脑外伤对大鼠骨折愈合过程中OPG/RANKL表达的影响

目的研究股骨骨折合并脑外伤大鼠骨痂中骨保护素（OPG）和核因子-KB受体活化因子配体（RANKL）的表达变化,探讨脑外伤对骨折愈合的影响及作用机制。方法48只雌性SD大鼠随机分成骨折合并脑外伤组和单纯骨折组,每组24只。建立大鼠开放骨折及脑外伤模型,术后7、14、21、28d4个时间点分批处死动物,标本切片后通过HE染色观察骨折愈合情况,免疫组织化学染色研究OPG和RANKL的表达变化。结果HE染色示单纯骨折组呈典型骨折愈合过程,而骨折合并脑外伤组骨痂形成及改造提前,骨折愈合加速。免疫组织化学染色显示OPG在骨折合并脑外伤组表达增强,术后各时间点OPG平均光密度值（OD值）均高于同一时间点单纯骨折组,差异有统计学意义（P〈0.05）。RANKL在骨折合并脑外伤组表达变化不显著,其OD值仅术后21d1个时间点高于单纯骨折组（P〈0.05）。骨折合并脑外伤组术后各时间点OPG与RANKL OD值的比值均高于同一时间点单纯骨折组,差异有统计学意义（P〈0.05）。结论脑外伤对骨折愈合有促进作用,可能与合并脑外伤后OPG和RANKL表达变化有关。

EFFECT OF BRAIN INJURY ON THE EXPRESSION OF OPG AND RANKL IN THE PROCESS OF FRACTURE HEALING IN RATS

Objective To investigate the change in the expression of osteoprotegerin （OPG） and receptor activator of nuclear factor-κB ligand （RANKL） in bone callus of rats with femoral fracture and brain injury so as to explore the effect of the brain injury on fracture healing and to explore the related mechanism. Methods Female SD rats were randomly divided into the fracture with brain injury group （n=24）, and the pure fracture group （n= 24） . Open fracture and brain injury models of rats were established. The animals were sacrificed at 4 time points （7, 14, 21 and 28 day ） after operation. After callus specimens were sectioned, the information of fracture healing was observed by HE staining and the expressions of OPG and RANKL were detected by immunohistochemical staining. Results HE staining indicated that the process of fracture healing in the pure fracture group was classical, but the callus formation and reforming in the fracture with brain injury group were ahead of schedule, and fracture healing was accelerated. Immunohistochemical staining showed that the expression of OPG in the fracture with brain injury group was enhanced. At all time points after operation, the average optical density （OD） value of OPG was higher in the fracture with brain injury group than in the pure fracture group at the same time point, with a statistically significant difference （P〈0. 05 ） . The expression of RANKL in the fracture with brain injury group was quiet. Only at one time point （21 day） was the OD value of RANKL higher in the fracture with brain injury group than in the pure fracture group （P〈0.05） . The ratio of OPG/RANKL OD value was higher in the fracture with brain injury group than in the pure fracture group at all time points, with a statistically significant difference （P〈0. 05） . Conclusion Brain injury can promote the fracture healing process, which is probably related to a change in the expression of OPG and RANKL after the brain injury.