[Insulin-receptor interaction and the structure of the plasma membrane of adipose tissue during aging]

Studies were carried out to characterize age-related changes in insulin binding with plasma membranes (PM) from rat adipose tissue. Kd for high affinity binding sites as well as binding capacity for PM of young rats (5-6 mos. old) were higher than those of aged rats (22-24 mos. old). Binding characteristics of insulin receptors were compared with physical and chemical parameters of lipid matrix. Considerable enrichment in the saturated fatty acid content was noted for PM from old rats as compared to young ones. No significant differences in the phospholipid composition and cholesterol content were observed. Age-related modifications of the fatty acid composition was accompanied by an increase in membrane lipid order sampled by means of the hydrophobic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. A conclusion is that insulin receptors may be sensitive to age-related changes in the structure of surrounding lipid environment causing changes in their properties.