed methods can achieve a deep hypothyroid state. The efficiency of expression of hypothyroidism models for lipid peroxidation processes: thyroidectomy (51.2 %) → mercazolyl (76.8 %) → thyroidectomy + mercazolyl (119.5 %). In our experiments, a compensatory increase in SOD activity was noted. Changes in the increase in SOD activity were as follows: thyroidectomy + mercazolyl (1.6 times) → mercazolyl (2.6 times) → thyroidectomy (3.2 times). Catalase activity changed ambiguously: in thyroidectomy it significantly increased 2.6 times, in feeding mercazolyl did not change significantly, and in combined pathology – decreased by 44.4 %.

Conclusions. 1. Thyroidectomy, mercazolyl using and its combination are reliable methods of inducing hypothyroidism in immature rats. As the hypothyroid state increases, these methods can be presented in the following order: thyroidectomy → mercazolyl → thyroidectomy + mercazolyl. 2. In hypothyroidism, the processes of lipid peroxidation activated as follows: thyroidectomy → mercazolyl → thyroidectomy + mercazolyl. In response to thyroid pathology, the superoxide dismutase activity of the blood compensatory increases: thyroidectomy + mercazolyl → mercazolyl → thyroidectomy.