Lipid peroxidation rate and the antioxidant protection system during a three-day dry immersion experiment

The content of lipid peroxidation products (diene conjugates, malondialdehyde, Schiff bases) and antioxidant defense system indices (the main lipid antioxidant tocopherol and the level of general antioxidant activity) were measured in the blood serum of five male volunteers aged 25?C40 years in a three-day dry immersion experiment. During the immersion test, no deviations of indices from the background values were found. An increase in the tocopherol concentration within 2 h after the beginning of the experiment was the only exception. A significant increase in the concentration of lipid peroxidation products, particularly, diene conjugates, was observed 2 h after immersion completion during the reconditioning period. However, the tocopherol content was significantly lower than the background values. It is concluded that the subjects?? adaptation to simulated microgravity conditions displays no pronounced stress component, whereas bringing back to normal vital functions after exposure to immersion induces a pronounced stress reaction illustrated by a significant increase in the lipid peroxidation product levels against a background of a decrease in the functional activity of the antioxidant defense system.