| Calorie restriction (CR) without malnutrition not only delays the onsets of age-related diseases but prolongs maximal life span in a wide variety of species. The free radical theory of aging proposes that accumulated oxidative stress over time results in aging, and CR has been shown to attenuate oxidative stress. Unsaturated fatty acids are a target of oxidative damage and the membrane theory of aging proposes that the number of double bonds in membrane phospholipids is inversely correlated with life span, and CR has been reported to alter membrane composition in a manner that decreases the degree of unsaturation of membranes. This decrease in membrane unsaturation is hypothesized to influence aging by protecting membranes against lipid peroxidation and preventing oxidative stress. However, alterations in membrane lipid composition can change membrane structure and influence the functions of membrane proteins. Thus, CR-related changes in membrane lipid composition could possibly influence aging by altering membrane processes such as mitochondrial reactive oxygen species (ROS) production, proton leak, and electron transport chain (ETC) enzyme activities. To determine the role mitochondrial membrane lipids play in the actions of CR, we manipulated membrane fatty acid composition by feeding CR mice diets that differ in their lipid composition. The objective of the current study was to determine if dietary lipid source (fish oil, soybean oil or lard) altered liver and skeletal muscle mitochondrial membrane composition, ROS production, proton leak, and ETC enzyme activities in mice fed a CR diet for one month or eight months. Overall, our results indicate that dietary lipid manipulations effectively alter mitochondrial membrane phospholipid composition in CR mice. Dietary lipid compositions can influence ROS production, proton leak, and ETC enzyme activities in CR animals. However, the extent to which dietary lipid compositions influence these aforementioned membrane processes are dependent on tissue and length of CR and/or age. |
