The Study On Early Pathological Changes Of Skin Tissue And The Correlation With Microvessels/nerve Fibers In Diabetic Rats

Objective To observe the early pathological changes of skin tissue in diabeticrats, and investigate its correlation with accompanied changes of microvessels/nervefibers. Moreover, discussing the role of glucose/AGEs on the epidermis/dermisstructure changes. Finally seeking further evidence of the hypothesis about cutaneousmicroenvironmental disorders of early.Methods Diabetic rat model is induced by STZ drug injection. The normalrats as control group. Collected the skin specimens on the back of rats in both groupsfrom1to12weeks. The glucose and AGEs in skin tissue were detected bybiochemical method. The thickness of epidermis and dermis were measured.Generally morphologic changes and ultrastructure of epithelium, microvessels andnerve fibers were investigated with HE dye or immunohistochemisty and electronmicroscopy. The thickness of epidermis and dermis were detected to compare therelationship with the trend of glucose and AGEs accumulation, and that ofmicrovessel density.Results Compared to the controls, the level of the glucose and AGEs weresignificantly increased after2th week and4th week (P<0.01, P<0.05respectively).The thickness of epidermis and dermis in diabetic skin were thinner than those incontrols since4th week (P<0.05or P<0.01respectively). Moreover, the trend ofcontinuous change of thickness was negative correlation with the AGEs. It also showed a similar correlation with the change of glucose content in the skin. The earlychanges were epithelium tissue, which showed a progressive decrease of the thicknessof epidermis/dermis.Though the typical changes of microvessels and nervefibers,such as endothelial cells swelling, axons compressed,demyelination etal,could be observed, those pathological changes occurred later than the significantlychanges of epithelial structures. In addition,microvessel density decrease happenedafter the middle course of disease process, and showed no relationship with theepidermis/dermis thickness changes.Conclusions The experimental study verified a close relationship betweenthe early thickness changes of epidermis/dermis and the accumulation of glucoseand AGEs in diabetic rat skin. It hints that the early pathological changes of diabeticskin, are directly caused by microenvironmental disorders of glucose andAGEs.Together with the two factors of microvessels and peripheral nerve fibers,theearly pathological change of diabetic skin itself, could also take a important role inthe formation and refractory healing of diabetic wound.