Brown rice bran fermented with Aspergillus oryzae attenuates cognitive decline in aged mice accompanied by induction of immediate early genes in hippocampus

Brown rice bran fermented with Aspergillus oryzae (FBRA), produced via fermentation of rice bran with the specific fungus, has antioxidant and anti-inflammatory properties in murine models. Because oxidative stress and neuroinflammation are critical in the brain aging and cognitive impairment, we hypothesized that FBRA would improve cognitive function. We explored the impact of FBRA on cognitive impairment in mice focusing on cognitive behaviors and the profile of hippocampal gene expression. Twenty-week-old male C57BL/6J mice were divided into four groups: lab chow (LCD), LCD+FBRA, high fat diet (HFD), and HFD+FBRA. After fifty weeks, cognitive function was examined by two behavioral tests. FBRA administration significantly improved cognitive function under both LCD and HFD conditions. Hippocampal microarray analyses revealed that expression levels of immediate early genes including Egr1 and Nr4a1 were exclusively increased in LCD+FBRA compared to LCD. These findings raise a possibility that FBRA improves cognitive function in aged mice at least partly by modulating hippocampal gene expression.