缺血预处理对大鼠胰腺移植缺血/再灌注损伤的保护机制

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。

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

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 IPC_ 1 (5 min ischemic and 5 min reperfusion), IPC_ 2 (5 min ischemic and 5 min reperfusion twice) and IPC_ 3 (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 superoxide 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 IPC_ 2 showed the most significant difference (P< 0.05 ).Conclusions Ischemic preconditioning can reduce apoptosis of the grafts after pancreas transplantation in rats, especially IPC_ 2 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.