Purpose: Middle-aged C57Bl/6J mice fed for 6 months with extra-virgin olive oil rich in phenols (H-EVOO, phenol dose/day: 6 mg/kg) showed cognitive and motor improvement compared to controls fed the same olive oil deprived of phenolics (L-EVOO). The aim of the present study was to evaluate whether these behavioral modifications were associated with changes in gene and miRNA expression in the brain.
Methods: Two brain areas involved in cognitive and motor processes were chosen: cortex and cerebellum. Gene and miRNA profiling were analyzed by microarray and correlated with performance in behavioral tests.
Results: After 6 months, most of the gene expression changes were restricted to the cerebral cortex. The genes modulated by aging were mainly down-regulated, and the treatment with H-EVOO was associated with a significant up-regulation of genes compared to L-EVOO. Among those, we found genes previously associated with synaptic plasticity and with motor and cognitive behavior, such as Notch1, BMPs, NGFR, GLP1R and CRTC3. The agrin pathway was also significantly modulated. miRNAs were mostly up-regulated in old L-EVOO animals compared to young. However, H-EVOO-fed mice cortex displayed miRNA expression profiles similar to those observed in young mice. Sixty-three miRNAs, out of 1203 analyzed, were significantly down-regulated compared to the L-EVOO group; among them, we found miRNAs whose predicted target genes were up-regulated by the treatment, such as mir-484, mir-27, mir-137, mir-30, mir-34 and mir-124.
Conclusions: We are among the first to report that a dietary intervention starting from middle age with food rich in phenols can modulate at the central level the expression of genes and miRNAs involved in neuronal function and synaptic plasticity, along with cognitive, motor and emotional behavior.
Keywords: Aging brain; Genomics; Nutraceuticals; Phenolic compounds; miRNomics.