High uptake of [2-(11)]acetyl-L-carnitine into the brain: A pet study

The brain uptake of acetylcarnitine was investigated in rhesus monkeys using different position labeled acetyl-L-carnitine and related molecules with C-11 by positron emission tomography. The uptake values of radio-labeled acetylcarnitine into the brain were quite different depending on the labeling positions of C-11. That is, the uptake values of L-[methyl-C-11]carnitine and acetyl-L-[methyl-C-11]carnitine were almost the same and extremely low, while the uptake of [1-C-11]acetyl-L-carnitine was slightly higher. The uptake value of [2-C-11]acetyl-L-carnitine was by far the highest among the C-11-labeled acetyl-L-carnitine and L-carnitine. The uptake of [2-C-11]acetyl-L-carnitine into the brain was suppressed by the intravenous administration of glucose. These results suggest that endogenous serum acetyl-L-carnitine has some roles on conveying an acetyl moiety into the brain especially under an energy crisis, and that an unknown metabolic pathway of [2-C-11]acetyl moiety might be rather active in the brain. (C) 1997 Academic Press.