The effects of Engelhardtia chrysolepis Hance on long-term memory and potential dopamine involvement in mice

Engelhardtia chrysolepis Hance (ECH) is a perennial plant used in traditional medicine. A major active ingredient of ECH is astilbin (ASB), which has recently been shown to have neuroprotective effects as well as to affect catecholamine neurotransmissions in brain areas such as the prefrontal cortex. In this study, we investigated the effects of ECH and ASB on long-term memory in mice using a battery of behavioral tests. Acute ECH treatments dose-dependently facilitated nonspatial, but not spatial, memory. ECH treatments also upregulated expression of tyrosine hydroxylase, the enzyme mediating catecholamine synthesis, in neuroblastoma cell culture. Acute ASB treatments similarly improved nonspatial memory, whereas chronic ASB treatments improved both nonspatial and spatial memory. In accordance with such behavioral effects, the increased ratio of tissue concentrations of dopamine metabolites over dopamine in striatal regions was observed in mice with chronic ASB treatments. These results suggest that ECH and its active ingredient ASB may facilitate long-term memory by modulating catecholamine transmission.