N-乙酰-L-半胱氨酸抗1型糖尿病模型比格犬晶状体上皮氧化损伤的作用

本研究旨在探讨N-乙酰-L-半胱氨酸(NAC)对1型糖尿病模型比格犬晶状体上皮氧化损伤的影响。将40只2～3岁比格犬随机分为对照组(CON组)、糖尿病模型组(DM组)、胰岛素治疗组(INS组)、NAC联合胰岛素治疗组(NAC+INS组)和NAC治疗组(NAC组),每组8只，各治疗组试验犬模型建立持续120 d。在造模前及造模后按试验设定时间对犬进行空腹血糖监测、胰岛素释放试验、房水葡萄糖测定、用裂隙灯进行白内障等级评定。对眼晶状体上皮进行病理组织学观察的同时，利用ELISA、RT-PCR等方法对晶状体内氧化应激指标进行检测。试验结果显示：空腹血糖监测和胰岛素释放试验显示，成功建立了1型糖尿病比格犬模型；与CON组相比，DM组犬在试验结束时，血清及房水葡萄糖显著升高(P<0.05),晶状体功能明显下降；裂隙灯结果显示，DM组犬的晶状体混浊等级在试验结束时达Ⅳ级，其余4组并未出现明显皮质混浊迹象，且DM组的晶状体上皮出现细胞核固缩和坏死小体等较为明显的病理变化；NAC、INS和NAC+INS组血糖虽呈下降趋势，但仍高于CON组，其中，NAC+INS组血糖较DM组显著下降(P<0...

Effect of N-acetyl-L-cysteine on Oxidative Damage of Lens Epithelium in Beagle Dogs with Type 1 Diabetes Mellitus

This study aimed to investigate the effect of N-acetyl-L-cysteine (NAC) on oxidative damage of lens epithelium in the beagle model of type 1 diabetes mellitus. Forty beagles, 2-3 years old, were randomly divided into control group (CON group), diabetes model group (DM group), insulin treatment group (INS group), NAC combined with insulin treatment group (NAC+INS group) and NAC treatment group (NAC group), 8 dogs in each group. The establishment of experimental dog model in each treatment group lasted for 120 days. Before and after modeling, insulin release test, fasting blood glucose and aqueous humor glucose were tested and cataract grade evaluation was carried out by slit lamp. The lens epithelium was histopathologically observed, and ELISA and RT-PCR detected the oxidative stress index and inflammatory factors in the lens. The results of insulin release test and fasting blood glucose showed that the model of type 1 diabetes beagle was established successfully; Compared with CON group, at the end of the experiment, the serum and aqueous glucose of DM group increased significantly (P<0.05), and the lens function decreased significantly; Slit-lamp results showed that the lens opacity of the DM group reached grade IV at the end of the experiment, while the other four groups showed no apparent signs of cortical opacity; In addition, obvious pathological changes such as nuclear pyknosis and necrotic bodies were observed in the lens epithelium of DM group; Blood glucose in NAC, INS and NAC+INS groups showed a downward trend，but was still higher than that in CON group; The blood glucose in NAC+INS group was significantly lower than that in DM group (P<0.05); and the lens opacity was also significantly improved; At the end of the experiment, compared with CON group，in the canine crystal epithelium and aqueous fluid, MDA content of DM group increased (P<0.05 or P<0.01), while GSH-Px activity and GSH/GSSG all had the noteworthy decrease (P<0.05 or P<0.01), GR activity decreased (P>0.05 in crystal epithelium; P<0.01 in aqueous fluid); After treatment of NAC combined with insulin, oxidative stress markers in crystal epithelium showed an opposite trend. The expression levels of SOD₂ and GR in DM group and all treatment groups were significantly increased (P<0.05). In conclusion, therapy of NAC combined with insulin has improvement for glycemic control and lens function in diabetic dogs, the protective effect of NAC combined with insulin on lens epithelial injury in diabetic dogs may be related to the inhibition of oxidative stress of the lens.