Abstract: OBJECTIVE: To investigate the role of Eclipta prostrata(E.prostrata) extract in improving spatial learning and memory deficits in D-galactose-induced aging in rats.METHODS: Rats were divided into five groups,with 10 animals in each group.Aging rats were produced by treatment with 100 mg· kg~(-1)· d~(-1) of D-galactose for 6 weeks.Rats in the E.prostrata treatment groups received an aqueous extract of E.prostrata orally at a concentration of 50, 100, or 200 mg· kg~(-1)· d~(-1) for 3 weeks.Animals in both the normal and model groups were treated with similar volumes of saline.Spatial memory performance was measured using the Morris water maze.The mRNA levels and enzyme activities of superoxide dismutase(SOD),catalase(CAT), glutathione peroxidase(GPx) and glutathione reductase(GR) were analyzed using real-time quantitative PCR and spectrophotometry,respectively.The levels of induced nitric oxide synthase(iNOS), nitric oxide(NO), dopamine(DA), norepinephrine(NE), and serotonin(5-HT) were determined using enzyme-linked immunosorbent assay and spectrophotometry.RESULTS: Compared with the normal group, rats in the D-galactose-treated model group exhibited significant memory loss.There was severe damage to the hippocampal CA1 area, and expression levels of SOD, CAT, GPx, and GR were significantly decreased in the model group compared with the normal group.In the model group, levels of iNOS and NO were significantly increased compared with the normal group.However, treatment with E.prostrata extract reversed the conditions caused by D-galactose-induced aging, especially in the groups with higher treatment concentrations.Compared with the normal group, the levels of DA, NE, and 5-HT were significantly lower in the D-galactose-treated model group.In the E.prostrata extract-treated groups, however, there was a dose-dependent upregulation of DA, NE, and 5-HT expression.CONCLUSION: Our results suggest that administration of E.prostrata extract can result in an improvement in the learning and memory impairments that are induced by D-galactose treatment in rats.This improvement may be the result of enhanced antioxidative ability, decreased iNOS and NO levels,and the induction of DA, NE, and 5-HT expression in the brain.

Key words: Eclipta, Galactose, Spatial learning, Memory disorders, Antioxidants