Seasonal features of functional activity of endocrine systems in residents of mountains

The article presents the results of studies of changes in the functional state of the endocrine systems of high-altitude residents, depending on the periods of the year that are associated with the ambient temperature, with the daylight regime and other factors. High altitude regions are distinguished by a severely continental climate, which is characterized by large temperature and barometric differences between the winter and summer months, expressed by the seasons of the year. The object of research was the indigenous people of the mountains, living at an altitude of 2800 m above sea level, from 18-55 years old. The level of thyroid hormones, TSH, cortisol, catecholamines and sex hormones in peripheral blood plasma was determined by the method of enzyme-linked immunosorbent assay using standard test kits (Russia). It was found that in high-altitude conditions there is a seasonal variability in the functional activity of the pituitary-thyroid system in healthy men leads to an increase in metabolism, since rhythmic changes in the secretion of thyroid hormones and biochemical parameters are interrelated. So, in winter, the level of triiodothyronine is increased with a slight change towards a decrease in thyroxine and thyroid-stimulating hormone of the adenohypophysis compared with the summer months. At the same time, the above studies did not reveal a clear relationship between the functional state of the thyroid gland and atmospheric pressure and ambient temperature. Norepinephrine and dopamine levels rise significantly in winter, with a slight decrease in other neurotransmitters, adrenaline and serotonin. In the studied mountainous region in winter, the ambient temperature is significantly lower than in summer, and has an additional effect on the functional state of the endocrine systems after hypoxia. Compensatory-adaptive changes when exposed to low temperature of the environment are triggered with the participation of catecholamines, which, by breaking down fats and carbohydrates, mobilize energy reserves, increase heat production and constrict the vessels of the body surface. Interacting with catecholamines, thyroid hormones activate metabolic processes, also increase heat generation, affecting the processes of oxidative phosphorylation, enhance the “calorigenic” effect of catecholamines, and also activate the secretion of ACTH and glucocorticosteroids. Fluctuations in the level of the studied hormones in the peripheral blood in the indigenous population of the highlands are subject to changes not only in the seasons of the year, but also in the duration of daylight hours. To date, there are data (including those obtained experimentally) that show the effect of light on the release of sex hormones and cortisol in humans, which indicate changes in the secretion of these hormones during the year, associated with a change in the length of daylight hours.