Dichotomous Distribution of Putative Cholinergic Interneurons in Mouse Accessory Olfactory Bulb.
Dichotomous Distribution of Putative Cholinergic Interneurons in Mouse Accessory Olfactory Bulb.
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DOI：
10.3389/fnana.2017.00010
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发表时间：
2017
影响因子：
2.9
通讯作者：
Lin W
中科院分区：
文献类型：
--
作者：
Marking S;Krosnowski K;Ogura T;Lin W
嗅球（OB）的感觉信息处理依赖于不同种群的球间神经元。在啮齿类动物中，副OB （AOB）分为两个球区，前（aAOB）和后（pAOB），它们的电路连接和相关行为有很大的不同。我们之前使用转基因小鼠在OB （MOB）中鉴定和表征了大量形态多样的胆碱能中间神经元，以可视化胆碱乙酰转移酶的细胞体（chat表达神经元和免疫标记（Krosnowski et al.,））。然而，AOB中是否存在胆碱能神经元尚存争议，目前尚无对该类神经元的详细描述。利用细菌人工染色体（BAC）增强绿色荧光蛋白（eGFP）转基因小鼠同一细胞系，我们研究了AOB中的胆碱能神经元。我们发现，在aAOB和pAOB之间，GFP-表达（GFP+），推测的胆碱能中间神经元的数量和位置存在显著差异。GFP+中间神经元在aAOB肾小球层（aGL）和pAOB二尖瓣/簇状细胞层（pMCL）中数量最多。我们还注意到环绕pMCL边界区域的高密度GFP+中间神经元。有趣的是，GL中间的一小部分肾小球接受强烈的MCL GFP+神经过程。这些局部胆碱能神经支配的肾小球位于aGL外，是pGL和aGL之间的分界线。AOB中许多（但不是全部）GFP+神经元被抗ChAT和囊状乙酰胆碱转运蛋白（VAChT）的抗体弱标记。我们进一步确定了这些GFP+中间神经元是否与其他先前表征的AOB中间神经元群体不同，发现AOB GFP+中间神经元既不表达gaba能标记也不表达多巴胺能标记，大多数也不表达谷氨酸能标记。与MOB的胆碱能中间神经元类似，部分AOB GFP+中间神经元表达钙结合蛋白calbinin - d28k。此外，暴露于雄性入侵者或交配笼中肮脏的被褥会导致表达c- fos的MCL GFP+神经元数量增加。综上所述，我们的数据揭示了AOB中大量未知的假定胆碱能神经元。它们在aAOB和pAOB中的二分类分布表明，区域特异性胆碱能参与嗅觉信息加工。
Sensory information processing in the olfactory bulb (OB) relies on diverse populations of bulbar interneurons. In rodents, the accessory OB (AOB) is divided into two bulbar regions, the anterior (aAOB) and posterior (pAOB), which differ substantially in their circuitry connections and associated behaviors. We previously identified and characterized a large number of morphologically diverse cholinergic interneurons in the main OB (MOB) using transgenic mice to visualize the cell bodies of choline acetyltransferase (ChAT-expressing neurons and immunolabeling (Krosnowski et al.,)). However, whether there are cholinergic neurons in the AOB is controversial and there is no detailed characterization of such neurons. Using the same line of ChAT(bacterial artificial chromosome, BAC)-enhanced green fluorescent protein (eGFP) transgenic mice, we investigated cholinergic neurons in the AOB. We found significant differences in the number and location of GFP-expressing (GFP+), putative cholinergic interneurons between the aAOB and pAOB. The highest numbers of GFP+ interneurons were found in the aAOB glomerular layer (aGL) and pAOB mitral/tufted cell layer (pMCL). We also noted a high density of GFP+ interneurons encircling the border region of the pMCL. Interestingly, a small subset of glomeruli in the middle of the GL receives strong MCL GFP+ nerve processes. These local putative cholinergic-innervated glomeruli are situated just outside the aGL, setting the boundary between the pGL and aGL. Many but not all GFP+ neurons in the AOB were weakly labeled with antibodies against ChAT and vesicular acetylcholine transporter (VAChT). We further determined if these GFP+ interneurons differ from other previously characterized interneuron populations in the AOB and found that AOB GFP+ interneurons express neither GABAergic nor dopaminergic markers and most also do not express the glutamatergic marker. Similar to the cholinergic interneurons of the MOB, some AOB GFP+ interneurons express the calcium binding protein, calbindin-D28K. Moreover, exposure to either a male intruder or soiled bedding from a mating cage leads to an increase in the number of c-Fos-expressing MCL GFP+ neurons. Taken together, our data reveal a population of largely unidentified putative cholinergic neurons in the AOB. Their dichotomous distribution in the aAOB and pAOB suggests region-specific cholinergic involvement in olfactory information processing.