Comparison Of The Effects Of The Immobilization And Denervation On The Biomechanical Properties And Calcitonin Gene-Related Peptide Content Of The Rabbit Tibia

ObjectiveTo observce the effect of the sciatic nerve transaction and hindlimb immobilization on the bone strength, bone mineral density and Calcitonin gene-related peptide (CGRP) expression in the rabbit tibia and to compare the effect of passive immobilization caused by denervation and the active immobilization caused by plaster fixation on bone remodeling, so it can provide a theoretical basis for the prevention and cure of osteoporosis in clinic.MethodsRandomly divide 18 male New Zealand white rabbits were randomly divided into immobilization group, denervation group and normal group, and 6 rabbits in each group; the immobilization group used plaster tubular fixed left hind legs;denervation group was surgically exposed the sciatic nerve stem and its branches on the left hind limb and severed from 1cm, resulting in the grading of Sunderland V injury in sciatic nerve; normal group do not do any treatment.28 days after the creation of the model, the left tibia was removed. Bone strength was observed by three point bending mechanics test, bone mineral density was observed by dual energy X-ray bone density detector and CGRP expression was observed by immunohistochemistry.Results1. Bone strength Compared with the normal group, the bone strength of the rabbits tibia in the immobilization group was significantly decreased, and the difference was significant (p<0.05); compared with normal group, the bone strength of rabbit tibia in denervation group was significantly decreased, and the difference was significant (p<0.05); compared with the denervation group, the bone strength of the rabbits tibial was slightly lower than that in the immobilization group, but there was no significant difference between the two groups (p>0.05).2.Bone mineral density Compared with the normal group, the bone mineral density of the rabbits tibia in the immobilization group was significantly decreased, and the difference was significant (p<0.05); compared with normal group, the bone mineral density of rabbit tibia in denervation group was significantly decreased, and the difference was significant (p<0.05);compared with the denervation group, the bone mineral density of the rabbits tibial was slightly lower than that in the immobilization group, but there was no significant difference between the two groups (p>0.05).3. CGRP Compared with the normal group, the CGRP expression of the rabbits tibia in the immobilization group was significantly decreased, and the difference was significant (p<0.05); compared with normal group, the CGRP expression of rabbit tibia in denervation group was significantly decreased, and the difference was significant (p<0.05);compared with the denervation group, the CGRP expression of the rabbits tibial was slightly lower than that in the immobilization group, but there was no significant difference between the two groups (p>0.05).Conclusions1. The bone strength, bone mineral density and CGRP expression were both decreased by immobilization and denervation, and there was no significant difference between them;2. The effect of the immobilization and denervation on bone strength and bone mineral density of the rabbits tibia may be related to the expression of CGRP.