Anatomical evidence of pruriceptive trigeminothalamic and trigeminoparabrachial projection neurons in mice.
Anatomical evidence of pruriceptive trigeminothalamic and trigeminoparabrachial projection neurons in mice.
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DOI：
10.1002/cne.23839
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发表时间：
2016-02-01
期刊：
影响因子：
--
通讯作者：
Carstens E
中科院分区：
文献类型：
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作者：
Akiyama T;Curtis E;Nguyen T;Carstens MI;Carstens E
瘙痒通过脊髓背角和髓质背角的投射神经元传递到更高的中枢。我们采用双标签方法来绘制三叉神经和脊髓神经元的上升投影。将逆行示踪剂氟金（FG）立体定向注入小鼠右侧丘脑或外侧臂旁区（LPb）。7天后，小鼠左颊皮下注射组胺、氯喹、辣椒素或载药。组胺、氯喹和辣椒素诱导了从三叉神经尾侧亚核到C2的浅髓内侧和脊髓背角fos阳性神经元的相似分布。在从丘脑逆行标记的神经元中，分别有43%、8%和22%的神经元在服用组胺、氯喹或辣椒素后呈fos阳性。在瘙痒或辣椒素刺激后的fos阳性神经元中，约1-2%被FG逆行标记。三叉神经旁叉部投射神经元在浅表背角表现出较高的双标记发生率。在LPb逆行标记的神经元中，分别有36%、29%和33%的神经元在注射组胺、氯喹和辣椒素后呈fos阳性。组胺、氯喹和辣椒素诱导的fos阳性神经元分别有3.7、4.3和4.1%逆行标记。目前的结果表明，总的来说，支配脸颊的痛觉和/或伤害性神经元的相对较小的亚群投射到丘脑或LPb。这些结果表明，绝大多数搔痒原和藻原反应性脊髓神经元可能作为中间神经元向投射神经元传递信息和/或参与节段性伤害回路。双标记策略鉴定了用氟金逆行标记的三叉神经投射神经元，以及在脸颊注射瘙痒或疼痛介质后标记fos免疫反应性的神经元。插图显示双标记的投射神经元（青色箭头）可能发出瘙痒或疼痛信号，而几个非突出的fos反应神经元（绿色）可能作为局部中间神经元起作用。
Itch is relayed to higher centers by projection neurons in the spinal and medullary dorsal horn. We employed a double-label method to map the ascending projections of pruriceptive and nociceptive trigeminal and spinal neurons. The retrograde tracer fluorogold (FG) was stereotaxically injected into the right thalamus or lateral parabrachial area (LPb) in mice. Seven days later, mice received intradermal (id) microinjection of histamine, chloroquine, capsaicin, or vehicle into the left cheek. Id histamine, chloroquine and capsaicin elicited similar distributions of Fos-positive neurons in the medial aspect of the superficial medullary and spinal dorsal horn from the trigeminal subnucleus caudalis to C2. Of neurons retrogradely labeled from the thalamus, 43, 8 and 22% were Fos-positive following id histamine, chloroquine or capsaicin. Of the Fos-positive neurons following pruritic or capsaicin stimuli, ∼1–2% were retrogradely labeled with FG. Trigeminoparabrachial projection neurons exhibited a higher incidence of double-labeling in the superficial dorsal horn. Of the neurons retrogradely labeled from LPb, 36, 29 and 33% were Fos-positive following id injection of histamine, chloroquine or capsaicin, respectively. Of Fos-positive neurons elicited by id histamine, chloroquine and capsaicin, respectively, 3.7, 4.3 and 4.1% were retrogradely labeled from LPb. The present results indicate that, overall, relatively small subpopulations of pruriceptive and/or nociceptive neurons innervating the cheek project to thalamus or LPb. These results imply that the vast majority of pruritogen- and algogen-responsive spinal neurons are likely to function as interneurons relaying information to projection neurons and/or participating in segmental nocifensive circuits. Double-label strategy identified trigeminal projection neurons retrogradely labeled with fluorogold, and those labeled for Fos-immunoreactivity following cheek injection of itch or pain mediators. Inset shows double-labeled projection neuron (teal arrow) potentially signaling itch or pain, and several non-projecting Fos-reactive neurons (green) that presumably function as local interneurons.