缺血预处理对大鼠胰腺移植缺血/再灌注损伤的保护机制

Protective mechanism of ischemic preconditioning on ischemic/reperfusion injury after pancreas transplantation in rats

目的探讨缺血预处理对大鼠胰腺移植缺血/再灌注损伤的保护机制。方法建立SD大鼠糖尿病模型。取糖尿病大鼠24只,随机分为缺血/再灌注组(I/R组,n=6)和缺血预处理组(IPC组,n=18),IPC组又平均分为3个亚组:IPC1组(阻断脾血管5min,再灌注5min)、IPC2组[(阻断脾血管5min,再灌注5min)×2次]和IPC3组[(阻断脾血管5min,再灌注5min)×3次]。另取健康SD大鼠6只作为对照组,仅打开腹腔,不做胰腺移植;I/R组和IPC组大鼠均行同种胰腺移植。检测各组胰腺移植再灌注后2h后移植胰组织中超氧化物歧化酶(SOD)和髓过氧化物酶(MPO)的活性;用原位末端脱氧核糖核酸转移标记(TUNEL)法观察移植胰组织的细胞凋亡情况;WesternBlot法检测移植胰组织Bcl-2和Bax基因表达情况。结果IPC各组与I/R组相比较,前者移植胰组织中SOD活性明显升高,MPO活性明显降低,细胞凋亡指数明显降低,Bcl-2表达明显升高,Bax表达明显降低,各项检测指标比较,差异均有统计学意义(P<0.05)。IPC各组中又以IPC2组的各项检测指标差异更为显著(P<0.05)。结论缺血预处理可以减少移植胰缺血/再灌注后的细胞凋亡,IPC2组的效果更为突出。其机制可能与缺血预处理减轻嗜中性粒细胞(PMNs)粘附与聚集、减少氧自由基、上调Bcl-2基因和下调Bax基因的表达有关。

Objective To investigate the protective mechanism of ischemic preconditioning on ischemic/reperfusion injury after pancreas transplantation in rats. Methods The model of diabetic SD rat was established. Twenty-four diabetic SD rats were randomly assigned to ischemic/reperfusion group （I/R group, n = 6） and ischemic preconditioning group （IPC group, n = 18）. The rats in group IPC were averagely assigned to 3 sub-groups： group IPC1 （5 min ischemic and 5 min reperfusion）, IPC2 （5 min ischemic and 5 min reperfusion twice） and IPC3 （5 min ischemic and 5 min reperfusion thrice）. Six normal SD rats whose abdomen was opened only served as control group, and they did not receive pancreas transplantation. I/R group and IPC group received pancreas transplantation. The su peroxide dismutase （SOD） and myeloperoxidase （MPO） activity of grafts were monitored 2 h after reperfusion, the apoptotic cells in grafts were observed by TUNEL method, and the expression of Bcl- 2 and Bax gene of the grafts was detected by Western blot. Results As compared with I/R group, the SIOD activity and the expression of Bcl-2 gene of grafts were significantly increased, while MPO activity, apoptotic index and the expression of the Bax gene in the grafts were markedly reduced in IPC group （P-~0. 05）. Among the IPC groups, group IPCa showed the most significant difference （P〈 0. 05）. Conclusions Ischemic preconditioning can reduce apoptosis of the grafts after pancreas transplantation in rats, especially IPO2 protocol. The possible mechanism might be as follows： relieving conglutination and aggregation of neutrophils, decreasing oxygen radical, up-regulating the expression of Bcl-2 gene and down-regulating the expression of Bax gene.