Protective Effect Of Edaravone On Corneal Nerve Of Rats With Experimental Diabetic Corneal Neuropathy

Background With the number of diabetics increasing, people paymore attention to the diabetic keratopathy. The major mechanism leadingto diabetic keratopathy is diabetic corneal neuropathy. So it is significantto observe pathologic mechanism of diabetic corneal neuropathy.Objective To investigate the protective effects of edaravone (a freeradical scavenger) on corneal nerve of rats with experimental diabeticcorneal neuropathy, then explain the effects of oxidative stress in thepathologic mechanism of diabetic corneal neuropathy.Methods Seventy Sprague-Daxley male rats were taken asexperimental subjects and20of them were used as normal group. Theremaining50were induced to be diabetic mellitus by a singleintraperitoneal injection of streptozotocin and divided into2groupsrandomly: edaravone treated group and isotonic Na chloride control group.In the edaravone group, edaravone (0.2g/L) eye drops were used3times aday until the animal was killed.In the isotonic Na chloride group, isotonicNa chloride were used3times a day until the animal was killed. Five ratsin each group were sacrificed at the6th,8th,10th and12th weekrespectively. Then the corneal sensation, number of corneal nerve fibers,morphology, content of malondialdehyde (MDA) and activity of superoxide dismutase(SOD) in the corneal tissue were detected.Results1.The corneal sensation detection:the corneal sensationdecreased at the6th week and decreased obviously at12th week in theisotonic Na chloride group. We couldn’t detect the corneal sensationdecreased at the6th week in the edaravone group,it was decreased at the8th,10th and12th week, but it was improved compared with the isotonicNa chloride group.2.Corneal nerve with acetylcholinesterase(AChE) staining andmorphology observation: the nerve stem of the corneal stroma wastapering,and its branches decreased. The neural network plexus’s density ofthe subepithelial was sparse, and the activity was decreased at the6th weekin the isotonic Na chloride group, these changes became more and moreobvious accompany with the prolongation of the disease couse day by day.Compared with the isotonic Na chloride group, both the morphologicalabnormalities in corneal nerve was improved significantly and nerveactivity elevated in the edaravone group.3.The number of corneal nerve fibers: the number of corneal nervefibers decreased at the6th week in the isotonic Na chloride group,thereduction was aggravated with the prolongation of the disease couse.Compared with the isotonic Na chloride group, the corneal nerve fibersincreased obviously in the edaravone group，and the difference wasstatistically significant(P<0.01).4.The content of MDA and the activity of SOD: the content of MDAwas increased, and the activity of SOD was decreased in the corneal tissueat the6th week in the isotonic Na chloride group, these changes becamemore and more obvious accompany with the prolongation of the disease couse day by day. Compared with the isotonic Na chloride group, thecontent of MDA was significantly decreased and the activity of SOD wassignificantly increased in the corneal tissue in the edaravone group，and thedifference was statistically significant(P<0.01).Conclusions1.Edaravone may lower diabetic corneal nerve of ratswith experimental diabetic corneal neuropathy injury;2.Oxidative stress is a critical pathologic mechanism of diabeticcorneal neuropathy.