Effect of exposure to an extremely low frequency-electromagnetic field on the cellular collagen with respect to signaling pathways in osteoblast-like cells.
The effect of exposure to extremely low frequency-electromagnetic field (ELF-EMF: 3 mT, 60 Hz) on differentiation of mouse osteoblast-like MC3T3-E1 cells was examined together with addition of insulin-like growth factor I (IGF-I). As a marker of the differentiation, the cellular collagen content was determined by the absorbance of Sirius red-stained cells measured at the wavelength of 510-520 nm with an imaging microspectroscopy. Exposure to ELF-EMF increased significantly the collagen in the cells. Treatment with PD98059, an inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2) activation, reduced the collagen in all of the cells examined on control, IGF-I addition and ELF-EMF exposure, however, PD98059 did not prevent the increase in the collagen caused by ELF-EMF exposure, and IGF-I also increased the collagen in the presence of the inhibitor. When phosphatidylinositol 3-kinase (PI3K) pathway was inhibited by LY294002, the increase in collagen induced by ELF-EMF exposure was accelerated, however, the increase in collagen observed by IGF-I addition was suppressed. Treatment with SB203580, an inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), suppressed the increase in the collagen induced by ELF-EMF exposure, whereas IGF-I addition increased the collagen in the presence of the inhibitor. These results suggested that collagen synthesis stimulated by ELF-EMF exposure was carried out by the participation of p38 MAPK pathway, and that PI3K pathway may have the role to suppress the collagen synthesis induced by ELF-EMF exposure, and that the suppression of the PI3K pathway may allow the acceleration of the collagen synthesis.
Soda
Akira
A
Department of Physiology, Pathophysiological Preventive Medicine, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan.
Ikehara
Toshitaka
T
Kinouchi
Yohsuke
Y
Yoshizaki
Kazuo
K
D016475:3T3 Cells; D000818:Animals; D002867:Chromones / Q000494:pharmacology; D003094:Collagen / Q000378:metabolism*; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004867:Equipment Design; D005419:Flavonoids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
D002867:Chromones; D003094:Collagen; D005419:Flavonoids; D007093:Imidazoles; D007334:Insulin-Like Growth Factor I; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one