Cai S Y, Pei J, Yan B, Liu Z Y, Chen Y, Sima C Y, Su C J, Yang Z H
Department of Nephrology, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
Department of Urology, Guizhou Provincial People's Hospital, Guiyang 550002, China.
Zhonghua Yi Xue Za Zhi. 2021 Apr 13;101(14):1036-1040. doi: 10.3760/cma.j.cn112137-20201011-02809.
To investigate the effects of normobaric hyperoxia intervention on renal ischemia-reperfusion injury in rats and its possible mechanism. 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. 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 0.05] and Cr [(81.0±3.7) μmol/L, (62.9±3.4) μmol/L vs (48.3±2.9) μmol/L, both 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 0.05], but the MDA content in group NBHO+I/R was lower than that of group I/R (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 (<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 (<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 (<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. Normobaric hyperoxia intervention may have protective effects on renal ischemia-reperfusion injury in rats by activating Keap1-Nrf2 signaling pathway.
探讨常压高氧干预对大鼠肾缺血再灌注损伤的影响及其可能机制。选取21只成年雄性SD大鼠，切除其右肾。两周后，将其随机分为3组，每组7只，即假手术组（S组）、缺血再灌注组（I/R组）和常压高氧+缺血再灌注组（NBHO+I/R组）。S组仅分离左肾蒂，但不进行缺血处理。而I/R组和NBHO+I/R组分离左肾蒂，采用无创动脉夹夹闭造成左肾缺血45分钟，再灌注24小时后，S组和I/R组大鼠吸入常规浓度氧气（21%），NBHO+I/R组大鼠吸入高浓度氧气（60%），每次2小时，每天1次，共7天。术后第7天，通过大鼠眶静脉取血检测血尿素氮（BUN）和肌酐（Cr）水平。从左肾组织中检测丙二醛（MDA）和超氧化物歧化酶（SOD）含量。分别采用qPCR和Western Blotting法检测肾组织中Keap1和Nrf2基因的mRNA和蛋白含量。采用苏木精-伊红染色（HE）观察肾组织病理变化。采用免疫组织化学染色检测肾组织中Keap1和Nrf2蛋白表达。与S组相比，I/R组和NBHO+I/R组大鼠血清BUN水平[（10.7±1.7）mmol/L，（8.4±1.0）mmol/L vs（6.1±1.3）mmol/L，均P<0.05]及Cr水平[（81.0±3.7）μmol/L，（62.9±3.4）μmol/L vs（48.3±2.9）μmol/L，均P<0.05]升高，且I/R组升高最为显著。与S组相比，I/R组和NBHO+I/R组大鼠肾组织MDA含量升高[（10.5±1.0）μmol/L，（8.6±0.8）μmol/L vs（6.5±0.5）μmol/L，均P<0.05]，但NBHO+I/R组MDA含量低于I/R组（P<0.05）。与S组相比，I/R组和NBHO+I/R组大鼠肾组织SOD含量降低。然而，NBHO+I/R组SOD含量高于I/R组（P<0.05）。与S组相比，I/R组和NBHO+I/R组肾组织中Keap1基因的mRNA和蛋白含量降低，且NBHO+I/R组降低最为显著（P<0.05）。然而，与S组相比，I/R组和NBHO+I/R组肾组织中Nrf2基因的mRNA和蛋白表达升高，且NBHO+I/R组升高最为显著（P<0.05）。术后病理结果显示，与S组相比，I/R组和NBHO+I/R组肾组织病理损伤加重，但NBHO+I/R组损伤程度低于I/R组。常压高氧干预可能通过激活Keap1-Nrf2信号通路对大鼠肾缺血再灌注损伤具有保护作用。
