Abstract
Few studies have investigated the role calcitonin gene-related peptide (CGRP) plays in the process of spinal fusion. The aim of the present study is to observe the temporal and spatial changes of CGRP induced by experimental fusion surgery in rats and elucidate the role of CGRP in spinal fusion. Male Sprague-Dawley rats were used in the study and the specimens were collected on the 7th, 14th, 21st, and 28th day, respectively. Then, histological and immunohistochemical analysis were applied to evaluate the fusion mass and spatiotemporal changes of CGRP chronologically. The results demonstrated that density of CGRP reached peak on the 21st day after surgery and most of the CGRP expression located surrounding the interface of allograft and fibrous tissue where the cells differentiate into osteoblasts, indicating that CGRP might be involved in the process of bone formation and absorption.
Highlights
The process of bone regeneration and remodeling has been extensively studied, but the mechanism of bone repair after spinal fusion surgery is poorly understood
On the 28th day after spinal fusion surgery, besides the fibrous tissues, new cartilage formed along the ventral side of the allograft with bone marrow cavities (Figure 1)
The present study demonstrated that Calcitonin gene-related peptide (CGRP)-positive nerve fibers could be observed on day 7 and continued on a high level until day 21, suggesting that CGRP potentially plays a role in promoting hematoma absorption, fibrous tissue formation, and angiogenesis
Summary
The process of bone regeneration and remodeling has been extensively studied, but the mechanism of bone repair after spinal fusion surgery is poorly understood. Bone modelling is regulated by regional factors, for instance, various growth factors and cytokines [3,4,5]. Increasing evidences reveal that the process of bone regeneration and remodeling is closely related to nerve fiber innervation [6]. Autonomic, sensory, and opioid neuropeptides have been investigated and found to regulate bone metabolism through specific receptors. CGRP is reported to act as a regulatory factor in bone metabolism [8] and to be involved in angiogenesis [9] during bone repair. The presence of CGRP-positive nerve fibers would increase callus formation and bone repair during spinal fusion [10]
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