人组织激肽释放酶对大鼠坐骨神经挤压伤后神经形态学及氧自由基的影响

Effects of human tissue kallikrein on nerve morphology and oxygen radicals in rats' crushed sciatic nerve

目的:评价人组织激肽释放酶(HTK)对SD大鼠坐骨神经挤压伤模型坐骨神经的形态学及氧自由基水平的影响。方法:取60只体质量为180～200 g的SD大鼠,随机分成3组(n=20):假手术组(Sham组),只分离坐骨神经不压迫损伤,不给予任何药物治疗;人组织激肽释放酶组(HTK组),坐骨神经挤压伤后半小时以及术后每日尾静脉注射17.5×10-3 PNAU/kg HTK治疗;对照组,坐骨神经挤压伤后半小时以及术后每日尾静脉注射等量的0.9%氯化钠溶液。随机抽取5只大鼠取受损段神经行光镜观察有髓神经纤维的数目和形态,另随机抽取5只大鼠坐骨神经电镜下观察神经形态学以及雪旺细胞(SCs)的凋亡情况,剩余10只大鼠取坐骨神经行丙二醛(MDA)含量和总超氧化物歧化酶(SOD)活性的测定。结果:与对照组相比,HTK组SOD活性较高(P<0.05),MDA含量则较低(P<0.05);术后14 d光镜观察,与HTK组相比,对照组神经纤维排列紊乱;术后14 d电镜观察,对照组神经纤维髓鞘水肿、神经纤维内部分细胞器水肿明显,并有大量SCs凋亡,而HTK组较对照组明显改善,且未观察到SCs凋亡。结论:HTK具有改善神经周围微环境,调节局部氧自由基水平,和促进周围神经系统损伤后修复的作用。

Objective： To evaluate the effect of human tissue kallikrein （HTK） on morphological changes ofthe sciatic nerve and the level of oxygen free radicals in sciatic nerve crush injury model. Methods： Sixty SD rats were randomly divided into three groups （n=20）： Sham group underwent a sham operation without crush and agent administration, human tissue kallikrein treated group （HTK group） received vena caudalis injections of HTK 17.5 ×10^-3 PNAU/kg 30 min after nerve crush and then daily for the following 13 days, and the control group received injection of saline with the same protocol as HTK group. Five rats were randomly selected to observe the number and morphology of myelinated nerve fibers of the damaged nerve under light microscope. Five rats were randomly selected to observe neural morphology and apoptosis of a large number of Schwann cells （SCs） in the sciatic nerve under electron microscope, the remaining ten rats＇ sciatic nerve line were taken to measure malondialdehyde （MDA） content and total superoxide dismutase （SOD） activity. Results： SOD activity of the HTK group was higher than that of the control group, and MDA content of the HTK group was lower than that of the control group. Disordered arrangement of nerve fibers, nerve fiber myelin edema, nerve fibers within organelles edema, and a large number of SCs apoptosis were observed in the control group in 14 days after surgery. But the HTK group was better than the control group, and the SCs apoptosis was not observed in the HTK group. Conclusion： The HTK is effective in promoting sciatic never recovery after nerve injury, and the possible mechanism is perineural microenvironment improvement and local regulation of the level of oxygen free radicals.