Subgroups of rostral ventrolateral medullary and caudal medullary raphe neurons based on patterns of relationship to sympathetic nerve discharge and axonal projections
Subgroups of rostral ventrolateral medullary and caudal medullary raphe neurons based on patterns of relationship to sympathetic nerve discharge and axonal projections
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DOI：
10.1152/jn.1997.77.1.65
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发表时间：
1997-01-01
影响因子：
2.5
通讯作者：
Gebber, GL
中科院分区：
文献类型：
--
作者：
Barman, SM;Gebber, GL
本研究旨在回答与交感神经放电(SND)有关的三个问题，即延髓头端腹外侧(RVLM)神经元和延髓尾侧中缝(CMR)神经元。1)在SND中，RVLM和CMR神经元的活动同时与心脏相关节律和IO-HZ节律相关、仅与10-HZ节律相关、仅与心脏相关节律相关的神经元所占的比例是多少？2)这些细胞类型中有哪些投射到脊髓？3)心脏相关节律和10-HZ节律产生器的输出在球脊髓神经元或其之前的中间神经元水平上汇聚吗？为了解决这些问题，我们在乌拉坦麻醉猫中记录了44个RVLM和48个CMR神经元，这些神经元具有交感神经相关活动，其中完整的颈动脉窦神经，但切断了主动脉降压神经和迷走神经。棘波触发平均、动脉脉搏触发分析和相干分析表明，24个RVLM神经元和41个CMR神经元的自然放电与下心节后SND的10 Hz节律和心脏相关节律有关。SND中其他神经元的放电仅与IO-HZ节律相关(15个RVLM和6个CMR神经元)或仅与心脏相关节律相关(5个RVLM神经元和1个CMR神经元)。时间控制碰撞实验证实，在18个与两种节律相关的RVLM神经元和31个CMR神经元中，有16个神经元被刺激脊髓第一胸段(T-1)白质逆行激活。相反，在10个RVLM神经元和4个CMR神经元中，只有1个神经元的活动仅与10赫兹节律相关，而刺激T1时，只有1个神经元能被反向激活。此外，仅与SND的心脏节律相关的3个RVLM神经元中，有0个被脊髓刺激反向激活。这些数据首次表明，发自RVLM和CMR的球脊髓交感神经通路几乎完全由神经元组成，其放电与SND的心脏相关节律和10-HZ节律有关。此外，数据支持心脏相关和10-Hz节律发生器的输出汇聚在RVLM和CMR球脊髓神经元而不是它们之前的中间神经元的假设。最后，数据表明，相当大比例的RVLM神经元和一小部分与SND相关的CMR神经元并不投射到胸髓。它们的放电只与SND的一种节律相关。它们的轴突轨迹和功能尚不清楚。
This study was designed to answer three questions concerning rostral ventrolateral medullary (RVLM) and caudal medullary raphe (CMR) neurons with activity correlated to sympathetic nerve discharge (SND). 1) What are the proportions of RVLM and CMR neurons that have activity correlated to both the cardiac-related and IO-Hz rhythms in SND, to only the 10-Hz rhythm, and to only the cardiac-related rhythm? 2) Which of these cell types project to the spinal cord? 3) Do the outputs of the cardiac-related and 10-Hz rhythm generators converge at the level of bulbospinal neurons or their antecedent interneurons? To address these issues we recorded from 44 RVLM and 48 CMR neurons with sympathetic nerve-related activity in urethan-anesthetized cats with intact carotid sinus nerves, but sectioned aortic depressor and vagus nerves. Spike-triggered averaging, arterial pulse-triggered analysis, and coherence analysis revealed that the naturally occurring discharges of 24 of these RVLM neurons and 41 of these CMR neurons were correlated to both the 10-Hz and cardiac-related rhythms in inferior cardiac postganglionic SND. The discharges of the other neurons were correlated to only the IO-Hz rhythm(15 RVLM and 6 CMR neurons) or to only the cardiac-related rhythm (5 RVLM neurons and 1 CMR neuron) in SND. The time-controlled collision test Verified that 16 of 18 RVLM and 31 of 34 CMR neurons with activity correlated to both rhythms were antidromically activated by stimulation of the white matter of the first thoracic (T-1) segment of the spinal cord. In contrast, only I of 10 RVLM neurons and 0 of 4 CMR neurons with activity correlated to only the 10-Hz rhythm could be antidromically activated by stimulation at T1. Also 0 of 3 RVLM neurons with activity correlated to only the cardiac-related rhythm in SND were antidromically activated by spinal stimulation. These data show for the first time that bulbospinal sympathetic pathways emanating from the RVLM and CMR are comprised almost exclusively of neurons whose discharges are correlated to both the cardiac-related and 10-Hz rhythms in SND. Moreover, the data support the hypothesis that the outputs of the cardiac-related and 10-Hz rhythm generators converge on RVLM and CMR bulbospinal neurons rather than on their antecedent interneurons. Finally, the data demonstrate that a substantial proportion of RVLM neurons and a small group of CMR neurons with activity correlated to SND do not project to the thoracic spinal cord. Their discharges were correlated to only one of the rhythms in SND. Their axonal trajectories and functions are unknown.