Abstract
Abstract. Visceral obesity (VO) can cause many diseases in the body, including leading to thyroid pathology. Therefore, the search and development of new effective methods for preventing of thyroid dysfunction in obesity is a relevant research area. One of these methods can be the use of the pineal gland hormone – melatonin. The aim was to study the effect of melatonin on the histomorphometric changes in the thyroid gland of rats with VO and to evaluate the possibility of its use as a prophylactic agent for gland dysfunction in this pathology. Material and methods. For the experiment, 30 male Wistar rats aged 3 months were selected. VO in animals was modeled by maintaining them on a high-calorie diet (HCD). 3 groups of rats were formed: group I – control, group II – animals that were on the HCD for 12 weeks, and group III – rats that were on the HCD for 8 weeks, and then for another 4 weeks, in addition to this diet, orally received melatonin (Unipharm Inc., USA) at a dose of 5 mg/kg. Histological preparations were made from the thyroid tissue. Histomorphometry was performed using the «ImageJ» computer program. The concentration of total lipids, triglycerides and cholesterol was determined in blood serum. Results. Rats received HCD showed clear signs of VO: the weight of visceral fat and the concentration of lipid metabolism indicators probably increased. Structural changes were found in the thyroid gland, which indicated its hypofunction. Follicles were emptied of colloid and its accumulation was inhibited. Hyperplasia of the thyroid gland was observed, which led to an increase in its size. Rats that received melatonin in addition to HCD had significantly less structural thyroid dysfunction. In addition, melatonin contributed to reducing the degree of obesity development, namely, it reduced the weight of visceral fat and returned lipid metabolism indicators to control values. Conclusion. Administration of melatonin to rats has a protective effect on the thyroid gland against the harmful effects of obesity. This may be of practical interest when using melatonin as a prophylactic agent for disorders of the structure and function of the thyroid gland caused by VO.
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