背景 糖尿病并发症的发生与脂质过氧化有关,而醛脱氢酶(ALDH)是已知的抗脂质过氧化物之一,研究ALDH在糖尿病眼组织中的活性与表达量的变化能为糖尿病性眼部并发症的诊断和治疗提供依据. 目的 研究ALDH在不同时期糖尿病大鼠眼组织中的活性与质量分数的变化趋势,探讨其在糖尿病所致眼部疾病发病过程中的作用机制.方法 将健康7～8周龄清洁级雄性SD大鼠28只按随机数字表法分为糖尿病模型组和正常对照组.糖尿病模型组大鼠腹腔注射65 mg/kg溶于柠檬酸钠缓冲液的链脲佐菌素(STZ),血糖达16.7 ～ 22.2 mmol/L为造模成功.正常对照组大鼠腹腔以同样的方式注射等量柠檬酸钠缓冲液.于造模成功后的2个月、4个月分别处死7只大鼠,制备大鼠角膜、晶状体及视网膜匀浆液,测定蛋白质质量浓度.采用M5多功能酶标仪测量角膜、晶状体及视网膜各组织中ALDH活性,采用酶联免疫吸附(ELISA)法检测ALDH在角膜、晶状体和视网膜匀浆中的表达量. 结果 模型建立后2个月、4个月糖尿病模型组大鼠血糖水平明显高于正常对照组,而体质量明显低于正常对照组,差异均有统计学意义(均P=0.000).造模后2个月、4个月时糖尿病模型组大鼠角膜、晶状体及视网膜中ALDH活性均明显高于相应时间点的正常对照组大鼠,差异均有统计学意义(F=396.601,P=0.000)；上述各组织中ALDH活性(A 340值)均随着造模时间的延长而升高,差异有统计学意义(F=53.139,P=0.000),其中4个月时糖尿病模型组大鼠角膜、晶状体、视网膜中ALDH活性较2个月时高,差异均有统计学意义(P＜0.01),而正常对照组大鼠角膜、晶状体及视网膜中的ALDH活性在2个时间点间相比差异均无统计学意义(P＞0.05)；2个时间点正常对照组与糖尿病模型组大鼠眼组织中ALDH活性均为角膜最高,视网膜次之,晶状体最低,差异有统计学意义(F=6973.000,P=0.000).造模后2个月、4个月时糖尿病模型组大鼠角膜、晶状体及视网膜匀浆中ALDH表达量均明显高于正常对照组大鼠,差异有统计学意义(F=312.985,P=0.000)；2个组大鼠ALDH表达均随着造模时间的延长而增加,差异有统计学意义(F=19.203,P=0.000),2个时间点各组大鼠眼组织中ALDH表达量均表现为角膜最高,视网膜次之,晶状体最低,差异有统计学意义(F=3243.000,P=0.000). 结论 ALDH可减轻糖尿病大鼠眼组织的脂质氧化损伤,可能在预防糖尿病相关性眼部并发症发生方面发挥一定的作用.%Background Diabetic complication is associated with lipid peroxidation.Aldehyde dehydrogenases (ALDH) catalyze the irreversible oxidation of a variety of biological aldehydes,including lipid-derived aldehydes (LDAs),and thus protect organs and tissues from toxic LDAs.Understanding the activity of ALDH in different ocular tissues in diabetic subjects is very important for prevention and treatment of diabetic ocular complications.Objective This research aimed to investigate the activity and expression of ALDH in different ocular tissues in diabetic rats and to explore the mechanism of ALDH in diabetes-induced eye disease.Methods Twenty-eight healthy SPF male Sprague-Dawley(SD) rats weighted 170-180 g were randomly divided into the normal control group and diabetic group.The diabetic animal model was established by intraperitonial injection of 4％ streptozotocin at 65 mg/kg.Isometric citric acid buffer was injected in the rats of the normal control group.The rats were sacrificed in each group 2 and 4 months after the establishment of the diabetic models,and eyeballs were obtained for the preparation of corneal,lens and retinal homogenates.ALDH activity was detected using a multifunctional microplate reader SpectraMax M5,and ALDH content was measured by ELISA at the wavelength of 450 nm with the SpectraMax M5 ELISA reader.Results The blood glucose level in diabetic rats was significantly elevated at various time points compared with the normal control group(P=0.000),and body weights were evidently lower in the diabetic group than in the normal group (P =0.000).The activities of ALDH (A340) in corneal,lens and retinal tissues in the diabetic group were increased in comparison with the normal control group (F =396.601,P=0.000),and showed an enhancement with the lapsing of time (F =53.139,P =0.000).In addition,the highest level of ALDH was found in the cornea and the lowest level in the lens(F =6973.000,P=0.000).The expression level of ALDH in the corneal,lens and retinal homogenates was significantly higher in the diabetic group compared with the normal control group (F=312.985,P =0.000) and showed a considerable increase over the course (F =19.203,P=0.000).The highest expression level was seen in the cornea and the lowest was in the lens,with a significant difference among these three kinds of tissues (F =3243.000,P =0.000).Conclusions ALDH can protect ocular tissue from the damage of lipid peroxidation.Thess results suggest that ALDH plays a role in preventing diabetes-related ocular complications.
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