Biogeomagnetism Group, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China.
Int J Mol Sci. 2022 Mar 26;23(7):3622. doi: 10.3390/ijms23073622.
Previous studies have found that hypomagnetic field (HMF) exposure impairs cognition behaviors in animals; however, the underlying neural mechanisms of cognitive dysfunction are unclear. The hippocampus plays important roles in magnetoreception, memory, and spatial navigation in mammals. Therefore, the hippocampus may be the key region in the brain to reveal its neural mechanisms. We recently reported that long-term HMF exposure impairs adult hippocampal neurogenesis and cognition through reducing endogenous reactive oxygen species (ROS) levels in adult neural stem cells that are confined in the subgranular zone (SGZ) of the hippocampus. In addition to adult neural stem cells, the redox state of other cells in the hippocampus is also an important factor affecting the functions of the hippocampus. However, it is unclear whether and how long-term HMF exposure affects ROS levels in the entire hippocampus (i.e., the dentate gyrus (DG) and ammonia horn (CA) regions). Here, we demonstrate that male C57BL/6J mice exposed to 8-week HMF exhibit cognitive impairments. We then found that the ROS levels of the hippocampus were significantly higher in these HMF-exposed mice than in the geomagnetic field (GMF) group. PCR array analysis revealed that the elevated ROS levels were due to HMF-regulating genes that maintain the redox balance in vivo, such as , . Since high levels of ROS may cause hippocampal oxidative stress, we suggest that this is another reason why HMF exposure induces cognitive impairment, besides the hippocampal neurogenesis impairments. Our study further demonstrates that GMF plays an important role in maintaining hippocampal function by regulating the appropriate endogenous ROS levels.
先前的研究发现，低磁环境（HMF）暴露会损害动物的认知行为；然而，认知功能障碍的潜在神经机制尚不清楚。海马体在哺乳动物的磁受体、记忆和空间导航中起着重要作用。因此，海马体可能是揭示其神经机制的关键区域。我们最近报道，长期 HMF 暴露通过减少海马体亚颗粒区（SGZ）内的内源性活性氧物种（ROS）水平，损害成年海马体神经发生和认知。除了成年神经干细胞外，海马体中其他细胞的氧化还原状态也是影响海马体功能的重要因素。然而，目前尚不清楚长期 HMF 暴露是否以及如何影响整个海马体（即齿状回（DG）和氨角（CA）区域）中的 ROS 水平。在这里，我们证明暴露于 8 周 HMF 的雄性 C57BL/6J 小鼠表现出认知障碍。然后我们发现，这些 HMF 暴露小鼠的海马体 ROS 水平明显高于地磁场（GMF）组。PCR 阵列分析显示，ROS 水平升高是由于 HMF 调节体内维持氧化还原平衡的基因，如 、 。由于高水平的 ROS 可能导致海马体氧化应激，我们认为这是 HMF 暴露引起认知障碍的另一个原因，除了海马体神经发生受损。我们的研究进一步表明，GMF 通过调节适当的内源性 ROS 水平，在维持海马体功能方面发挥重要作用。
