The Neuroprotective Effect Of Vascular Endothelium Growth Factor (VEGF) To The Retinal Ganglion Cells Of Rats With Chronic Intraocular Hypertesion

ObjectivesTo investigate how vascular endothelium growth factor (VEGF) contributes to the expression of Pigment epithelium-derived factor (PEDF) in retina of rats and evaluate the neuroprotection of VEGF for retinal ganglion cells of rats with chronic intraocular hypertesion and it's potential approach. Methods1. Rats were deeply anesthetized by intraperitoneal injection of 1% amobarbital sodium, and an increase in intraocular pressure (IOP) was achieved by cauterizing two episcleral veins. IOP was measured by using a portable tonometer (Tonopen-XL), at Oh, 1h, 12h, 1d, 3d, 7d, 14d, 21d and 28d, respectively.2. Shortly after two episcleral veins were cauterized, rats were intravitreously injected of 2 μ1 VEGF (concentration: 0.05 μ g/ μ1) from the the position 2.0mm behind limbus. To keep the IOP, 2μl vitreous body were drawn out before the intravitreous injection.3. Sprague Dawley rats were randomly devided into four groups: normal group, normal + VEGF group, chronic intraocularhypertension group, and chronic intraocular hypertension + VEGF group. Rats were killed in different times and their eyes were removed and fixed in 4% paraformaldehyde at 4°C. Eye sections were cut to a thickness of 12 u m, then mounted onto gelatin-coated slides and stored at -20°C until needed. Frozen sections were thawed for 2h at room temperature before they were stained. TUNEL and Fluoro- Jade (FJ) staining protocol were carried out to detect apoptotic cells and degenerated neurons.4. Sections were immunohistochemically stained for PEDF and P-tubulin in rats' retinas of different groups. Immunofluorescent double labeling was performed to identify which cells were PEDF-positive cells in the retina. Western blotting was proformed to semi-quantitative analysis PEDF in the retina.Results1. The mean IOP at daytime was (1.61 ± 0.20)kPa normally. The IOP was obviously high than the normal after the operation. The IOP was stably in a high level after Id of the operation and lasted more than 28 days.2. Immunohistochemistry analysis of rats' retinal tissues showed that the PEDF-positive cells were in retinal pigment epithelium (RPE), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL), retinal ganglion cell layer (RGCL), retinal nerve fiber layer (RNFL) in normal group. The number of PEDF-positive cells in normal + VEGF group, chronic intraocular hypertension group, and chronic intraocular hypertension + VEGF group were increased in the same layer of retina, especially in RGCL and RNFL. There were no significant changes in the number of PEDF-positive cells after lh and 12h of the operation (P...