Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
J Comp Neurol. 2023 Jun;531(8):921-934. doi: 10.1002/cne.25474. Epub 2023 Mar 28.
The locus coeruleus (LC) is a small noradrenergic brainstem nucleus that plays a central role in regulating arousal, attention, and performance. In the mammalian brain, individual LC neurons make divergent axonal projections to different brain regions, which are distinguished in part by which noradrenaline (NA) receptor subtypes they express. Here, we sought to determine whether similar organizational features characterize LC projections to corticobasal ganglia (CBG) circuitry in the zebra finch song system, with a focus on the basal ganglia nucleus Area X, the thalamic nucleus DLM, as well as the cortical nuclei HVC, LMAN, and RA. Single and dual retrograde tracer injections reveal that single LC-NA neurons make divergent projections to LMAN and Area X, as well as to the dopaminergic VTA/SNc complex that innervates this CBG circuit. Moreover, in situ hybridization revealed that differential expression of mRNA encoding α and α adrenoreceptors distinguishes LC-recipient CBG song nuclei. Therefore, LC-NA signaling in the zebra finch CBG circuit employs a similar strategy as in mammals, which could allow a relatively small number of LC neurons to exert widespread yet distinct effects across multiple brain regions.
蓝斑核（LC）是一个小的去甲肾上腺素能脑干核，在调节觉醒、注意力和表现方面起着核心作用。在哺乳动物大脑中，单个 LC 神经元向不同的脑区发出不同的轴突投射，这些投射在一定程度上是由它们表达的哪种去甲肾上腺素（NA）受体亚型来区分的。在这里，我们试图确定 LC 投射到斑马雀鸣系统皮质基底节（CBG）回路是否具有类似的组织特征，重点关注基底节核 Area X、丘脑核 DLM 以及皮质核 HVC、LMAN 和 RA。单和双逆行示踪剂注射表明，单个 LC-NA 神经元向 LMAN 和 Area X 以及向多巴胺能 VTA/SNc 复合物发出不同的投射，该复合物支配着这个 CBG 回路。此外，原位杂交显示，编码α和α肾上腺素能受体的 mRNA 的差异表达区分了 LC 接受的 CBG 鸣禽核。因此，斑马雀 CBG 回路中的 LC-NA 信号传递采用了与哺乳动物相似的策略，这可能使相对较少的 LC 神经元能够在多个脑区发挥广泛但又不同的作用。
