Total Ginsenoside Extract from Panax ginseng Enhances Neural Stem Cell Proliferation and Neuronal Differentiation by Inactivating GSK-3β.

Abstract

To study the effects of total ginsenosides (TG) extract from Panax ginseng on neural stem cell (NSC) proliferation and differentiation and their underlying mechanisms. The migration of NSCs after treatment with various concentrations of TG extract (50, 100, or 200 µ g/mL) were monitored. The proliferation of NSCs was examined by a combination of cell counting kit-8 and neurosphere assays. NSC differentiation mediated by TG extract was evaluated by Western blotting and immunofluorescence staining to monitor the expression of nestin and microtubule associated protein 2 (MAP2). The GSK-3β/β-catenin pathway in TG-treated NSCs was examined by Western blot assay. The NSCs with constitutively active GSK-3β mutant were made by adenovirus-mediated gene transfection, then the proliferation and differentiation of NSCs mediated by TG were further verified. TG treatment significantly enhanced NSC migration (P<0.01 or P<0.05) and increased the proliferation of NSCs (P<0.01 or P<0.05). TG mediation also significantly upregulated MAP2 expression but downregulated nestin expression (P<0.01 or P<0.05). TG extract also significantly induced GSK-3β phosphorylation at Ser9, leading to GSK-3β inactivation and, consequently, the activation of the GSK-3β/β-catenin pathway (P<0.01 or P<0.05). In addition, constitutive activation of GSK-3β in NSCs by the transfection of GSK-3β S9A mutant was found to significantly suppress TG-mediated NSC proliferation and differentiation (P<0.01 or P<0.05). TG promoted NSC proliferation and neuronal differentiation by inactivating GSK-3β.