替普瑞酮对大鼠视网膜缺血-再灌注损伤的保护作用

Protective effects of geranylgeranylacetone on rat retinal ischemia/reperfusion injury

背景视网膜缺血-再灌注损伤是眼科常见的病理过程，可引起永久性的视力障碍，严重影响患者的视功能，是目前国内外研究的重点课题之一。目的探讨替普瑞酮对大鼠视网膜缺血-再灌注损伤的保护作用。方法44只SD大鼠按随机数字表法分为正常对照组4只、单纯模型组20只和替普瑞酮治疗组20只。单纯模型组及替普瑞酮治疗组造模前分别给予大鼠生理盐水和替普瑞酮灌胃，1周后采用前房加压法制作大鼠视网膜缺血-再灌注损伤模型，并分别于再灌注后6、24、48、72h制备视网膜铺片，经苏木精-伊红染色观察各组大鼠视网膜组织结构的变化，采用免疫组织化学法检测大鼠视网膜中热休克蛋白70（HSP70）和caspase-3的表达。结果视网膜缺血-再灌注后1～6h单纯模型组大鼠角膜及视网膜出现水肿，24h视网膜水肿加重，72h视网膜水肿减轻、结构较紊乱。替普瑞酮治疗组大鼠各时间点视网膜水肿较单纯模型组轻，缺血-再灌注后72h大鼠视网膜结构损害较单纯模型组减轻。正常对照组大鼠视网膜未见HSP70及caspase-3呈阳性表达。单纯模型组大鼠在再灌注后6h可见视网膜神经节细胞（RGCs）中HSP70呈阳性表达，再灌注后24h达高峰，之后逐渐下降。替普瑞酮治疗组各时间点HSP70在大鼠RGCs中的表达较单纯模型组明显增强，差异均有统计学意义（P〈0．05）。再灌注后6h可见单纯模型组大鼠RGCs中caspase-3表达，24h时caspase-3的表达量达高峰，48h后开始下降，72h仅有少量表达，而各时间点替普瑞酮治疗组视网膜中caspase-3的表达较单纯模型组大鼠明显减弱，差异均有统计学意义（P〈0．05）。结论在视网膜缺血-再灌注损伤大鼠模型中，替普瑞酮可通过上调视网膜中HSP70的表达和下调caspase-3的表达对RGCs起保护作用。

Background Retinal ischemia/reperfusion injury is a common pathological process in ophthalmology. It can cause permanent visual impairment. The prevention and treatment of retinal ischemia/ reperfusion injury is one of the focus topics at home and abroad up to now. Objective Present study was to evaluate the protective effects of geranylgeranylacetone （GGA） on retinal ischemia/reperfusion injury. Methods The retinal ischemia/reperfusion models were established in 40 SD rats by the infusion of normal saline solution into the anterior chamber to elevate the intraocular pressure for 1 hour and then remove the process. GGA of 2 ml （800 mg/kg） was intragastrically administered in 20 model rats as GGA group, and the equal volume of normal saline solution was used at the same way in other 20 models as model group. Four normal matched SD rats were served as normal control group. The histological changes of retina in 6,24,48,72 hours after modeling was examined by hematoxylin-eosin staining under the light microscope, and the expression of heat shock protein 70 （HSP70） and caspase-3 in retina at the time points mentioned above was detected by immunohistochemistry. Results The edema of cornea and retina of rats appeared in 1 hour and peaked in 24 hours after modeling. In 72 hours after modeling,the edema was alleviated but the disorder of retina structure was found in model group. However, although the pathological change process was similar to that of model group,the damage of retina tissue was milder in the rats of GGA group under the light microscope. HSP70 and caspase-3 were absent in the retina of normal rats. But, the expression of HSP70 in retinal ganglion cells （RGCs） was found in 6 hours after modeling,reached peak in 24 hours and declined after that in model group. The numbers of positive cells for HSP70 in retina was significantly increased in various time points in GGA group, showing statistically significant differences between model group and GGA group （ P〈0.05 ）. In model group, a few of caspase-3 positive cells were found 6 hours after reperfusion and increased gradually until reaching the peak 24 hours and then decreased gradually 48 hours later. Few caspase-3 positive cells were found 72 hours after reperfusion. The numbers of positive cells for caspase-3 decreased in GGA group compared with model group during the experimental duration with the considerable difference between these two groups （ P 〈 0. 05 ）. Conclusion GGA could protect RGCs against ischemia/reperfusion injury by upregulating the expression of HSP70 and downregulating the expression of caspase-3 in retina.