[Ginsenoside Rg_1 attenuates OGD/R induced HT22 cell damage by inhibiting oxidative stress via ROS-ATM-CHK2 pathway]

This study focused on ginsenoside Rg_1(GRg_1) and aimed to explore whether it could alleviate oxygen-glucose deprivation/reoxygenation(OGD/R)-induced damage in mouse hippocampal neuronal(HT22) cells by regulating the reactive oxygen species(ROS)-ataxia telangiectasia mutated(ATM)-checkpoint kinase 2(CHK2) signaling pathway, thereby influencing apoptosis and oxidative stress responses. First, assessment of HT22 cell viability showed that GRg_1 significantly enhanced the viability of HT22 cells. Second, Western blot analysis demonstrated that GRg_1 markedly reduced the apoptosis rate and decreased the expression levels of B-cell lymphoma-2(Bcl-2)-associated X protein(Bax) and cleaved cysteine-aspartic acid specific protease-3(cleaved caspase-3), while the expression level of Bcl-2 showed an increasing trend. Further analysis revealed that intracellular ROS levels gradually increased following OGD/R induction, whereas GRg_1 treatment significantly reduced ROS levels. Concurrently, the activities of the antioxidant enzymes superoxide dismutase(SOD), catalase(CAT), and glutathione peroxidase(GSH) were also enhanced, suggesting that GRg_1 augments antioxidant capacity and consequently reduces malondialdehyde(MDA) accumulation. Notably, GRg_1 decreased the ratio of phosphorylated(p)-ATM to total ATM and the ratio of p-CHK2 to total CHK2 in OGD/R-treated cells. Furthermore, pretreatment with the ATM inhibitor KU-55933 or the CHK2 inhibitor BML further potentiated the inhibitory effect of GRg_1 on OGD/R-induced ROS production and neuronal apoptosis. Both target protein stability analysis and cellular thermal shift assay collectively confirmed that GRg_1 directly interacts with ATM. In conclusion, GRg_1 may ameliorate OGD/R-induced HT22 cell damage by suppressing ROS production via the ROS-ATM-CHK2 signaling pathway, thereby providing a theoretical basis for the application of GRg_1 in the treatment of cerebral ischemia.