The effects of different doses of E2 pre-treatment on PC12 cell viability and cell damage. (A) MTT assay was used to test the cell viability after OGD-R. 10 nM and 20 nM E2 significantly promoted the cell viability. The cell viability in the cells treated with 10 μM and 20 μM E2 group significantly decreased. (*p < 0.01 compared with the control and DMSO groups, #p < 0.05 compared with the control and DMSO groups). (B) LDH release assay was used to detect cell necrosis after OGD-R. 10 nM and 20 nM E2 did not significantly attenuate LDH release; and 10 μM and 20 μM E2 the LDH release in group had not markedly declined (v.s. the control and DMSO groups).