2,3,7,8-四氯二苯并二噁英与Aroclor 1254单独与联合作用对大鼠外周血淋巴细胞DNA的损伤效应

Damage Effects of Individual and Combined Exposure to 2,3,7,8-Tetrachlorodibenzo-p-Dioxin and Aroclor 1254 on DNA in Peripheral Blood Lymphocyte of Rats

为探讨2,3,7,8-四氯二苯并二噁英(TCDD)和多氯联苯(Aroclor 1254)联合染毒对大鼠外周血淋巴细胞DNA的损伤效应,将20只雄性Sprague-Dawley(SD)大鼠随机均分为4组,即对照组(橄榄油)、Aroclor 1254单独染毒组(10mg·kg-1)、TCDD单独染毒组(10μg·kg-1)和联合染毒组(TCDD 10μg·kg-1+Aroclor 1254 10 mg·kg-1).大鼠每天灌胃染毒1次,连续染毒6d.染毒过程中记录大鼠的体征和体重.末次染毒后24h取外周血,分离淋巴细胞,采用碱性单细胞凝胶电泳技术(彗星试验)检测外周血淋巴细胞DNA损伤,并采用CASP软件分析各组彗星的尾部DNA百分含量(Tail DNA%)、尾长(Tail Length)和尾矩(Tail Moment).结果表明,染毒结束时TCDD单独染毒和联合染毒组大鼠体重显著低于对照组,且联合染毒组表现更为明显.TCDD单独染毒组和联合染毒组大鼠外周血淋巴细胞DNA可见明显损伤,TailDNA%、Tail Length和Tail Moment均显著高于对照组(p<0.05),且联合染毒组大鼠细胞DNA损伤更为严重,但Arolor 1254单独染毒组大鼠未见明显DNA损伤.析因分析提示TCDD与Aroclor 1254对大鼠外周血淋巴细胞DNA损伤的联合毒性效应为协同作用.本研究结果表明TCDD与Aroclor 1254联合染毒可加重大鼠外周血淋巴细胞DNA损伤,在对PCBs与二噁英的混合暴露进行危险性评估时要注意这种联合毒性作用.

To study the damage effects of individual and combined exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin （TCDD）and polychlorinated biphenyls （PCBs） on DNA in peripheral blood lymphocyte of rats, twenty Sprague-Dawley male rats were randomly and equally divided into 4 groups, and were treated intragastrically with vehicle （olive oil）, Aroclor 1254（Aroclor 1254 10mg·kg-1）, TCDD（TCDD 10μg·kg-1）and the combination（TCDD 10μg·kg-1＋Aroclor 1254 10mg·kg-1）once a day for 6 consecutive days, respectively. The clinical signs and the body weight were recorded during the treatment. After 6-d exposure, peripheral blood lymphocytes were obtained and detected for DNA damage by single cell gel electrophoresis （SCGE）. Tail Length, Tail DNA % and Tail Moment were analyzed by SCGE image analysis software （CASP）. Results showed that the body weight of rats decreased significantly in the TCDD group and the combined group after treatment, and this effect was greater in the combined group. Significant DNA damage was observed in both TCDD group and the combined group, as evidenced by significantly higher Tail Length, Tail DNA % and Tail Moment than those in the control （p0.05）, and the DNA damage was more severe in the combined group. However, no obvious DNA damage was observed in Aroclor 1254 group. Factorial analyse of the results showed that the effect of combination of TCDD with Aroclor 1254 on peripheral blood lymphocytes of rats may be synergic. The present study demonstrated that the combined exposure to TCDD and Aroclor 1254 aggravates DNA damage in peripheral blood lymphocyte of rats, indicating that it is important to understand the combined toxic effects in the risk assessment of coexposure of PCBs and TCDD.