ABSTRACT
Objective To study the remodeling of alveolar bone and change in expression of forkhead box O1 (FOXO1) during orthodontic tooth movement (OTM) in rat, so as to preliminarily investigate the role of FOXO1 in alveolar bone remodeling induced by orthodontic force. Methods The rat OTM models were established and the left maxillary 1st molars were moved with force of 50 g. The rats were executed on the 1st, 3rd and 7th day of OTM, respectively. HE staining and immunohistochemical staining were used to observe the remodeling of alveolar bone in the inter-radicular region of the 1st molars and expression of FOXO1 at different time points during OTM. Results The 1st molars were constantly moved mesially under orthodontic force. There were more osteoclasts in the alveolar bone of OTM group than that in non-OTM group, and the osteoclasts on the 3rd day of OTM showed the highest activity. The number of active osteoblasts gradually increased in the inter-radicular region of alveolar bone under orthodontic force, with the enhanced osteoblast activity. Expression of FOXO1 in OTM group was elevated compared with non-OTM group. Most osteoblasts in alveolar bone during OTM were FOXO1 positive, and the expression of FOXO1 was gradually increased with the number of osteoblasts increasing. Conclusions Orthodontic force induces bone remodeling of alveolar bone in the inter-radicular region during OTM, and the change in FOXO1 expression may be related to alveolar bone remodeling during OTM.
ABSTRACT
Objective To evaluate differences in genes expression of rat bone marrow stromal cells (rBMSCs) under continuous mechanical strain by gene microarray technology．Methods rBMSCs were isolated and cultured in vitro. Continuous stresses with amplitude of 10% and frequency of 1 Hz were applied on rBMSCs for 6 hours by Flexercell mechanical loading system to investigate rBMSC gene expression profiles, and quantitative PCR was used to verify gene expression changes related to osteoblastic differentiation. Results Compared with the control group, 1 244 differentially expressed genes were found in mechanical loading group, among which 793 genes were up-regulated, while 451 genes were down-regulated．GO (gene ontology) analysis suggested that differentially expressed genes were mainly involved in multicellular organismal development, cell differentiation, chemotaxis, cell adhesion and so on. Four signaling pathways as Notch, Wnt, FGF and IGF might participate in the regulation of stress-induced osteoblastic differentiation. PCR validation results were consistent with the gene chip results. Conclusions Mechanical stress could induce osteoblastic differentiation of the BMSCs, while several differentially expressed genes screened by gene microarray may attribute to this process.