Department of Physiology, Third Military Medical University, Chongqing 400038, PR China.
Department of Physiology, Third Military Medical University, Chongqing 400038, PR China.
Environ Res. 2014 Oct;134:74-80. doi: 10.1016/j.envres.2014.06.025. Epub 2014 Jul 19.
In the present study, we investigated the effects of chronic exposure (14 and 28 days) to a 50 Hz, 0.5 mT extremely low-frequency magnetic field (ELF-MF) on the NMDAR and AMPAR subunit expressions and rat spatial learning and memory. Using the Western blotting method, we found ELF-MF exposure specifically decreased the expressions of GluA2 in the EC post 28 day exposure and GluA3 of AMPAR subunits in the PFC after 14 day exposure, while it did not affect the AMPAR subunit expression in the hippocampus at both time points. As for NMDAR subunits, 14 day ELF-MF exposure significantly increased the levels of GluN2A and GluN2B in the hippocampus. Moreover, the levels of GluN1 and GluN2A were enhanced in the EC and PFC after two weeks of ELF-MF exposure. Interestingly, 28 day ELF-MF exposure induced a different expression pattern for NMDAR subunits. The increased GluN2A expression observed at 14 day post ELF-MF exposure was recovered after prolonged exposure in the hippocampus and PFC. In the EC, the increased expression of GluN1 achieved to control level and, specifically, a decrease in GluN2A level was observed. Surprisingly, neither 14 nor 28 day ELF-MF did affect the rat spatial reference memory as assessed by water maze. These results indicate that the dynamic and brain-region specific changes in ionotropic glutamate receptor expression induced by ELF-MF are insufficient to influence the rat spatial learning ability.
在本研究中,我们调查了慢性暴露(14 天和 28 天)于 50 Hz、0.5 mT 极低频磁场(ELF-MF)对 NMDA 受体和 AMPA 亚基表达以及大鼠空间学习和记忆的影响。使用 Western blot 方法,我们发现 ELF-MF 暴露特异性地降低了 GluA2 在 EC 中的表达(28 天后)和 GluA3 在 PFC 中的表达(14 天后),而在这两个时间点,它都没有影响海马中的 AMPA 亚基表达。对于 NMDA 受体亚基,14 天 ELF-MF 暴露显著增加了海马中的 GluN2A 和 GluN2B 水平。此外,在两周的 ELF-MF 暴露后,EC 和 PFC 中的 GluN1 和 GluN2A 水平也得到了增强。有趣的是,28 天 ELF-MF 暴露诱导了 NMDA 受体亚基的不同表达模式。在 ELF-MF 暴露后 14 天观察到的 GluN2A 表达增加在延长暴露后在海马和 PFC 中得到恢复。在 EC 中,增加的 GluN1 表达达到对照水平,并且观察到 GluN2A 水平特异性降低。令人惊讶的是,无论是 14 天还是 28 天的 ELF-MF 都没有影响水迷宫评估的大鼠空间参考记忆。这些结果表明,ELF-MF 诱导的离子型谷氨酸受体表达的动态和脑区特异性变化不足以影响大鼠的空间学习能力。
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