Objective: To investigate the effects of normobaric hyperoxia intervention on renal ischemia-reperfusion injury in rats and its possible mechanism. Methods: Twenty-one adult male SD rats were enrolled and their right kidneys were excised. After two weeks, they were randomly assigned to 3 groups, with 7 rats in each group, namely sham-operated group (Group S), ischemia-reperfusion group (Group I/R), and normobaric hyperoxia+ischemia-reperfusion group (Group NBHO+I/R). In group S, only the left renal pedicle was isolated, but no ischemic treatment was performed. However, in group I/R and group NBHO+I/R, left renal pedicles were separated and left renal ischemia was induced by noninvasive arterial clamp for 45 min, and after 24 h of reperfusion, rats in group S and group I/R inhaled regular concentration of oxygen (21%), while rats in group NBHO+I/R inhaled high concentration of oxygen (60%), 2 h at each time, once a day for 7 days. On the 7th day after surgery, blood urea nitrogen (BUN) and creatinine (Cr) levels were measured by taking blood from the orbital veins of rats. The content of malondialdehyde (MDA) and superoxide dismutase (SOD) was detected from the left kidney tissues. The mRNA and protein contents of Keap1 and Nrf2 gene in kidney tissues were determined by qPCR and Western Blotting, respectively. Hematoxylin-eosin staining (HE) was employed to observe the pathological changes of kidney tissue. Immunohistochemical staining was used to measure the protein expression of Keap1 and Nrf2 in kidney tissues. Results: Compared with group S, the serum BUN [(10.7±1.7) mmol/L, (8.4±1.0) mmol/L vs (6.1±1.3) mmol/L, both P<0.05] and Cr [(81.0±3.7) μmol/L, (62.9±3.4) μmol/L vs (48.3±2.9) μmol/L, both P<0.05] levels of rats in the group I/R and group NBHO+I/R increased, and the I/R group had the most significant increase. Compared with group S, the MDA content of kidney tissue in the rats of group I/R and NBHO+I/R increased [(10.5±1.0) μmol/L, (8.6±0.8) μmol/L vs (6.5±0.5) μmol/L, both P<0.05], but the MDA content in group NBHO+I/R was lower than that of group I/R (P<0.05). Compared with group S, the SOD content in the kidney tissues of rats in both group I/R and group NBHO+I/R decreased. However, the SOD content of group NBHO+I/R was higher than that of group I/R (P<0.05). Compared with group S, the mRNA and protein contents of Keap1 gene in kidney tissues of group I/R and group NBHO+I/R decreased, and group NBHO+I/R had the most significant decrease (P<0.05). However, compared with group S, mRNA and protein expressions of Nrf2 gene increased in kidney tissues of group I/R and group NBHO+I/R, and NBHO+I/R group had the most significant increase (P<0.05). Postoperative pathological results suggested that compared with group S, the pathological damage of kidney tissues in group I/R and group NBHO+I/R increased, but the degree of damage in group NBHO+I/R was lower than that in group I/R. Conclusion: Normobaric hyperoxia intervention may have protective effects on renal ischemia-reperfusion injury in rats by activating Keap1-Nrf2 signaling pathway.
目的： 探讨高浓度常压氧干预治疗对大鼠肾脏缺血再灌注损伤的影响及其可能机制。 方法： 成年雄性SD大鼠21只，均切除右侧肾脏建立孤肾模型，2周后随机分为3组，每组7只：假手术组（S组）、缺血再灌注组（I/R组）、高浓度常压氧+缺血再灌注组（NBHO+I/R组），S组仅分离左侧肾蒂，不给予缺血处理；I/R组和NBHO+I/R组分离左侧肾蒂并用无创动脉夹致左肾缺血45 min，再灌注24 h后，将3组大鼠置于密闭氧舱中，S组和I/R组吸入常规浓度氧气（21%），NBHO+I/R组吸入高浓度氧气（60%），每天1次，每次2 h，持续7 d。术后第7天，通过大鼠眶静脉取血测量血清尿素氮和肌酐水平；取大鼠左侧肾脏，测量肾脏组织中丙二醛（MDA）和超氧化物歧化酶（SOD）含量；通过实时定量PCR（qPCR）和Western印迹法检测肾脏组织中Kelch样环氧氯丙烷相关蛋白-1（Keap1）和核因子E2相关因子2（Nrf2）mRNA和蛋白含量；苏木精-伊红（HE）染色观察肾脏组织病理改变；免疫组化染色观察肾脏组织中Keap1和Nrf2蛋白表达水平。 结果： 与S组相比，I/R组和NBHO+I/R组大鼠血清尿素氮［（10.7±1.7）mmol/L、（8.4±1.0）mmol/L比（6.1±1.3）mmol/L，均P<0.05］和肌酐［（81.0±3.7）μmol/L、（62.9±3.4）μmol/L比（48.3±2.9）μmol/L，均P<0.05］水平均增加，但NBHO+I/R组较I/R组降低（均P<0.05）；I/R组和NBHO+I/R组肾脏组织MDA含量［（10.5±1.0）μmol/L、（8.6±0.8）μmol/L比（6.5±0.5）μmol/L，均P<0.05］均增加，但NBHO+I/R组较I/R组降低（P<0.05）；I/R组和NBHO+I/R组肾脏组织SOD含量均下降，但NBHO+I/R组较I/R组增加（P<0.05）。与S组相比，I/R组和NBHO+I/R组肾脏组织中Keap1 mRNA和蛋白含量均降低，其中NBHO+I/R组下降最多（均P<0.05）；I/R组和NBHO+I/R组肾脏组织中Nrf2 mRNA和蛋白表达水平均增加，其中NBHO+I/R组增加最多（均P<0.05）。术后病理结果提示，与S组相比，I/R组和NBHO+I/R组肾脏组织病理损伤均加重，但NBHO+I/R组损伤程度较I/R组减轻。 结论： 高浓度常压氧干预治疗可能通过激活Keap1-Nrf2信号通路，对大鼠肾脏缺血再灌注损伤产生保护性作用。.