Selective distribution and function of primary afferent nociceptive inputs from deep muscle tissue to the brainstem trigeminal transition zone
Selective distribution and function of primary afferent nociceptive inputs from deep muscle tissue to the brainstem trigeminal transition zone
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DOI：
10.1002/cne.21062
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发表时间：
2006-09-20
影响因子：
2.5
通讯作者：
Ren, Ke
中科院分区：
文献类型：
--
作者：
Wang, Hu;Wei, Feng;Ren, Ke
口面损伤激活三叉神经脊束复合体中的两个不同区域，即极间亚核/尾侧亚核（Vi/Vc）过渡区和层压Vc或髓背角（MDH）。研究表明，Vi/Vc过渡区在口面深层信息的加工过程中起着重要作用。为了验证这一假设，我们采用了双重追踪策略，比较了支配咬肌和覆盖皮肤的初级传入神经元的中枢投射。在同一只大鼠中，中心（Fluoro-Gold：腹侧Vi/Vc或MDH）或外周（麦胚凝集素结合辣根过氧化物酶或霍乱毒素B：咬肌或覆盖皮肤）注射不同的示踪剂。处理三叉神经节组织切片用于单或双免疫组织化学。神经节神经元的双重标记指示其外周和中枢神经支配的部位。一个人口的小到中等大小的神经元被双重标记后，注射到咬肌-Vi/Vc，咬肌-MDH，或皮肤-MDH的示踪剂。然而，只有少数双标记神经元注射到皮肤后，偶尔观察到的示踪剂-Vi/Vc。注射N-甲基-D-天冬氨酸受体拮抗剂AP-5到Vi/Vc和MDH减弱咬肌炎性痛觉过敏。相比之下，咬肌上皮肤炎症后的痛觉过敏通过将AP-5注射到MDH中而不是Vi/Vc中而减弱。这些结果表明，虽然咬肌和皮肤输入项目的MDH，咬肌传入提供了一个额外的输入Vi/Vc。这些研究结果提供了进一步的证据，支持三叉神经过渡区的作用，口面深部损伤的反应。
Orofacial injury activates two distinct regions in the spinal trigeminal complex, the subnuclei interpolaris/caudalis (Vi/Vc) transition zone and the laminated Vc, or medullary dorsal horn (MDH). Studies suggest that the Vi/Vc transition zone plays an important role in processing orofacial deep input. To test this hypothesis, we employed a double-tracing strategy to compare central projections of primary afferent neurons that innervate the masseter muscle and the overlying skin. Different tracers were injected either centrally (Fluoro-Gold: ventral Vi/Vc, or MDH) or peripherally (wheat germ agglutinin-conjugated horseradish peroxidase or cholera toxin B: masseter or overlying skin) in the same rat. Trigeminal ganglion tissue sections were processed for single or double immunohistochemistry. The double labeling of ganglion neurons indicates their site of peripheral and central innervations. A population of small to medium-sized neurons was doubly labeled after injections of the tracers into the masseter-Vi/Vc, masseter-MDH, or the skin-MDH. However, only a few double-labeled neurons were occasionally observed after injections of the tracers into the skin-Vi/Vc. Injection of an N-methyl-D-aspartate receptor antagonist, AP-5, into the Vi/Vc and MDH attenuated masseter inflammatory hyperalgesia. In contrast, hyperalgesia after inflammation of the skin overlying the masseter was attenuated by injection of AP-5 into the MDH but not Vi/Vc. These results indicate that while both masseter and cutaneous inputs project to the MDH, masseter afferents provide an additional input to the Vi/Vc. These findings provide further evidence to support a role of the trigeminal transition zone in response to orofacial deep injury.