【作者】 王丽丽；

【导师】 梅兵；

【作者基本信息】 华东师范大学 ， 生理学， 2011， 硕士

【摘要】 噪音是一种不和谐的声音,由各种不同频率和强度的声音无规律杂乱组合而成。在现代社会中,来自于工作环境、城市交通和家庭设施等的噪音日益严重的影响着人类健康。噪音严重时会诱发免疫、呼吸和心血管系统功能的失调。近年来,噪音对中枢神经系统的影响也越来越引起人们的关注。长期慢性噪音暴露可造成耳蜗损伤、听力下降,并影响睡眠、工作记忆和神经发生等；但噪音对情绪和注意力的影响,特别是对有机体青少年期的影响研究尚少。本文将6周龄C57BL/6雄性小鼠持续暴露在噪音环境中,通过行为学实验检测慢性噪音对其情绪和注意力行为的影响,并利用定量PCR方法探讨其行为变化的分子基础,同时使用毛细管电泳方法检测大脑内单胺类神经递质的水平,为研究慢性噪音暴露对青少年时期实验动物行为变化的影响及其可能的分子机制提供实验基础。1.慢性噪音暴露诱发小鼠低焦虑样行为为探讨持续的噪音暴露对情绪和注意力的影响,本文分别给予6周龄C57BL/6雄性小鼠环境噪音(对照)、音乐、噪音、白噪音的不同声音刺激(75dB,8小时/天)暴露,连续30天后检测小鼠与情绪和注意力相关的行为表现。实验结果发现,在开场运动实验中,噪音组小鼠在中心区域运动距离的百分比高于其他组,噪音组小鼠在明暗箱实验中呈现在明箱中探究的时间增多,以及在强迫游泳实验中静止不动时间显著减少,说明噪音组小鼠表现出低焦虑样行为。噪间组小鼠在痕迹恐惧实验的学习阶段中应对新环境的基础僵直程度低于其他组小鼠,且其在新事物探索实验中进入中心区域的延迟时间也低于其他组小鼠,再次证实噪音组小鼠的低焦虑样行为；检测噪音组小鼠的注意力行为,结果显示其在痕迹恐惧实验线索式恐惧测试中的僵直程度与其他组小鼠表现相似；在新事物探索实验中其对新物体的探究能力与其他组相似；且筑窝行为实验中噪音组小鼠与对照组小鼠筑窝能力相似,这些结果说明慢性噪音暴露并没有影响小鼠的注意力行为。2.Q-PCR探究噪音组小鼠低焦虑样行为的分子基础为探讨噪音组小鼠低焦虑行为的分子基础,采用实时荧光定量PCR技术研究了四组小鼠中海马(含杏仁核)、前额叶皮层和下丘脑组织部分递质系统相关分子的表达水平。结果显示,在海马中,噪音组和白噪音组小鼠NR1 mRNA的表达量高于对照组和音乐组,噪音组小鼠NR2A/NR2B比例显著低于其他三组；在前额叶中,噪音组和白噪音组小鼠该比例低于对照组和音乐组；下丘脑中,噪音组小鼠该比例显著低于对照组。在海马和前额叶,噪音组和白噪音GAD65mRNA的表达量明显低于对照组和音乐组,有显著差异,但GAD67mRNA的表达量四组显示出相似水平；在海马和下丘脑中,噪音组小鼠GABAα1/GABAα3比例低于对照组和音乐组；在前额叶中,噪音组和白噪音组小鼠GABAα1/GABAα3的比例低于对照组和音乐组。同时噪音组BDNF、htr2a(5-羟色胺受体)的表达水平显著下降。由于NR2A/NR2B比例与NMDA的突触功能可塑性成反比,GABAAα1/GABAAα3比例的升高与GABAA受体的成熟呈正相关,因此噪音组小鼠低焦虑样行为的分子基础可能涉及到谷氨酸能神经元兴奋性功能增强,同时抑制性神经元如GABA和5-HT功能减弱以及营养因子BDNF的变化。3.单胺类神经递质的浓度利用毛细管电泳法检测噪音组和对照组小鼠前脑皮层、海马、下丘脑以及前脑其他部位各单胺类神经递质的含量。结果显示,与对照组相比,噪音组小鼠5-羟色胺(5-HT)、肾上腺素(E)和去甲肾上腺素(NE)的浓度显著降低,多巴胺(DA)含量显著升高。这些实验结果说明,噪音暴露后小鼠单胺类神经递质的水平发生了变化,这些变化和噪音引起的低焦虑行为具有并行性。而单胺类神经递质的变化是噪音引起的直接结果还是间接结果,以及单胺类递质在焦虑行为中的作用如何,还有待进一步研究。更多还原

【Abstract】 Noise, unharmonious sound, is combined by a variety of different frequencies and intensity sounds, which is recognized as a serious health disruptor in our modern societies. Noise can result in the immune, respiration, cardiovascular system disorders. In recent years, the impact of noise in center nervous system is concerned. Chronic noise can not only damage cochlear system, resulting in hearing loss, but also can cause sleep disturbance, reduce work memory and neurogenesis. However, the report about the effects of noise on emotion and attention, especially in adolescence, is limited.In this paper, C57BL/6 male mice (postnatal 6 weeks) were continued exposure to noise environment for 30 days. Then the behavior of emotion and attention were detected by behavior tests and the potential molecular basis of behavior abnormal was analyzed using real time quantitative PCR.1. Showed low-anxiety behavior after mice exposure to chronic noiseTo explore the effects of noise on emotion and attention, the C57BL/6 male mice (postnatal six weeks) were exposed to noise, white noise, music and environment noise (control) stimulates separately (75 dB,8 h daily for 30 days), then their behaviors were analyzed. The behavioral results showed that the noise group explored the center portion of the environment (as a percentage of total exploratory activity) more than the other groups did in open field test. The noise mice explored the light compartment to a greater extent than the others did in light-dark box test and exhibited lower immobility time in forced swim test compared to the control group, with marked difference. These results demonstrated that chronic noise induced low-anxiety behavior in mice. In addition, in trace fear conditioning test, the freezing of baseline in training stage in noise group is lower than the others, while noise group mice showed lower latency to center region, which confirmed once again that the noise group mice exhibited low-anxiety behavior phenotype. Detecting the attention behavior, we obtained that chronic noise exposure didn’t influence the attention behavior bases on the following results:the time spent freezing in the cued test was similar separately at each of three consecutive tones testing among the four groups; exploration time in new object also has no difference in novel object exploratory test; at the same time noise mice exhibited similar nest building ability.2. To explore the molecular mechanism resulting in low-anxiety by Q-PCR.We detected the mRNA expression of correlative molecules in hippocampus (including amygdale), prefrontal cortex and hypothalamus regions from the four groups using real time quantitative PCR. We found, in hippocampus, NR1 mRNA level in noise and white noise group increased compared to control and music group, and the NR2A/NR2B ratio in noise group was markedly lower than other three groups did; In prefrontal cortex, the ratio of noise and white noise group reduced compared to control and music group; And the ratio of noise group also showed lower than control mice in the hypothalamus. The expression of GAD65 mRNA, not GAD67 mRNA, decreased all in hippocampus, prefrontal cortex in noise and white noise group. In hippocampus and hypothalamus, we found that the GABAAα1/GABAAa3 ratio in noise mice was lower than control and music group, and the ratio in white noise mice also decreased compared to music group. In prefrontal cortex, the ratio of noise and white noise group also decreased compared to control and music group. Meanwhile, the expression level of BDNF and htr2a also reduced in noise group.These results showed the mice exhibited excited or low-anxiety behavior after being exposed to chronic noise, and the mechanism might be that the glutamatergic neurons activity was enhanced while the GABAergic neurons activity was reduced, and maybe also regulated by 5-HT receptor and BDNF. 3. The concentration of monoamine neurotransmitter in the brainBy using capillary electrophoresis assay, monoamine neurotransmitters in cortex, hippocampus, hypothalamus and other forebrain regions were detected in control and noise group mice. The results exhibited that the concentration of 5-serotonin(5-HT), epinephrine (E) and norepinephrine (NE) in the whole brain of the noise group mice decreased markedly, while the level of dopamine increased compared to control group mice. These results demonstrated that noise exposure can change the level of monoamine neurotransmitter. However, whether this is a direct result or not induced by noise needs to be further investigated.更多还原