【摘要】 目的：研究高氧环境下N乙酰半胱氨酸（NAC）和牛磺酸(Tau)对离体兔晶状体的作用。方法：新鲜兔晶状体24只随机分为对照组、高氧组、20mmol/L NAC处理组和80mmol/L Tau处理组。除对照组正常培养外，其余各组培养在高氧环境（氧浓度>80%）下4h/d×7。每天观察其透明度，培养7d后检测各项生化指标。结果：培养7d后高氧组晶状体出现重度皮质混浊，正常组和80mmol/L牛磺酸处理组中度皮质混浊，20mmol/L NAC处理组仅轻度皮质混浊；高氧组与对照组相比谷胱甘肽含量及Na, KATPase活性分别下降了37.8%（P<0.05）和53.5%（P<0.05），两药物处理组均有不同程度升高，20mmol/L NAC处理组较80mmol/L Tau处理组升高更明显；过氧化氢酶、谷胱甘肽还原酶活性及水溶性蛋白含量的变化在各组间没有统计学意义。结论：NAC对高氧环境下兔晶状体皮质混浊的抑制作用优于Tau。
【关键词】 N 乙酰半胱氨酸 牛磺酸 高氧 晶状体 兔
INTRODUCTION
Oxidative stress is thought to be one of the underlying factors of most cataracts [1,2]. Loss of protein sulfhydryl groups, oxidation of methionine residues and damaged of enzymatic antioxidant defence system were induced by oxidative stress [3]. Nacetylcysteine (NAC) and Taurine(Tau) were known as antioxygen agents, which had potential biological and therapeutic significance against cataract. Based on our previous studies of NAC [46] and Tau [7], the aim of present study was to further investigate whether NAC and Tau can prevent the lens damages induced by hyperoxia.
MATERIALS AND METHODS
Materials NAC and Tau were purchased from Sigma. Rabbits were provided by Animal Laboratories of the Fourth Military Medical University, Xian, China. Protein and enzyme quantification kits were obtained from Jiancheng Biol Co (Nanjing). All other chemicals and solvents were analytic grade and obtained commol/Lercially from local companies.
Methods
Hyperoxia treatment All the lenses isolated from adult rabbits were immol/Lersed in Dulbeccos Modified Eagle Medium (DMEM, Sigma) and incubated for 8 hours. Only the intact clear lenses were chosen for the further experiment. In the experiment, each lens was cultured in 5mL of medium having a liquidgas interphase surface area of 3.6cm2 under 37℃, 50mL/L CO2. The selected clear lenses were divided into four groups: the control group; the hyperoxiaexposed group; the 20mmol/L NAC treated group and the 80mmol/L Tau treated group. Except the control group was cultured conventionally, other groups were incubated with hyperoxia (more than 80%) for 4 hours per day throughout a 7day period. All lenses were subjected to gross morphological examination daily. In addition, after the 7day incubation period, quantitative analyses of enzyme activities and watersoluble protein were performed for the lenses of all groups.
Morphological examination of the lenses This was performed by gross examination as well as under the magnification of a dissecting microscope against a background of black gridlines. The degree of opacification was graded based on Geraldine described as follows: grade 0, absence of opacification (gridlines clearly visible); grade 1, slight degree of opacification (minimal clouding of gridlines and gridlines still visible); grade 2, diffuse opacification involving almost the entire lens (moderate clouding of gridlines and gridlines faintly visible); grade 3, extensive thick opacification involving the entire lens (total clouding of gridlines and gridlines not seen at all) [8].
Protein determination Protein concentration was determined by Coomassie brilliant blue method using protein assay kit. All lenses were ground in 9g/L physiological saline (1∶9) and homogenized by a handheld homogenizer for 15 minutes over ice and then centrifuged (3000r/min, 10minutes) in Eppendorf tubes. The clear supernatant was used for watersoluble protein determination, which was according to the method described with the kits (Jiancheng, China).
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