The Effects On Blood-retinal Barrier Of Rat Following Acute High Intraocular Pressure

OBJECTIVE:To study the impact of AHIOP on BRB to find its spatial and temporal feature based on the retinal microenvironment, and investigate the relationship between the expression of HIF-1a and BRB injury.METHOD:144 SD rats were randomly divided into normal groups, experimental control groups and experimental groups. Rats of experimental groups were made into AHIOP model and rats of experimental control groups were executed the sham operation, then survived for 3h,12h,1d,3d,7d respectively.3% Evans blue (EB) was injected into the saphenous vein of 108 rats 2 hours before the rats were killed. The distribution of EB in the retinal wholemount and retinal slice was observed by using confocal microscopy and the EB content of retina was measured by using Spectrophotometer. The HIF-1αexpression in rat's retina was detected with immunohistochemistry on the other 36 rats.RESULTS:EB red fluorescence spots were occasionally seen in the normal retina, which was mainly distributing in the ganglion cell layer around capillaries following AHIOP. In 3h,12h and 1d it was also found in the inner nuclear layer surrounding the capillaries. The EB red fluorescence spots of the central retina began to increase in 3h following AHIOP, and reached its peak in 12h, and then gradually decreased. Most of it in the peripheral retina following AHIOP was found in 3h, and then gradually decreased. The peak of EB leakage in the peripheral retina preceded the central retina. Further quantitative analysis showed that compared with the normal control group, the EB leakage of central retina in 3h following AHIOP began to upregulate, when 12h it reached its peak, then gradually decreased, and returned to normal in 7d.The EB leakage of the peripheral retina following AHIOP reached its peak in 3h, then gradually decreased, and returned to normal in 7d. The peak of EB leakage in the peripheral retina preceded the central retina. Immunohistochemistry showed that no positive expression of retinal HIF-1αwas seen in the control group. HIF-1αexpression upregulated in 3h after AHIOP and reached its peak in 12h,then gradually decreased in ld,3d,7d.HIF-1αpositive products were mainly distributed in the ganglion cell layer, and also been found in the inner nuclear layer in 3h and 12h after AHIOP.CONCLUSIONS:1. BRB damage of rat was more evident in its early stage after AHIOP, and restored gradually in its late stage. The serious breakdown of BRB in the peripheral retina preceded the central retina. BRB damage was mainly distributed in the ganglion cell layer.2. The expression of HIF-1αincreased obviously in the early stage after AHIOP and gradually restored in the late stage, and the space-time characteristics of HIF-la expression was consistent with the spatial and temporal characteristics of BRB damage, suggesting that upregulation of expression of HIF-la following AHIOP may be concerned with BRB damage.