Chrysin Protects against Memory and Hippocampal Neurogenesis Depletion in D-Galactose-Induced Aging in Rats

The interruption of hippocampal neurogenesis due to aging impairs memory. The accumulation of D-galactose (D-gal), a monosaccharide, induces brain aging by causing oxidative stress and inflammation, resulting in neuronal cell damage and memory loss. Chrysin, an extracted flavonoid, has neuroprotective effects on memory. The present study aimed to investigate the effect of chrysin on memory and hippocampal neurogenesis in brains aged using D-gal. Male Sprague-Dawley rats received either D-gal (50 mg/kg) by i.p. injection, chrysin (10 or 30 mg/kg) by oral gavage, or D-gal (50 mg/kg) and chrysin (10 or 30 mg/kg) for 8 weeks. Memory was evaluated using novel object location (NOL) and novel object recognition (NOR) tests. Hippocampal neurogenesis was evaluated using Ki-67, 5-bromo-2′-deoxyuridine (BrdU), and doublecortin (DCX) immunofluorescence staining to determine cell proliferation, cell survival, and number of immature neurons, respectively. We found that D-gal administration resulted in memory impairment as measured by NOL and NOR tests and in depletions in cell proliferation, cell survival, and immature neurons. However, co-treatment with chrysin (10 or 30 mg/kg) attenuated these impairments. These results suggest that chrysin could potentially minimize memory and hippocampal neurogenesis depletions brought on by aging.