本研究旨在讨论富硒长双歧杆菌DD98（Selenium-enriched Bifidobacterium longum DD98，Se-DD98）对X射线所致发射性肝损伤小鼠的保护作用。雄性SPF级balb/c小鼠随机分为5组：正常对照组、辐射对照组、Se-DD98高剂量组、Se-DD98低剂量、DD98对照组，连续给药28 d并监测体重。第29 d采用X射线全身照射，实验结束后进行指标检测。与辐射对照组的体重（24.44 g）和肝脏指数（4.49%）比较，Se-DD98高剂量组体重（26.96 g）及肝脏指数（5.10%）显著改善、血清肝功能指标（ALT、AST）和体内氧化压力水平（MDA、LDH）显著降低，抗氧化酶活力（CAT、SOD、GSH-Px）显著升高。实时荧光定量PCR结果表明，Se-DD98高剂量组肝脏中Sod1（3.58）和Gpx1（7.14）表达显著上调，分别上调16.41、10.19倍，促炎因子IL-1β表达（2.16）显著下调1.61倍，抑炎因子IL-10（7.09）显著上调1.40倍。此外，Se-DD98高、低剂量组均能减轻X射线所致的肝脏损伤。最后，Se-DD98高剂量组各项指标与正常对照组相比差异不大，与辐射对照组差异显著。因此，富硒长双歧杆菌DD98可以通过减少氧化压力水平、增强抗氧化酶活力及抑制组织炎症来缓解X射线所致的小鼠放射性肝损伤。

The purpose of this study was to examine the protective effects of selenium-enriched Bifidobacterium longum DD98 (Se-DD98) on X-ray-induced hepatic damage in mice were investigated. Male SPF-grade balb/c mice were randomly divided into 5 groups: normal control group, radiation control group, Se-DD98 high-dose group, Se-DD98 low-dose group and DD98 control group. After 28 days of administration, the body weights of mice were monitored. Whole body X-ray irradiation was used on the 29th day, and then relevant indicators were measured after the experiment. Compared with the body weight (24.44 g) and liver index (4.49%) of the radiation control group, the body weight (26.96 g) and liver index (5.10%) of the Se-DD98 high-dose group increased significantly, with the levels of their serum liver function indicators (ALT, AST) and body oxidative stress indicators (MDA, LDH) decreasing significantly, and the activities of their antioxidant enzymes (CAT, SOD, GSH-Px) increasing significantly. Real-time fluorescent quantitative PCR results showed that the expression of Sod1 (3.58) and Gpx1 (7.14) in the liver of the Se-DD98 high-dose group was significantly up-regulated (by 16.41 and 10.19 times, respectively), and the expression of pro-inflammatory factor IL-1β (2.16) was significantly down-regulated (by 1.61 times). The mRNA levels of hepatic Sod1 (3.58) and Gpx1 (7.14) were significantly up-regulated respectively by 16.41 and 10.19 times in Se-DD98 high-dose group. In addition, both the high- and low-dose Se-DD98 groups could reduce X-ray-induced liver damage. Finally, the indices of the Se-DD98 high-dose group differed very little from the normal control group but differed significantly from the radiation control group. Therefore, Se-DD98 can alleviate X-ray-induced hepatic damage in mice through reducing the level of oxidative stress, boosting the activities of the antioxidant enzymes and inhibiting tissue inflammation.

国家自然科学基金项目(81872775)；上海市科技人才计划项目（17XD1423200）