Effects of Populational Factors on Phospholipid Composition of Various Tissues in Natural Populations of the Tundra Vole Microtus oeconomus

The lipid composition of tissue membranes was studied in tundra voles at different phases of population cycle. At the period of depression of the volume of population, there were found a sharp rise of the content of lysophosphatidylcholine (LPC) in lipids of liver and spleen, the appearance of trace amounts of lysoforms in the brain tissue, and a reduction of portion of main fractions, particularly phosphatidylethanolamine (PE), in all studied tissues. It is at this period that the minimal content of more easily oxidizable fractions in phospholipids (PL) of all tissues was observed, with the maximal PC/PE ratio in lipids of liver and brain in most animal groups studied, which indicates the greatest rigidity of tissue membranes and minimal ability of lipids to oxidation. These particularities of the lipid fractional composition in vole tissues at different phases of population cycle are closely associated with the physiological state of the animals, specifically with their hormonal status depending on the population cycle phase, while elevation in the blood of stress-realizing hormones provides prerequisites for hyperactivation of peroxide oxidation of lipids (POL). The revealed pronounced changes of the tissue phospholipid composition in voles from natural populations at the depression of the population size can be considered as a part of non-specific reaction and associated intensification of POL processes.