核酸对铅染毒大鼠DNA损伤的干预效应

Interventional effect of nucleic acid on DNA damage in plumbum infected rats

目的:探讨抗氧化物质核酸对铅染毒大鼠淋巴细胞和肝细胞DNA损伤的干预效应。方法:实验于2003-03/05在哈尔滨医科大学公共卫生学院完成。选用32只纯种雄性健康3月龄Wistar大鼠,清洁级,32只大鼠随机分为4组,空白组、模型组、低剂量和高剂量核酸组各8只。空白组正常饮水,其余3组饮醋酸铅水溶液8g/L。空白组、模型组灌胃蒸馏水,低剂量和高剂量核酸组分别灌胃核酸200,700mg/kg,末次灌胃后24h,尾部取抗凝血,分离淋巴细胞,制成细胞悬液,24h内待测。5周后断头处死各组动物,取出肝脏,制成肝细胞悬液,24h内待测。采用单细胞凝胶电泳技术(彗星细胞实验)对淋巴细胞和肝细胞DNA损伤进行观察,细胞中DNA损伤单链断裂时会出现拖尾的彗星细胞。每片随机观察30个细胞,计数彗星细胞百分率,用目镜测微尺测量彗星细胞尾长。结果:32只大鼠全部进入结果分析,无脱失。①淋巴细胞中彗星细胞百分率和尾长比较:模型组与核酸低、高剂量组大鼠淋巴细胞中彗星细胞百分率和尾长均显著高于空白组[(50.25±6.21)%,(41.25±6.96)%,(35.38±5.93)%,(6.88±1.13)%;(23.25±4.23)μm,(16.50±4.24)μm,(13.63±2.62)μm,(6.75±1.17)μm,(q=11.28～42.94,P<0.01)]。核酸低、高剂量组彗星细胞百分率及彗星细胞尾长均明显低于模型组(q=8.91～15.77,P<0.01)。②肝细胞中彗星细胞百分率和尾长比较:模型组与核酸低、高剂量组大鼠肝细胞彗星细胞百分率和尾长均明显高于空白组(56.25±6.71)%,(42.25±6.09)%,(39.25±7.17)%,(8.25±1.28)%;(27.63±4.98)μm,(19.25±3.54)μm,(18.50±5.48)μm,(7.88±0.99)μm,(q=14.07～45.24,P<0.01)。核酸低、高剂量组彗星细胞百分率和尾长也显著低于模型组(q=11.10～16.02,P<0.01)。结论:慢性铅染毒可导致大鼠淋巴细胞和肝细胞DNA损伤,饮食核酸能显著提高对淋巴细胞和肝细胞DNA损伤的修复作用。

AIM: To investigate the interventional effect of the anti-oxidative substancenucleic acid on the DNA damage of lymphocytes and hepatocytes in plumbum infected rats. METHODS: The experiment was carried out in the College of Public Health, Harbin Medical University, Harbin 150001, Heilongjiang Province, China between March and May 2003. Thirty-two health male pure Wistar rats, which were 3 months old and clean degree, were randomly divided into 4 groups with 8 rats in each group: blank group, model group, low and high dose nucleic acid groups. Rats in the blank group drank water normally, and those in the other 3 groups drank the aqueous solution of lead acetate(8 g/L). Rats in the blank group and model group were treated with gastric perfusion of distilled water, and those in the low and high dose nucleic acid groups received gastric perfusion of nucleic acid 200 and 700 mg/kg respectively; 24 hours after the last gastric perfusion, anti-coagulation blood was drawn from tail, and lymphocytes were isolated to prepare cell suspension, which was to be detected within 24 hours. All the rats were killed by cutting down the heads after 5 weeks, liver was taken and made into hepatocytes suspension, which was to be detected within 24 hours. The DNA damages of lymphocytes and hepatocytes were observed with the technique of single cell gel electrophoresis(comet assay), comet cells with pulling tail occurred when the DNA damaged single chain broke. Thirty cells were randomly observed in each slice, the percentage of comet cells was counted, and the tail length of comet cell was measured with ocular micrometer. RESULTS: All the 32 rats were involved in the analysis of results without deletion. ① The percentage and tail length of comet cells in lymphocytes were all significantly higher in the model group and low and high dose nucleic acid groups than in the blank group [(50.25±6.21)%, (41.25±6.96)%, (35.38±5.93)%, (6.88±1.13)%; (23.25±4.23) μm, (16.50±4.24) μm, (13.63±2.62) μm, (6.75±1.17) μm, (q=11.28 to 42.94, P < 0.01)], and those were obviously lower in the low and high dose nucleic acid groups than in the model group (q=8.91 to 15.77, P < 0.01). ② The percentage and tail length of comet cells in hepatocytes were all obviously higher in the model group and low and high dose nucleic acid groups than in the blank group [(56.25±6.71)%, (42.25±6.09)%, (39.25±7.17)%, (8.25 ±1.28)%; (27.63±4.98) μm, (19.25±3.54)μm, (18.50±5.48) μm, (7.88 ±0.99)μm, (q=14.07 to 45.24, P < 0.01), and those were significantly lower in the low and high dose nucleic acid groups than in the model group (q =11.10 to 16.02, P<0.01). CONCLUSION: Chronic plumbum infection can result in the DNA damage of ymphocytes and hepatocytes in rats, and dietary nucleic acid can significantly improve the repair of the DNA damage of ymphocytes and hepatocytes.