Effects of dietary restriction on age-related changes in the phospholipid fatty acid composition of various rat...

Polyunsaturated fatty acids (PUFAs) are essential components of the cell lipid bilayer and are involved in membrane fluidity and normal functioning, but they are vulnerable to free radical attack. Given the role of oxidative stress in the aging process, age-related changes in phospholipid fatty acid (PLFA) composition in rat liver, kidney and heart were assessed in 3-, 12- and 24-month-old rats fed either ad libitum but only every other day, or daily but only 60% of the quantity normally consumed by age-matched controls.

Lipids were extracted and phospholipids (PLs) were separated using the solid phase extraction technique, then transesterified and assayed by gas-liquid chromatography.

Saturated fatty acids (FAs) did not change significantly with age; mono- and bi-unsaturated FAs decreased in the liver and heart, and the ratio of the former to the latter increased in the liver, kidney and heart. PUFAs increased in the liver and heart. As regards individual FAs, 20:1(n-9) decreased in all organs, 14:1 and 18:1(n-7) increased in the kidney and heart, 18:1(n-9) increased in the kidney, 20:2(n-6), 18:2(n-6) and 22:5(n-3) decreased in the liver and heart, 20:3(n-6) decreased in the kidney and increased in the heart. The most abundant PUFAs, 20:4(n-6) and 22:6(n-3), either remained the same or increased with age. The N-9 family increased in the kidney, the N-7 family increased in the kidney and heart, the N-6 family decreased in all three organs, and the N-3 family increased in the liver and kidney. Dietary restriction (DR) significantly counteracted most of these changes, but changes in some FAs [20:2(n-6) in the heart] were magnified by DR and may not be age-related.

Most age-related changes (that occurred in the rat liver, kidney and heart and were counteracted by the two different types of DR) may be involved in the mechanism of aging.