Over the course of 1 year, low levels of plasma selenium affect GP activity and thyroid hormone levels in humans living in North European Russia.

No abstract

The purpose is to study the annual dynamics of activity of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GP), glutathione reductase (GR) of erythrocytes, the content of selenium in blood serum, provision with vitamins A (tocopherol) and E (retinol) in young men (18-22 years), residents of the North (62° northern latitude) and involved in manual work in the open air by trade. Methods. The cohort study was carried out. The SOD activity was estimated by quantity of nitro-formazan. GP was estimated by the loss of reduced glutathione at its oxidation with a tret-butil hydroperoxide. GR was estimated by oxidation rate of NADPH. The concentration of retinol and tocopherol was determined on the intensity of lipid extract fluorescence of blood serum. The concentration of selenium in plasma was identified by a fluorimetric method with 2,3 diamino-naphthalene. Results. Data analysis showed decrease of SOD activity up to 45.17 ± 0.34 (Ôβ1/2.Ññ/ml erythrocytes) during the cold period of the year (November-March) and increase up to 71.09 ± 0.53 (Ôβ1/2.Ññ/ml erythrocytes) during the warm period of the year (June - August), whereas the activity of GP and GR, selenium level in blood serum increased during the cold period of year and decreased during the warm period of the year. For example, activity of GP was 112.35 ± 6.29 (micron/min./rHb) in November and 35.87 ± 2.47 (micron/min/rHb) in July. The level of tocopherol in the blood serum varied from 2.39 to 6.53 mcg/ml during the year and it was considerably lower than middle-latitude norm (8-15 mcg/ ml). The minimum level of tocopherol was in August, September, October, January and maximum in November and March. Dynamics of the content of retinol in the blood serum was similar within a year. Level of retinol had the annual dynamics similar to tocopherol and was at the lower limit of normal (30-80 mcg/ml). Conclusion. Seasonal fluctuations of SOD and GP of erythrocytes activity, vitamins' contents, selenium in blood serum can be treated as adaptation processes of the organism to natural and climatic factors.