大鼠半乳糖性白内障模型的表现和病理特征

Findings and pathological characteristics of rat galactose cataract model

背景建立稳定的糖尿病性白内障动物模型是研究白内障发病机制和药物治疗的前提。目前半乳糖性白内障模型已被广泛用于相关的研究，但不同的给糖方式会导致白内障出现的时间、程度及形态的差异。目的探讨半乳糖性白内障的眼部表现和病理特征。方法56只sD大鼠按随机数字表法随机分为模型组和对照组，每组28只。模型组大鼠用质量分数50％D－半乳糖饲料喂养SD大鼠共30d，对照组大鼠给予普通饲料喂养。喂养期间隔日在裂隙灯显微镜下观察晶状体的混浊部位及其形态，并对Suryanarayana提出的晶状体混浊的分级标准进行改良。于半乳糖喂养后的第5、10、15、20、25和30天分别观察大鼠的体质量变化，上述各时间点分别获取大鼠的晶状体并制作样本切片，行苏木精一伊红染色，检测晶状体的组织病理学改变。此外分别测量晶状体的湿质量和干质量，评估晶状体内水含量的变化特点。结果实验后10～30d，模型组大鼠的体质量较对照组均明显下降，差异均有统计学意义（P〈0．05）。在喂养半乳糖的过程中，随着时间的延长，模型组大鼠晶状体均发生不同级别的皮质和核的混浊，而对照组大鼠晶状体始终透明。裂隙灯下和晶状体的组织病理学检查均表明晶状体的混浊起始于赤道部皮质纤维，逐渐向中心区皮质扩展，随后晶状体核逐渐混浊、膨胀。组织学检查示晶状体皮质纤维水肿，晶状体上皮细胞分化、脱核延迟。实验第30天，模型组大鼠晶状体的湿质量明显高于对照组，差异有统计学意义（t=138．571，P〈O．05）；模型组大鼠晶状体的干质量明显低于对照组，差异有统计学意义（t=－52．468，P〈0．05），实验过程中模型组大鼠晶状体干湿质量比明显下降，而对照组无明显变化，各时间点2组间的差异均有统计学意义（P〈0.05）。结论大鼠半乳糖性白内障模型的病程与人年龄相关性皮质性白内障的自然病程和发病机制相似。喂养50％D－半乳糖饲料造模的方法具有成模时间适中、临床分期特征明确等特点，是一种较理想的研究白内障发病机制和药物防治的模型。

Background A stable diabetic cataract animal model is a premise for screening and evaluating the drug for cataract therapy. Galactose cataract model is widely used in relevant experimental study,but the onset, extent and the type of lens opacification may be different due to different modeling way. Objective This study was to investigate the manifestations and pathological characteristics of cataract induced by D-galactose. Methods Fifty-six SPF SD rats were randomly divided into cataract-model group and control group and 28 rats for each group. 50% D-galactose feed was given daily in model group,and regular feed was given in control group. Lenses of rats were examined under the slit lamp through the 30-day period at a 2-day interval, and then the opacity of lenses was graded on the modified Suryanarayana criteria. The body weight of rats was recorded and compared between two groups at day 5,10,15,20,25 and 30. The lenses samples were obtained for the histopathological examination by hemoloxylin and eosin staining. The wet weight,dry weight of the lenes and their ratio were detected and compared between these two groups. The use of animals followed the Regulation for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission. Results The body weight was reduced in model rats compared with control rats with the statistically significant difference from 10 days through 30 days（ P〈0.05 ）. The different grades of opacification of lens cortical and nuclear progressed in model rats throughout the experiment duration, but the lenses were clear in control rats. The slit-lamp microscopy and pathological examinations revealed that lenses opacity in model rats started from the cortex at the equator zone and developed towards central zone gradually with the lapse of experimental time. Following the entire opacity of lens cortex, lens nucleus were cloudy and expanded. The swelling and degeneration of the fiber cells in lens cortex, the differentiation, migration and denuelearation delay of lens epithelial cells were seen in model rats under the light microscope. The wet weight of lenses was increased and the dry weight was decreased in model rats in comparison with control rats in experimental 30 days, showing significant difference between two groups （ t = 138.571 , t = 52. 468, P 〈 0.05 ）. Conclusion The development of galaetose- induced cataract animal model resemble one of age-related cortical cataract in human with the similar generating mechanism. This cataract model is reproducible and classifiable.