title: Effects of different magnitudes of mechanical strain on Osteoblasts in vitro.
abstract: In addition to systemic and local factors, mechanical strain plays a crucial role in bone remodeling during growth, development, and fracture healing, and especially in orthodontic tooth movement. Although many papers have been published on the effects of mechanical stress on osteoblasts or osteoblastic cells, little is known about the effects of different magnitudes of mechanical strain on such cells. In the present study, we investigated how different magnitudes of cyclic tensile strain affected osteoblasts. MC3T3-E1 osteoblastic cells were subjected to 0%, 6%, 12% or 18% elongation for 24h using a Flexercell Strain Unit, and then the mRNA and protein expressions of osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANKL) were examined. The results showed that cyclic tensile strain induced a magnitude-dependent increase (0%, 6%, 12%, and 18%) in OPG synthesis and a concomitant decrease in RANKL mRNA expression and sRANKL release from the osteoblasts. Furthermore, the induction of OPG mRNA expression by stretching was inhibited by indomethacin or genistein, and the stretch-induced reduction of RANKL mRNA was inhibited by PD098059. These results indicate that different magnitudes of cyclic tensile strain influence the biological behavior of osteoblasts, which profoundly affects bone remodeling.
authors.affiliation: Department of Orthodontics, College of Stomatology, The Fourth Military Medical University, Xi'an Shaanxi 710032, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Tang
authors.forename: Zhu
authors.initials: Z
authors.lastname: Lin
authors.forename: Yong-ming
authors.initials: YM
authors.lastname: Li
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D005419:Flavonoids / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D007213:Indomethacin / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D053244:Osteoprotegerin; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D053245:RANK Ligand; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism*; D013718:Tensile Strength / Q000187:drug effects
chemical_list: D002352:Carrier Proteins; D005419:Flavonoids; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D047428:Protein Kinase Inhibitors; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D019833:Genistein; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D007213:Indomethacin