Protective Effects of 17 beta-Estradiol on Benzo(e) pyrene[B(e)P]-induced Toxicity in ARPE-19 cells

Purpose: The aim of this study was to examine the effect of 17 beta-estradiol on Benzo(e)pyrene [B(e)P]-induced toxicity in ARPE-19 cells. Methods: We pretreated ARPE-19 cells with 20 nM and 40 nM 17 beta-estradiol for 6 hours, followed by addition of 300 mu M B(e) P for additional 24 hours. Cell viability was measured using Trypan blue dye-exclusion assay. JC-1 assay was performed to measure mitochondrial membrane potential (Delta Psi m). For a quantitative estimation of cell death, apoptotic markers such as caspase-3/7, caspase-9, and caspase-12 were measured. Results: Our results demonstrated that when treated with B(e) P, the viability and Delta Psi m of ARPE-19 cells declined by 25% and 63%, respectively (P < 0.05). However, pretreating with 17 beta-estradiol increased the viability of ARPE-19 cells by 21% (20 nM) and 10% (40 nM) (P < 0.05). Furthermore, the significantly reduced Delta Psi m in beta E+ B(e) P treated cells ARPE-19 cells was restored by pre-treatment with 17 beta-estradiol-Delta Psi m was increased by 177% (20 nM) and 158% (40 nM) (P < 0.05). We further observed a significant up-regulation in the activity of Caspases-3/7, -9, and -12 in B(e) P-treated ARPE-19 cells. However, 17 beta-estradiol treatment significantly reduced the activity of all apoptotic markers (P < 0.05). Conclusion: In conclusion, our results demonstrate that 17 beta-estradiol protects ARPE-19 cells against B(e) P-induced toxicity by decreasing apoptosis, preventing cell death, and restoring mitochondrial membrane potential.