糖尿病大鼠皮肤的组织化学改变

目的：研究糖尿病(DM)大鼠皮肤的组织化学改变，探讨DM难愈创面形成和发展的病理机制。方法： 用链脲佐菌素（STZ）将SD大鼠诱导成速发型DM大鼠模型，并以正常大鼠作对照，分别于致病后4、8和12周获取大鼠背部中央的皮肤标本。应用HE染色，观察皮肤组织学的改变；应用Beckman’s生化自动分析仪检测皮肤组织匀浆的糖含量；采用F－3010荧光分光光度计测定皮肤胶原提取液的荧光强度；应用免疫组化和图像分析技术检测皮肤组织晚期糖基化终末产物（AGEs）含量。结果： 组织学观察可见，DM大鼠表皮组织变薄，表皮细胞层次欠清晰，部分表皮缺乏复层排列；真皮层部分胶原萎缩、肿胀，退化变性，并伴有程度不等的炎性细胞浸润；皮下脂肪进行性萎缩或消失。皮肤糖含量在各时相点均显著高于正常对照（P<0.01）。皮肤胶原提取液的荧光值亦高于相应年龄正常鼠（P<0.05），并随病程增加。AGEs蛋白主要沉积于真皮基质和细胞中，以及皮肤血管基底膜周围，并随病程的发展，染色逐渐加深，呈片状。结论： DM皮肤在损伤前就已发生明显的组织化学改变，而这些改变可能是由于局部高糖和AGEs累积所引发，并可能是DM难愈创面形成和发展的病理基础之一。

Histochemical changes of skin in diabetic rats

AIM: To explore the histochemical changes of diabetic skin and the pathogenesis of impaired wound healing in diabetes. METHODS: 54 male Sprague-Dawley (SD) rats weighing 200-220 g were randomized into control and STZ-induced diabetic groups. The shaved skin specimens from the back of rats were collected in 4, 8 and 12 weeks post STZ-induction, respectively. Hematoxylin-eosin dye was used for histological examination. Meanwhile, the skin glucose contents were measured by Beckman’s autoanalyzer. Skin AGEs concentrations were assessed by detecting total fluorescence in tissue collagen and immunohistochemistry assay. RESULTS: The skin thickness in diabetic animals was decreased, with the features of multilayer epithelium structure disappeared in epidermis and collagen fibers atrophied, swollen and degenerated in dermis; The inflammatory responses in the dermis of diabetic animals were increased obviously. The results also revealed that skin glucose contents in diabetic rats ［(2.64±1.03）mg/g skin］ were 2-3 times higher than those in the controls ［(0.74±0.33)mg/g skin］ (P<0.01). The collagen fluorescence and AGEs positive expressions in diabetic skin enhanced significantly when compared with age-matched controls over the whole experimental course (P<0.05). CONCLUSIONS: A histochemical changes had already been occurred in diabetic skin before injury, which may be result from the local biochemical factors such as high concentrations of glucose and AGEs. These might be an important mechanism in the pathogenesis of impaired wound healing in diabetes.