Features of Lipid Metabolism in Young and Middle-Aged Cosmonauts Who Have Completed Long-Term Flights to the International Space Station

Two groups of cosmonauts were examined in the dynamics of the post-flight period: a young age group (35–43 years old), 15 people who completed flights lasting from 139 to 200 days and a middle-aged group (46–53 years old), after expeditions lasting from 125 to 203 days. The serum levels of cholesterol, high, low, and very-low density lipoprotein cholesterol, apolipoproteins A1 and B, triglycerides, non-esterified fatty acids, and phospholipids were determined. The values of the ratio of HDL cholesterol/LDL cholesterol, Apolipoprotein B/Apolipoprotein A1, and the value of the atherogenicity index were calculated. It was found that on the first day of the post-flight period, both young and middle-aged cosmonauts observed a redistribution of the content of apolipoproteins A1 and B in the blood. In both groups, there is an increase in lipolysis, more pronounced in the middle-aged group. At the same time, in the middle-aged group, the level of cholesterol and its atherogenic fraction of low-density lipoprotein cholesterol increases. On the 7th day of the recovery period, young cosmonauts show a return of all the above-mentioned indices to the background level, while in the middle-aged group the changes persist, indicating a higher risk of developing cardiovascular pathology in them.