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.