The aim of this study was to evaluate the effect of long-term Carnitine supplementation on age-related changes in tissue carnitine levels and in lipid metabolism. The total carnitine levels in heart, skeletal muscle, cerebral cortex and hippocampus were about 20 % less in aged rats than in young rats. On the contrary, serum carnitine levels were not affected by aging. Young and aged rats were given acetyl-L-carnitine (ALCAR, 100 mg/kg BW/day) for 3 months and sacrificed at ages of 6 and 22 months. This treatment significantly increased the tissue carnitine levels in aged rats, but had little effect on the tissue carnitine levels in young rats. Serum triacylglycerol, cholesterol and phospholipid levels were higher in aged rats than in young rats. Lipoprotein analyses revealed that triacylglycerol levels in very low density lipoprotein (VLDL), and cholesterol levels in low density lipoprotein (LDL) and in high density lipoprotein (HDL) were all significantly higher in aged rats than in young rats. Supplementation of ALCAR decreased all lipoprotein fractions and consequently the levels of triacylglycerol and cholesterol. The reduction in serum cholesterol contents in aged rats when treated with ALCAR was mainly due to a decrease of cholesteryl esters 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.
Tanaka Y, Sasaki R, Fukui F, Waki H, Kawabata T, Okazaki M, Hasegawa K, Ando S Acetyl-L-carnitine supplementation restores decreased tissue carnitine levels and impaired lipid metabolisms in aged rats. J Lipid Res. 2004 January