Department of Orthopaedic Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan.
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan.
Neurosci Lett. 2021 Apr 1;749:135707. doi: 10.1016/j.neulet.2021.135707. Epub 2021 Feb 15.
The dorsal spinal cord contains projection neurons that transmit somatosensory information to the brain and interneurons which then modulate neuronal activity of these projection neurons and/or other interneurons. Interneurons can be subdivided into two groups: excitatory and inhibitory neurons. While inhibitory interneurons are thought to play a crucial role in analgesia, it is unclear whether they are involved in neuropathic pain. In the present study, we aimed to assess the proportion and neuronal activity of excitatory/inhibitory neurons in the dorsal spinal cord using a neuropathic pain model in rats. Following partial sciatic nerve ligation (PSNL), rats showed significant mechanical hyperalgesia, and subsequent immunohistochemical studies were conducted in laminae I-III of the dorsal spinal cord. We found that the number of FosB-immunoreactive cells was significantly higher; there was no change in the percentage of Pax2 positive/negative neurons in NeuN positive neurons; Pax2 negative neurons, but not Pax2 positive neurons, were predominantly activated in PSNL rats; and the immunofluorescence intensity of the calcium channel α2δ1 subunit was significantly higher. These results indicate that while peripheral nerve injury might not affect the proportion of excitatory and inhibitory neurons, it predominantly activates excitatory neurons in laminae I-III of the rat dorsal spinal cord.
背根脊髓包含投射神经元，它们将躯体感觉信息传递到大脑，中间神经元随后调节这些投射神经元和/或其他中间神经元的神经元活动。中间神经元可分为两类：兴奋性神经元和抑制性神经元。虽然抑制性中间神经元被认为在镇痛中发挥关键作用，但它们是否参与神经病理性疼痛尚不清楚。在本研究中，我们旨在使用大鼠的神经病理性疼痛模型来评估背根脊髓中兴奋性/抑制性神经元的比例和神经元活性。部分坐骨神经结扎（PSNL）后，大鼠表现出明显的机械性痛觉过敏，随后在背根脊髓的 I-III 层进行了免疫组织化学研究。我们发现 FosB 免疫反应性细胞的数量明显增加；Pax2 阳性/阴性神经元在 NeuN 阳性神经元中的百分比没有变化；Pax2 阴性神经元而非 Pax2 阳性神经元在 PSNL 大鼠中主要被激活；钙通道α2δ1 亚基的免疫荧光强度明显升高。这些结果表明，外周神经损伤可能不会影响兴奋性和抑制性神经元的比例，但会主要激活大鼠背根脊髓 I-III 层的兴奋性神经元。
