Expression and significance of neuropeptides in callus of rats after brain injury and tibial fracture / 中国组织工程研究

ABSTRACT

AIM:It is suggested that the peptidergic nerves containing substance P(SP),calcitonin gene-related peptide(CGRP),vasoactive intestinal peptide(VIP),neuropeptide Y(NPY) and tyrosine hydroxylase(TOH) co-exist in bone tissues and distribute in the active bone metabolism area,indicating these peptidergic nerves are closely related with bone growth and development. In this study,the expression of neuropeptides in tibial callus of rats after brain injury was observed. METHODS:The experiment was conducted in the Experimental Animal Center of Guangxi Medical University from February to May 2007. ①130 male Wistar rats of 3-4 months old and 450-550 g were randomly divided into fracture group(n =60),brain injury plus fracture group(n =60) and control group(n =10). ②The right parietal bone of anesthetized rats was exposed,and bone window of 5 mm was opened 2 mm near median line,then moderate brain injury was made by sap pressure,and the rat models of tibial fracture were established. The fracture group was only subjected to cranial bone window,and the control group was not given any treatment. ③The distribution of neuropeptide in tibia and callus succession as well as fracture healing were observed by HE and immunohistochemical staining on postoperatively days 3,7,14,21,28,and 35 days. The callus area in brain injury plus fracture group and fracture group was detected by computed radiography(CR) at 14,21 and 28 days after operation. RESULTS:All 130 rats were involved in the result analysis. ①At early stage after brain injury,there were a quantity of fibrous callus and cartilaginous callus formation in brain injury and fracture group and many neuropeptides immunoreactive nerve fibers in callus were found. Strong immunoreactivites of CGRP,SP,VIP,NPY,TOH occurred to osteogenitor cells and chondroblast,which proliferated in thickened endothecium. ②In brain injury and fracture group on day 14,the chondrocyte group was enlarged and subperiosteum chondrocyte layer was thickened;on day 21,bone trabecula was significantly thickened,and cartilage islands were increased;on day 28,there were still quantity of fibrous callus and cartilaginous callus,and sparse woven bones surrounding chondrocyte groups. In fracture group,periosteal reaction was slight,and fibrous callus was few;osteogenesis in bone and cartilage occurred,but mainly in bone. Moreover,the fracture healing was remarkably later than brain injury and fracture group. ③Callus area in brain injury and fracture group was larger than that in fracture group on days 14 and 21(P