Centre National de la Recherche Scientifique UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, 5 rue Blaise Pascal, 67000, Strasbourg, France.
Brain Struct Funct. 2019 Apr;224(3):1067-1095. doi: 10.1007/s00429-018-01825-1. Epub 2019 Jan 4.
The central extended amygdala (EAc) is a forebrain macrosystem which has been widely implicated in reward, fear, anxiety, and pain. Its two key structures, the lateral bed nucleus of the stria terminalis (BSTL) and the central nucleus of the amygdala (CeA), share similar mesoscale connectivity. However, it is not known whether they also share similar cell-specific neuronal circuits. We addressed this question using tract-tracing and immunofluorescence to reveal the EAc microcircuits involving two neuronal populations expressing either protein kinase C delta (PKCδ) or somatostatin (SOM). PKCδ and SOM are expressed predominantly in the dorsal BSTL (BSTLD) and in the lateral/capsular parts of CeA (CeL/C). We found that, in both BSTLD and CeL/C, PKCδ+ cells are the main recipient of extra-EAc inputs from the lateral parabrachial nucleus (LPB), while SOM+ cells constitute the main source of long-range projections to extra-EAc targets, including LPB and periaqueductal gray. PKCδ+ cells can also integrate inputs from the basolateral nucleus of the amygdala or insular cortex. Within EAc, PKCδ+, but not SOM+ neurons, serve as the major source of inputs to the ventral BSTL and to the medial part of CeA. However, both cell types can be involved in mutual connections between BSTLD and CeL/C. These results unveil the pivotal positions of PKCδ+ and SOM+ neurons in organizing parallel cell-specific neuronal circuits within CeA and BSTL, but also between them, which further reinforce the notion of EAc as a structural and functional macrosystem.
中央延伸杏仁核（EAc）是一个大脑前系统，广泛涉及奖励、恐惧、焦虑和疼痛。它的两个关键结构，外侧终纹床核（BSTL）和杏仁核中央核（CeA），具有相似的中尺度连接。然而，目前尚不清楚它们是否也具有相似的细胞特异性神经元回路。我们使用示踪和免疫荧光来揭示 EAc 微电路，涉及两种表达蛋白激酶 C 德尔塔（PKCδ）或生长抑素（SOM）的神经元群体。PKCδ和 SOM 主要表达在背侧 BSTL（BSTLD）和杏仁核的外侧/囊状部分（CeL/C）。我们发现，在 BSTLD 和 CeL/C 中，PKCδ+细胞是来自外侧臂旁核（LPB）的 EAc 外输入的主要接收者，而 SOM+细胞构成了向 EAc 外靶标（包括 LPB 和导水管周围灰质）的长程投射的主要来源。PKCδ+细胞还可以整合来自杏仁核基底外侧核或岛叶皮质的输入。在 EAc 内，PKCδ+，而不是 SOM+神经元，是向腹侧 BSTL 和 CeA 内侧部分的主要输入源。然而，这两种细胞类型都可以参与 BSTLD 和 CeL/C 之间的相互连接。这些结果揭示了 PKCδ+和 SOM+神经元在组织 CeA 和 BSTL 内以及它们之间的平行细胞特异性神经元回路中的关键作用，进一步强化了 EAc 作为一个结构和功能的大系统的概念。
