Objective: To assess the neuroprotective effects of ginsenoside Rg1 against β-amyloid peptide (Aβ(25-35))-induced apoptosis in primarily cultured rat cortical neurons.
Methods: Primarily cultured cortical neurons were obtained from embryonic (E18d) rat fetus and maintained in neurobasal medium for 7d. Primary neurons pretreated with 1 μmol/L, 10 μmol/L or 20 μmol/L Rg1 for 24 h were challenged with 10 μmol/L Aβ(25-35) for 72 h. Morphological changes of neurons were evaluated; mitochondrial membrane potential (ΔΨm) was measured; with JC-1 staining and the expression of neural apoptosis-related proteins was detected by Western blot analysis.
Results: Exposure to Aβ(25-35) for 72 h caused serious neural cell insults. A pretreatment with Rg1 significantly reduced Aβ(25-35)induced cell death in a dose-dependent manner, with a maximal effect (-90%) obtained at 20 μmol/L. The JC-1 staining results demonstrated the loss of ΔΨm after Aβ(25-35) treatment, while Rg1 maintained the normal level of ΔΨm. A series of mitochondrion-mediated apoptotic events happened after Aβ(25-35) treatment, such as decrease of Bcl-2/Bax, release of cytochrome C and activation of caspase 9 and caspase 3, which were all blocked by Rg1 pretreatment. Both estrogen receptor (ER) antagonist ICI182, 780 and glucocorticoid receptor (GR) antagonist RU486 blocked the antiapoptotic effects of Rg1.
Conclusion: Ginsenoside Rg1 protects primary cultured rat cortical neurons from Aβ(25-35)-induced injury, which may be associated with mitochondrion-mediated antiapoptosis pathway.