OBJECTIVETo explore the relationship between differential activation of mitogen-activated protein kinase (MAPK) signal transduction system and apoptosis in PC12 cells induced by electromagnetic irradiation.

METHODSCultured PC12 cells were exposed to 65 mW/cm(2) electromagnetic wave for 20 min. The PC12 cells apoptosis was detected by flow cytometry 0, 3, 12, 24 h after electromagnetic irradiation. The phosphorylations of ERK1/2, JNK and P38 MAPK were tested by Western-blot.

RESULTSElectromagnetic irradiation induced apoptosis in PC12 cells soon after irradiation. The apoptotic rate of PC12 cells increased to about 23.5% at 3 h. But compared with that at 3 h, there was no significant difference in the apoptotic rate at 12 h (P > 0.05). The apoptotic rate of PC12 cells increased sharply again at 24 h. After exposure to electromagnetic irradiation, the phosphorylations of ERK1/2 and JNK increased significantly. The increased phosphorylation of ERK1/2 lasted for 3 hours, but of JNK lasted for 12 hours, and 24 hours after irradiation. The phosphorylation of both ERK1/2 and JNK were significantly lower than that of control. The phosphorylation of P38 MAPK was always higher after electromagnetic irradiation, and there were two phosphorylation peaks at 3 h and 24 h.

CONCLUSIONThe electromagnetic irradiation can induce the activation of MAPK signal transduction system, and ERK1/2, JNK, P38 MAPK showed differential activation. The differential activation of MAPKs may play an important role in the apoptosis of PC12 cells induced by electromagnetic irradiation.