Chronic exposure to an extremely low‐frequency magnetic field induces depression‐like behavior and corticosterone secretion without enhancement of the hypothalamic–pituitary–adrenal axis in mice

An extremely low‐frequency magnetic field (ELF‐MF) is generated by power lines and household electrical devices. Many studies have suggested an association between chronic ELF‐MF exposure and anxiety and/or depression. The mechanism of these effects is assumed to be a stress response induced by ELF‐MF exposure. However, this mechanism remains controversial. In the present study, we investigated whether chronic ELF‐MF exposure (intensity, 3 mT; total exposure, 200 h) affected emotional behavior and corticosterone synthesis in mice. ELF‐MF‐treated mice showed a significant increase in total immobility time in a forced swim test and showed latency to enter the light box in a light–dark transition test, compared with sham‐treated (control) mice. Corticosterone secretion was significantly high in the ELF‐MF‐exposed mice; however, no changes were observed in the amount of the adrenocorticotropic hormone and the expression of genes related to stress response. Quantification of the mRNA levels of adrenal corticosteroid synthesis enzymes revealed a significant reduction in Cyp17a1 mRNA in the ELF‐MF‐exposed mice. Our findings suggest the possibility that high intensity and chronic exposure to ELF‐MF induces an increase in corticosterone secretion, along with depression‐ and/or anxiety‐like behavior, without enhancement of the hypothalamic–pituitary–adrenal axis. Bioelectromagnetics 34:43–51, 2013. © 2012 Wiley Periodicals, Inc.