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 molec ules with C-11 by positron emission tomography. The uptake values of r adio-labeled acetylcarnitine into the brain were quite different depen ding 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 almo st the same and extremely low, while the uptake of [1-C-11]acetyl-L-ca rnitine was slightly higher. The uptake value of [2-C-11]acetyl-L-carn itine 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 br ain was suppressed by the intravenous administration of glucose. These results suggest that endogenous serum acetyl-L-carnitine has some rol es on conveying an acetyl moiety into the brain especially under an en ergy crisis, and that an unknown metabolic pathway of [2-C-11]acetyl m oiety might be rather active in the brain. (C) 1997 Academic Press.