Involvement of CGRP–Positive Nerve Fibers in Consolidation Stage of Distraction Osteogenesis

Abstract

To investigate the temporal and spatial distribution of calcitonin gene-related peptide (CGRP) positive nerve fibers during the consolidation stage of distraction osteogenesis (DO), twenty New Zealand white rabbits were used for unilateral DO. Distraction started at the 7th day after osteotomy with 1 mm of length per day. The lengthening lasted for 10 days. Four rabbits were sacrificed at each of the following time point at 7-day, 14-day, 21-day, 28-day and 42-day post-distraction. The entire distraction callus and 2 mm of neighboring cortical bone on the proximal and distal sides was removed en bloc for assessments. The results showed that CGRP-positive nerve fibers were observed in the periosteal, intercortical and endocortical regions at 7-day post-distraction. After that, CGRP-positive nerve fibers were mainly found in the fibrous tissue of periosteal region and bone marrow of bony callus. Moreover, the density of CGRP innervations was significantly higher at 21-day post-distraction than that of other time point. In conclusion, the observed spatial and temporal distribution of CGRP-positive nerve fibers during consolidation stage of DO suggested CGRP innervation is associated with DO.Keywordsbonetibial lengtheningCGRP-positive nerve fibers