Synapse-specific localization of vesicular glutamate transporters in the rat olfactory bulb
Synapse-specific localization of vesicular glutamate transporters in the rat olfactory bulb
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DOI：
10.1111/j.1460-9568.2007.05400.x
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发表时间：
2007-03-01
影响因子：
3.4
通讯作者：
Lledo, Pierre-Marie
中科院分区：
文献类型：
--
作者：
Gabellec, Marie-Madeleine;Panzanelli, Patrizia;Lledo, Pierre-Marie
囊泡谷氨酸转运体(VGLUT)介导兴奋性神经递质谷氨酸包装成突触小泡。到目前为止，已经鉴定出三种VGLUT亚型，在成人大脑中有不同的表达模式。在这里，我们研究了三种VGLUT在大鼠嗅球中的空间分布，嗅球是一个包含各种谷氨酸突触的大脑区域，既有轴突也有树突。利用多标记共聚焦显微镜和电子显微镜免疫细胞化学技术，我们发现每种VGLUT亚型在嗅球突触中都有高度选择性的定位。VGLUT1存在于由输出神经元(二尖瓣细胞和簇状细胞)与肾小球层和外丛状层的球状间神经元建立的树突状突触，以及颗粒细胞层的轴突突触。相比之下，VGLUT2在嗅觉神经元的轴突终末强烈表达，嗅觉神经元与肾小球神经束中的二级神经元建立突触。VGLUT2也存在于外网状层的外层和颗粒细胞层，但只与VGLUT1部分共存。最后，我们发现VGLUT3仅定位于肾小球神经纤维层，在那里它广泛地与囊泡抑制性氨基酸转运体泡状GABA转运体共存，这表明它与抑制性突触的一个子集有关。综上所述，这些观察结果扩展了先前关于VGLUT在前脑中分布的发现，并表明每种VGLUT亚型在表征嗅球回路的轴-树和树-树突触的不同特征中具有特定的功能。
Vesicular glutamate transporters (VGLUTs) mediate the packaging of the excitatory neurotransmitter glutamate into synaptic vesicles. Three VGLUT subtypes have so far been identified, with distinct expression patterns in the adult brain. Here, we investigated the spatial distribution of the three VGLUTs in the rat olfactory bulb, a brain region containing a variety of glutamate synapses, both axodendritic and dendrodendritic. Using multilabelling confocal microscopy and electron microscopic immunocytochemistry, we showed that each VGLUT isoform has a highly selective localization in olfactory bulb synapses. VGLUT1 is present at dendrodendritic synapses established by the output neurones (mitral and tufted cells) with bulbar interneurones in the glomerular layer and external plexiform layer, as well as in axonal synapses of the granule cell layer. By contrast, VGLUT2 is strongly expressed in axon terminals of olfactory sensory neurones, which establish synapses with second-order neurones in the glomerular neuropil. VGLUT2 is also found in the outer part of the external plexiform layer and in the granule cell layer but colocalizes only partially with VGLUT1. Finally, we showed that VGLUT3 is exclusively located in the glomerular neuropil, where it colocalizes extensively with the vesicular inhibitory amino acid transporter vesicular GABA transporter, suggesting that it is associated with a subset of inhibitory synapses. Together, these observations extend previous findings on VGLUT distribution in the forebrain, and suggest that each VGLUT subtype has a specific function in the distinct features of axodendritic and dendrodendritic synapses that characterize the olfactory bulb circuit.