Lipoic Acid On Experimental Diabetic Rat Corneal Epithelial Injury And Repair Influence

PurposeDiabetic keratopathy is a particular disease, which emerges and persists following the undue stress including intra-ocular surgery or photocogulation. Now there is no effective therapy for diabetic keratopathy. DL-a-Lipoic acid (LA) , which plays an essential role in mi-tochondrial dehydrogenase reactions, has recently gained considerable attention as a promising drug for this disease. In order to elucidate the anti-diabetic keratopathy mechanisms of LA, we investigated the changes in cornea of STZ-induced diabetic rats, and evaluated the effect of LA to prevent them.MethodThe experiments were performed on barrier-sustained female Brown-Norway rats, fed a standard rat chow diet and divided into the following groups: 1) Control group without LA in diet ( CTL group) ; 2) Diabetic group without LA in diet ( DM group) ; 3) Diabetic group with 0.3% LA in diet ( LA group). Diabetes was induced by a single caudal vein injection of 2% streptozotocin (50mg/kg). To assess the general body state of the rats, we observed the changes of weight, daily diet amount, blood sugar level in rats. We studied the cornea! morphological modification using an Anterior Eye Segment Analysis System (EAS-1000, NIDEK) and fluorescein photograph-shooting, analyzed the images with the Cornea! Injury Quantity Program 2(Qcd 2). To elucidate the LA's protective effect to cornea! impairment due to anesthetic, we gave the rats 0. 4% Benoxil eyedrops (lOjjJ) and studied the fluorescein stained cornea! images 15 minutes later. Moreover, we studied the rats' cornea which received severer injury factor - 150mJ/cm2 ultraviolet ray irradiation plus vitamin B2 interval eyedrops.ResultsThe survival rates in three groups are CTL 100% , DM 36% and LA 71% , respectively. The mean body weight is DM > CTL > LA; and the daily diet amount is DM > CTL > LA. Since the 3rd month, EAS-1000 scanning revealed severe cornea! injury in DM, mild in LA, and no in CTL. The injury severity level is DM > LA, but no significant statistical difference between the two groups. Cornea! injury values due to anesthetic eyedrops are CTL 4. 66 +0. 85, DM 6.51 + 1. 81, LA 5.99 +2.42. Corneal injury values of DM and LA groups significandy increased after anesthetic eyedrops, but no significant difference between these two groups. Corneal injury values due to ultraviolet ray irradiation plus vitamin B2 interval eyedrop are CTL 4.56 +0. 47, DM 5. 8 + 1. 49, LA 4. 96 + 0. 63. There are significant differences between each two groups (P <0.05). Blood sugar level is DM>LA>CTL (P<0.01).Conclusions1) Diabetes-induced impairment and repair delay in rats' cornea are significandy prevented by DL-a-Lipoic acid.2) DL-a-Lapoic acid oral treatment is effective in reducing the blood sugar level of STZ-induced diabetic rats.3 ) DL-a-Lipoic acid can partially improve the development of the diabetic rats.