Study of the molecular mechanism of synaptogenesis using withanolides, novel anti-dementia drugs

灌胃给予薇菜皂苷IV(10μ/kg/天)，显著改善Aβ(25-35)注射(25nmol.i.c.v)引起的记忆障碍。并防止轴突、树突和突触的丢失。苦参苷IV可增强正常小鼠的物体再认记忆。在脊髓损伤的小鼠中，口服10μ/kg/d，连续21天，可改善小鼠的运动功能，增加轴突密度和周围神经系统髓鞘水平。梭米酮(1μM)可显著促进10μM Aβ(25-35)损伤的大鼠皮质神经元的轴突和树突再生以及突触重建。为了阐明索米酮的分子机制，我们在原代培养的神经元中鉴定了受体或相关分子，并用磷酸化抗体阵列将其磷酸化。小胶质细胞和神经元中的磷酸化RET水平增加。神经元内磷酸化AcK1水平升高。利用siRNA进行的基因敲除实验表明，RET和AcK1都参与了黏液的伸展。这些结果表明，RET和AcK1是神经元重建的关键分子。

Oral administration of withanoside IV (10 μmol/kg/day), an isolated compound from roots of Withania somnifera significantly improved memory deficits in Aβ(25-35)-injected (25 nmol, i.c.v.) mice and prevented loss of axons, dendrites, and synapses. The treatment with withanoside IV could enhance the object recognition memory in normal mice. In spinal cord injured mice, per oral treatment with withanoside IV (10 μmol/kg/day, for 21 days) improved locomotor functions in mice, and increased axonal density and the peripheral nervous system myelin level.Sominone, an aglycone of withanoside IV, was identified as the main metabolite after oral administration of withanoside IV. Sominone (1 μM) induced axonal and dendritic regeneration and synaptic reconstruction significantly in cultured rat cortical neurons damaged by 10 μM Aβ(25-35).To clarify the molecular mechanism of sominone, we identified receptors or associated molecules in primary cultured neurons, which were phosphorylated by sominone stimulation using phosphorylation antibody arrays. The level of phosphorylated RET increased in microglias and neurons. The level of phosphorylated ACK1 increased in neurons. Knockdown experiments using siRNA showed that both RET and ACK1 were involved in dedritic extension. These results suggest that roles of RET and ACK1 as key molecules for reconstruction of the neuronal