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[Expression of vascular endothelial growth factor and pigment epithelium derived factor in mouse oxygen-induced retinopathy and its significance].

OBJECTIVE
To investigate the expression and significance of vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) in oxygen-induced mouse retinopathy.


METHODS
This experiment was a control experiment study. Newborn C57BL-6 mice were exposed to hyperoxia, and then returned to normoxia to induce retinal neovascularization. Mice were sacrificed at postnatal days 12, 14 and 17 and the retina were processed for RT-PCR, Western Blot and fluorescein angiography. Analysis of variance and Dunnett's t3 was used to compare the mRNA and protein level of VEGF and PEDF between experiment and control groups. Statistical difference was considered significant at a P value less than 0.05.


RESULTS
At any of the time points tested, there was significant difference at VEGF protein level (A value) between the experiment (0.47 +/- 0.12, 2.15 +/- 0. 46, 5.49 +/- 0.97) and control (l.81 +/- 0.50, 0.90 +/- 0.05, 0.88 +/- 0.91) groups (P = 0.009, 0.010, 0.000, respectively); the same situation occurred at PEDF protein level (P = 0.002, 0.046, 0.000, respectively). At postnatal day 12, 14 and 17, a significant difference at VEGF protein level was observed among the different experiment groups (P = 0.002, 0.001, 0.000, respectively); the same situation occurred at PEDF protein level (P = 0.009, 0.010, 0.000, respectively). There was significant difference at VEGF mRNA level between the experiment and control groups (P = 0.001, 0.000, 0.001); at postnatal day 12 and 14, the same situation occurred at PEDF protein level (P = 0.001, 0.000, respectively), but there was no significant difference at postnatal day 17 (P = 0.612). At postnatal day 12, 14 and 17, a significant difference at VEGF mRNA level was observed among different experiment groups (P = 0.000, 0.001, 0.000, respectively); the same situation occurred at PEDF mRNA level (P = 0.000, 0.001, 0.000, respectively). The time course of the decrease of PEDF was consistent with the increase of VEGF expression. VEGF/PEDF ratio change was correlated with the development and progression of retinal neovascularization. The time course of PEDF mRNA down-regulation was consistent with the VEGF mRNA up-regulation, similar with the changes of the protein. The change of VEGF and PEDF mRNA was prior to that of the protein.


CONCLUSIONS
One of the mechanisms for development of retinal neovascularization is the changes of VEGF\PEDF level in the retina.