缺氧诱导因子-1α与基质金属蛋白酶-2在慢性压迫性颈脊髓损伤大鼠模型中的表达及意义

The expression and significance of HIF-1α and MMP-2 in chronic compressive spinal cord in rat models

目的 :探讨缺氧诱导因子-1α(hypoxia inducible factor-1α,HIF-1α)和基质金属蛋白酶-2(matrix metalloproteinases-2,MMP-2)在慢性压迫性颈脊髓损伤大鼠模型中的表达及意义。方法 :将80只成年SD大鼠随机分为假手术组和慢性压迫性颈脊髓损伤组(脊髓压迫组),每组40只。大鼠麻醉后充分显露C5和C6椎板,切除C5左侧半椎板,显露硬脊膜,脊髓压迫组在C6椎板和硬脊膜之间置入吸水后可膨胀聚氨酯薄板(1×3×1mm);假手术组只显露硬脊膜不置入压迫物。两组分别通过BBB(Basso Beattie Bresnahan)评分和体感诱发电位(somatosensory evoked potential,SEP)检测评估脊髓功能;于造模后7d、28d、42d和70d时处死大鼠取颈脊髓组织进行HIF-1α及MMP-2免疫组化染色,检测其在各时间点的表达量(IOD值),采用独立样本t检验比较两组各时间点的差异,分析HIF-1α、MMP-2与脊髓功能变化的相关性。结果:造模后7d时,两组BBB评分无显著性差异;SEP潜伏期显著性延长,波幅显著性降低;HIF-1α显著性降低,MMP-2显著性升高。28d时脊髓压迫组BBB评分显著性低于假手术组,SEP潜伏期与7d比较显著性延长(P<0.05)、波幅显著性降低(P<0.05),HIF-1α表达显著性增高(P<0.05),而MMP-2表达显著性降低(P<0.05)。42d时,脊髓压迫组BBB评分、SEP潜伏期和波幅与28d时比较无显著性差异,HIF-1α表达显著性增高(P<0.05),而MMP-2表达显著性降低(P<0.05);70d时脊髓压迫组神经功能较28d时显著性改善,BBB评分显著性增高(P<0.05),SEP潜伏期显著性缩短(P<0.05)、波幅显著性升高(P<0.05);HIF-1α表达较前显著性降低,而MMP-2表达升高,但与假手术组比较仍有显著性差异(P<0.05)。HIF-1α表达量与BBB评分呈显著性负相关(r=-0.458,P<0.05),MMP-2表达量与BBB评分呈显著性正相关(r=0.903,P<0.05)。结论:大鼠慢性压迫性脊髓损伤后具有一定程度的自我修复能力,HIF-1α、MMP-2表达变化与慢性脊髓压迫性损伤后神经功能改善相关。

Objectives： To investigate the expression and significance of hypoxia inducible factor-1α（HIF-1α） and matrix metalloproteinases-2（MMP-2） in rats of chronic compressive spinal cord. Methods： Eighty adult SD rats were randomly divided into sham surgery group（n=40） and spinal cord compression group（n=40）. A C5 semi-laminectomy was performed in the sham group only, while a water-absorbable polyurethane polymer was implanted into C6 epidural space in the compression group. The Basso Beattie Bresnahan（BBB） score and somatosensory evoked potentials（SEP） were used to evaluate neurological function. The expressions of HIF-1α and MMP-2 in the cervical spinal cords of the sham group and the compression group were detected by immunohistochemistry respectively on the 7th, 28th, 42nd and 70th day after chronic spinal cord compressive injury. The variation of the expression of HIF-1α and MMP-2（IOD value） was analyzed by using the independent samples t-test. The correlation between HIF-1α, MMP-2 and neurological function after spinal cord compression was analyzed by using correlation analysis of paired samples at different time points. Results： At the 7th day, there was no difference of BBB score between the two groups（P〉0.05）. The latency of SEP was prolonged and the amplitude decreased. Immunohistochemistry showed that HIF-1α expression significantly decreased and MMP-2 expression was significantly increased（P〈0.05）. BBB score in the compression group had a significant reduction at the 28th day. Compared with the 7th day, the significantly extended latency and decreased amplitude were found in SEP at the 28th day（P〈0.05）. However, the expression of HIF-1α increased significantly and MMP-2 expression decreased at this time point（P〈0.05）. At the 42th day, there was no differences in terms of BBB score and SEP between the two groups compared with the 28th day （P〉0.05）. HIF-1α expression increased and MMP-2 expression decreased（P〈0.05）. At the 70th day, neurological function in the compression group was significantly improved compared with that at the 28th day. BBB score increased, the latency of SEP was shorter and the amplitude of SEP increased （P〈0.05）. HIF-1α expression decreased compared with before. The expression of MMP-2 increased, while there was still significantly difference compared with the sham group（P〈0.05）. The expression of HIF-1α and neurologic function were negatively correlated（r=-0.458, P=0.02）; the expression of MMP-2 and neurologic function were positively correlated（r=0.903, P〈0.05）. Conclusions： There is a certain degree of self-repair in rat models of chronic compressive spinal cord injury. The expression of HIF-1α and MMP-2 is correlated with neurological function change after chronic compressive spinal cord injury.