Abstract
The effects of long-term carnitine supplementation on age-related changes in tissue carnitine levels and in lipid metabolism were investigated. The total carnitine levels in heart, skeletal muscle, cerebral cortex, and hippocampus were approximately 20% less in aged rats (22 months old) than in young rats (6 months old). On the contrary, plasma carnitine levels were not affected by aging. Supplementation of acetyl-l-carnitine (ALCAR; 100 mg/kg body weight/day for 3 months) significantly increased tissue carnitine levels in aged rats but had little effect on tissue carnitine levels in young rats. Plasma lipoprotein analyses revealed that triacylglycerol levels in VLDL and cholesterol levels in LDL and in HDL were all significantly higher in aged rats than in young rats. ALCAR treatment decreased all lipoprotein fractions and consequently the levels of triacylglycerol and cholesterol. The reduction in plasma cholesterol contents in ALCAR-treated aged rats was attributable mainly to a decrease of cholesteryl esters rather than to a decrease of free cholesterol. Another remarkable effect of ALCAR was that it decreased the cholesterol content and cholesterol-phospholipid ratio in the brain tissues of aged rats. These results indicate that chronic ALCAR supplementation reverses the age-associated changes in lipid metabolism.
Highlights
The effects of long-term carnitine supplementation on age-related changes in tissue carnitine levels and in lipid metabolism were investigated
Analyses of plasma samples from humans and experimental animals indicate that cholesterol and triacylglycerol levels increase with aging [1,2,3]
Long-term feeding with ALCAR was reported to reduce age-related increments of sphingomyelin and cholesterol in rat brains [28]
Summary
The effects of long-term carnitine supplementation on age-related changes in tissue carnitine levels and in lipid metabolism were investigated. Another remarkable effect of ALCAR was that it decreased the cholesterol content and cholesterol-phospholipid ratio in the brain tissues of aged rats These results indicate that chronic ALCAR supplementation reverses the age-associated changes in lipid metabolism.— Tanaka, Y., R. Several studies reported beneficial effects of carnitine supplementation on age-related changes in lipid metabolism. Carnitine levels and lipidic parameters were determined in young and aged rats, and the effect of ALCAR supplementation on these values was examined. We report that beneficial effects of ALCAR on lipid metabolism are not seen in young rats but are observed in aged rats that have low tissue carnitine levels
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