Effect of the glial envelope on extracellular K(+) diffusion in olfactory glomeruli.
Effect of the glial envelope on extracellular K(+) diffusion in olfactory glomeruli.
复制标题
神经胶质包膜对嗅觉肾小球细胞外 K( ) 扩散的影响。
DOI：
10.1152/jn.00569.2001
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Tolbert,LeslieP
中科院分区：
文献类型：
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作者：
Goriely,AnitaR;Secomb,TimothyW;Tolbert,LeslieP
在许多物种中，包括脊椎动物和无脊椎动物，一级嗅觉神经鞘被组织成球形肾小球，部分被胶质边界包裹。这种特征组织对嗅觉信息处理的影响知之甚少。在气味诱导的激活后，特定肾小球中嗅觉受体轴突周围的细胞外钾离子浓度（[K+]）必须升高。为了探讨K+积累的时间过程和幅度以及这种积累对肾小球内和肾小球之间神经活动的可能影响，我们建立了一个理论模型来模拟K+在蛾Manducasexta肾小球细胞外空间的扩散。由激活的轴突释放的K+被假定为通过肾小球中的细胞外间隙和围绕它们的神经胶质边界扩散。在球坐标系下，采用有限差分法求解含时扩散方程。结果表明，神经胶质包膜形成了一个显着的障碍，相邻的肾小球之间的K+的传播，从而降低了肾小球之间的串扰的可能性，并可能导致升高的细胞外[K+]的水平，影响神经活动的激活肾小球内许多秒。这种效应可以分别增强嗅觉辨别力和灵敏度。
In many species, including vertebrates and invertebrates, first-order olfactory neuropils are organized into spherical glomeruli, partially enveloped by glial borders. The effect of this characteristic organization on olfactory information processing is poorly understood. The extracellular concentration of potassium ions ([K+]) must rise around olfactory receptor axons in specific glomeruli following odor-induced activation. To explore the time course and magnitude of K+accumulation and possible effects of such accumulation on neural activity within and among glomeruli, we developed a theoretical model to simulate the diffusion of K+in extracellular spaces of the glomeruli of the mothManduca sexta. K+released by activated axons was assumed to diffuse through the extracellular spaces in glomeruli and the glial borders that surround them. The time-dependent diffusion equations were solved in spherical coordinates using a finite-difference method. The results indicate that the glial envelope forms a significant barrier to the spread of K+between neighboring glomeruli, thus reducing the likelihood of cross-talk between glomeruli, and may cause elevation of extracellular [K+] to levels that influence neural activity within the activated glomerulus for many seconds. Such effects could enhance olfactory discrimination and sensitivity, respectively.