X波段高功率微波对小鼠情绪认知影响的研究和机制探索

Effects of X-band high-power microwave on emotional cognition in mice

  • 摘要:
    背景 现有研究发现低频电磁辐射可引起情绪认知功能改变,但 X 波段高功率微波(X-band high power microwave,X-Band HPM)对情绪认知的影响及其分子机制尚未明确。目的 探讨X-Band HPM对小鼠情绪认知的影响及其潜在机制。方法 将8 ~ 10周龄雄性C57BL/6小鼠随机分为空白对照组、低剂量照射组、高剂量照射组,每组8 ~ 10只。对照组不进行照射,照射组选用X-Band HPM作为辐射源(发射频率9.4 GHz,脉冲宽度100 ns,脉冲重复频率30 Hz),低剂量组峰值功率密度 26 W/cm2 ,平均功率密度 0.078 mW/cm2 ;高剂量组峰值功率密度 1 750 W/cm2 ,平均功率密度 5.25 mW/cm2 。实验进行单只照射,照射后采用旷场实验、高架十字迷宫实验、悬尾实验评估小鼠情绪行为改变,采用新物体识别实验评估小鼠认知行为改变。通过HE和TUNEL染色观察海马组织形态结构,透射电镜观察海马DG区域超微结构。采用超高效液相色谱-质谱联用法检测海马组织神经递质含量。通过WB检测海马组织PSD95、BDNF的表达水平。结果旷场实验中,高、低剂量组中央区域活动路程与时间、总路程均显著低于对照组(P<0.05);高架十字迷宫实验中,高剂量组开放臂进入次数和滞留时间、低剂量组滞留时间均显著降低(P<0.01);悬尾实验中,高剂量组静止时间显著延长(P< 0.01)。新物体识别实验中,高、低剂量组认知指数均显著低于对照组(P<0.01)。HE染色和TUNEL染色结果显示,高剂量照射组可见部分神经元皱缩,细胞形状不规则,细胞体积减小,胞核、胞质分界不清晰,染色加深,细胞排列不规则,细胞排列的紧密程度下降,局部出现空隙。透射电镜结果显示,低剂量组突触和线粒体部分受损,其它结构状态尚可;高剂量组突触结构、神经递质小泡、线粒体等均受到不同程度损伤。神经递质检测显示,与空白对照组相比,高剂量照射组小鼠海马组织中γ-GABA、Gln、Pro、胱硫醚及L-肌肽含量显著降低(P<0.05),而Glu和Orn含量显著升高(P<0.05);低剂量照射组中,胱硫醚含量显著低于对照组(P<0.01),γ-GABA、L-AA、Abu、Hyl及Aib含量则显著升高(P<0.05)。WB结果显示海马组织PSD95、BDNF表达量显著降低(P<0.01)。结论 X-Band HPM可致小鼠焦虑抑郁和认知功能障碍,其机制可能与海马突触结构完整性受损、可塑性下降及相关神经递质分泌失调有关。

     

    Abstract: Background Current studies have found that low-frequency electromagnetic radiation can cause changes in emotional and cognitive functions, but the effects of X-Band HPM on emotional cognition and their molecular mechanisms remain unclear. Objective To investigate the effects of X-band high power microwave on emotion and cognition in mice and the underlying mechanisms.Methods Male C57BL/6 mice aged 8-10 weeks were randomly divided into blank control group, low-dose irradiation group, high-dose irradiation group, with 8-10 mice in each group. The control group received no irradiation, while the irradiation groups were exposed to X-Band HPM as the radiation source (emission frequency: 9.4 GHz, pulse width: 100 ns, pulse repetition frequency: 30 Hz). The low-dose group had a peak power density of 26 W/cm² and an average power density of 0.078 mW/cm², whereas the high-dose group had a peak power density of 1 750 W/cm² and an average power density of 5.25 mW/cm². Each mouse was individually irradiated. After irradiation, the open field test, elevated plus maze test, and tail suspension test were  used to evaluate changes in emotional behavior, while the novel object recognition test was applied to assess cognitive behavioral changes. The morphological structure of hippocampal tissue was observed by HE staining and TUNEL staining, and the ultrastructure of the DG region in the hippocampus was observed by TEM. The neurotransmitter content in hippocampal tissue was detected by ultra-high performance liquid chromatography-mass spectrometry. The expression levels of PSD95 and BDNF in hippocampal tissue were detected by WB.Results In the open-field test, the distance and time spent in the central area, as well as the total distance traveled, were significantly lower in both high-dose and low-dose groups compared to the control group (P<0.05). In the elevated plus-maze test, the number of entries into open arms and the residence time in the high-dose group, as well as the residence time in the low-dose group, were significantly reduced (P<0.01). In the tail suspension test, the immobility time was significantly prolonged in the high-dose group (P<0.01). In the novel object recognition test, the cognitive indices of both high-dose and low-dose groups were significantly lower than those of the control group (P<0.01). HE staining and TUNEL staining results showed that in the high-dose irradiation group, partial neuronal shrinkage was observed, with irregular cell shapes, reduced cell volume, unclear boundaries between nucleus and cytoplasm, deepened staining, irregular cell arrangement, decreased compactness of cell arrangement, and local gaps. Transmission electron microscopy results indicated that synapses and mitochondria were partially damaged in the low-dose group, while other structures were in acceptable condition; in the high-dose group, synaptic structures, neurotransmitter vesicles, mitochondria, etc., were damaged to varying degrees. Neurotransmitter detection showed that compared with the blank control group, the contents of γ-GABA, Gln, Pro, cystathionine, and L-carnosine in the hippocampal tissue of mice in the high-dose irradiation group were significantly reduced (P<0.05), while the contents of Glu and Orn were significantly increased (P<0.05). In the low-dose irradiation group, the content of cystathionine was significantly lower than that of the control group (P<0.01), while the contents of γ -GABA, L-AA, Abu, Hyl, and Aib were significantly higher (P<0.05). WB results demonstrated that the expression levels of PSD95 and BDNF in hippocampal tissue were significantly decreased (P<0.01). Conclusion X-Band HPM can induce anxiety, depression, and cognitive dysfunction in mice, and the mechanism may be related to impaired hippocampal synaptic structural integrity, decreased plasticity, and dysregulation of related neurotransmitter secretion.

     

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