失神经支配兔下颌骨骨折愈合过程中CGRP对OPG/RANKL表达的影响

目的明了失神经支配兔下颌骨骨折愈合过程中CGRP对OPG/RANKL表达的影响及其调节骨折愈合的机制.方法 40只新西兰白兔随机分为:单纯下颌骨骨折组及下齿槽神经离断 下颌骨骨折组.分别于骨折术后7、14、21、28 d处死,取骨痂标本行HE及免疫组织化学染色.结果单纯骨折组骨折后7 d骨痂中即可见到降钙素基因相关肽(CGRP)阳性神经纤维,沿血管分布,14、21 d在编织骨边缘有大量的CGRP阳性神经纤维,28 d仍较多.同时骨折后7 d 骨保护素(OPG)强阳性表达,以后逐渐下降,但均保持较高水平的表达.破骨细胞分化因子(RANKL)的表达高峰则在骨折后第14天;而失神经骨折组除7 d骨痂中见CGRP阳性表达外,7 d后骨痂中仅有极低水平的CGRP表达.同样,OPG在骨折后7 d在骨痂中阳性表达以后持续弱阳性表达.RANKL则持续强阳性表达.结论在骨折愈合过程中,CGRP能够上调OPG/RANKL的表达量的比值,从而参与骨折愈合过程的调节,失神经支配失去了CGRP对OPG/RANKL表达的调节作用,不利于骨折愈合.

Study of changes of OPG and RANKL expression in denervated rabbits

Objective To investigate the changes of the expression of osteoprotegerin (OPG) and receptor activator nuclear factor kappa B ligand (RANKL) during the healing of mandibular fracture after the transection of the inferior alveolar nerve (IAN) in rabbits. Methods Forty rabbits were randomly divided into 2 groups and each group consisted of 20 animals. The rabbits of the first group underwent mandibular fracture and transection of IAN and those of the second group underwent mandibular fracture only. The rabbits were killed at 7, 14, 21, 28 day after fracture. The callus tissue of the rabbits was collected and paraffin sections of the callus tissue were prepared. The callus sections were subjected to HE staining. The effects of calcitonin gene-related peptide (CGRP) on the expression of OPG and RANKL were observed with immunohistochemical staining. Results There were only a few CGRP immunoreactive nerve fibers at day 7 after IAN section. Low level of OPG expression was found throughout the repair process but RANKL was intensively expressed in the rabbits of the first group. Conclusion CGRP can up-regulate the expression ratio of OPG/RANKL and promote the healing process of fracture. The loss of CGRP is unfavorable to bony healing.