论文标题:Ca～（2+）通道在背根节神经元重复放电中的作用
Effects of Calcium Channel on the Repetitive Firing of Dorsal Root Ganglion Neuron
论文作者
论文导师 胡三觉,论文学位 博士,论文专业 生理学
论文单位 第四军医大学,点击次数 83,论文页数 112页File Size3328K
1997-06-01论文网 http://www.lw23.com/lunwen_180754642/
背根节(Dorsal root ganglion，DRG)神经元是传导感觉信息的初级感觉神经元。近年来，其胞体的特性及化学敏感性受到越来越多的重视。这不仅因为胞体本身与其中枢和外周末梢具有许多相似的特性，更重要的是当神经元轴突或胞体受损后，生理情况下自发放电很少的神经元可产生许多自发电活动，而且兴奋阈值下降，兴奋性增高，表现出超兴奋状态。这与临床上常见的坐骨神经痛、下腰痛等病征的产生有密切关系。了解DRG神经元的生理特性，将为进一步阐明病理条件下，神经元兴奋性异常增高的机理奠定基础。重复放电是神经元功能活动的基本表现，起到重要的信息编码作用。目前已获得的大量资料表明，Na~+、K~+和Ca~(2+)都参与了自发放电或去极化诱发的重复放电活动。由于Ca~(2+)通道种类多，作用复杂，对于Ca~(2+)离子及Ca~(2+)通道在自发和重复放电中的作用存在着不同的看法。因此，本实验以新鲜分离的正常DRG神经元为研究对象，着重观察Ca~(2+)、膜电位振荡和去极化速率对其重复放电的影响，并分析Ca~(2+)依赖性K~(2+)电流的特点，以及在后电位中的作用。试图阐明正常DRG神经元重复放电的机理和影响因素。主要结果如下： 1、生理状态下，向DRG神经元胞内注入去极化电流，大多数(14／17)神经元只在去极化电流开始时出现一个动作电位，重复放电的出现率较低(3／17)。诱发出的重复放电的动作电位时程长，频率约为8.3 Hz(500pA，600ms)，并有明显的频率适应现象。 2、胞内加入11mmol／L EGTA，去极化电流诱发的重复放电出现率明显增高(84／84)，频率增快，约为50 Hz(400pA，400ms)，
Dorsal root ganglion is the primary affarent neuron transducting the sensory information. In recently years, more interests have been focused on the properties and chemosensitivity of the somata due to the following reasons: the somata possesses some properties as its central and peripheral terminals, and more importantly, the physiologically less firing neurons may arise spontaneous discharges because of decreased exciting threshold, increased excitability following somata or peripheral nerve damage. These observation have prompted the close relationship between the hyperexcitability of the neurons and the mechanism involved in the common illnesses such as sciatica and low back pain. The physiological properties of DRG neurons may help us to better understand the mechanisms of hyperexcitability of the neurons under pathological conditions. The essential behavior of neural functional activity is repetitive firing which plays an important role in information encoding. Many research results showed that Na~+ , K~+ and Ca~(2+) channels are involved in the spontaneous and repetitive firing induced by sustained depolarizing currents. As there are many types of calcium channel with diverse properties, studies on the functions of calcium ion and calcium channels in this process have not shown consistent results. The purpose of this study is to elucidate the possible mechanisms involved
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