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

The chemical α-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 α-asarone on nitric oxide (NO) levels in the hippocampus and temporal cortex of the rat after injection of the fraction 25-35 from amyloid-β (Aβ_(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 Aβ_(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 α-asarone improves the memory correlated with NO overproduction and neuronal damage caused by the injection of Aβ_(25-35) into rats. Then animals received a 16-day treatment of α-asarone before the Aβ_(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 α-asarone-treated group. Our results suggest that α-asarone may protect neurons against Aβ_(25-35)-caused neurotoxicity by inhibiting the effects of NO overproduction in the hippocampus and temporal cortex.