A CLUSTER-ANALYSIS STUDY OF ACETYL-L-CARNITINE EFFECT ON NMDA RECEPTORS IN AGING

Aging is associated with a reduction in the maximum density of n-methy l-d-aspartate (NMDA)-sensitive glutamate binding sites in the hippocam pus of Fischer 344 rats. This study was designed to investigate the ef fect of acetyl-l-carnitine (ALCAR) on NMDA receptors in the old rat (2 4 months) after chronic or single-dose treatments. The number of NMDA receptors was significantly decreased in the old rat hippocampus by 19 .5% compared with the young rat. A six-month treatment with ALCAR in t he old rat attenuated the loss of NMDA binding sites in the hippocampu s. A single-dose treatment with ALCAR in the old rat increased the B(m ax) value by 35%, while no change was observed in the young group. We conclude that ALCAR can exert two actions: a trophic/neuro-preserving one when chronically administered during aging, and a stimulatory one when given at a single dose in the aged rat.