Abstract. The present study investigated an ethanol extract of the aerial part of Aralia cordata Thunb. (Araliaceae) for possible neuroprotective effects on neurotoxicity induced by amyloid β (Aβ) protein (25 -35) in cultured rat cortical neurons and antidementia activity in mice. Exposure of cultured cortical neurons to 10 μM Aβ(25 -35) for 36 h induced neuronal apoptotic death. At 1 -10 μg/ml, A. cordata inhibited neuronal death, elevation of intracellular calcium ([Ca 2+ ] i ), glutamate release into the medium, and generation of reactive oxygen species (ROS) induced by in primary cultures of rat cortical neurons. Memory loss induced by intracerebroventricular injection of ICR mice with 15 nmol Aβ(25-35) was inhibited by chronic treatment with A. cordata (50 and 100 mg/kg, p.o. for 7 days) as measured by a passive avoidance test, and corresponding reductions were observed in brain cholinesterase activity and neuronal death measured histologically in the hippocampal region. Oleanolic acid isolated from A. cordata also inhibited neuronal death, elevation of [Ca 2+ ] i , glutamate release, and generation of ROS induced by Aβ(25-35) in cultured rat cortical neurons, suggesting that the neuroprotective effect of A. cordata may be, at least in part, attributable to this compound. From these results, we suggest that the antidementia effect of A. cordata is due to its neuroprotective effect against Aβ(25-35)-induced neurotoxicity and that A. cordata may have a therapeutic role in preventing the progression of Alzheimer's disease.

This study investigated an ethanol extract from Glycyrrhizae radix (GR), the root of Glycyrrhiza uralensis (Leguminosae), for possible neuroprotective effects on neurotoxicity induced by amyloid β protein (Aβ) (25-35) in cultured rat cortical neurons. Exposure of cultured cortical neurons to 10 μM Aβ (25-35) for 36 h induced neuronal apoptotic death. GR (10-50 μg/mL) prevented the Aβ (25-35)-induced neuronal apoptotic death, as assessed by a MTT assay and Hoechst 33342 staining. Furthermore, GR decreased the expression of Bax and active caspase-3, proapoptotic proteins, and increased Bcl-2, an antiapoptotic protein. GR also significantly inhibited Aβ (25-35)-induced elevation of the intracellular Ca(2+) concentration ([Ca(2+)](i)) and generation of reactive oxygen species (ROS) measured by fluorescent dyes. Isoliquiritigenin (1-20 μM), isolated from GR as an active component, inhibited Aβ (25-35)-induced neuronal apoptotic death, elevation of [Ca(2+)](i), ROS generation, and the change of apoptosis-associated proteins in cultured cortical neurons, suggesting that the neuroprotective effect of GR may be, at least partly, attributable to this compound. These results suggest that GR and isoliquiritigenin prevent Aβ (25-35)-induced neuronal apoptotic death by interfering with the increases of [Ca(2+)](i) and ROS, and GR may have a possible therapeutic role for preventing the progression of neurodegenerative disease such as Alzheimer's disease.

Versatile biological activities of Hericium erinaceus (HE) have been reported in many brain diseases. However, roles of HE in major psychiatric disorders such as depression and anxiety remain to be investigated. Therefore, we evaluated whether HE could reduce anxiety and depressive behaviors in the adult mouse and its underlying mechanisms. Male C57BL/6 mice were administered HE (20 or 60 mg/kg, p.o.) or saline once a day for 4 weeks. Open field and tail suspension tests were performed 30 min after the last administration of HE, followed by forced swim test 2 days later. We found that chronic administration of HE showed anxiolytic and antidepressant-like effects. To elucidate possible mechanisms, proliferative activity of the hippocampal progenitor cells was assessed by immunohistochemistry of proliferating cell nuclear antigen (PCNA) and Ki67. Moreover, to evaluate neuronal survival in the dentate gyrus, 5-bromo-2'-deoxyuridine (BrdU) (120 mg/kg, i.p.) was given at the first day of HE administration, followed by isolation of the brains 4 weeks later. HE (60 mg/kg) increased the number of PCNA- and Ki67-positive cells in the subgranular zone of the hippocampus, indicating increased proliferation of hippocampal progenitors. In addition, BrdU- and BrdU/NeuN-positive cells in the dentate gyrus were significantly increased when treated with HE (60 mg/kg) compared with the saline-treated group, demonstrating enhanced neurogenesis by HE treatment. Taken together, the results indicate that chronic HE administration can exert anxiolytic and antidepressant-like effects, possibly by enhancing adult hippocampal neurogenesis.

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This study investigated a methanol extract from the leaf and stem of Vitis amurensis (Vitaceae) for possible neuroprotective effects on neurotoxicity induced by amyloid β protein (Aβ) (25-35) in cultured rat cortical neurons and also for antidementia activity in mice. Exposure of cultured cortical neurons to 10 μM Aβ (25-35) for 36 h induced neuronal apoptotic death. At concentrations of 1-10 μg/mL, V. amurensis inhibited neuronal death, the elevation of intracellular calcium ([Ca(2+)](i)) and the generation of reactive oxygen species (ROS), all of which were induced by Aβ (25-35) in primary cultures of rat cortical neurons. Memory loss induced by intracerebroventricular injection of ICR mice with 16 nmol Aβ (25-35) was inhibited by chronic treatment with V. amurensis extract (50 and 100 mg/kg, p.o. for 7 days), as measured by a passive avoidance test. Amurensin G, r-2-viniferin and trans-ɛ-viniferin isolated from V. amurensis also inhibited neuronal death, the elevation of [Ca(2+)](i) and the generation of ROS induced by Aβ (25-35) in cultured rat cortical neurons. These results suggest that the neuroprotective effect of V. amurensis may be partially attributable to these compounds. These results suggest that the antidementia effect of V. amurensis is due to its neuroprotective effect against Aβ (25-35)-induced neurotoxicity and that the leaf and stem of V. amurensis have possible therapeutic roles for preventing the progression of Alzheimer's disease.