BACKGRAUND
The problem of seasonal dynamics of sex hormone levels remains not fully understood due to the inconsistency of the data obtained in different territories and populations of the examined individuals, which is especially important for the European North with pronounced contrast photoperiodism. The study of photoperiodic fluctuations of sex hormones can help in the development of preventive measures aimed at preventing the development of disadaptation reactions from the reproductive system of men.
OBJECTIVE
To show changes in serum levels of hormones of the hypothalamus-pituitary-gonadal system in a group of practically healthy men aged 22-45 living in the European North under different photoperiods.
MATERIALS AND METHODS
The observational, single-center, prospective, selective, uncontrolled study included 20 healthy men aged 33.8±1.1 years, born and permanently residing in the Arctic zone of the Russian Federation (Arkhangelsk). Blood collection was carried out during periods of increasing daylight hours (March), maximum duration (June), decrease (September) and minimum daylight hours (December) to measure: lutropin (LH), follitropin (FSH), prolactin, progesterone, testosterone (T), free testosterone (fT), estradiol (E2), dehydroepiandrosterone sulfate (DHEA-S). The ratio of testosterone/estradiol (T/E2) and testosterone/lutropin (T/LH) was calculated.
RESULTS
In December, the minimum serum concentrations of fT (3.81 pg/ml), LH (3.27 IU/l), FSH (3.92 IU/l) and E2 (0.199 nmol/l) were noted. At the same time, the values of the index T/E2 and T/LH are maximum (103.07 c.u. and 5.94 c.u., respectively). In March, the levels of fT increase significantly (5.05 pg/ml, p=0.033), as well as increase and reach the maximum annual concentrations of LH (4.26 IU/l, p=0.002), FSH (4.25 IU/l, p=0.011), progesterone (7.1 nmol/l, p<0.001), prolactin (17.88 ng/ml); DHEA-S levels are minimal (10.51 µmol/l). The valuesof progesterone in 85—95% (17—19 people) and DHEA-S in 25—55% (5—11 people) of the examined men were above the upper limit of the standards in all periods of the survey.
CONCLUSIONS
The main contrast periods with variations in the levels of the hypothalamus-pituitary-gonadal system hormones in men of the European North are December and March, when the minimum and maximum activity of the hypothalamus-pituitary-gonadal system was recorded, which may be associated with both melatonin production and changes in thyroid activity. The increase in the T/E2 and T/LH ratios in December suggests a possible role of bound testosterone fractions in the adaptive mechanisms aimed at maintaining its free forms, which provide the main metabolic processes in the body. It has been shown that sufficient reserves for the synthesis of sex hormones are provided in the spring-summer period by their production in the testes (progesterone), and in the autumn-winter period, the adrenal nature of their origin (DHEA-S) is recorded.
