Aging brain: effect of acetyl-L-carnitine treatment on rat brain energy and phospholipid metabolism. A study by phosphorus-31 and proton NMR spectroscopy

The effects of acetyl-L-carnitine (ALCAR) on metabolites involved in energy and phospholipid metab. were evaluated by means of 31P and 1H NMR spectroscopy on adult (6 mo) and old (24 mo) rat brains. A significant increase of glycerophosphorylcholine (GroPCho) in aged rat brain was obsd. as compared with adult rat brain. No variations in ATP, phosphocreatine (PCr), Cr, lactate, ADP, and inorg. phosphate (Pi) levels were found between aged and adult brains. Treatment with ALCAR caused a significant increase in PCr levels and a decrease in lactate and sugar phosphate in adult and aged rat brain. These results are suggestive of treatment with ALCAR being responsible for a redn. in brain glycolytic flow and for enhancing the utilization of alternative energy sources, such as lipid substrates or ketone bodies. Furthermore, the changes in GroPCho levels obsd. after treatment with ALCAR may be indicative of a modulating effect on the activity of the enzymes involved in the acylation-reacylation process of membrane phospholipids