Differences in gene expression in the hippocampus of aged rats are associated with better long-term memory performance in a passive avoidance test.

Microarray analysis was used to identify genes differentially expressed in the hippocampus of aged rats showing diverse long-term (3 and 6 h) spatial-associative memory performance in a single-trial inhibitory avoidance task. The transcription of 43 genes (including genes functionally linked to signal transduction, cell growth and differentiation, translation, energy metabolism, and nucleic acid processing) was significantly upregulated in good-versus bad-performing animals, whereas that of 18 genes (including genes functionally linked to transcription, cell growth and differentiation, apoptosis, and protein transport) was significantly downregulated in good-versus bad-performing animals. The differential expression of 14 of these genes was confirmed by real-time polymerase chain reaction.