137 The cutaneous “Underlying disorder” in diabetic rats

Objective To investigate the histological characteristics and pathophysiological changes in diabetic skin. Methods: 12 Sprague-Dawley rats weighing 200–220 g were divided into control and STZ-induced diabetic groups. The shaved skin specimens from the back of rats were collected on 8 w post STZ-inducing. The cutaneous histological characteristics were observed. The local contents of glucose, advanced glycation end products(AGEs) and hydroxyproline, the levels of aMMP-2 and TIMP-2, and the cell cycles of both keratinocytes and dermal cells were determined. Results: The thicknesses of epidermis layer and dermis layer were both reduced obviously in diabetic skin, with the morphological characteristics of the obscured multilayer epithelium features and the decreased amount of spinous in epidermis; the atrophied, swollen and degenerated collagen fibers with a focal chronic inflammatory cells infiltration. The results also revealed that contents of glucose, AGEs, the level of aMMP-2 and the ratio of aMMP-2/TIMP-2 in diabetic skin were higher than those in the controls. In diabetic group, the percentages of S stage and G2/M stages of keratinocytes were obviously decreased, while the dermal cells showed the higher percentage of S stage and the normal percentage of G2/M stages, when compared with the control group. Conclusion: The cutaneous histological and pathophysiological alterations in diabetes mellitus has already been occurred when exogenous damage is not existed, which presented an “underlying disorder” characteristics in diabetic skin. The cutaneous “underlying disorder” in diabetes might be a critical risk factor leading to ulceration and one of the most important mechanisms in the pathogenesis of impaired wound healing.