长期存活的小鼠脊髓缺血损伤模型的建立

Development of long-term survival spinal cord ischemia model in mice

目的制备模仿胸腹主动脉瘤术后脊髓缺血性损伤且长期存活的小鼠模型。方法夹闭胸主动脉8、10、12min，假手术组为对照组，术中测定脊髓表面血流量，多时间点测定小鼠后肢运动功能，术后7d观察小鼠脊髓切片，术后4周分析小鼠生存曲线。应用SPSS17．0软件进行数据分析。结果胸主动脉夹闭术中小鼠脊髓表面血流量降低到基础水平的（7．2±3．5）％。对照组小鼠后肢运动功能无障碍且脊髓切片正常，各手术组小鼠术后1h时后肢运动功能障碍最严重。夹闭8min可以引起后肢运动功能障碍，但2周后BBB评分恢复，与对照组比较差异有统计学意义（P〉0．05），夹闭10min可以引起持续到4周的后肢功能障碍（BBB评分和Roterod运动评分，与对照组比较差异有统计学意义（P〈0．01）和运动神经元死亡（脊髓前脚存活神经元数目与对照组比较，差异有统计学意义（P〈0．01），且小鼠能够长期存活（中位生存期为24．7d，与夹闭8min组比较，差异无统计学意义（P〉0．05），夹闭12min虽然可以引起严重的后肢运动功能障碍和神经元死亡，但长期存活的可能性小（中位生存期为14．7d，与夹闭8、10min组比较，差异有统计学意义（P〈0．01）。结论通过夹闭胸主动脉制备小鼠脊髓缺血模型，10min为最佳夹闭时间，得到的动物模型可以长期存活，有利于研究脊髓缺血损伤长时间内的动态变化。

Objective To develop long-term survival spinal cord ischemia model mimicking the injury from the surgery of thoracoabdominal aneurysm in mice. Methods Thoracic aorta was clamped for 8, 10 and 12 min via left lateral thoraeotomy. The mice subject to sham operation served as control group. The lumbar spinal cord blood flow was measured during thoracic aorta cross-clamping. Hind limbs movement function was evaluated before and 1 h, 1, 3, 5, 7 days, and 2, 4 weeks post-injury. The slices of the spinal cord were observed and survival neurons in the ventral horn were evaluated at 7th day post-inju-ry. Survival curve was analyzed at 4th week post-injury in mice. The data were statistically analyzed using SPSS 17.0 software. Results The blood flow was reduced to （7.2 ± 3.5 ） % of the baseline after crossclamping the thoracic aorta. There was no hind limbs movement functional deficit, and histological staining of the spinal cord ischemia slices was normal in the control group. There was a most serious hind limbs movement functional deficit at 1st h post-injury. The duration of 8 min cross-clamping could result in movement functional deficit, but open field Basso Beattie Bresnahan （BBB） score recovered at 2nd week postinjury （P 〉 0.05 vs. control group）. The duration of 10 min cross-clamping could result in continuous and stable hind limbs movement functional deficit at 4th week （P 〈 0.01 vs. control group for open field BBB score and latency to fall from Rota rod） and neuronal cell death （P 〈 O. 01 vs. control group for the ventral horn neurons）. Most importantly, the mice had a long term survival in 10 min group （the median survival period was 24. 7 days, P 〉0. 05 vs. 8 min group）. The duration of 12 min cross-clamping could result in less probability of long-term survival （ the median survival period was 14. 7 days, P 〈 0. 01 vs. 8 min group and 10 min group）, although it could result in serious hind limbs movement functional deficit. Conclusion Ten min was the best duration for mice spinal cord ischemia model through thoracic aorta cross-clamping. This kind of model can be used to study the dynamic changes of spinal cord ischemia because of the animals＇ long-term survival.