不同高压氧预处理方案对兔脊髓缺血再灌注损伤的影响

目的 探讨不同高压氧预处理方案对兔脊髓缺血再灌注损伤的影响.方法 新西兰大白兔45只,月龄4～5月,体重2.0～2.5 kg,随机分为5组:假手术组(S组,n=5)开腹剥离左肾动脉下段腹主动脉但不阻断血流,20 min后关腹;脊髓缺血再灌注组(IR组,n=10)采用左肾动脉下段腹主动脉阻断法建立脊髓缺血再灌注损伤模型,缺血20 min后恢复灌注;不同方案高压氧预处理组(H_(1～3)组,n=10)分别接受连续5 d(H_1组)、10 d(H_2组)或20 d(H_3组)高压氧预处理(2.5 ATA,吸入氧浓度100%),1h/d,末次高压氧预处理结束后24 h时,建立脊髓缺血再灌注模型.再灌注48 h时,采用修正Tarlov评分,评价后肢运动功能.然后取L_5脊髓节段,分别行HE、TUNEL和nuoro-Jade B染色,计数脊髓正常神经元、凋亡神经元和变性神经元.结果 与S组比较,IR组后肢运动功能评分和脊髓前角正常神经元计数降低(P<0.01);与IR组比较,H_1组和H_2组后肢运动功能评分和脊髓前角正常神经元计数升高,凋亡神经元计数和变性神经元计数降低(JP<0.01),H_3组各指标差异无统计学意义(P>0.05);H_1组和h_2组各指标比较差异无统计学意义(P>0.05);与H_1组和H_2组比较,H_3组后肢运动功能评分和脊髓前角正常神经元计数降低,凋亡神经元计数和变性神经元计数升高(P<0.01).结论 连续5 d或10 d高压氧预处理(2.5 ATA,吸入氧浓度100%)可减轻脊髓缺血再灌注损伤;而连续20 d高压氧预处理无神经保护作用.

Effect of different programs of hyperbaric oxygen preconditioning on spinal cord ischemia- reperfusion injury in rabbits

Objective To investigate the effect of different programs of preconditioning with hyperbaric oxygen (HBO) on spinal cord ischemia-reperfusion injury (I/R) in rabbits. Methods Forty-five New Zealand rabbits aged 4-5 months weighing 2.0-2.5 kg were randomly divided into 5 groups: group S, sham operation ( n = 5);group IR, spinal cord I/R injury (n = 10);group H_(1～3) , the animals were pretreated with 100% O_2 at 2.5 ATA 1 h/d for 5 (group H_1 ), 10 (group H_2 ) , or 20 (group H_3 ) consecutive days respectively 24 h before spinal cord I/R. The animals were anesthetized with iv pentobarbital sodium 30 mg/kg. The artery in the ear and left femoral artery were cannulated for proximal and distal mean blood pressure monitoring. Spinal cord ischemia was produced by cross-clamping of abdominal aorta distal to renal artery for 20 min. Hind-limb motor function was assessed at 48 h after reperfusion according to the modified criteria established by Tarlov (0 = no spontaneous movement, 4= normal motor function) . The animals were then killed and the L_5 segment of the spinal cord was removed for detection of neuronal survival (by HE staining), apoptosis (by TUNEL) and degeneration (by Fluoro-Jade B staining). Results Preconditioning with 5 or 10 d of HBO improved the hind-limb motor function and preserved more normal neurons in the spinal cord after I/R injury. Both apoptotic and degenerative cell death were attenuated in H_1 and H_2 groups. There was no significant difference in hind-limb motor dysfunction and the number of normal neurons in the lumbar spinal cord between H_3 group and I/R group. Conclusion Preconditioning with 5 d or 10 d HBO induces tolerance against spinal cord I/R injury, whereas preconditioning with 20 d of HBO fails to protect the spinal cord from I/R injury.