孕鼠肢体缺血预处理对窘迫胎鼠复氧后脑组织神经元caspase-3表达的影响

Effect of maternal limb ischemic preconditioning on expression of caspase-3 in neurons in brain tissues after reoxygenation in fetal rats with intrauterine distress

目的 探讨孕鼠肢体缺血预处理对窘迫胎鼠复氧后脑组织神经元caspase-3表达的影响。方法 孕19 d的SD大鼠40只，采用随机数字表法分为4组（n＝10）：假手术组（S组）、肢体缺血预处理组（LIP组）、胎鼠窘迫组（FD组）和肢体缺血预处理＋胎鼠窘迫组（LIP＋FD组）。采用微动脉夹阻断孕鼠子宫和卵巢动静脉15 min制备胎鼠窘迫/复氧模型。止血带法于孕鼠右侧腹股沟处阻断其后肢血流，阻断/开放各5 min，共循环3次制备孕鼠肢体缺血预处理模型。LIP＋FD组于阻断子宫和卵巢动静脉的同时施行肢体缺血预处理。各组处理结束后2 d时剖宫，计算胎鼠死亡率；取活胎海马组织，采用TUNEL法确定海马CA1区神经元凋亡指数，采用Western blot法检测caspase-3的表达，采用RT-PCR法检测caspase-3 mRNA的表达。结果 与S组比较，FD组和LIP＋FD组胎鼠死亡率和海马神经元凋亡指数升高，胎鼠海马CA1区caspase-3及其mRNA表达上调（P〈0.05或0.01），LIP组上述指标差异无统计学意义（P〉0.05）；与FD组比较，LIP＋FD组胎鼠死亡率和海马神经元凋亡指数降低，海马CA1区caspase-3及其mRNA表达下调（P〈0.05或0.01）。结论孕鼠肢体缺血预处理抑制窘迫胎鼠复氧后脑组织神经元凋亡的机制与下调caspase-3表达有关。

Objective To investigate the effect of maternal limb ischemic preconditioning on the expression of caspase-3 in neurons in brain tissues after reoxygenation in the fetal ＇rats with intrauterine distress. Methods Forty Sprague-Dawley rats at 19 days of gestation were randomly divided into 4 groups （n= 10 each） using a random number table： sham operation group （group S）, limb ischemic preconditioning group （ group LIP）, fetal rat distress group （ group FD） , and limb ischemic preconditioning ＋ fetal rat distress group （group LIP＋FD）. Distress/reoxygenation model was established by clamping the uterine and ovarian arteries and veins with a micro-artery clamp for 15 min followed by removal of the clamp to permit reperfusion. Limb ischemic preconditioning was induced by 3 cycles of occlusion of the lower limb blood flow at the site of the right groin for 5 min with a tourniquet followed by 5 min unclamping. In group LIP＋ 17D, the uterine and ovarian arteries and veins were clamped, and limb ischemic preconditioning was performed at the same time. Cesarean section was performed on 2 days after the end of treatments in each group, and the fetal rat mortality rate was calculated. The fetal rats alive were sacrificed, and the hippocampi were isolated for determination of neuronal apoptosis （by TUNEL） and expression of caspase-3 protein and mRNA （by Western blot and real-time reverse transcriptase polymerase chain reaction, respectively） in hippocampal CA1 region. Apoptosis index was calculated. Results Compared with group S, the fetal rat mortality rate and apoptosis index were significantly increased, and the expression of caspase-3 protein and mRNA in hippocampal CA1 region was significantly up-regulated in FD and LIP＋FD groups （P〈 0.05 or 0.01 ） , and no significant ehange was found in the parameters mentioned above in group LIP （ P〉 0.05）. Compared with group FD, the fetal rat mortality rate and apoptosis index were significantly decreased, and the expression of easpase-3 protein and mRNA in hippocampal CA1 region was significantly down-regulated in group LIP＋FD （P〈0.05 or 0.01）. Conclusion The mechanism by which maternal limb ischemic preconditioning inhibits apoptosis in neurons after reoxygenation is related to down-regulation of the expression of caspase-3 in the fetal rats with intrauterine distress.