Age-related changes in LTP and antioxidant defenses are reversed by an α-lipoic acid-enriched diet

Among the age-related changes identified in rat hippocampus are impairments in LTP and glutamate release. These deficits have been coupled with decreased arachidonic acid concentration. In this study we compared LTP and glutamate release in groups of aged and young rats fed for 8 weeks on a control diet or on a diet enriched in α-lipoic acid. Dietary supplementation in aged rats restored hippocampal arachidonic acid concentration to levels observed in tissue prepared from young rats. We observed that aged rats that received the experimental diet sustained LTP in perforant path-granule cell synapses in a manner indistinguishable from young rats whereas the age-related impairment in glutamate release was reversed in synaptosomes prepared from dentate gyrus obtained from these rats. The evidence presented supports the hypothesis that the α-lipoic acid-enriched diet has antioxidant properties, because the age-related increase in superoxide dismutase activity and decrease in α-tocopherol concentration were reversed. The finding that the age-related increase in interleukin-1 (IL-1)β concentration was also reversed suggests a possible role for this cytokine in ageing.