AXONAL PROJECTION PATTERNS OF VENTROLATERAL MEDULLOSPINAL SYMPATHOEXCITATORY NEURONS
AXONAL PROJECTION PATTERNS OF VENTROLATERAL MEDULLOSPINAL SYMPATHOEXCITATORY NEURONS
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DOI：
10.1152/jn.1985.53.6.1551
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发表时间：
1985-01-01
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
我们研究了投射到胸髓的猫延髓腹外侧区(VLM)神经元的以下特性：它们的自发活动与下心节后交感神经的自发活动之间的关系，它们对压力感受器反射激活的反应，它们的轴突传导速度，它们的轴突的索状轨迹，它们的轴突可能的终止位置，以及它们的轴突分支模式。在第二胸段脊髓(T2)的微刺激反向激活67个VLM神经元(通过自发和诱发动作电位的时间控制碰撞来确定)，其活动与心下交感神经放电(由峰触发平均法确定)相关。我们测试了压力感受器反射激活对其中20个VLM脊髓神经元放电率的影响。由于每次放电频率都有所下降，这些神经元显然具有交感兴奋功能。本文研究了51个VLM-脊髓交感兴奋性神经元的轴突分支模式。34个神经元被刺激在T2灰质和更尾侧的胸椎节段(T11和/或T6)逆行激活。在每种情况下，刺激T2灰质引起的逆行反应都是由于轴突分支的激活，而不是主轴突的激活(通过电流传播到白质)。这一点在测试中得到了证实，这些测试包括由刺激T2和更尾侧的胸椎节段引发的动作电位的时间控制碰撞。一些投射到T11的VLm-脊髓轴突在T6和T2也有分支。这些数据表明，一些VLM-脊髓神经元对交感神经流出具有广泛的兴奋性影响。17个支配T2灰质的VLM交感兴奋神经元不能被刺激T5、T6和T11逆行激活，尽管在每个水平都进行了广泛的搜索。因此，一些VLM-脊髓神经元的轴突投射仅限于上胸段。T2逆行标测显示，VLM交感兴奋神经元的轴突穿过背外侧索或腹外侧索，支配中间外侧核区。平均轴突传导速度为3.5m/-0.3m/S，局限于上胸段的VLm-脊髓轴突一般位于分布较远的胸段的背侧和/或内侧。另外35个被T2刺激反向激活的VLM神经元的放电与交感神经活动无关。
We studied the following properties of cat ventrolateral medullary (VLM) neurons that projected to the thoracic spinal cord: the relationship between their spontaneous activity and that in the inferior cardiac postganglionic sympathetic nerve, their responses to baroreceptor-reflex activation, their axonal conduction velocities, the funicular trajectories of their axons, the likely sites of termination of their axons, and their axonal branching patterns. Microstimulation in the second thoracic spinal segment (T2) antidromically activated 67 VLM neurons (as determined with time-controlled collision of spontaneous and evoked action potentials), whose activity was correlated to inferior cardiac sympathetic nerve discharge (as determined with spike-triggered averaging). We tested the effect of baroreceptor-reflex activation on the firing rate of 20 of these VLM-spinal neurons. Because the firing rate decreased in each instance, these neurons apparently subserved a sympathoexcitatory function. The axonal branching patterns of 51 VLM-spinal sympathoexcitatory neurons were studied. Thirty-four neurons were antidromically activated by stimulation in the T2 gray matter and in more caudal thoracic spinal segments (T11 and/or T6). In each case, the antidromic response evoked by stimulation in the T2 gray matter was due to activation of an axonal branch rather than the main axon (via current spread to the white matter). This was demonstrated with tests that included time-controlled collision of the action potentials initiated by stimulation in T2 and a more caudal thoracic spinal segment. Some VLM-spinal axons that projected to T11 branched in T6 as well as in T2. These data indicate that some VLM-spinal neurons exerted widespread excitatory influences on sympathetic outflow. Seventeen VLM sympathoexcitatory neurons that innervated the T2 gray matter could not be antidromically activated by stimulation in T5, T6, and T11 despite an extensive search at each level. Thus the axonal projections of some VLM-spinal neurons were restricted to upper thoracic segments. Antidromic mapping in T2 revealed that the axons of VLM sympathoexcitatory neurons coursed through the dorsolateral or ventrolateral funiculus to innervate the region of the intermediolateral nucleus. Mean axonal conduction velocity was 3.5 +/- 0.3 m/s. Those VLM-spinal axons restricted to upper thoracic segments generally were located dorsally and/or medially to those that innervated widely separated thoracic segments. The discharges of 35 other VLM neurons that were antidromically activated by T2 stimulation were not related to sympathetic nerve activity.(ABSTRACT TRUNCATED AT 400 WORDS)