海马自发同步化活动机制及CA3-CA1突触联系研究

发布时间：2018-06-30 08:51

本文选题：海马 + 振荡　；参考：《华东师范大学》2011年硕士论文

【摘要】：目前关于自发节律性活动的产生及锥体细胞的同步化机制的探讨,主要观点有两种：(1)大脑中存在少量的Pacemaker细胞,它们可以产生自发活动,从而带动群体细胞的同步化活动；(2)另一主要观点认为自发节律性活动的产生是由神经环路中群体细胞共同相互作用带动大量细胞同步化活动的。如GABA能的中间神经元的轴突存在大量分枝,通过这些分枝可以增强对局部范围内的群体锥体细胞的同步化抑制。针对大脑的节律性活动的研究主要集中在两个方面：(1)神经细胞节律性活动的细胞化学机制(2)节律性活动如何产生,传播并影响群体细胞的同步化。而关于这两方面的研究主要集中在离体海马脑片及在体多通道记录。海马脑片的制备往往是在剥离海马后,利用振动切片机将其切成400μm厚的薄片,多用于突触水平的研究。而切取脑片的这一过程会损坏大量的纤维,导致突触连接的通路被阻断,从而破坏了海马内部复杂的环路,影响单个神经细胞的信号输入与输出。在体多通道研究可以记录到动物清醒状态下,海马对多信号输入的整合处理结果,更符合生理水平的研究。而本实验选用的实验材料是离体完整海马,记录到自发产生的低频节律性振荡。该实验材料的选择,保证了海马内部复杂环路的完整性,也排除了其他脑区信号输入的干扰,更有利于研究海马自发活动产生的根源。 1. GABAA受体活动介导的海马CA3-CA1区的同步性自发活动目前关于海马的节律性活动的研究,主要集中在两个方面,一是海马细胞节律性活动产生的机制,另一方面是节律性活动的传播及如何影响群体细胞的同步化。我们发现离体完整海马可以自发产生低频节律性振荡(0.8-2Hz),而且同时记录的局部场电位和全细胞记录显示,这种自发活动在同时记录的CA1-CA1, CA3-CA3及CA3-CA1锥体细胞之间是同步化的。灌流液中加入GABAA受体阻断剂Bicuculline可以显著性降低自发活动的频率,而不影响锥体细胞的同步化。Ih通道胞外阻断剂ZD7288也可以降低自发活动的频率,仍不影响锥体细胞自发活动的同步化。而在加入AMPA受体阻断剂DNQX后,低频自发活动消失。总之,离体完整海马自发产生的低频振荡,是AMPA受体依赖的,而且这种自发活动的产生与GABAA受体和Ih通道的作用密切相关。 2.海马CA3与CA1之间的突触联系关于海马不同细胞间的突触联系的研究主要在海马脑片上进行的,一般是突触前给予单个或串刺激,分析突触后的反应。而脑片制备的过程中大量的纤维被切断,导致突触联系受损。但完整海马内部的网络环路及突触联系保持完整,这更有利于单独分析单个CA3锥体细胞与CA1锥体细胞之间的联系概率。我们在这种实验材料的基础上,记录了10对细胞,其中3对有明显的突触后兴奋性反应,反应幅度一般在2pA。这一概率明显高于在脑片上记录到的突触联系概率。在我们所建立的离体完整海马模型上,可以更精确的记录CA3-CA1之间的投射概率,对于海马功能的研究提供更好的基础。
[Abstract]:There are two main points of view about the generation of spontaneous rhythmic activity and the synchronization mechanism of pyramidal cells: (1) there are a small number of Pacemaker cells in the brain that can produce spontaneous activity, thus driving the synchrotron activity of the group cells; (2) the other main point of view is that spontaneous rhythmic activity is produced by the nerve. The common interaction of the group cells in the loop drives a large number of cell synchronization activities, such as a large number of branching in the axons of the intermediate neurons of the GABA, which can enhance the synchronization inhibition of the local pyramidal cells in a local area.
The research on rhythmic activity of the brain focuses on two aspects: (1) the cytochemical mechanism of the rhythmic activity of neural cells (2) how rhythmic activity is produced, spreading and affecting the synchronization of group cells.
The study of these two aspects is mainly focused on the isolated hippocampal slices and in vivo multichannel recording. The preparation of hippocampal slices is often used to cut into 400 mu m thick slices with a vibratory slice machine after the exfoliation of the hippocampus. The process of cutting brain slices can damage a large number of fibers and lead to synaptic connections. The road is blocked, which destroys the complex loop inside the hippocampus and affects the signal input and output of a single nerve cell. In the body multichannel study, the integrated processing results of the multiple signal input of the hippocampus can be recorded in the sober state of the animal. The experimental material used in this experiment is a complete hippocampus in vitro. The selection of the experimental materials ensures the integrity of the complex loop inside the hippocampus and the interference of signal input from other brain regions, which is more conducive to the study of the origin of the spontaneous activity of the hippocampus.
1. GABAA receptor activity mediates synchronous spontaneous activity in hippocampal CA3-CA1 region.
At present, the study of rhythmic activity in the hippocampus focuses on two aspects, one is the mechanism of rhythmic activity in the hippocampus, the other is the propagation of rhythmic activity and how to synchronize the group cells. We find that the intact hippocampus can spontaneously produce low frequency rhythmic oscillations (0.8-2Hz), and it is recorded at the same time. The local field potential and whole cell record showed that the spontaneous activity was synchronized between the CA1-CA1, CA3-CA3 and CA3-CA1 pyramidal cells recorded at the same time. The addition of GABAA receptor blocker Bicuculline in the perfusion solution could significantly reduce the frequency of spontaneous activity, without affecting the synchronous.Ih channel extracellular blocker ZD7288 in pyramidal cells. It can also reduce the frequency of spontaneous activity, but it does not affect the synchronization of spontaneous activity of the pyramidal cells. The spontaneous activity of low frequency disappears after adding the AMPA receptor blocker DNQX. In a word, the spontaneous oscillation of the intact hippocampus is dependent on the AMPA receptor, and the spontaneous activity is closely related to the effect of the GABAA receptor and the Ih channel. Relevant.
2. synaptic connections between CA3 and CA1 in the hippocampus
The study of synaptic connections between different cells in the hippocampus is mainly carried out on the hippocampal slices. Generally, a single or series of stimuli are given before synapses to analyze the post synaptic response. The synapses are damaged by a large number of fibers during the preparation of the brain slices, but the complete network loop and synaptic connections within the inner hippocampus remain intact. On the basis of this experimental material, 10 pairs of cells were recorded on the basis of this experimental material, of which 3 pairs had obvious postsynaptic excitability reactions, and the probability of the reaction was generally higher than the probability of the synaptic connections recorded on the brain slices in the 2pA.. The established intact hippocampal model can more accurately record the projection probability between CA3-CA1 and provide a better basis for the study of hippocampal function.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：R33

【共引文献】