Neuroprotective effect of alpha-asarone on spatial memory and nitric oxide levels in rats injected with amyloid-beta((25-35)).

The chemical alpha-asarone is an important active substance of the Acori graminei rhizome (AGR). It has pharmacological effects that include antihyperlipidemic, antiinflammatory, and antioxidant activity. Our aim was to study the effects alpha-asarone on nitric oxide (NO) levels in the hippocampus and temporal cortex of the rat after injection of the fraction 25-35 from amyloid-beta (Abeta((25-35))). In addition we examined the working spatial memory in an eight-arm radial maze. Our results showed a significant increase of nitrites in the hippocampus and temporal cortex of Abeta((25-35))-treated rats. Other evidence of neuronal damage was the expression of a glial-fibrillar-acid protein and a silver staining. There were impairments in the spatial memory evaluated in the eight-arm radial maze. We wanted to determine whether alpha-asarone improves the memory correlated with NO overproduction and neuronal damage caused by the injection of Abeta((25-35)) into rats. Then animals received a 16-day treatment of alpha-asarone before the Abeta((25-35)) injection. Our results show a significant decrease of nitrite levels in the hippocampus and temporal cortex, without astrocytosis and silver-staining cells, which correlates with memory improvement in the alpha-asarone-treated group. Our results suggest that alpha-asarone may protect neurons against Abeta((25-35))-caused neurotoxicity by inhibiting the effects of NO overproduction in the hippocampus and temporal cortex.