Purpose: To investigate the effect of estrogen on expression of pigment epithelium derived factor (PEDF) in cultured rat retinal Müller cells under hypoxic condition.

Methods: The mRNA expression of PEDF was studied by reverse-transcription PCR (RT-PCR), and protein levels were assayed by Western Blot. Different concentrations of E₂ (10^-7, 10^-6, 10^-5 mmol/l) and estrogen receptor antagonist tamoxifen (10^-4 mmol/l) were added into the cell culture medium of different groups, while the phosphate-buffered saline (PBS) was added in the control group instead. Culture conditions were set to be under normoxia and hypoxia. The results of each group were detected after 24 hours.

Results: (1) Under hypoxia, gene expression of PEDF decreased compared with the normal group. There is evident positive correlation between the mRNA and protein levels of PEDF. (2) Under hypoxia, E₂ increased the mRNA and protein levels of PEDF in a concentration-dependent manner. (3) tamoxifen (10^-4 mmol/l) reversed the effect of E₂ (10^-5 mmol/l).

Conclusions: E₂ increases the gene expression of PEDF in cultured rat retinal Müller cells under hypoxic condition. The effect of E₂ on PEDF expression may play an important role on retinal neovascularization.