title: Enhanced secretion of prostaglandin E2 from osteoblasts by exposure to a strong static magnetic field.
abstract: Exposure to static magnetic fields (SMFs) has been reported to promote osteoblast differentiation in vitro, and increase bone formation in vivo and in clinical studies. Prostaglandins respond early to exogenous mechanical loading, and play an important role in bone formation. In this study, we investigated whether exposure to a strong SMF affects prostaglandin E(2) (PGE(2)) secretion from a mouse osteoblastic cell line, MC3T3-E1. We also investigated the PGE(2)-synthesizing enzyme, cyclooxygenase 2 (Cox-2), and translocation of the transcription factor nuclear factor kappa B (NF-kappaB), which is involved in the induction of Cox-2 expression. In the SMF exposures, experiments were performed at the 10 T-exposure position, at which the magnetic flux density was highest, and at the 6 T-exposure position, at which the magnetic field gradient was highest (41.7 T/m). PGE(2) secretion was not affected by exposure at the 10 T-exposure position compared to sham-exposure, but was enhanced at the 6 T-exposure position (about 1.5-fold). Similarly, Cox-2 expression and NF-kappaB translocation were not enhanced at the 10 T-exposure position, but increased at the 6 T-exposure position (about twofold, two- to threefold, respectively). These findings suggested that exposure to a high magnetic field gradient induced secretion of PGE(2) and expression of the Cox-2 protein, which was mediated through increased translocation of NF-kappaB.
authors.affiliation: Department of Radiological Life Sciences, Division of Medical Life Sciences, Graduate School of Health Sciences, Hirosaki University, Hirosaki, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Sakurai
authors.forename: Shingo
authors.initials: S
authors.lastname: Terashima
authors.forename: Junji
authors.initials: J
authors.lastname: Miyakoshi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism* / Q000528:radiation effects*; D011829:Radiation Dosage
chemical_list: D016328:NF-kappa B; D051546:Cyclooxygenase 2; D015232:Dinoprostone