Nuclei-specific differences in nerve terminal distribution, morphology, and development in mouse visual thalamus
Nuclei-specific differences in nerve terminal distribution, morphology, and development in mouse visual thalamus
复制标题
DOI：
10.1186/1749-8104-9-16
复制
发表时间：
2014-07-10
影响因子：
3.6
通讯作者：
Fox, Michael A.
中科院分区：
文献类型：
--
作者：
Hammer, Sarah;Carrillo, Gabriela L.;Fox, Michael A.
背景：小鼠视觉丘脑已成为理解神经回路形成和功能机制的强大模型。小鼠丘脑内的三个不同的核接受视网膜输入：背侧膝状体核（dLGN）、腹侧外侧膝状体核（vLGN）和膝状体间核（IGL）。然而，在每个核中，视网膜输入的数量远远超过来自皮质和皮质下来源的非视网膜输入。尽管 dLGN 回路内相关的视网膜和非视网膜末梢已得到很好的表征，但我们对小鼠视觉丘脑其他核团的神经末梢组织、分布和发育知之甚少。结果：用针对囊泡相关神经递质转运蛋白或神经递质合成酶的抗体对突触的特定子集进行免疫标记，揭示了 dLGN、vLGN 和 IGL 中非视网膜末梢的组成、分布和形态的显着差异。例如，抑制性末端在vLGN中分布更密集，皮质末端在dLGN中分布更密集。总体而言，IGL 中的突触末端密度似乎最低。使用免疫标记、基因标记、轴突追踪和连续块面扫描电子显微镜观察到视网膜末梢类似的细胞核特异性差异：与 dLGN 相比，vLGN 中的视网膜末梢更小、形态复杂度更低、分布更密集。由于谷氨酸末端大小通常与突触功能相关，因此我们使用体外全细胞记录和急性准备的丘脑切片中的视束刺激来揭示vLGN中的兴奋性突触后电流（EPSC）要小得多，并且在配对刺激后显示出不同的反应。最后，在整个出生后早期发育过程中视网膜末梢的顺行标记表明，视网膜神经末梢结构的解剖学差异在突触最初形成时不可观察到，而是随着视网膜原化回路的成熟而发展。结论：综上所述，这些结果揭示了小鼠视觉丘脑中神经末梢组成、分布和形态的细胞核特异性差异。这些结果提出了一些有趣的问题，即这些原子核在处理光衍生信息方面的不同功能，以及它们独特的、原子核特异性发育背后的机制差异。
Background: Mouse visual thalamus has emerged as a powerful model for understanding the mechanisms underlying neural circuit formation and function. Three distinct nuclei within mouse thalamus receive retinal input, the dorsal lateral geniculate nucleus (dLGN), the ventral lateral geniculate nucleus (vLGN), and the intergeniculate nucleus (IGL). However, in each of these nuclei, retinal inputs are vastly outnumbered by nonretinal inputs that arise from cortical and subcortical sources. Although retinal and nonretinal terminals associated within dLGN circuitry have been well characterized, we know little about nerve terminal organization, distribution and development in other nuclei of mouse visual thalamus.Results: Immunolabeling specific subsets of synapses with antibodies against vesicle-associated neurotransmitter transporters or neurotransmitter synthesizing enzymes revealed significant differences in the composition, distribution and morphology of nonretinal terminals in dLGN, vLGN and IGL. For example, inhibitory terminals are more densely packed in vLGN, and cortical terminals are more densely distributed in dLGN. Overall, synaptic terminal density appears least dense in IGL. Similar nuclei-specific differences were observed for retinal terminals using immunolabeling, genetic labeling, axonal tracing and serial block face scanning electron microscopy: retinal terminals are smaller, less morphologically complex, and more densely distributed in vLGN than in dLGN. Since glutamatergic terminal size often correlates with synaptic function, we used in vitro whole cell recordings and optic tract stimulation in acutely prepared thalamic slices to reveal that excitatory postsynaptic currents (EPSCs) are considerably smaller in vLGN and show distinct responses following paired stimuli. Finally, anterograde labeling of retinal terminals throughout early postnatal development revealed that anatomical differences in retinal nerve terminal structure are not observable as synapses initially formed, but rather developed as retinogeniculate circuits mature.Conclusions: Taken together, these results reveal nuclei-specific differences in nerve terminal composition, distribution, and morphology in mouse visual thalamus. These results raise intriguing questions about the different functions of these nuclei in processing light-derived information, as well as differences in the mechanisms that underlie their unique, nuclei-specific development.