Institute of Liberal Arts and Sciences, Tokushima University, Tokushima, Japan.
Student Lab, Tokushima University Faculty of Medicine, Tokushima, Japan.
PLoS One. 2016 Apr 21;11(4):e0154167. doi: 10.1371/journal.pone.0154167. eCollection 2016.
Extremely low-frequency magnetic fields (ELF-MFs) are generated by power lines and household electrical devices. In the last several decades, some evidence has shown an association between ELF-MF exposure and depression and/or anxiety in epidemiological and animal studies. The mechanism underlying ELF-MF-induced depression is considered to involve adrenal steroidogenesis, which is triggered by ELF-MF exposure. However, how ELF-MFs stimulate adrenal steroidogenesis is controversial. In the current study, we investigated the effect of ELF-MF exposure on the mouse adrenal cortex-derived Y-1 cell line and the human adrenal cortex-derived H295R cell line to clarify whether the ELF-MF stimulates adrenal steroidogenesis directly. ELF-MF exposure was found to significantly stimulate adrenal steroidogenesis (p < 0.01-0.05) and the expression of adrenal steroid synthetic enzymes (p < 0.05) in Y-1 cells, but the effect was weak in H295R cells. Y-1 cells exposed to an ELF-MF showed significant decreases in phosphodiesterase activity (p < 0.05) and intracellular Ca2+ concentration (p < 0.01) and significant increases in intracellular cyclic adenosine monophosphate (cAMP) concentration (p < 0.001-0.05) and cAMP response element-binding protein phosphorylation (p < 0.05). The increase in cAMP was not inhibited by treatment with NF449, an inhibitor of the Gs alpha subunit of G protein. Our results suggest that ELF-MF exposure stimulates adrenal steroidogenesis via an increase in intracellular cAMP caused by the inhibition of phosphodiesterase activity in Y-1 cells. The same mechanism may trigger the increase in adrenal steroid secretion in mice observed in our previous study.
极低频磁场（ELF-MF）由电力线和家用电器设备产生。在过去的几十年中，一些证据表明，在流行病学和动物研究中，ELF-MF 暴露与抑郁和/或焦虑之间存在关联。ELF-MF 诱导抑郁的机制被认为涉及肾上腺类固醇生成，这是由 ELF-MF 暴露引发的。然而，ELF-MF 如何刺激肾上腺类固醇生成仍存在争议。在当前的研究中，我们研究了 ELF-MF 暴露对小鼠肾上腺皮质衍生的 Y-1 细胞系和人肾上腺皮质衍生的 H295R 细胞系的影响，以阐明 ELF-MF 是否直接刺激肾上腺类固醇生成。研究发现，ELF-MF 暴露显著刺激 Y-1 细胞中的肾上腺类固醇生成（p < 0.01-0.05）和肾上腺类固醇合成酶的表达（p < 0.05），但对 H295R 细胞的影响较弱。暴露于 ELF-MF 的 Y-1 细胞显示出磷酸二酯酶活性的显著降低（p < 0.05）和细胞内 Ca2+浓度的显著降低（p < 0.01），以及细胞内环腺苷酸（cAMP）浓度的显著增加（p < 0.001-0.05）和 cAMP 反应元件结合蛋白磷酸化（p < 0.05）。用 NF449 处理不能抑制 cAMP 的增加，NF449 是 G 蛋白 Gs alpha 亚基的抑制剂。我们的结果表明，ELF-MF 暴露通过抑制 Y-1 细胞中磷酸二酯酶活性导致细胞内 cAMP 增加来刺激肾上腺类固醇生成。同样的机制可能触发我们之前的研究中观察到的小鼠肾上腺类固醇分泌增加。
