制动与失神经对兔胫骨生物力学性能及降钙素基因相关肽表达的对比研究

Contrastive study of the effect of immobilization and denervation on the biomechanical properties and calcitonin gene-related peptide expression of the rabbit tibia

目的:对比研究后肢制动与坐骨神经离断对兔胫骨骨强度、骨密度及降钙素基因相关肽(calcitonin gene-related peptide,CGRP)含量的影响,比较神经学因素和力学因素对维持骨量并防止骨质疏松,哪个因素更为重要。方法:采用随机数表法将18只新西兰大耳白兔分为制动组、失神经组和正常组,每组6只,制动组用石膏管状固定左后肢;失神经组对左侧后肢手术切断坐骨神经取下1cm,造成其坐骨神经SunderlandⅤ级损伤;正常组不做任何处理。造模后安静饲养28d取兔左侧胫骨,采用三点弯曲力学试验观察骨强度,双能X线骨密度检测仪观察骨密度,免疫组化检测CGRP表达。结果:(1)骨强度:与正常组比较,制动组和失神经组的兔胫骨骨强度明显降低,差异有显著性意义(P<0.05);与失神经组相比,制动组兔胫骨骨强度稍有降低,但差异无显著性意义(P>0.05);(2)骨密度:与正常组比较,制动组和失神经组的兔胫骨骨密度明显降低,差异有显著性意义(P<0.05);与失神经组相比,制动组兔胫骨骨强度稍有降低,但差异无显著性意义(P>0.05);(3)CGRP:与正常组比较,制动组和失神经组的兔胫骨CGRP表达明显降低,差异有显著性意义(P<0.05);与制动组相比,失神经组兔胫骨CGRP表达稍有降低,但差异无显著性意义(P>0.05)。结论:(1)制动和失神经均会降低兔胫骨强度、密度及CGRP表达水平,且两者之间差异无显著性意义;(2)制动与失神经对兔胫骨强度、密度的影响可能与CGRP表达水平有关;(3)力学因素对骨质的影响可能稍大,但两者之间差异无显著性意义。

Objective： To study the effect of hindlimb immobilization and sciatic nerve transaction on the bone strength, bone density and calcitonin gene-related peptide （CGRP） expression of the rabbit tibia, and to compare which is more important for maintaining bone mass and prevent osteoporosis. Method： 18 New Zealand white rabbits were randomly divided into immobilization group, denervation group and normal group with 6 rabbits in each group. The immobilization group was treated with plaster shell immobilization on the left hindlimb. The denervation group was treated with cutting off the sciatic nerve of the left hindlimb 1cm long. The normal group accept none of above treatments. 28 days after modeling, the left tibia was taken for strength evaluation with three point bending mechanics test, and bone mineral density measure with dual energy X-ray absorptiometry,and the expression of CGRP detection by immunohistochemistry. Result： ①Bone strength： compared with the normal group, the tibia bone strength of the rabbits in the immobilization group and the denervated group was significantly decreased, and the strength of the tibial bone of the rabbits in the immobilization group was slightly lower than that in the denervated group, but the difference was not statistically significant （P〉0.05）; ②Bone mineral density （BMD）： compared with the normal group, the BMD of the tibia in the immobilization group and the denervated group was significantly decreased, and those in the immobilization group was slightly lower than those in the denervated group, but the difference was not statistically significant （P〉0.05）; ③CGRP： compared with the normal group, the CGRP expression in the tibia of the rabbits in the immobilization group and the denervated group was significantly decreased, and the difference was statistically significant （P〈0.05）; compared with the immobilization group, those in the tibia of the denervated rabbits was slightly lower, but the difference was not statistically significant （P〉0.05）. Conclusion： ①Immobilization and denervation can reduced the strength, density and CGRP expression level of the rabbit tibia, and there was no significant difference between them; ②The effects of the immobilization and denervation on tibia strength and density in rabbits may be related to the expression of CGRP; ③Dynam factors for preventing osteoporosis may be slightly important, but the difference was not statistically significant.