Study On The Mechanism Of Drpl Promotting Onset Of Diabetic Peripheral Neuropathy And Effects Of Cliclazide Intervention On It

OBJECTIVE1To establish experimental diabetes models in SD rats by anintraperitoneal injection of streptozotocin(STZ) and maintain the high blood glucoseenvironment.2To explore the roles of dynamin-related protein l (Drp1) in diabeticperipheral neuropathy (DPN).3To study the intervention effects of gliclazide on DPNand provide theory basis for the clinical treatment of DPN.METHODS A single intra-peritoneal injection of streptozotocin(STZ) was adopted toinduce diabetic rat models. Fasting blood glucose above16.67mmol/L is the standard ofdiabetes models. The diabetic rats were randomly divided into two groups, diabeticcontrol group (group M) and gliclazide intervention group (group G). Normal controlgroup which matched the former two groups on age, nest and body weight (group N)was set up too. During the breeding, rats weight and blood glucose were regularlymonitored to maintain the high blood glucose level in the rat models.8weeks later,normal conditions of rats were observed, fasting blood glucose and body weight andnerve conduction velocity （NCV）of each rat was measured and sciatic nerves weredissected. The left the sciatic nerve was cut in half. one was fixed in10%formaldehydesolution and the other was stored in‐80℃refrigerator. The right of sciatic nerve wasmade into10%tissue homogenate immediately which was used for oxidative stressindex determination. Morphological alteration was valued by Chromotrope2R-Brilliantgreen staining, MDA level and SOD activity were detected with kits, the expression ofCaspase-3and8-hydroxy-deoxyguanosine (8-OHdG) in sciatic nerve tissue was detected with immunohistochemistry, and the expression of Drp1, Bax and Bcl-2wasdetected with western blotting.RESULTS After injection, the rats in group M and group G showed significantly higherblood glucose, listlessness, poor activity, and dark hair. Urine, food and water intakewere also increased. Eight weeks later, the weight of rats in group M and group G didnot obviously increase than before, when the weight increased physiologically in groupN(P＜0.05). Group M and group G still showed higher blood glucose than group N（P＜0.05）. But the blood glucose level in group G was lower than group M（P＜0.05）.Compared to group N, the sciatic nerve tissues showed obvious morphologicalalteration that myelin thickness was thinner, ring structure was not complete, interstitialhyperplasia composition appeared accidently, and demyelinating change or emptybubble kind change was visible. Compared to group N, NCV of group M decreasedsignificantly, the expression of protein Drp1, Bax, Bcl-2，Caspase-3,8-OHdG and MDAlevel increased, and the SOD activity decreased significantly(P＜0.05).Compared togroup M, NCV of group G increased significantly and the sciatic nerve morphologicalalteration was improved, the expression of protein Drp1, Bax, Caspase-3,8-OHdG andMDA level decreased significantly, and the SOD activity increased significantly(P＜0.05).Although the expression of protein Bcl-2in group G was less than group M, therewas no significant difference.CONCLUSION Drp1regulates the mitochondria shape by mediating mitochondrialfission and plays an important role in the process of oxidative stress and apoptosis. Highexpression of Drp1which promotes oxidative stress and apoptosis—two importantpathogenesis theory of DPN, possibly is a crucial step in inducing DPN. We assume thatover-expression of protein Drp1participated in and promoted apoptosis in sciatic nerveof diabetic rat by mediating mitochondria fission, enhancing production of ROS andexpression of apoptosis-related factors. Gliclazide could show a certain protective effect on diabetic rat sciatic nerve by lowering blood glucose level, interfering with expressionof protein Drp1, improving oxidative stress, and reducing nerve cell injury andapoptosis.