Department of Physiology, University of Oklahoma Health Sciences Center, PO Box 26901, Oklahoma City, OK 73190, USA.
Brain Res. 2010 Dec 17;1366:71-84. doi: 10.1016/j.brainres.2010.09.058. Epub 2010 Nov 3.
Postsynaptic dorsal column (PSDC) neurons transmit noxious visceral information from the lower thoracic and lumbosacral spinal cord. Cuneothalamic neurons in the PSDC pathway and upper thoracic (T(3)-T(4)) spinal neurons ascending through the ventrolateral funiculus (VLF) have been shown to transmit nociceptive cardiac information. Therefore, we hypothesized that upper thoracic PSDC neurons transmit noxious cardiac information. Neuronal responses to intrapericardially injected mechanical (1.0 ml saline) and noxious chemical (0.2 ml algogenic chemicals) stimuli were recorded from antidromically activated PSDC and VLF neurons in the T(3)-T(4) spinal cord of anesthetized Sprague-Dawley rats. Of the PSDC neurons, 43% responded to mechanical stimulation, but only one responded to noxious chemical stimuli. Fifty-eight percent of VLF neurons responded to mechanical stimulation and all responded to noxious chemical stimulation. Fluoro-Ruby (FR)-labeled PSDC neurons in the T(3)-T(4) spinal cord of Sprague-Dawley rats were processed for c-fos immunohistochemistry following intrapericardial stimulation with mechanical, chemical, or control stimuli. Sections were viewed under epifluorescence and light microscopy to detect FR-labeled neurons containing a c-fos immunoreactive (IR) nucleus. An average of 6 PSDC neurons per rat was found in the T(3) and T(4) spinal segments. The average number of c-fos-IR neurons per segment varied by type of stimulus: 12 (control), 67 (chemical) and 85 (mechanical) for T(3) and 8 (control), 37 (chemical) and 62 (mechanical) for T(4). None of the 200 PSDC neurons examined expressed c-fos-IR regardless of stimulus. Together, these results suggest that thoracic PSDC neurons transmit mechanical cardiac information, but they play a minimal role in cardiac nociception.
Postsynaptic dorsal column (PSDC) 神经元从胸下部和腰骶部脊髓传递有害内脏信息。已经证明 PSDC 通路中的楔状丘脑神经元和通过腹外侧束（VLF）上升的胸上部（T(3)-T(4)）脊髓神经元传递伤害性心脏信息。因此，我们假设胸上部 PSDC 神经元传递有害的心脏信息。在麻醉的 Sprague-Dawley 大鼠 T(3)-T(4)脊髓中，通过逆行激活 PSDC 和 VLF 神经元记录到心包内注射机械（1.0 ml 生理盐水）和有害化学（0.2 ml 致痛化学物质）刺激的神经元反应。在 PSDC 神经元中，43%对机械刺激有反应，但只有一个对有害化学刺激有反应。58%的 VLF 神经元对机械刺激有反应，所有神经元对有害化学刺激有反应。在 Sprague-Dawley 大鼠 T(3)-T(4)脊髓的 PSDC 神经元用氟-罗丹明（FR）标记，并用机械、化学或对照刺激进行心包内刺激后，进行 c-fos 免疫组织化学处理。用荧光和光学显微镜观察切片，以检测含有 c-fos 免疫反应（IR）核的 FR 标记神经元。在 T(3)和 T(4)脊髓段，每只大鼠平均发现 6 个 PSDC 神经元。每个节段的 c-fos-IR 神经元数量因刺激类型而异：T(3)为 12（对照）、67（化学）和 85（机械），T(4)为 8（对照）、37（化学）和 62（机械）。无论刺激如何，在检查的 200 个 PSDC 神经元中，没有一个表达 c-fos-IR。这些结果表明，胸 PSDC 神经元传递机械性心脏信息，但它们在心脏伤害感受中作用不大。
