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首页> 外文期刊>American Journal of Physiology >Effects of corticospinal tract stimulation on renal sympathetic nerve activity in rats with intact and chronically lesioned spinal cords.
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Effects of corticospinal tract stimulation on renal sympathetic nerve activity in rats with intact and chronically lesioned spinal cords.

机译：皮质脊髓束刺激对完整和慢性病变脊髓大鼠的肾交感神经活动的影响。

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摘要

Sympathetic preganglionic neurons and interneurons are closely apposed (presumably synapsed upon) by corticospinal tract (CST) axons. Sprouting of the thoracic CST rostral to lumbar spinal cord injuries (SCI) substantially increases the incidence of these appositions. To test our hypothesis that these additional synapses would increase CST control of sympathetic activity after SCI, we measured the effects of electrical stimulation of the CST on renal sympathetic nerve activity (RSNA) and arterial pressure (AP) in alpha-chloralose-anesthetized rats with either chronically intact or chronically lesioned spinal cords. Stimuli were delivered to the CST at intensities between 25-150 muA and frequencies between 25 and 75 Hz. Stimulation of the CST at the midcervical level decreased RSNA and AP. These decreases were not mediated by direct projections of the CST to the thoracic spinal cord because we could still elicit them by midcervical stimulation after acute lesions of the CST at caudal cervical levels. Incontrast, caudal thoracic CST stimulation increased RSNA and AP. Neither the responses to cervical nor thoracic stimulation were affected by chronic lumbar SCI. These data show that the CST mediates decreases in RSNA via a cervical spinal system but excites spinal sympathetic neurons at caudal thoracic levels. Because chronic lumber spinal cord injury affected responses evoked from neither the cervical nor thoracic CST, we conclude that lesion-induced or regeneration-induced formation of new synapses between the CST and sympathetic neurons may not affect cardiovascular regulation.
机译：交感神经节前神经元和中间神经元由皮质脊髓束（CST）轴突紧密并置（大概突触）。胸廓CST角质发芽至腰脊髓损伤（SCI）会大大增加这些并发的发生率。为了检验我们的假设，即这些额外的突触会增强SCI后CST对交感神经活动的控制，我们测量了CST电刺激对α-氯代海洛糖麻醉的大鼠肾交感神经活性（RSNA）和动脉压（AP）的影响。慢性完好无损或慢性病变的脊髓。刺激以25-150μA之间的强度和25-75 Hz之间的频率传递到CST。子宫颈中段的CST刺激降低了RSNA和AP。这些减少不是由CST直接投射到胸脊髓所介导的，因为我们仍然可以通过在尾颈水平CST急性损伤后通过宫颈中刺激来诱发它们。相反，尾胸CST刺激可增加RSNA和AP。慢性腰椎脊髓损伤既不影响对颈椎的刺激，也不影响胸腔的刺激。这些数据表明，CST通过颈椎脊髓系统介导的RSNA减少，但在尾椎水平激发脊髓交感神经元。由于慢性木材脊髓损伤不影响颈椎和胸廓CST引起的反应，因此我们得出结论，病灶诱导或再生诱导的CST与交感神经元之间新突触的形成可能不会影响心血管调节。

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