Trigeminal transition zone/rostral ventromedial medulla connections and facilitation of orofacial hyperalgesia after masseter inflammation in rats
Trigeminal transition zone/rostral ventromedial medulla connections and facilitation of orofacial hyperalgesia after masseter inflammation in rats
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DOI：
10.1002/cne.20797
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发表时间：
2005-12
影响因子：
2.5
通讯作者：
S. Sugiyo;M. Takemura;R. Dubner;K. Ren
中科院分区：
文献类型：
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作者：
S. Sugiyo;M. Takemura;R. Dubner;K. Ren
最近的研究表明，三叉神经内插肌/尾肌（Vi/Vc）过渡区在对口面部损伤的反应中起作用。通过联合神经元示踪和Fos蛋白免疫细胞化学，我们研究了Vi/Vc过渡区与吻侧腹内侧髓质（RVM）之间的功能联系，RVM是下行疼痛调节的关键结构。大鼠在咬肌注射完全弗氏佐剂前7天向RVM注射逆行示踪剂fluorgold，并在炎症后2小时灌注。与尾侧腹外侧髓质重叠的腹侧Vi/Vc和三叉神经尾侧亚核（Vc） V层的神经元群体显示出FluoroGold/Fos双重染色，表明炎症后三叉神经- RVM通路被激活。在Vc /Vc背侧和Vc的I-IV层未发现双标记神经元。将顺行示踪剂Phaseolus vulgaris白细胞凝集素注射到RVM中，导致标记谱与显示fluorgold /Fos双标记的区域重叠，表明RVM与Vi/Vc之间存在相互联系。体选择性神经毒素伊博tenic酸损伤Vc，可显著降低炎症诱导的Fos表达以及腹侧Vi/Vc中fluorgold /Fos双标记神经元的数量（P < 0.05）。与对照大鼠相比，伊博tenic酸损伤RVM （n = 6）或Vi/Vc （n = 6）可消除或减轻咬肌炎症后出现的咬肌痛觉过敏/异常性疼痛（P < 0.05 ~ 0.01）。本研究证明了腹侧Vi/Vc过渡区与RVM之间的相互联系。Vi/Vc‐RVM通路在口面深部组织损伤后被激活，在促进口面痛觉过敏中起关键作用。[j] .中华神经医学杂志，2006,33(3):559 - 559。©2005 Wiley‐Liss, Inc。
Recent studies have implicated a role for the trigeminal interpolaris/caudalis (Vi/Vc) transition zone in response to orofacial injury. Using combined neuronal tracing and Fos protein immunocytochemistry, we investigated functional connections between the Vi/Vc transition zone and rostral ventromedial medulla (RVM), a key structure in descending pain modulation. Rats were injected with a retrograde tracer, FluoroGold, into the RVM 7 days before injection of an inflammatory agent, complete Freund's adjuvant, into the masseter muscle and perfused at 2 hours postinflammation. A population of neurons in the ventral Vi/Vc overlapping with caudal ventrolateral medulla, and lamina V of the trigeminal subnucleus caudalis (Vc), exhibited FluoroGold/Fos double staining, suggesting the activation of the trigeminal‐RVM pathway after inflammation. No double‐labeled neurons were found in the dorsal Vi/Vc and laminae I–IV of Vc. Injection of an anterograde tracer, Phaseolus vulgaris leucoagglutinin, into the RVM resulted in labeling profiles overlapped with the region that showed FluoroGold/Fos double labeling, suggesting reciprocal connections between RVM and Vi/Vc. Lesions of Vc with a soma‐selective neurotoxin, ibotenic acid, significantly reduced inflammation‐induced Fos expression as well as the number of FluoroGold/Fos double‐labeled neurons in the ventral Vi/Vc (P < 0.05). Compared with control rats, lesions of the RVM (n = 6) or Vi/Vc (n = 6) with ibotenic acid led to the elimination or attenuation of masseter hyperalgesia/allodynia developed after masseter inflammation (P < 0.05–0.01). The present study demonstrates reciprocal connections between the ventral Vi/Vc transition zone and RVM. The Vi/Vc‐RVM pathway is activated after orofacial deep tissue injury and plays a critical role in facilitating orofacial hyperalgesia. J. Comp. Neurol. 493:510–523, 2005. © 2005 Wiley‐Liss, Inc.