亚低温对急性辐射损伤小鼠的保护作用及其机制研究

Mechanism of the protective effect of mild hypothermia on acute radiation injury in mice

目的 探讨亚低温对急性辐射损伤小鼠的辐射防护作用及其机制.方法 105只雄性BALB/c小鼠按随机数字表法分为3组,即单纯照射组、亚低温干预组和健康对照组,每组35只.单纯照射组和亚低温干预组小鼠均接受6 Gy60Coγ射线单次全身照射,亚低温干预组在照后即刻进行亚低温干预并维持6h,观察照后1、3、7、14、21和28 d小鼠外周血白细胞数、骨髓有核细胞计数,骨髓病理组织学变化,照后6和24 h,检测小鼠血清中丙二醛（MDA）含量、谷胱甘肽过氧化物酶（GSH-px）和超氧化物歧化酶（SOD）活力,采用流式细胞术检测骨髓细胞周期.结果 与单纯照射组比较,亚低温干预组小鼠外周血白细胞数和骨髓有核细胞数在照后早期较高（t=-2.63、-3.41,P＜0.05）,且提前1周恢复;同时,小鼠骨髓细胞衰减较晚,恢复较早.受照后6h与其他组相比,亚低温干预组小鼠血清MDA含量较低（=3.83,P＜0.05）,SOD活力较高（t=-6.57,P＜0.05）,骨髓S期细胞比例较高（t=-4.67,P＜0.05）,G2期细胞较低（t=3.04,P＜0.05）;受照后24 h与其他组相比,亚低温干预组小鼠血清GSH-px活力较高（t=-3.13,P＜0.05）,骨髓S期细胞比例较单纯照射组降低（=7.19,P＜0.05）.结论 照后亚低温干预对急性辐射损伤有较好的保护作用,机制与亚低温可增强机体抗氧化力、抑制骨髓细胞周期进程有关.

Objective To explore the effect of mild hypothermia on acute radiation injury in mice and investigate the underlying mechanism.Methods Totally 105 BALB/c mice were randomly divided into 3 groups of equal number：irradiation group,mild hypothermia prevention group and normal control group.Mice in groups of irradiation and mild hypothermia prevention were administered with whole body irradiation of 6 Gy γ-rays,mice in irradiation group were treated with mild hypothermia after irradiation immediately and maintenance for 6 h.White blood cells,nucleated cells and histopathological changes in bone marrow were observed at 1,3,7,14,21 and 28 d after irradiation.At 6 and 24 h after irradiation,the content of malondiadehyde （MDA） and the activities of superoxide dismutase enzyme （SOD） and glutathione peroxidase enzyme （GSH-px） in serum were detected,and the cell cycle distribution of bone marrow cells were also measured with flow cytometry.Results The numbers of white blood cell and nucleated cells in bone marrow in mild hypothermia prevention group were much higher than those in irradiation group （t =-2.63,-3.41,P 〈 0.05） at the early period after irradiation so that they were recovered 1 week earlier.Pathology measurement showed that cells in bone marrow of mild hypothermia prevention group decayed later and recovered 1 week earlier than irradiation group.At 6 h after irradiation,in mild hypothermia prevention group,MDA content was lower （t =3.83,P 〈 0.05） and the activity of SOD was higher （t =-6.57,P 〈 0.05） than that in irradiation group,meanwhile,the S-phase cells in bone marrow were higher （t =-4.67,P 〈0.05） and the G2-phase cells were lower （t =3.04,P 〈0.05） than those of irradiation group.At 24 h after irradiation,for mild hypothermia prevention group,the activity of GSH-px was higher （t =-3.13,P 〈0.05） and the S-phase cells in bone marrow was lower （t =7.19,P 〈 0.05） than those in irradiation group.Conclusions Mild hypothermia has protective effect on acute radiation injury by enhancing the antioxidant capacity and inhibiting bone marrow cell cycle progress.