Immunohistochemical investigation of the distribution of laminin, type IV collagen and fibronectin in sciatic nerve of streptozotosin diabetic rats

95 VH. SUMMARY Diabetic neuropathy is one of the most frequent complications of diabetes. The most common form of diabetic neuropathy is a polyneuropathy characterized by the loss of peripheral sensation. One of the most important factors in the pathogenesis of diabetic neuropathy is the formation of advanced glycation end- products due to non-enzymatic glication of proteins. For the last ten years, studies are focused on the effects of glication of extracellular matrix proteins which have very important functions in nerve development and regeneration. So in this work, we investigated the immunohistochemical distribution of type IV collagen, fibronectin and laminin in peripheral nerves of STZ diabetic rats. We found that increased deposition of type IV collagen, fibronectin and laminin was observed in the perineurium, and endoneurium surrounding microvessels and Schwann cells. Fibronectin and laminin immune reactions were slightly stronger in diabetic nerves. Laminin expression was most evident in the innermost layers of perineurium. But interestingly, there was almost no fibronectin expression in the same layers. Type IV collagen expression in diabetics didn't obviously differ from that in controls. As a result, we concluded that diabetes mellitus might increase the expression of extracellular matrix components. But diabetes could also destroy the structure of these proteins and prevent them from binding immunohistochemical antibodies leading to diminished staining.