| Objectives1. To improve upon the experimental intraocular hypertension model in rats and to analyze the changes of expression of heat shock protein (HSP) 70 in retinal ganglion cells (RGCs) under acute intraocular hypertension;2. To establish the heat shock model in rats and to measure and analysis electroretinogram changes in experimental intraocular hypertension rats after induced by heat shock response and the changes of expression of heat shock protein (HSP) 70 in rat retinal ischemic-reperfusion injury;3. To investigate the ultrastructural changes of neurosensory retina cells under acute intraocular hypertension condition after heat shock response;4. To evaluate protective effects of heat shock protein 70 in rat retinal intraocular-hypertension-induced-ischemic-reperfusion injury.Methods1. Intraocular pressure (IOP) was elevated to 80 mmHg unilaterally for 2 hours in Wistar rats via an intracameral catheter. The density of retinal ganglion cells was studied by HE staining method. The expression and changes of Hsp70 were studied by immunohistochernical (ABC) staining for Hsp70 and analyzed by computer- image analytic system on results of ABC method.2. We established the heat shock model in rats by method of high temperature environment. Quercetin, an inhibitor of HSPexpression was injected in the rats with heat stress. According to International Society for Clinical Visual Electrophysiology's standard program, we recorded, by Guo Te medical system, the Dark-adapted electroretinogram (D-ERG), oscillatory potentials (OPs) and light-adapted electroretinogram (L-ERG) in experimental intraocular hypertension rats after induced by heat shock response. Western blotting test was taken to show expression of heat shock protein 70 in groups.3. The neurosensory retina were taken out after the rats were killed in reperfusion 0 h, 8h, 24 h, 48 h, 7 d. The specimen were fixed, sliced and observed with electron microscope.Results1. After 48 h reperfusing, the density of retinal ganglion cell layer(3.22?.64 -t-/100um) decreased remarkably (P<0.05). The difference between control and reperfusion groups was significant(P<0.05). Along with the progression of reperfusion, the gray level changed in degrees. The gray level of retinal ganglion cell layer in Reperfusion 24 h was lowest among groups (P<0.05 ) .2. Heat shock protein 70 expressed in perfusion after heat shock response group (P+H) more highly than other groups, but the expression of HSP70 in two groups with injection of quercetin was inhibited significantly. The amplitudes of ERG's a- and b-waves and Ops' 62-wave decreased and the implicit times of them were delayed significantly in rats after intracameral perfusion. The amplitude of scot-ERG's b-wave and Ops' O2-wave in (P+H) is higher than that in perfusion group (P). At Oh after perfusion, P+H [a-wave(13.9?.1)#V, b-wave(79.5?0.2)#V, O2-wave (26.5?0.5) #V ] vs P [ a-wave(10.7?.6)#V,b-wave(68.7?7.2)#V, O2-wave(21.3?.5) #V] . At 24h after perfusion P+H still recovered better than P group. But in other groups, perfusion after injection of quercetin group(P+Q) and perfusion after injection of quercetin and heat shock response(P+Q+H), the implicit times of ERG's waves and OPs' O2-wave were longer and the amplitude were lower, even some waves disappeared.3. After 8 hours reperfusing, apoptosis occurred in outer nuclear layer, edema and vacuole-like structure in mitochondria were appeared in nerve fiber layer. Apoptosis of retinal ganglion cells reached to the highest level after 24 hours reperfusion. In 7th day, we found atrophy of retina, which had low density of cell and few apoptosis cells.Conclusions1. HSP70 expression was closely related with ischemia-reperfusion time. HSP70 may be useful to prevent neuronal degeneration in ganglion cells layer.2. The electrophysiological results demonstrate the possibility of novel therapeutic approac...
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