Neurochemical properties of the synapses in the pathways of orofacial nociceptive reflexes.
Neurochemical properties of the synapses in the pathways of orofacial nociceptive reflexes.
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口面部伤害性反射通路中突触的神经化学特性
DOI：
10.1371/journal.pone.0034435
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Li YQ
中科院分区：
文献类型：
--
作者：
Dong YL;Wang W;Li H;Li ZH;Zhang FX;Zhang T;Lu YC;Li JL;Wu SX;Li YQ
面神经核（VII）和舌下神经核（XII）的脑干运动前神经元可以整合三叉神经脊束核（Vc）的口面伤害性信息，协调口面伤害性反射（ONR）反应。然而，ONR通路的突触结构仍然是未知的。在本研究中，我们研究了GABA能运动前神经元在脑干局部ONR通路中的分布，它们与加入脑干ONR通路的Vc投射的连接以及这些连接的神经化学性质。将逆行示踪剂荧光金（FG）注入VII或XII，将顺行示踪剂生物素化葡聚糖胺（BDA）注入Vc。抑制性/兴奋性神经递质免疫荧光组织化学标记结合BDA/FG示踪显示，GABA能前运动神经元主要分布于桥脑延髓网状结构的两侧，以同侧为主。部分GABA能运动前神经元与Vc发出的BDA标记纤维紧密贴壁，主要分布于小细胞网状结构（PCRt）、延髓背侧网状结构（MdD）和三叉上核（Vsup）。在共聚焦激光扫描显微镜和电子显微镜下进一步观察了第VII和第XII核Vc投射纤维与运动前神经元之间的突触关系，发现在运动前神经元上形成非对称性突触的BDA标记轴突终末呈囊泡谷氨酸转运体2（VGluT 2）样免疫反应。这些结果表明，GABA能运动前神经元接受来自Vc的兴奋性神经传递，并可能有助于调节紧张性ONR的产生。
The brainstem premotor neurons of the facial nucleus (VII) and hypoglossal (XII) nucleus can integrate orofacial nociceptive input from the caudal spinal trigeminal nucleus (Vc) and coordinate orofacial nociceptive reflex (ONR) responses. However, the synaptoarchitectures of the ONR pathways are still unknown. In the current study, we examined the distribution of GABAergic premotor neurons in the brainstem local ONR pathways, their connections with the Vc projections joining the brainstem ONR pathways and the neurochemical properties of these connections. Retrograde tracer fluoro-gold (FG) was injected into the VII or XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the Vc. Immunofluorescence histochemical labeling for inhibitory/excitatory neurotransmitters combined with BDA/FG tracing showed that GABAergic premotor neurons were mainly distributed bilaterally in the ponto-medullary reticular formation with an ipsilateral dominance. Some GABAergic premotor neurons made close appositions to the BDA-labeled fibers coming from the Vc, and these appostions were mainly distributed in the parvicellular reticular formation (PCRt), dorsal medullary reticular formation (MdD), and supratrigeminal nucleus (Vsup). We further examined the synaptic relationships between the Vc projecting fibers and premotor neurons in the VII or XII under the confocal laser-scanning microscope and electron microscope, and found that the BDA-labeled axonal terminals that made asymmetric synapses on premotor neurons showed vesicular glutamate transporter 2 (VGluT2) like immunoreactivity. These results indicate that the GABAergic premotor neurons receive excitatory neurotransmission from the Vc and may contribute to modulating the generation of the tonic ONR.