Objective: To investigate the effects of activating silent information regulator 1 (SIRT1) on the early kidney damage in rats with severe burn. Methods: Thirty healthy male SD rats were divided into sham injury group (SI), pure burn group (PB), and SIRT1 activator group (SA) according to the random number table, with 10 rats in each group. Rats in groups PB and SA were inflicted with 30% total body surface area full-thickness scald (hereinafter referred to as burn) on the back. Immediately after injury, rats in group PB were intraperitoneally injected with normal saline in the dosage of 50 mL/kg, and those in group SA with 1 mg/mL (final mass concentration) resveratrol in the dosage of 50 mL/kg. Rats in group SI were sham injured and intraperitoneally injected with normal saline in the dosage of 50 mL/kg immediately after injury. Kidney tissue and abdominal aorta blood of rats in the three groups were collected at 24 hours after injury. The morphology of kidney tissue was observed after HE staining. The serum content of creatinine and urea nitrogen was determined with enzyme-linked immunosorbent assay. Protein expressions of SIRT1, Bax, and Bcl-2 in kidney tissue were determined with Western blotting. mRNA expressions of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-10 in kidney tissue were determined with real-time fluorescent quantitative reverse transcription polymerase chain reaction. Data were processed with one-way analysis of variance and LSD-t test. Results: (1) In rats of group SI, structures of kidney tubules and glomeruli were intact. In rats of group PB, structures of kidney tubules were not clear with casts in them, and glomeruli showed pyknosis. In rats of group SA, structures of kidney tubules were relatively intact, and the pyknosis of glomeruli were slighter as compared with that of group PB with fewer glomeruli showing pyknosis. (2) The serum content of creatinine and urea nitrogen in rats of group PB was (67±14) μmol/L and (22.0±4.4) mmol/L, respectively, which was significantly higher than that of group SI [(28±7) μmol/L and (5.5±1.2) mmol/L respectively, with t values respectively 6.07 and 11.53, P values below 0.01]. The serum content of creatinine and urea nitrogen in rats of group SA was (39±9) μmol/L and (14.1±1.7) mmol/L, respectively, significantly lower than that of group PB (with t values respectively 4.09 and 4.17, P values below 0.01). (3) Compared with those of group SI, protein expressions of SIRT1 and Bcl-2 in kidney tissue of rats in group PB were significantly decreased (with t values respectively 16.32 and 19.58, P values below 0.01), while the protein expression of Bax was significantly increased (t=5.98, P<0.01). Compared with those of group PB, protein expressions of SIRT1 and Bcl-2 in kidney tissue of rats in group SA were significantly increased (with t values respectively 6.94 and 5.37, P values below 0.01), while the protein expression of Bax was significantly decreased (t=3.44, P<0.01). (4) mRNA expressions of TNF-α, IL-1β, and IL-10 in kidney tissue of rats in group PB were 17.0±4.0, 2.27±0.59, and 2.5±0.9, respectively, significantly higher than those of group SI (1.0, 1.00, and 1.0, respectively, with t values from 3.27 to 8.93, P<0.05 or P<0.01). mRNA expressions of TNF-α and IL-1β in kidney tissue of rats in group SA were 6.8±1.2 and 1.18±0.26, respectively, significantly lower than those of group PB (with t values respectively 4.59 and 4.32, P values below 0.01). mRNA expression of IL-10 in kidney tissue of rats in group SA was 5.0±1.0, significantly higher than that of group PB (t=5.51, P<0.01). Conclusions: Activating SIRT1 on early stage of severe burn in rats can decrease levels of creatinine and urea nitrogen, thus improving the kidney function. It can down-regulate the protein expression of Bax and up-regulate the protein expression of Bcl-2, thus reducing the apoptosis in kidney tissue. Meanwhile, it can inhibit expressions of TNF-α and IL-1β and promote the expression of IL-10, thus alleviating the inflammatory response in kidney.
目的： 探讨行沉默信息调节因子1(SIRT1)活化对大鼠严重烧伤早期肾损害的影响。 方法： 取30只雄性SD大鼠，按照随机数字表法分为假伤组、单纯烧伤组、SIRT1激动剂组，每组10只。单纯烧伤组和SIRT1激动剂组大鼠背部造成30%TBSA Ⅲ度烫伤(下称烧伤)，伤后即刻分别腹腔注射生理盐水、终质量浓度为1 mg/mL白藜芦醇溶液50 mL/kg；假伤组大鼠致假伤，伤后即刻腹腔注射生理盐水50 mL/kg。伤后24 h收集3组大鼠肾脏组织及腹主动脉血，HE染色观察肾脏组织形态，ELISA法检测血清肌酐、尿素氮含量，蛋白质印迹法检测肾脏组织中SIRT1、Bax、Bcl－2蛋白表达，实时荧光定量RT－PCR法检测肾脏组织中TNF－α、IL－1β、IL－10的mRNA表达。对数据行单因素方差分析、LSD－t检验。 结果： (1)假伤组大鼠肾小管、肾小球结构完整；单纯烧伤组大鼠肾小管内管型形成，小管结构不清，肾小球固缩；SIRT1激动剂组大鼠肾小管结构较为完整，肾小球固缩程度较单纯烧伤组轻且固缩的肾小球数量较少。(2)单纯烧伤组大鼠血清肌酐、尿素氮含量分别为(67±14)μmol/L、(22.0±4.4)mmol/L，显著高于假伤组的(28±7)μmol/L、(5.5±1.2)mmol/L(t值分别为6.07、11.53，P值均小于0.01)。SIRT1激动剂组大鼠血清肌酐、尿素氮含量分别为(39±9)μmol/L、(14.1±1.7)mmol/L，显著低于单纯烧伤组(t值分别为4.09、4.17，P值均小于0.01)。(3)单纯烧伤组大鼠肾脏组织中SIRT1、Bcl－2蛋白表达量显著低于假伤组(t值分别为16.32、19.58，P值均小于0.01)，Bax蛋白表达量显著高于假伤组(t＝5.98，P<0.01)。SIRT1激动剂组大鼠肾脏组织中SIRT1、Bcl－2蛋白表达量显著高于单纯烧伤组(t值分别为6.94、5.37，P值均小于0.01)，Bax蛋白表达量显著低于单纯烧伤组(t＝3.44，P<0.01)。(4)单纯烧伤组大鼠肾脏组织中TNF－α、IL－1β、IL－10的mRNA表达量分别为17.0±4.0、2.27±0.59、2.5±0.9，显著高于假伤组的1.0、1.00、1.0(t值为3.27～8.93，P<0.05或P<0.01)。SIRT1激动剂组大鼠肾脏组织中TNF－α、IL－1β的mRNA表达量分别为6.8±1.2、1.18±0.26，显著低于单纯烧伤组(t值分别为4.59、4.32，P值均小于0.01)；IL－10的mRNA表达量为5.0±1.0，显著高于单纯烧伤组(t＝5.51，P<0.01)。 结论： 活化SIRT1可以降低大鼠严重烧伤早期肌酐及尿素氮水平，改善肾功能；下调Bax蛋白表达，上调Bcl－2蛋白表达，减轻肾脏组织细胞凋亡；同时可抑制TNF－α和IL－1β表达，促进IL－10表达，减轻肾脏炎症反应。.
Keywords: Apoptosis; Burns; Inflammatory response; Kidney; Silent information regulator 1.