Study On The Expression And Role Of CGRP And OPG/RANKL In Different Degrees Of Traumatic Craniocerebral Injury Complicated With Femoral Fracture In Rats

Objective: To explore the expression changes of calcitonin gene-related peptide(CGRP)and osteoprotegerin(OPG)/ receptor activator of nuclear factor-κ B ligand(RANKL)system in rats with different degrees of traumatic brain injury(TBI)complicated with femoral fracture,and to further analyze the effect of different degrees of TBI on fracture healing and its molecular mechanism.Methods: The rat models of TBI with femoral fracture in different degrees(mild,moderate and severe)were divided into 5 groups according to neurological severity score(NSS): mild TBI with left femoral fracture group,moderate TBI with left femoral fracture group,severe TBI with left femoral fracture group,simple left femoral fracture group and sham operation group.After successful modeling,ELISA technique was used to detect the expression level of CGRP and OPG/RANKL system in serum of rats in each group,X-ray and HE staining were used to detect fracture healing,fracture healing score was used to evaluate the speed of fracture healing,and the volume of callus was measured by vernier caliper.Results: A total of 100 male rats were included in the statistical analysis.Compared with the sham operation group,the concentration of serum CGRP and OPG and the ratio of OPG/RANKL in mild TBI with femoral fracture group and simple femoral fracture group slightly increased(P<0.05),while the serum CGRP and OPG concentration and OPG/RANKL ratio increased significantly in moderate and severe TBI with femoral fracture group(P<0.05).Compared with mild TBI with femoral fracture group and simple femoral fracture group,the concentration of serum CGRP and OPG and the ratio of OPG/RANKL in moderate and severe TBI with femoral fracture group increased significantly(P<0.05),the volume of callus formed at the fracture site increased(P<0.05),and the healing time shortened(P<0.05).Compared with the simple femoral fracture group,the concentration of serum CGRP and OPG and the ratio of OPG/RANKL in the mild TBI with femoral fracture group were similar,but there was no significant difference in callus volume and healing time between the mild femoral fracture group and the simple femoral fracture group(P>0.05).Conclusion: Moderate and severe TBI can effectively promote callus growth and shorten fracture healing time,which may be related to the increase of serum CGRP concentration and OPG/RANKL expression ratio.