Untangling Peripheral Sympathetic Neurocircuits.
Untangling Peripheral Sympathetic Neurocircuits.
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DOI：
10.3389/fcvm.2022.842656
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发表时间：
2022
影响因子：
3.6
通讯作者：
Habecker BA
中科院分区：
文献类型：
--
作者：
Clyburn C;Andresen MC;Ingram SL;Habecker BA
交感神经系统在调节包括心律在内的许多自主神经功能中起着关键作用。交感神经节中的节后神经元是将交感信号传递到目标组织的重要组成部分，其活动的破坏会导致不良的健康结果。尽管如此，人们对交感神经节内的神经回路知之甚少。通常，节后交感神经元被认为仅仅是由脊髓中外侧细胞柱的节前胆碱能神经元的单突触输入激活。早期对周围神经干受电刺激的交感神经节的电生理学研究发现，除了逆行动作电位外，还存在兴奋性胆碱能突触事件，这导致一些人推测存在兴奋性侧支投射。然而，这似乎不太可能，因为已知交感神经节后神经元合成和释放去甲肾上腺素，并且双神经化学表型的表达尚未得到很好的认识。体外研究清楚地证实了培养的交感神经元在整个发育过程中甚至在病理生理条件下表达和释放乙酰胆碱和去甲肾上腺素的能力。鉴于此，我们认为神经节传导的规范观点需要重新评估，并可能提供对疾病中自主神经失衡的机制理解。进一步的研究可能需要遗传模型来控制交感神经节内的神经化学表型，以解决神经节后神经元之间胆碱能侧支投射的功能。在这篇前瞻性文章中，我们将讨论交感神经节侧支投射的证据，确定当前的实验室技术是否可以解决这些问题，并讨论潜在的障碍和警告。
The sympathetic nervous system plays a critical role in regulating many autonomic functions, including cardiac rhythm. The postganglionic neurons in the sympathetic chain ganglia are essential components that relay sympathetic signals to target tissues and disruption of their activity leads to poor health outcomes. Despite this importance, the neurocircuitry within sympathetic ganglia is poorly understood. Canonically, postganglionic sympathetic neurons are thought to simply be activated by monosynaptic inputs from preganglionic cholinergic neurons of the intermediolateral cell columns of the spinal cord. Early electrophysiological studies of sympathetic ganglia where the peripheral nerve trunks were electrically stimulated identified excitatory cholinergic synaptic events in addition to retrograde action potentials, leading some to speculate that excitatory collateral projections are present. However, this seemed unlikely since sympathetic postganglionic neurons were known to synthesize and release norepinephrine and expression of dual neurochemical phenotypes had not been well recognized. In vitro studies clearly established the capacity of cultured sympathetic neurons to express and release acetylcholine and norepinephrine throughout development and even in pathophysiological conditions. Given this insight, we believe that the canonical view of ganglionic transmission needs to be reevaluated and may provide a mechanistic understanding of autonomic imbalance in disease. Further studies likely will require genetic models manipulating neurochemical phenotypes within sympathetic ganglia to resolve the function of cholinergic collateral projections between postganglionic neurons. In this perspective article, we will discuss the evidence for collateral projections in sympathetic ganglia, determine if current laboratory techniques could address these questions, and discuss potential obstacles and caveats.