L-瓜氨酸预处理对大鼠缺血／再灌注损伤肾的功能及蛋白表达影响

ERK, Akt and p38MAPK are involved in the renal protective effect of glycine on ischemia/reperfusion induced injury in rats

目的研究L-瓜氨酸对大鼠缺血／再灌注（ischemia—reperfusion，I／R）损伤肾组织的保护作用机制。方法18只雄性SD大鼠分为假手术组（Sham组）、模型组（I／R组）和L-瓜氨酸组（L—Cit组），每组6只。采用夹闭双肾动脉45min后再灌注制备肾L／R损伤模型。L—Cit组于造模前连续7天灌胃给予L-瓜氨酸600mg／kg。于再灌注3h活体摘取双肾，并行腹主动脉穿刺抽血2ml。检测各组大鼠血清肌酐、尿素氮，Western blot检测肾组织ERK1／2、p38MAPK和Akt的磷酸化表达。结果与Sham组相比，I／R组大鼠血清肌酐、尿素氮水平升高，肾组织ERK1／2和Akt的磷酸化表达明显降低，p38MAPK的磷酸化表达明显增高；L—Cit组与I／R组相比，ERK1／2和Akt的磷酸化表达明显增高，而p38MAPK的磷酸化表达明显降低，血清尿素氮、肌酐水平明显降低。结论L-瓜氨酸可能通过激活ERK1／2和Akt信号通路、抑制p38MAPK信号来保护大鼠肾缺血／再灌注损伤。

Objective To investigate the mechanism of protection against renal ischemia/reperfusion （I/R） injury by L - citrulline. Methods Eighteen rats were randomized into 3 groups （ n = 6 each） ： Sham operated ; I/R （45 rain renal ischemia and 3 h reperfusion） ; 1/R ＋ L- eitrulline （600 mg .kg^-1 1 d^-1 , i. g. ）. Renal arteries of the rat were ligated to block the blood flow completely and loosened after 45 rain to reperfuse when the blood flow recovered. 2 ml blood was taken by puncturing the abdominal artery of the double kidneys 3 h after reperfusion followed by test by various indexes, and then the kidneys were removed. The phosphorylation activity of ERK1/2, p38MAPK and Akt were detected by western blot. Results Our results showed that pretreatment with L - citrulline （600 mg . kg^-1 ） significantly ameliorated the renal injury caused by ]JR. The level of serum creatinine and urea nitrogen significantly increased compared with Sham operated group （ P 〈 0.05 ） after 3 h of reperfusion, while were significantly suppressed by L - citrulline （ P 〈 0.05 ）. The phosphorylated ERK1/2 and Akt in the kidneys were significantly decreased in L/R rats compared with Sham group and were significantly prevented by L- eitrulline （P 〈 0.05 ）. In addition, p38MAPK was activated in I/R group rats and was suppressed by L - citrulline. Conclusion These results suggest that L - citrulline administration exhibits significant protection against renal I/R injury. Activation of ERK1/2 and Akt, and suppression of p38MAPK may con- tribute to the protective effect of L - citrulline on I/R injury.