NMDA-sensitive glutamate receptors are involved in the regulation of neuronal plasticity, and contribute to the synaptic mechanisms underlying the learning process. Aging is associated with a reduction in the maximal density of NMDA-sensitive glutamate binding sites in rat hippocampus. This reduction is attenuated after long-term administration with L-acetylcarnitine (10 mg/Kg i.p. once a day for 4 months). These results support a neuroprotective and neurotrophic role for L-acetylcarnitine during aging.