Corneal afferents differentially target thalamic- and parabrachial-projecting neurons in spinal trigeminal nucleus caudalis.
Corneal afferents differentially target thalamic- and parabrachial-projecting neurons in spinal trigeminal nucleus caudalis.
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DOI：
10.1016/j.neuroscience.2012.11.033
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发表时间：
2013-03-01
期刊：
影响因子：
3.3
通讯作者：
Hegarty DM
中科院分区：
文献类型：
--
作者：
Aicher SA;Hermes SM;Hegarty DM
背角神经元向丘脑核和臂旁核发出上行投射，这些通路被认为是伤害性信息中枢处理的关键通路。来自眼睛角膜表面的传入神经介导来自该组织的伤害感受，该组织对临床上重要的疼痛综合征敏感。本研究检测了三叉神经背角的角膜传入，并比较了丘脑和臂旁投射神经元的传入。我们使用霍乱毒素B亚单位的顺行追踪来鉴定三叉神经背角的角膜传入投射，并使用逆行示踪剂FluoroGold来鉴定投射神经元。在成年雄性Sprague-Dawley大鼠中进行研究。我们的分析进行了两个不同的水平的三叉神经亚核尾侧（Vc）接受角膜传入投射。我们发现，角膜传入项目更密集的嘴极比尾极Vc。我们还量化了接受角膜传入的Vc区域中丘脑和臂旁投射神经元的数量。两组投射神经元的角膜传入输入也更丰富的嘴极的Vc。最后，通过比较丘脑与臂旁投射神经元的角膜传入贴壁频率，我们发现角膜传入优先靶向三叉神经背角的臂旁投射神经元。这些结果表明，角膜的伤害性疼痛可能主要由非丘脑上行通路介导。
Dorsal horn neurons send ascending projections to both thalamic nuclei and parabrachial nuclei; these pathways are thought to be critical pathways for central processing of nociceptive information. Afferents from the corneal surface of the eye mediate nociception from this tissue which is susceptible to clinically important pain syndromes. This study examined corneal afferents to the trigeminal dorsal horn and compared inputs to thalamic- and parabrachial-projecting neurons. We used anterograde tracing with cholera toxin B subunit to identify corneal afferent projections to trigeminal dorsal horn, and the retrograde tracer FluoroGold to identify projection neurons. Studies were conducted in adult male Sprague-Dawley rats. Our analysis was conducted at two distinct levels of the trigeminal subnucleus caudalis (Vc) which receive corneal afferent projections. We found that corneal afferents project more densely to the rostral pole of Vc than the caudal pole. We also quantified the number of thalamic- and parabrachial-projecting neurons in the regions of Vc that receive corneal afferents. Corneal afferent inputs to both groups of projection neurons were also more abundant in the rostral pole of Vc. Finally, by comparing the frequency of corneal afferent appositions to thalamic- versus parabrachial-projecting neurons, we found that corneal afferents preferentially target parabrachial-projecting neurons in trigeminal dorsal horn. These results suggest that nociceptive pain from the cornea may be primarily mediated by a non-thalamic ascending pathway.
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