Dependence of GABAergic synaptic areas on the interneuron type and target size
Dependence of GABAergic synaptic areas on the interneuron type and target size
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DOI：
10.1523/jneurosci.20-01-00375.2000
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发表时间：
2000-01-01
影响因子：
5.3
通讯作者：
Kawaguchi, Y
中科院分区：
文献类型：
--
作者：
Kubota, Y;Kawaguchi, Y
在新纹状体中，已知存在几种具有不同放电模式和神经活性物质表达的中间神经元。我们发现两种类型的新纹状体中间神经元，即含有小清蛋白的快速尖峰 (FS) 细胞和含有生长抑素的低阈值尖峰 (LTS) 细胞，在大鼠浸没固定的脑切片中，其轴突末端均对 GABA 具有免疫反应性。为了揭示这两种类型的 GABA 能中间神经元之间突触连接的差异，通过细胞内染色的轴突末端的电子显微镜图像的三维重建来比较突触后目标及其突触结构。 FS 细胞与体细胞的突触接触比例高于 LTS 细胞。尽管 FS 和 LTS 细胞的末端结块体积相似，但它们的突触连接区域在大小分布以及与突触后树突轴或棘尺寸的关系方面不同。 FS 细胞的突触连接面积 (0.024-0.435 μ m(2); n = 28) 随突触后树突或棘的周长 (0.939-5.146 μ m) 急剧线性增加，而 LTS 细胞的连接面积 (0.02-0.103 μ m(2); n = 29) 与周长的斜率(0.844-4.252μm) 的陡度较小，并且相关性弱得多。除了放电模式、表达分子、轴突树枝化和突触后靶点方面的差异外，突触区域对靶点大小依赖性的变化表明 GABA 能中间神经元的功能分化。
In the neostriatum, several types of interneuron with distinct firing patterns and expression of neuroactive substances are known to exist. We found two types of neostriatal interneurons, parvalbumin-containing fast-spiking (FS) cells and somatostatin-containing low-threshold spike (LTS) cells to both be immunoreactive for GABA at their axon terminals in immersion-fixed brain slices from rat. To reveal the differences in synaptic connections between these two types of GABAergic interneurons, the postsynaptic target and their synaptic structure were compared by three-dimensional reconstructions from electron microscopic images of intracellularly stained axon terminals. FS cells made a greater proportion of synaptic contacts onto somata than LTS cells. Although terminal boutons of FS and LTS cells were similar in volume, their synaptic junctional areas differed in size distribution and relation to the dimensions of postsynaptic dendritic shafts or spines. Whereas the synaptic junctional areas of FS cells (0.024-0.435 mu m(2); n = 28) sharply and linearly increased with the circumference of the postsynaptic dendrites or spines (0.939-5.146 mu m), the slope for the junctional area of LTS cells (0.02-0.103 mu m(2); n = 29) against circumference (0.844-4.252 mu m) was less steep, and a much weaker correlation was seen. In addition to the differences in firing patterns, expressed molecules, axonal arborizations, and postsynaptic targets, this variation in dependency of the synaptic area on the target size suggests functional differentiation of GABAergic interneurons.