中枢和周围神经损伤对降钙素基因相关肽含量及骨折愈合的影响

摘要

目的 研究骨折合并中枢和周围神经损伤后大鼠的血浆、脊髓前角运动神经元及背根神经节中降钙素基因相关肽(calcitonin gene-related peptide,CGRP)的含量变化及对骨折愈合的影响. 方法 健康成年SD大鼠72只,随机平均分成4组:左侧胫骨骨折组(A组)、左侧坐骨神经损伤+左侧胫骨骨折组(B组)、T9-11脊髓横断+左侧胫骨骨折组(C组)和右侧大脑皮层损伤+左侧胫骨骨折组(D组).每组大鼠于伤后即刻、2 d、1周、2周及4周,放射免疫法测定血清中CGRP含量;于伤后1周、2周及4周对骨折处拍摄x线片,放射免疫法测定脊髓前角运动神经元及背根神经节中CGRP含量;2周取骨折局部骨痂做HE染色. 结果 各组大鼠1周及2周X线片骨折线清晰,4周除B组外,其余各组骨折线消失.2周HE染色显示骨痂量变化:B组少于A组;C组及D组多于A组.各组大鼠在血清中及脊髓前角运动神经元中各时间点CGRP含量变化差异无统计学意义(P>0.05).在脊髓背根神经节中CGRP含量变化:1周时,B组及D组与A组比较,差异无统计学意义(P>0.05),C组低于A组(P<0.01);2周时,B组及D组与A组比较,差异无统计学意义(P>0.05),但D组高于B组(P<0.05),C组高于A组(P<0.01);4周时,与A组比较,其余各组大鼠CGRP含量均升高,其中C组最明显(P<0.01). 结论 骨折合并周围神经损伤后,骨折愈合慢,而骨折合并脊髓损伤及大脑皮层损伤后,骨折愈合快,提示合并中枢损伤能促进骨折愈合,此现象可能与CGRP有一定的相关性.%Objective To investigate the changes of calcitonin gene-related peptide (CGRP) in rat' s blood plasma, spinal anterior motorneuron and dorsal root ganglion (DRG) after fractures combined with central or peripheral nerve injuries and possible influence on fracture healing. Methods A total of 72 healthy adult SD rats were divided into four groups, ie, left tibial fracture group (Group A), left tibial fracture combined with left sciatic nerve injury group (Group B), left tibial fracture combined with T9-11 spinal cord transection injury group (Group C) and left tibial fracture combined with right cerebral cortex injury group (Group D). The concentration of serum CGRP was measured by radioimmunoassay immediately, 1, 2 and 4 weeks after injury. The concentration of serum CGRP in spinal anterior motor-neuron and dorsal root ganglion was measured and X ray photograph taken at 1,2 and 4 weeks after inju-ry. Bony callus was collected at 2 weeks after injury for HE staining. Results The fracture line was still clear on X-ray of all groups 1 and 2 weeks after injury but disappeared with complete healing four weeks after injury in all groups except for Group B. Two weeks after injury, HE staining showed less bony callus contents in Group B than that of Group A but more bony callus contents in Groups C and D than that of Group A. CGRP concentration in blood plasma and spinal anterior motorneuron represented no apparentstatistical difference among all groups at each time point (P>0.05). Changes of CGRP con-centration in dorsal root ganglion were as follows: one week after injury, there was no apparent statistical difference in Groups B and D compared with Group A (P > 0.05), but Group A showed more CGRP than Group C (P <0.01); two weeks after injury, there was no apparent statistical difference in Groups B and D compared with Group A(P > 0.05), but CGRP in Group D was more than that in Group B (P < 0.05) and CGRP in Group C more than Group A (P <0.01); four weeks after injury, CGRP concentration was elevated in all groups especially Group C compared with Group A (P < 0.01). Conclusions When fracture is combined with peripheral nerve injury, the healing process can be slowed down. In contrast, fracture combined with spinal'injury and cerebral cortex injury will accelerate healing process, when CGRP may exert positive effect.