Ethanol Extract of Euonymus alatus Leaf Prevents Scopolamine‐Induced Learning and Memory Impairment in Mice

Our previous in vitro study demonstrated that the ethanol extract from young leaves of Euonymus alatus (so‐called burning bush spindle tree) had antioxidant and neuroprotective activities. In the present study, we examined whether oral supplementation of the extract recovers learning and memory capabilities in a scopolamine‐induced acute hypomnesic mouse model. Behavioral tests showed that spatial learning and memory were improved by the extract treatment in scopolamine‐treated mice. Histological damage observed in the hippocampal region of the scopolamine‐treated mouse brain was attenuated by oral administration of the extract. Oxidative stress markers, including plasma 8‐hydroxy‐2′‐deoxyguanosine and hepatic malondialdehyde increased in scopolamine‐injected mice were decreased by the extract treatment. The expression levels of antioxidant proteins such as heme oxygenase‐1 and nuclear factor (erythroid‐derived 2)‐like 2 in the hippocampal tissue homogenates were decreased in group treated with scopolamine alone while the expression of those proteins was restored by the extract treatment. In addition, synaptic plasticity biomarkers such as neurotrophic factors, including postsynaptic density protein‐95, brain‐derived neurotrophic factor and N‐methyl‐D‐aspartate receptor, were enhanced in the extract‐treated mouse hippocampal tissue compared to the group exposed to scopolamine alone. These findings indicate that Euonymus alatus leaf extract could rescue learning and memory impairment caused by oxidative stress‐dependent hippocampal damage through upregulated antioxidant response and strengthened synaptic function of neuronal circuits particularly in the hippocampus. Support or Funding Information This study was funded by the Forest Resources Development Institute of Gyeongsanbuk‐do, Andong, Republic of Korea.