西咪替丁对0．7Gy照射小鼠嗜多染红细胞微核的保护作用

Protective effects of cimetidine on micronucleated polychromatic erythrocytes in mice irradiated with 0.7Gy

目的选择辐射敏感指标(骨髓嗜多染红细胞微核率)评价西咪替丁对单次低剂量照射小鼠的损伤防护作用。方法健康雄性C57BL/6小鼠48只,随机分为正常对照组、模型对照组、200mg/kg WR2721组(阳性药组)及7.5、15、30mg/kg西咪替丁组(n=8)。西咪替丁组于照射前2h腹腔注射给药1次,阳性药组照射前连续腹腔注射给药2d,每日1次。单次照射剂量为0.7Gy,剂量率为5.83m Gy/min。照射后24h检测小鼠外周血象,血清和肝脏中的SOD活力与MDA含量,骨髓DNA含量和骨髓嗜多染红细胞微核率。结果与正常对照组比较,照后24h小鼠外周血白细胞显著降低(P<0.01),嗜多染红细胞微核率显著升高(P<0.01),除15mg/kg西咪替丁组外,其余各组小鼠骨髓DNA含量显著降低(P<0.01,P<0.05)。照后24h各组小鼠SOD活性和MDA含量无明显变化。与模型对照组比较,西咪替丁各剂量组外周血白细胞和骨髓DNA含量均无明显变化;7.5mg/kg西咪替丁组嗜多染红细胞微核率为0.027‰,明显低于模型对照组(P<0.01),且剂量减低系数(DRF)值达到3.338。结论西咪替丁对0.7Gy单次低剂量照射小鼠嗜多染红细胞微核有较好的保护作用。

Objective To study the radioprotective effect of cimetidine on single low-dose irradiated mice with radiosensitive detection indexes. Methods Forty-eight healthy male C57BL/6 mice were randomly divided into normal control group, model control group, positive group （200mg/kg WR2721） and cimetidine groups （7.Smg/kg, 15mg/kg and 30mg/kg）. The mice were given intraperitoneal injection of cimetidine 2h before irradiation in cimetidine groups and WR2721 before irradiation once a day for two days in positive group. All the mice except those in normal control group were irradiated with 0.7Gy 6~Co ^-ray at 5.83mGy/min rate. Peripheral blood cells, superoxide dismutase （SOD） activity and malondialdehyde （MDA） content both in serum and liver, bone marrow DNA content and frequency of micronucleated polychromatic erythrocytes （fMPEs） were determined 24h after irradiation. Results Compared with normal control group, the peripheral white blood cells （WBCs） of irradiated mice decreased significantly （P〈0.01）, and fMPEs increased significantly （P〈O.O1） after irradiation. Except for 15mg/kg cimetidine group, the bone marrow DNA content was decreased significantly after irradiation （P〈0.01, P〈0.05）. The SOD activity and MDA content in irradiated mice showed no significant difference compared with that of normal mice. Compared with model control group, peripheral WBCs and bone marrow DNA content showed no significant changes in treatment groups. The fMPE of 7.Smg/kg cimetidine group was 0.027‰, which was decreased significantly compared with that of model control group （P〈0.01）, and the dose reduction factor （DRF） of 7.Smg/kg cimetidine group was 3.338. Conclusion Cimetidine has good protective effect on micronucleated polychromatic erythrocytes （MPEs） in mice irradiated by 0.7Gy in single low-dose.