Experimental Research On Interrelation Between Microvascular Permeability And Peripheral Neuropathy In Diabetic Rats

Objective: To investigate the correlation between microvascular permeability of sciaticnerve and peripheral neuropathy in experimental diabetic rat.Methods: The male SD rats (220±20g) were randomly divided into the experimentalgroup (T，n=60) and normal control group(N，n=12).All of the60rats in the experimentalgroup were injected streptozotocin (STZ) intraperitoneally at a dose of65mg/kg bodyweight to made experimental T1DM rat models.At0w,2w,4w,8w,12w after molding,12male SD rats （T0、T2、T4、T8、T12）were randomly selected to acquaint the permeabilityof the nourishing vascular of sciatic nerve by measuring the OD values withspectrophotometer and the amount of fluorescence with a fluorescence microscope afterthe rats were injected Evans Blue through tail vein and cardiac perfusion. The moisturecontent of sciatic nerve tissues was measured too. Also, their sciatic nerve conductionvelocity and observe their pathological changes including HE staining and ultrastructuralchanges through electron microscopy were tested. And the linear correlation analysis of thesciatic nerve moisture content and NCV，EB content and NCV were dealt. The expressionof vascular endothelial growth factor (VEGF) in the rat sciatic nerve was detected withimmunohistochemistry.Results:1. After Evans Blue perfusion, the OD values of sciatic nerve of diabetic rats weresignificantly increased from4W; under fluorescence microscope, the vascular wall ofepineurium of sciatic nerve appeared strong red fluorescence from4W, so did theendoneurium and nerve tract. Compared with the normal control group, the moisturecontent of sciatic nerve of T8and T12diabetic rats appeared to increase significantly.2.Compared with normal control group, sciatic nerve conduction velocity was significantlydecreased from2W (P <0.05). Under optical lens, sciatic nerve fibers began to appearmyelin thinning, irregular, axons stained shallow and axonal atrophy from4w; Under theelectron microscope, myelin lamellar of myelinated nerve fiber appeared gage distortion、 separation, loss, localized thickening and loose structure at4W、8W、12W, whichgradually aggravated over time.3. The result of the linear correlation analysis of thesciatic nerve moisture content and NCV，EB content and NCV prompted that during thecourse of diabetes, the sciatic nerve moisture content is negatively related to NCV (r=-0.903); EB content is negatively related to NCV and NCV (r=-0.799).4. In the schwanncells, axons and myelin of sciatic nerve fiber of T2, T4, T8diabetic rats, the expression ofVEGF was positive. On the vascular wall, the expression of VEGF was enhanced. In theschwann cells of sciatic nerve fiber of T12diabetic rats, the expression of VEGF waspositive, while in the axonal and myelin, the expression of VEGF was negative, and theexpression of VEGF on the vascular wall was weaker, similar with the N and T0diabeticrats.Conclusion:1. The microvascular permeability of the diabetic rats has changed at4W.2.The sciatic nerve function of diabetic rats has changed a t2W. The structure of the sciaticnerve of diabetic rats appeared to change at4W.3. The changes of sciatic nervemicrovascular permeability of experimental diabetic rats are associated with sciatic nervestructural and functional changes.4. The microvascular permeability and sciatic nervelessions are related, and the possible mechanism may be that diabetes has induced theexpression of vascular endothelial growth factor (VEGF).