Dendritic Arborization Patterns of Small Juxtaglomerular Cell Subtypes within the Rodent Olfactory Bulb
Dendritic Arborization Patterns of Small Juxtaglomerular Cell Subtypes within the Rodent Olfactory Bulb
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DOI：
10.3389/fnana.2016.00127
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发表时间：
2017-01-20
影响因子：
2.9
通讯作者：
Egger, Veronica
中科院分区：
文献类型：
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作者：
Bywalez, Wolfgang G.;Ona-Jodar, Tiffany;Egger, Veronica
在啮齿类动物嗅球的肾小球层内，许多局部中间神经元亚型有助于传入感觉信息的早期处理。在这里，我们已经调查了多巴胺能和其他小的局部肾小球细胞在大鼠和小鼠和其特征在于其树突树枝化模式相对于个别肾小球荧光标记通过修补和重建树突和肾小球轮廓从双光子成像数据。在转基因小鼠系中鉴定多巴胺能神经元，其中用GFP标记多巴胺转运体（DAT）的表达。在DAT+细胞中，我们发现了一个小的短轴突细胞（SAC）亚型，具有迄今未描述的树突状特化。这些密集的分支结构主要围绕着其他肾小球神经元的胞体，这些神经元也很小，非多巴胺能，在很大程度上非GABA能。在野生型小鼠和幼年大鼠中也观察到抱握SAC。在DAT+ SAC树突，单一的反向传播动作电位引起强大的钙离子进入整个扣和非扣室。除了抱握的SAC，大多数其他小神经元要么对应于经典的肾小球周围细胞类型（PGCs），这是从来没有DAT+，或者是一个小的树突树和低兴奋性的小型细胞。除了在SAC树突的存在下，许多树突形态的描述符，如树突的数量和分支的程度没有显着不同的抱索SAC和PGC。然而，一个详细的形态学分析，肾小球轮廓显示，树枝状的抱抱SAC大多在arborized肾小球空间，从来没有进入一个以上的肾小球（如果在所有），而大多数PGC树突仅限于他们的父母肾小球，类似于二尖瓣细胞的顶丛。这些互补的树枝化模式可能是高度互补的功能连接的基础。形态学方法也可以用于区分其他亚型的肾小球神经元，有助于确定假定的突触伙伴，从而建立一个更精细的图片肾小球网络的相互作用，在气味感知。
Within the glomerular layer of the rodent olfactory bulb, numerous subtypes of local interneurons contribute to early processing of incoming sensory information. Here we have investigated dopaminergic and other small local juxtaglomerular cells in rats and mice and characterized their dendritic arborization pattern with respect to individual glomeruli by fluorescent labeling via patching and reconstruction of dendrites and glomerular contours from two-photon imaging data. Dopaminergic neurons were identified in a transgenic mouse line where the expression of dopamine transporter (DAT) was labeled with GFP. Among the DAT+ cells we found a small short-axon cell (SAC) subtype featuring hitherto undescribed dendritic specializations. These densely ramifying structures clasped mostly around somata of other juxtaglomerular neurons, which were also small, non-dopaminergic and to a large extent non-GABAergic. Clasping SACs were observed also in wild-type mice and juvenile rats. In DAT+ SAC dendrites, single backpropagating action potentials evoked robust calcium entry throughout both clasping and non-clasping compartments. Besides clasping SACs, most other small neurons either corresponded to the classical periglomerular cell type (PGCs), which was never DAT+, or were undersized cells with a small dendritic tree and low excitability. Aside from the presence of clasps in SAC dendrites, many descriptors of dendritic morphology such as the number of dendrites and the extent of branching were not significantly different between clasping SACs and PGCs. However, a detailed morphometric analysis in relation to glomerular contours revealed that the dendrites of clasping SACs arborized mostly in the juxtaglomerular space and never entered more than one glomerulus (if at all), whereas most PGC dendrites were restricted to their parent glomerulus, similar to the apical tufts of mitral cells. These complementary arborization patterns might underlie a highly complementary functional connectivity. The morphometric approach may serve to differentiate also other subtypes of juxtaglomerular neurons, help to identify putative synaptic partners and thus to establish a more refined picture of glomerular network interactions during odor sensing.