大鼠theta和gamma神经振荡参与调节突触可塑性及潜在机制探究

发布时间：2018-02-13 14:42

本文关键词： 神经振荡 theta节律 gamma节律突触可塑性抑郁症 C6胶质瘤　出处：《南开大学》2013年博士论文　论文类型：学位论文

【摘要】：研究背景大脑对复杂的认知功能的执行需要多个脑区间的神经元相互协同作用,而大脑中的神经振荡将相关的神经元集群的活动联系在一起,为脑区间的协调作用提供了机制。Theta和gamma振荡是中枢神经系统中非常重要的两类神经振荡,它们不仅作为诸多认知和记忆功能实现的关键因素,还参与了多种神经精神疾病中功能缺失的调节。突触可塑性是认知和记忆过程的细胞学基础,那么神经振荡与突触可塑性之间的联系可能是其调节认知功能的潜在机制。目的本研究通过建立大鼠病理模型,并将电生理实验与数值计算方法相结合,深入地探讨theta和gamma节律及其相位同步、相位耦合以及相位-幅值交叉耦合(PAC)是如何反映突触可塑性的改变,进而调控认知功能的潜在机制。方法实验动物分为三部分第一部分：成年雄性Wistar大鼠18只,随机分为正常组(Con,n=6)、应激模型组(Dep,n=6)和美金刚治疗组(MEM,n=6)对Dep和MEM组采用慢性不可预见性应激(CUS)模型进行21天建模。从建模第2天起对MEM组大鼠腹腔给予美金刚药物,至建模完成后1天。建模过程中测量体重并进行糖水摄入/消耗实验以验证建模成功。随后的电生理实验中记录丘脑LDDM核团和前额叶皮层(mPFC)的局部场电位(LFPs),之后诱导这条通路的长时程增强(LTP)。通过数值计算分析采集的LFPs数据,分别应用多窗谱估计法计算功率谱能量、样品熵计算信号复杂度、相锁值(PLV)度量相位同步、演化映射法(EMA)和条件互信息(CMI)度量耦合方向指数和单向耦合系数。第二部分：成年雄性Wistar大鼠44只,随机分为正常组(Con,n=14)、应激模型组(Dep,n=14)、多巴胺D1受体拮抗剂干预组(SCH, n=8)和5-HT1A受体激动剂干预组(8-OH,n=8)其中Con组和Dep组各6只大鼠作补充实验。其中只对Dep组大鼠建立CUS模型。对SCH和8-OH组,分别给予急性侧脑室注射SCH-23390和8-OH-DPAT。随后对四组大鼠进行电生理实验,诱导腹侧海马CA1-mPFC通路的LTP,并分别在加药前后和LTP前后记录这两个脑区的自发LFPs。通过数值计算分析采集的LFPs数据,分别应用多窗谱估计法计算功率谱能量、PLV度量相位同步、EMA和CMI度量单向耦合系数、PAC多种算法度量theta与低频gamma (LG)和theta与高频gamma (HG)节律间的交叉耦合强度。第三部分：成年雄性SD大鼠24只,随机分为正常对照组(CTRL, n=12)和胶质瘤模型组(GLIO,n=12)。对GLIO组大鼠脑内注射C6胶质瘤细胞,CTRL组注射DMEM培养基。随后对两组大鼠进行电生理实验,记录肿瘤对侧脑区的背侧海马CA3和CA1区的自发LFPs。通过数值计算分析采集的LFPs数据,分别应用PAC多种算法及提出的基于时滞的新算法CF-CMI和CF-EMA来度量节律间的交叉耦合强度。结果 1.CUS增强了mPFC的能量,尤其在delta、theta和beta节律上。但CUS大鼠mPFC的样本熵值明显下降,美金刚对功率谱和样本熵无显著作用。 2.丘脑LDDM-mPFC在theta节律的耦合方向指数d及单向的耦合强度指数cLDDM→mPFC(EMA算法)和iLDDM→mPFC(CMI算法)在CUS大鼠中显著降低,且美金刚治疗后对theta节律的相位耦合强度有所回升。 3.CUS大鼠海马CA1-mPFC之间theta节律的相位耦合受到抑制,与急性加入多巴胺D1受体拮抗剂后变化一致：而gamma节律的相位耦合被CUS增强了,这与急性给予5-HT1A受体激动剂后的结果相似。并且,CUS还抑制了海马CA1区theta-HG节律间的PAC强度,同样的变化发生在5-HT1A受体的急性激活后。 4.正常大鼠和CUS大鼠中,海马CA1→mPFC的theta节律单向相位耦合在诱导LTP后较诱导前均显著增强,但在CUS大鼠中的增强幅度低于正常大鼠,这与海马CA1-mPFC突触可塑性在CUS大鼠中的变化相一致。 5.海马CA1区theta-LG节律间PAC强度在高频刺激后长时程的增强(60min),而theta-HG节律间PAC强度只存在短时程的增长(30min)。 6.海马CA3区的交叉耦合模式以theta-LG节律间的PAC为主,而CA1区同时存在theta-LG和theta-HG两种PAC模式,其中theta-LG的PAC受到了CA3区神经元对其的传导。C6胶质瘤大鼠的CA3区内和CA3-CA1脑区间theta-LG节律PAC强度明显减弱,进而使得CA1区内theta-LG节律PAC也被降低。 7.改进了基于时滞参数τ的两种新算法CF-CMI和CF-EMA,其应用表明CA3-CA1脑区间PAC在达到最大强度时的时滞τmax单峰聚集于20ms左右的时间尺度,提示时滞PAC可能是CA3-CA1网络中交叉耦合强度的真实度量。结论 1.CUS抑制了丘脑LDDM-mPFC的theta节律单向相位耦合强度,与其对这条神经通路上LTP的抑制相一致,提示丘脑与皮层间的theta节律相位耦合与突触可塑性存在着某种联系。 2.CUS大鼠中海马CA1→mPFC的theta节律单向相位耦合在LTP前后的增幅显著降低,进一步印证了theta节律的相位耦合与海马CA1-mPFC突触可塑性相关。在海马CA1区内,theta-LG PAC与长时程增强相关,而theta-HG PAC只与短时程增强相关。 3.CUS对海马CA1-mPFC之间theta节律相位耦合的抑制受到多巴胺系统的调节；而对gamma节律相位祸合的促进可能是激活5-HT1A受体所致。另外,5-HT1A受体还调节了海马CA1区theta-HG PAC现象。 4.C6胶质瘤在大鼠脑内的种植降低了海马CA3-CA1神经网络中theta-LGPAC的强度,这可能与其对认知功能的损伤相关。 5.海马CA3-CA1脑区间存在时滞的PAC现象,能够更为精确的度量交叉耦合强度,并且时滞可能与突触传递相关。
[Abstract]:Research background
The brain of complex cognitive functions required for the implementation of multiple brain regions of neurons interact synergistically and neural oscillations in the brain neuron clusters of related activities together, coordinating role for brain regions provides a mechanism for.Theta and gamma oscillation is the central nervous system of two kinds of neural oscillation is very important in the system, they not only as a key factor in many cognitive and memory functions, is also involved in the regulation of a variety of neuropsychiatric disorders and loss of function. The synaptic plasticity is the cellular basis of learning and memory process, then the oscillation between neural and synaptic plasticity contact may be a potential mechanism regulating the cognitive function.
objective
This study established a rat pathological model, combining the experimental and numerical calculation method of physical power, in-depth study of theta and gamma rhythm and phase synchronization, phase coupling and phase amplitude cross coupling (PAC) is how to reflect the changes in synaptic plasticity, potential mechanism and control of cognitive function.
Method
The experimental animals are divided into three parts
The first part: 18 male Wistar rats, were randomly divided into normal group (Con, n=6), stress model group (Dep, n=6) and memantine treatment group (MEM, n=6) on the Dep and MEM groups of chronic unpredictable stress (CUS) model for 21 days. The drug given memantine modeling the rats of group MEM were from modeling second days to 1 days after modeling. The modeling process of measuring the weight and sucrose intake / consumption experiment to verify the modeling success. LDDM nucleus thalamus and prefrontal cortex recorded electrophysiological experiments followed by (mPFC) local field potentials (LFPs), after induction of this the pathway of long-term potentiation (LTP). Through numerical calculation and analysis of LFPs data acquisition, multi window were used to calculate the power spectrum energy spectrum estimation, signal calculation complexity, sample entropy, phase locking value (PLV) to measure the phase synchronization, evolution mapping method (EMA) and mutual information (CMI) to measure the coupling direction index And the unidirectional coupling coefficient.
The second part: 44 male Wistar rats, were randomly divided into normal group (Con, n=14), stress model group (Dep, n=14), dopamine D1 receptor antagonist intervention group (SCH, n=8) and 5-HT1A receptor agonist group (8-OH, n=8) in Con group and Dep group 6 rat complement experiment. Only Dep rats to establish CUS model. The SCH and 8-OH group were given SCH-23390 and acute lateral intraventricular injection of 8-OH-DPAT. followed by electrophysiological experiments on four groups of rats induced by ventral hippocampal CA1-mPFC pathway and LTP, respectively before and after dosing and LTP before and after spontaneous LFPs. proceedings these two brain regions through numerical calculation and analysis of LFPs data acquisition, multi window were used to calculate the power spectrum energy spectrum estimation, PLV measurement of phase synchronization, EMA and CMI to measure the one-way coupling coefficient, PAC algorithm and multiple metric theta low frequency gamma (LG) and theta gamma (HG) and high frequency cross rhythms between Coupling strength.
The third part: 24 male SD rats, were randomly divided into normal control group (CTRL, n=12) and glioma model group (GLIO, n=12). The rats in group GLIO intracerebral injection of C6 glioma cells, CTRL group were injected with DMEM medium. Then the electrophysiological experiments were performed on two rats. Spontaneous LFPs. contralateral brain region of the dorsal hippocampus CA3 and CA1 recorded the tumor area through numerical calculation and analysis of LFPs data acquisition, respectively using PAC algorithms and proposed a new algorithm of CF-CMI and CF-EMA delay based on the measured cross coupling strength between the rhythm.
Result
1.CUS enhanced the power of mPFC, especially in Delta, theta and beta rhythm. But CUS rats mPFC sample entropy decreased significantly, memantine had no significant effect on power spectrum and sample entropy.
2. thalamic LDDM-mPFC in the coupling direction index theta rhythm D and one-way coupling strength index cLDDM, mPFC and iLDDM (EMA algorithm) and mPFC (CMI algorithm) was significantly reduced in CUS rats, and memantine after treatment phase coupling strength of the theta rhythm rebounded.
Phase coupling between CA1-mPFC in hippocampus of 3.CUS rats theta rhythm was inhibited, consistent with acute with dopamine D1 receptor antagonists and phase coupling changes after gamma rhythm by CUS was enhanced, and the acute administration of 5-HT1A receptor agonist after similar results. In addition, CUS also suppressed the intensity of PAC in CA1 area of hippocampus theta-HG rhythm the same changes in 5-HT1A receptor activation after acute.
4. in normal rats and CUS rats, the unidirectional phase coupling of CA1 theta mPFC in hippocampus increased significantly after induction of LTP, but increased significantly in CUS rats than in normal rats, which was consistent with the change of hippocampal CA1-mPFC synaptic plasticity in CUS rats.
5. the intensity of PAC between theta-LG rhythms in the hippocampal CA1 region was enhanced after the high frequency stimulation (60min), while the PAC intensity between the theta-HG rhythms increased only in the short time period (30min).
Cross coupled mode 6. CA3 region of the hippocampus in theta-LG rhythm between PAC, and the CA1 theta-LG and theta-HG two and PAC theta-LG PAC model, which is CA3 neurons on the conduction of rat.C6 glioma CA3 zone and CA3-CA1 theta-LG PAC of brain rhythms decreased, thus making CA1 theta-LG in the rhythm of PAC was also reduced.
7. improved and two new algorithms CF-CMI and CF-EMA delay parameters based on the application of PAC in brain regions showed that CA3-CA1 reached the maximum when the intensity of the delay Max peak gather at 20ms about the time scale, suggesting that PAC may delay is a measure of the true cross coupling strength in the CA3-CA1 network.
conclusion
1.CUS inhibits the unidirectional phase coupling intensity of LDDM-mPFC theta rhythm in thalamus, which is consistent with its inhibition on LTP in this neural pathway. It suggests that there is a connection between the theta rhythm phase coupling between thalamus and cortex and synaptic plasticity.
Theta single phase coupling 2.CUS rhythm in hippocampus of rats with CA1 and mPFC decreased significantly in the LTP before and after the increase, further confirms the phase coupling and synaptic plasticity in hippocampus CA1-mPFC theta rhythm. In the hippocampal CA1 region, theta-LG PAC and LTP, while theta-HG and PAC only short-term potentiation.
3.CUS inhibits the theta phase coupling between hippocampal CA1-mPFC, which is regulated by dopamine system. The promotion of gamma rhythm phase mismatch may be activated by 5-HT1A receptor. In addition, 5-HT1A receptor also regulates theta-HG PAC phenomenon in the hippocampus CA1 region.
The growth of 4.C6 glioma in the rat brain reduces the intensity of theta-LGPAC in the hippocampal CA3-CA1 neural network, which may be related to the impairment of cognitive function.
5. there is a time-delay PAC phenomenon in the CA3-CA1 brain region of the hippocampus, which can more accurately measure the cross coupling strength, and the time delay may be related to the synaptic transmission.

【学位授予单位】：南开大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R749.4

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