Barman Susan M, Yates Bill J
Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States.
Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, United States.
Front Neurosci. 2017 Dec 22;11:730. doi: 10.3389/fnins.2017.00730. eCollection 2017.
Sympathetic nerve activity (SNA) contributes appreciably to the control of physiological function, such that pathological alterations in SNA can lead to a variety of diseases. The goal of this review is to discuss the characteristics of SNA, briefly review the methodology that has been used to assess SNA and its control, and to describe the essential role of neurophysiological studies in conscious animals to provide additional insights into the regulation of SNA. Studies in both humans and animals have shown that SNA is rhythmic or organized into bursts whose frequency varies depending on experimental conditions and the species. These rhythms are generated by brainstem neurons, and conveyed to sympathetic preganglionic neurons through several pathways, including those emanating from the rostral ventrolateral medulla. Although rhythmic SNA is present in decerebrate animals (indicating that neurons in the brainstem and spinal cord are adequate to generate this activity), there is considerable evidence that a variety of supratentorial structures including the insular and prefrontal cortices, amygdala, and hypothalamic subnuclei provide inputs to the brainstem regions that regulate SNA. It is also known that the characteristics of SNA are altered during stress and particular behaviors such as the defense response and exercise. While it is a certainty that supratentorial structures contribute to changes in SNA during these behaviors, the neural underpinnings of the responses are yet to be established. Understanding how SNA is modified during affective responses and particular behaviors will require neurophysiological studies in awake, behaving animals, including those that entail recording activity from neurons that generate SNA. Recent studies have shown that responses of neurons in the central nervous system to most sensory inputs are context-specific. Future neurophysiological studies in conscious animals should also ascertain whether this general rule also applies to sensory signals that modify SNA.
交感神经活动（SNA）对生理功能的控制有显著贡献，因此SNA的病理改变可导致多种疾病。本综述的目的是讨论SNA的特征，简要回顾用于评估SNA及其控制的方法，并描述在清醒动物中进行神经生理学研究的重要作用，以提供对SNA调节的更多见解。对人类和动物的研究均表明，SNA是有节律的或组织成爆发形式，其频率根据实验条件和物种而变化。这些节律由脑干神经元产生，并通过多种途径传递至交感神经节前神经元，包括来自延髓头端腹外侧的那些途径。尽管在去大脑动物中存在节律性SNA（表明脑干和脊髓中的神经元足以产生这种活动），但有大量证据表明，包括岛叶和前额叶皮质、杏仁核以及下丘脑亚核在内的多种幕上结构向调节SNA的脑干区域提供输入。还已知在应激和特定行为（如防御反应和运动）期间，SNA的特征会发生改变。虽然可以确定幕上结构在这些行为期间对SNA的变化有贡献，但这些反应的神经基础尚未确立。了解SNA在情感反应和特定行为期间如何被改变，将需要在清醒、行为活跃的动物中进行神经生理学研究，包括那些需要记录产生SNA的神经元活动的研究。最近的研究表明，中枢神经系统中神经元对大多数感觉输入的反应是情境特异性的。未来在清醒动物中进行的神经生理学研究还应确定这一普遍规律是否也适用于调节SNA的感觉信号。
