Figure 2. Downregulation of the CB₁ receptor protected RPE cells from H₂O₂-induced damage. A: Primary human RPE cells were transfected with CB₁ receptor siRNA for 24 h. CB₁ receptor mRNA levels were detected using real time RT–PCR. B: Primary human RPE cells were transfected with CB₁ receptor siRNA for 48 h, and CB₁ receptor protein levels were detected by western blot assay. C: After the si-NC or si-CB₁ siRNA-treated RPE cells received different concentrations of H₂O₂ for 24 h, cell viability was examined with the MTT assay. ***p<0.001, si-NC versus si-CB₁ siRNA-treated cells. D: After the si-NC or si-CB₁ siRNA-treated RPE cells received different concentrations of H₂O₂ for 24 h, cell viability was examined with the SRB assay. *p<0.05,***p<0.001, si-NC versus si-CB₁ siRNA-treated cells. The statistical test of C and D are two way ANOVA, n=4 per group.