Introduction. Due to the ongoing active economic and scientific development of the Arctic, interest in the study of adaptation and preservation of human health during stay and work in high latitudes remains relevant.

The study aims to identify the dynamics of saliva hormones, the sorption activity of the epithelium of the oral fluid, as well as indicators of cellular immunity of participants in a three-week Arctic route.

Materials and methods. Scientists have examined 39 participants of the Arctic Floating University expedition: 26 women and 13 men aged 30 to 52 years (Me=23 years). Morning saliva was collected at the beginning, in the middle and at the end of the 21-day route. The researchers determined the levels of cortisol and testosterone by enzyme immunoassay, and determined the activity of the epithelium in the sediment by microscopy, estimating the average number of microbial bodies on the surface of 100 squamous epitheliocytes. Blood sampling was carried out at the beginning and at the end of the expedition. The experts determined the number of white blood cells in Goryaev's chamber, and they calculated the leukocyte formula in blood smears.

Results. The maximum concentrations of cortisol at the beginning of the flight in men (21.3 nmol/L) and women (23.6 nmol/L) decrease by 4 and 3.2 times in the middle, respectively, and by the end of the route they are 7.4 and 13.5 nmol/l. Testosterone levels significantly increased in the middle of the route by 2.4 times in men (1.72 versus 0.73 nmol/L) and 6 times in women (0.26 versus 0.05 nmol/L) and remained elevated by the end of the expedition. The testosterone/cortisol index increases 10 times in men and 13 times in women in the middle of the route, and its values are 8 and 10 times higher at the end of the route than at the beginning. The sorption activity of the epithelium decreases slightly in the middle of the route (p=0.071). By the end of the expedition, the men's neutrophil-lymphocyte index decreased (2.36 versus 3.78 units, p=0.005) and the Garkavi index increased (0.51 versus 0.27 units, p=0.004).

Limitations. A disproportionately large number of women and the inability to measure the background values of indicators before the route.

Conclusion. The dynamics of hormonal parameters reflect the restructuring of regulatory systems towards anabolic processes, starting from the middle of the route, which contributes to adaptation during the period of intense physical work. There is also a slight decrease in the mechanisms of local immune defense in the middle of the route. Only men had a significant increase in the Garkavi index and a decrease in the neutrophil-lymphocyte index at the end of the route. In women, however, hormonal changes are more pronounced and a greater number of correlations between immune and hormonal parameters have been revealed.

Ethics. The study was conducted in compliance with Ethical standards (Protocol No. 003-25/06 of the meeting of the Ethics Committee dated 06/25/2025).

Contributions:Elfimova A.E. — concept and design of research, collection and processing of material, writing text;Patyavina O.I. — collection and processing of material, statistical processing;Kulikova I.K. — collection and processing of material, statistical processing;Shtaforov V.A. — material processing, text writing;Patrakeeva V.P. — research concept and design, editing;Tipisova E.V. — research concept and design, editing;Zyabisheva V.N. — material processing, text writing;Molodovskaya I.N. — material processing;Alikina V.A. — material processing.

Gratitude. The authors express their gratitude to the Arctic Floating University project and the participants of this study, without whom it would not have taken place.

Funding. The study was carried out with the financial support of the Ministry of Education and Science of the Russian Federation in accordance with the plans of the Federal Research Institute.

Conflict of interest. The authors no conflict of interest.

Received: 12.03.2026 / Accepted: 30.04.2025 / Published: 02.06.2026