运动训练对高血压大鼠脑缺血后锥体束再生的影响

Effects of physical training on pyramidal tract regeneration in hypertensive rats with focal cerebral infarction

目的 观察运动训练对脑缺血高血压大鼠运动功能恢复及锥体束再生的影响.方法 采用电凝法建立易卒中型肾血管性高血压大鼠单侧大脑中动脉闭塞（MCAO）模型,随机数字表法分为3组：假手术组（n=15）、运动训练组（n=10）、对照组（n=12）.采用改良神经功能缺陷评分（mNSS）和抓力测试评估术后3、7、14、21、28、35、42 d脑缺血大鼠的神经功能情况;尼氏染色法观察梗死灶周围神经元的病理变化;脑缺血后42 d经皮质注射顺行神经示踪剂生物素化葡聚糖胺（BDA）和Cascade Blue标记的葡聚糖胺（CB）,注射14 d后分别观察梗死同侧和对侧锥体束的神经纤维延伸情况.结果 脑缺血28、35、42 d,运动训练组mNSS评分[（4.0±1.1.2.7±0.7,2.6±0.5）分]较相同时间点对照组[（6.0±1.3,5.6±1.0,5.6±1.1）分]降低（均P＜0.01）.脑缺血后14、21、28、35、42 d,运动训练组大鼠的患肢抓力[（379±41,344±15,430±48,471±47,454±17）g]较相同时间点对照组[（276±8,170±5,236±12,283±14,317±15）g]提高（均P＜0.05）.与对照组（0.571±0.060）相比,运动训练（0.734±0.035）可减少神经元的丧失（P＜0.05）.运动训练组（0.096 8±0.022 6）BDA标记的颈膨大跨中线纤维/注射点同侧大脑脚基底部纤维百分率高于对照组（0.014 2±0.003 9）（P＜0.016 7）.对照组（0.521±0.020）与运动训练组（0.499±0.034）的梗死侧纹状体/梗死侧皮质CB荧光比例均低于假手术组（0.824±0.017）（均P＜0.01）,但对照组与训练组之间差异无统计学意义（P＞0.05）.结论 运动训练可促进高血压大鼠脑缺血后功能恢复和健侧锥体束再生.

Objective To explore the effects of exercise training on motor functional recovery and pyramidal tract regeneration in hypertensive rats with focal cerebral infarction.Methods Middle cerebral artery occlusion （MCAO） model was generated by electric coagulation on stroke-prone renovascular hypertensive Sprague-Dawley rats.The rats were randomly allocated to three groups of sham （n =15）,exercise training （n =10） and control （n =12）.The exercise training group had running wheel exercise.The neurological function was evaluated with the modified neurological severity scores（mNSS） and forelimb grip strength test at Days 3,7,14,21,28,35 and 42 post-ischemia.The pathological changes of neurons around infarct cortex were measured by Nissl staining.At Day 42 post-ischemia,anterograde tract tracers of biotinylated dextran amine （BDA） and cascade blue-labeled dextran amine （CB） were injected into cortex.And axonal extension of ipsi-and contra-lesional pyramidal tract was observed at Day 14 postinjection.Results The mNSS score declined in the exercise training group （4.0 ± 1.1,2.7 ± 0.7,2.6 ±0.5）versus those in the control group（6.0 ± 1.3,5.6 ± 1.0,5.6 ± 1.1）at Days 28,21 and 35 postischemia （all P 〈 0.01）.The grip strength of paralytic forelimb increased in the exercise training group （（379 ±41,344 ± 15,430 ± 48,471 ± 47,454 ± 17） g） versus those in the control group （（276 ± 8,170 ± 5,236 ± 12,283 ± 14,317 ± 15） g） at Days 14,21,28,35 and 42 post-infarction （all P 〈 0.05）.Compared with the control group（0.571 ±0.060）,exercise training （0.734 ±0.035） reduced neuron loss （P 〈 0.05）.Moreover,the percentage of the number of BDA-positive,midline-crossing fibers over the number of labeled fibers in cerebral peduncle ipsilateral to injection site increased in the exercise training group （0.096 8 ±0.022 6） versus those in the control group （0.014 2 ±0.003 9） at the level of cervical enlargement （P 〈 0.016 7）.The percentage of CB immunofluorescence in striatum ipsilateral to lesion-sided motor cortex over those in ischemic cortex was lower in the control group （0.521 ± 0.020）and the exercise training group（0.499 ±0.034）than that in the sham group（0.824 ±0.017） （all P 〈0.01）.However,no significant difference existed between control and exercise training groups （P 〉 0.05）.Conclusion Exercise training promotes the recovery of motor function and contralesional pyramidal tract regeneration after cerebral infarction.