色素上皮衍生因子的表达与早期糖尿病大鼠视网膜血管形态学的改变

目的探讨色素上皮衍生因子(pigment epithelium derived factor,PEDF)mRNA在不同病程糖尿病大鼠模型视网膜中的表达水平及其与早期糖尿病大鼠视网膜血管病变之间的关系。方法 48只健康Wistar大鼠随机分成糖尿病1个月组(DM1)、3个月组(DM3)和6个月组(DM6)与正常对照1个月组(CON1)、3个月组(CON3)、6个月组(CON6),每组各8只。链脲佐菌素诱导糖尿病大鼠动物模型,分别于造模后1个月、3个月、6个月行视网膜血管铺片和PEDFmRNA的原位杂交,观察大鼠视网膜微血管的改变和PEDFmRNA表达情况。结果 (1)DM3和DM6组可见毛细血管迂曲,走形不规则,管腔粗细不均,以DM6组病变最重,可见无细胞毛细血管。(2)周细胞数量:DM1组与CON1组相比差异无统计学意义(CON1组6.45±0.64,DM1组6.52±0.75,P>0.05),DM3及DM6组均较CON3组、CON6组明显减少(CON3组6.51±0.70、DM3组6.06±0.65,CON6组6.47±0.60、DM6组5.45±0.80),差异均有统计学意义(均为P<0.05)。(3)CON1和DM1组PEDFmRNA在节细胞层、内核层及RPE层均有阳性细胞表达,CON1组64±10、DM1组53±8,差异无统计学意义(P>0.05);CON3组和DM3组PDEFmRNA在节细胞层、内核层、RPE层阳性反应细胞表达减少,CON3组68±11、DM3组49±12,差异有统计学意义(P<0.05);CON6组和DM6组PEDFmRNA仅在内核层和节细胞层表达,RPE层只见极少阳性细胞,CON6组58±8、DM6组34±14,差异有显著统计学意义(P<0.01)。结论糖尿病视网膜病变的发生、发展与周细胞数量减少、PEDFmRNA表达降低密切相关,两者的表达同糖尿病视网膜病变的发生、发展存在时效和空间关系。

Expression of pigment epithelium derived factor and changes of morphology of retinal cells in rats with early diabetic retinopathy

Objective To study the expression of pigment epithelium derived factor(PEDF) mRNA in retina of rats with different stages of diabetes mellitus(DM) and to evaluate its correlation with diabetic retinopathy.Methods About 48 healthy Wistar rats were randomly divided into DM for 1 month(DM1) group,DM for 3 months(DM3) group and DM for 6 months(DM6) group,normal control for 1 month(CON1) group,normal control for 3 months(CON3) group and normal control for 6 months(CON6) group,8 rats in each group.Streptozotocin was used to induce diabetic rat models.Stretched preparation of retinal vessels was taken and the expression of PEDF mRNA was tested during different periods of DR with in situ hybridization at 1 month,3 months and 6 months.Changes of retinal microvessels and expression of PEDF mRNA were observed.Results(1) In DM3 and DM6 groups,capillary became circuitous and irregular.The lumens were uneven.The change was the most obvious at DM6 group and there was acellular capillary.(2) Numbers of pericytes were 6.45±0.64 for CON1 group,6.52±0.75 for DM1 group,there was no difference(P>0.05),but the numbers of pericytes were 6.06±0.65 for DM3 group and 5.45±0.80 for DM6 group,which were obviously lower than 6.51±0.70 for CON3 group and 6.47±0.60 for CON6 group,there were statistical differences(both P<0.05).(3) There were positive expressions of PEDF mRNA in layer of ganglion cells,inner nuclear layer and RPE layer in CON1 and DM1 groups,and the expressions were 64±10 in CON1 group and 53±8 in DM1 group.There was no difference(P>0.05).There were less positive expressions of PEDF mRNA in layer of ganglion cells,inner nuclear layer and RPE layer in CON3 and DM3 groups,and the expressions were 68±11 in CON3 group and 49±12 in DM3 group.There was statistical difference(P<0.05).PEDF mRNA only expressed in inner nuclear layer and layer of ganglion cells,and only less positive cells in RPE layer for CON6 group and DM6 group.Its expressions were 58±8 in CON6 group and 34±14 in DM6 group,and there was significant statistical difference(P<0.01).Conclusion The development of diabetic retinopathy closely correlates with the decrease of pericytes and PEDF mRNA expression,and also with time and space relationship between the two factors.