Roch M, Messlinger K, Kulchitsky V, Tichonovich O, Azev O, Koulchitsky S
Institute of Physiology and Pathophysiology, University of Erlangen-Nuernberg, Universitätsstr. 17, 91054 Erlangen, Germany.
Neuroscience. 2007 Dec 12;150(3):681-91. doi: 10.1016/j.neuroscience.2007.09.032. Epub 2007 Sep 19.
Ongoing activity of spinal trigeminal neurons is observed under various conditions and suggested to be responsible for ongoing headache. It can be spontaneous, i.e. arising intrinsically from the neuron, or the product of descending influences from other central neurons, or maintained by ongoing afferent input. The aim of the present study was to examine if ongoing activity of neurons in different subnuclei of the spinal trigeminal nucleus is driven from peripheral afferent input. Experiments were performed in Wistar rats anesthetized with isoflurane or Nembutal/urethane. Ongoing activity of single wide-dynamic range (WDR) neurons was recorded with carbon fiber glass microelectrodes in two subnuclei of the spinal trigeminal nucleus: oral (Sp5O) and caudal (Sp5C). Peripheral receptive fields were evaluated using von Frey filaments. Sp5O neurons received peripheral input from facial areas innervated by the mandibular branch of the trigeminal nerve. Units in Sp5C had receptive fields in the surgically exposed dura mater and in facial areas innervated by the ophthalmic and maxillary branch of the trigeminal nerve. Saline or the local anesthetic lidocaine was locally applied onto the exposed dura mater or microinjected into V3 (for Sp5O units) or V1/V2 (for Sp5C units) divisions of the trigeminal ganglion via the infraorbital channel. Local application of lidocaine onto the exposed dura caused mechanical insensitivity of dural receptive fields but not significant decrease in ongoing activity. Microinjection of lidocaine but not saline into the trigeminal ganglion was followed by a substantial decrease in both the receptive field size and the activity of the recorded WDR units. Mechanical insensitivity of receptive fields after trigeminal ganglion blockade was accompanied by the disappearance of ongoing activity. We conclude that the ongoing activity of WDR neurons in the spinal trigeminal nucleus, which may be indicative for processes of sensitization, is driven remotely by ongoing afferent input.
在各种情况下都能观察到三叉神经脊束核神经元的持续活动，且这种活动被认为与持续性头痛有关。它可以是自发的，即神经元内在产生的，也可以是其他中枢神经元下行影响的产物，或者由持续的传入输入维持。本研究的目的是检验三叉神经脊束核不同亚核中神经元的持续活动是否由外周传入输入驱动。实验在使用异氟烷或戊巴比妥/乌拉坦麻醉的Wistar大鼠身上进行。用碳纤维玻璃微电极在三叉神经脊束核的两个亚核：口侧（Sp5O）和尾侧（Sp5C）记录单个广动力范围（WDR）神经元的持续活动。使用von Frey细丝评估外周感受野。Sp5O神经元从三叉神经下颌支支配的面部区域接受外周输入。Sp5C中的神经元在手术暴露的硬脑膜以及三叉神经眼支和上颌支支配的面部区域有感受野。将生理盐水或局部麻醉剂利多卡因局部应用于暴露的硬脑膜，或通过眶下通道微量注射到三叉神经节的V3（对于Sp5O单位）或V1/V2（对于Sp5C单位）分支中。将利多卡因局部应用于暴露的硬脑膜会导致硬脑膜感受野的机械不敏感，但不会使持续活动显著降低。向三叉神经节微量注射利多卡因而非生理盐水后，记录的WDR单位的感受野大小和活动均大幅下降。三叉神经节阻断后感受野的机械不敏感伴随着持续活动的消失。我们得出结论，三叉神经脊束核中WDR神经元的持续活动可能指示敏化过程，是由持续传入输入远程驱动的。
