Figure 4 SIRT1 overexpression increased cell viability and decreased cell apoptosis in OGD-induced primary rat neuronal cells. Primary rat neuronal cells were transfected with SIRT1-plasmid or control-plasmid for 48 h, then the cells were exposed to OGD for 48 h. (A) Cell proliferation was assessed using MTT assay. (B) Flow cytometry was used to determine apoptotic cells. (C) Quantification of apoptotic cells. (D) Bax and Bcl-2 protein levels were determined by Western blot assay. (E, F) The ratio of Bcl-2/GAPDH and Bax/GAPDH was calculated and presented. Control: cells without any treatment; OGD: cells were subjected to OGD treatment; OGD+control-plasmid: cells were transfected with control-plasmid and then subjected to OGD treatment; OGD+SIRT1-plasmid: cells were transfected with SIRT1-plasmid and then subjected to OGD treatment. The results showed as the mean±SD. ** P<0.01 vs. control group; ## P<0.01 vs. OGD group. OGD – oxygen and glucose deprivation; SIRT1 – sirtuin-1.