correlation of aging-related anxiety with dentate gyrus and protective effect of rosemary extract

Background: aging is an unavoidable process that causes destructive changes to the brain. however, using plants with unique properties, such as rosemary, may help prevent complications related to aging. therefore, we aimed to evaluate the effect of rosemary on anxiety associated with aging.methods: male wistar rats were divided into two groups: young and old, each with two subgroups: old rats receiving solvent (so), old rats receiving rosemary extract (eo), young rats receiving solvent (sy), and young rats receiving rosemary extract (ey). after 12 weeks, anxiety behavior was tested through the elevated plus maze. real-time rt-pcr was used to evaluate bdnf expression in the dentate gyrus region. finally, the thickness of the granular layer and intact neurons in the dentate gyrus were assessed by nissl staining.results: the results showed a significant reduction in the percentage of entries and number of entrances into the open arms in aged rats compared to young groups (p ≥ 0.05). however, the administration of rosemary significantly improved anxiety compared to the so group (p ≥ 0.05). additionally, administration of rosemary (100 mg/kg) proved a significant elevation of bdnf expression in the treated rats compared to the so group (p ≥ 0.05). also, aging meaningly decreased the thickness of the granular layer and the number of intact neurons in the dentate gyrus compared to other groups (p ≤ 0.05).conclusion: normal aging can increase anxiety and tissue changes in the dentate gyrus, while it seems that rosemary extract improves anxiety and can reduce neuronal damage in the dentate gyrus.