早期糖尿病大鼠视网膜形态变化及相关影响因子分析

背景糖尿病视网膜病变（DR）的病理基础是血-视网膜屏障受损，是多种因子共同影响的结果。目的探讨早期糖尿病大鼠视网膜形态变化与血清中血管内皮生长因子（VEGF）、内皮素（ET）和一氧化氮（NO）的关系。方法40只健康雌性SD大鼠按随机数字表法分为实验组和正常对照组，每组20只。实验组腹腔注射60mg／kg链脲佐菌素（STZ）建模成功后，按病程分为糖尿病2、4、6、8个月组；正常对照组腹腔注射等体积缓冲液，根据与实验组年龄匹配原则平均分为4组，每组5只。分别在造模后2、4、6、8个月采用ELISA双抗体夹心法测定2组大鼠血清中VEGF质量浓度，^125碘（^125I）放射免疫法测定血清中ET质量浓度，硝酸还原法测定血清中NO浓度并进行比较。于造模后8个月摘除大鼠眼球行常规视网膜组织形态学检查。结果正常对照组大鼠在实验各时间点视网膜组织形态学无明显改变。实验组大鼠造模后4个月开始出现视网膜组织水肿，视网膜各层细胞排列紊乱，造模后6个月可见视网膜出血，造模后8个月可见视网膜血管破裂。实验组大鼠在造模后2、4、6、8个月血清中VEGF和ET质量浓度较同时间点正常对照组大鼠明显升高，差异均有统计学意义（P〈0．05），糖尿病2个月组血清中NO浓度较同时间点正常对照组升高（Z=-2．193，P〈0．05），糖尿病4个月组与正常对照组比较，血清中NO浓度的差异无统计学意义（Z=-2．611，P〉0．05），而糖尿病6个月组及糖尿病8个月组血清NO浓度较同时间点正常对照组低（Z=-2．449、-2．236，P〈0．05）。随着病程的延长，实验组血清中VEGF、ET质量浓度逐渐升高，NO浓度逐渐降低（P〈0．05）。糖尿病大鼠血清中VEGF与ET质量浓度间呈正相关（r=0．821，P〈0．01），血清中VEGF质量浓度与NO浓度间呈负相关（r=-0．814，P〈0．01）；糖尿病大鼠血清中ET质量浓度与NO浓度间呈负相关（r=-0．803，P〈0．01）。结论糖尿病大鼠血清中VEGF、ET和NO水平与视网膜病理改变的严重程度密切相关，考虑血清中VEGF、ET与NO水平可以间接反映糖尿病大鼠视网膜病变的严重程度。

Retinal morphologic change and related factor analysis in rats with early stage of diabetes mellitus

Background The pathological foundation of diabetic retinopathy is the breakdown of the bloodretina barrier induced by multifactors.Objective This study was to investigate the retinal morphologic change and the levels of serum vascular endothelial growth factor(VEGF),endothelin(ET)and nitric oxide(NO)in diabetic rats.Methods Forty healthy female SD rats were randomly divided into experimental group and control group and 20 rats for each group.Acute diabetes models were established by the intraperitoneal injection of 60 mg/kg streptozotocin in experimental group and the equal volume of buffer solution was injected at the same way in the control group.The serum VEGF level,ET level and NO concentration of diabetic and control rats were detected using ELISA double antibody sandwich method,125I radioimmune method and nitrate reduction method respectively at 2,4,6 and 8 weeks after injection.The eyeballs of rats were enucleated at the eighth week for retinal pathologic examination.This experiment followed the Measures for the administration of experimental animals of Shanghai City.Results The retinal structure was normal throughout the experimental duration in the control group.However,retinal edema and cellular disorganization appeared at 4 months and retinal blooding could be seen with the extending of diabetes course.The levels of serum VEGF and ET in each experimental group were significantly higher than those in control groups(P＜0.05).The levels of serum NO elevated in 2-month experimental group compared with same-phase control group(Z =-2.193,P＜0.05),and those in 6-and 8-month experimental groups were significantly lower than in corresponding control groups(Z =-2.449,Z =-2.236,P＜0.05).With the progression of the disease,the levels of VEGF and ET increased gradually,but the levels of NO decreased gradually,showing statistically significant differences(P＜0.05).The level of serum VEGF showed a positive correlation with serum ET level and a negative correlation with the serum NO concentration(r=-0.814,r=-0.803,P＜0.01)in the experimental group.A negative leaner relation was also found between serum ET level and serum NO concentration(r=0.821,P＜0.01).Conclusions The serum VEGF,ET and NO levels are closely associated with the degree of retinal lesion in early diabetic models.These results suggest that serum VEGF,ET and NO levels may be the important indexes predicting the course of retinal disease in diabetic rats.