Mechanical and structural changes in diabetic rat peripheral nerve collagens

An underlying mechanism for ultrastructural changes in collagens of the peripheral nerve tissue of diabetic animals may be an increase in endoneurial fluid pressure observed with prolonged diabetic neuropathy. We hypothesize that the extracellular matrix of both the endoneurium and epineurium remodel in response to the modified chemical and mechanical environment present in diabetic peripheral neuropathy. Our approach involves quantitative comparisons of mechanical properties, image analysis, and content (collagens I, III and IV) analysis of healthy and diabetic sciatic nerve collagens from Sprague-Dawley rats. Experimental data for these three comparative approaches were obtained via uniaxial mechanical testing, atomic force microscopy, and in situ immunohistochemistry, respectively. Atomic force microscopy (AFM) revealed larger collagen fibrils in both endoneurium and epineurium. Mechanical tests revealed slight stiffening of the tissues. Both of these results suggest that the extracellular matrix of both the endoneurium and epineurium remodel in the presence in diabetic peripheral neuropathy, and suggest that mechanical factors may play a role in the permanence of these changes.