Postsynaptic targets of GABAergic basal forebrain projections to the basolateral amygdala.
Postsynaptic targets of GABAergic basal forebrain projections to the basolateral amygdala.
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DOI：
10.1016/j.neuroscience.2011.03.027
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发表时间：
2011-06-02
期刊：
影响因子：
3.3
通讯作者：
Mascagni F
中科院分区：
文献类型：
--
作者：
McDonald AJ;Muller JF;Mascagni F
最近的研究表明，基底外侧杏仁核与新皮质和海马一样，除了已确定的胆碱能输入之外，还接收来自基底前脑的 GABA 能输入。由于这些输入的神经元目标尚未确定，因此很难预测这种神经支配的功能意义。本研究通过在光和电子显微镜分析水平上采用顺行束追踪结合免疫组织化学在大鼠中解决了这个问题。来自基底前脑的杏仁核轴突主要针对杏仁核的基底外侧核（BL）。这些轴突的形态是异质的，包括含有囊泡 GABA 转运蛋白 (VGAT) 的 GABA 能轴突。这些轴突被指定为 1 型，表现出独特的大轴突静脉曲张，通常沿着轴突的长度聚集。 1 型轴突与含有小清蛋白（PV+）的中间神经元的细胞体和树突形成多次接触，但与含有钙结合蛋白和生长抑素的中间神经元的接触相对较少。在超微结构分析水平上，1 型轴突的大末端表现出大量线粒体，并且密集地充满突触小泡。各个末端与 BL PV+ 中间神经元形成广泛的对称突触，并且通常与 BL 锥体细胞形成额外的对称突触。一些单独的 1 型末端仅与 BL 锥体细胞形成对称突触。这些结果表明基底前脑的 GABA 能神经元对 BL 锥体神经元提供间接去抑制和直接抑制。讨论了这些回路可能参与与情绪学习、注意力和唤醒相关的节律振荡。
Recent studies indicate that the basolateral amygdala, like the neocortex and hippocampus, receives GABAergic inputs from the basal forebrain in addition to the well-established cholinergic inputs. Since the neuronal targets of these inputs have yet to be determined, it is difficult to predict the functional significance of this innervation. The present study addressed this question in the rat by employing anterograde tract tracing combined with immunohistochemistry at the light and electron microscopic levels of analysis. Amygdalopetal axons from the basal forebrain mainly targeted the basolateral nucleus (BL) of the amygdala. The morphology of these axons was heterogeneous and included GABAergic axons that contained vesicular GABA transporter protein (VGAT). These axons, designated type 1, exhibited distinctive large axonal varicosities that were typically clustered along the length of the axon. Type 1 axons formed multiple contacts with the cell bodies and dendrites of parvalbumin-containing (PV+) interneurons, but relatively few contacts with calretinin-containing and somatostatin-containing interneurons. At the ultrastructural level of analysis, the large terminals of type 1 axons exhibited numerous mitochondria and were densely packed with synaptic vesicles. Individual terminals formed broad symmetrical synapses with BL PV+ interneurons, and often formed additional symmetrical synapses with BL pyramidal cells. Some solitary type 1 terminals formed symmetrical synapses solely with BL pyramidal cells. These results suggest that GABAergic neurons of the basal forebrain provide indirect disinhibition, as well as direct inhibition, of BL pyramidal neurons. The possible involvement of these circuits in rhythmic oscillations related to emotional learning, attention, and arousal is discussed.