大鼠口面部躯体和上消化道内脏伤害性传入汇聚于三叉神经脊束间质核含CB神经元

三叉神经脊束间质核(interstitial nucleus of the spinal trigeminal tract,INV)为位于三叉神经脊束内的一些灰质团块,经三叉神经和舌咽及迷走神经接受口面部的三叉神经躯体传入与上消化道的内脏伤害性传入。INV内含有大量含calbinding D-28k(CB)神经元,但尚不清楚支配口面部的三叉神经躯体传入与支配上消化道的内脏伤害性传入是否汇聚于INV内含CB的神经元。本文应用跨节追踪法并结合CB和Fos免疫组织化学的激光共聚焦显微镜和电镜技术,研究了下牙槽神经(interior alveolarnerve．IAN)的初级传入和上消化道伤害性信息向INV内含CB神经元的汇聚。结果如下：(1)将生物素化的葡聚糖胺(biotinylated dextran amine,BDA)和甲醛分别注入IAN和上消化道后,BDA跨节标记的浓密初级传入纤维和末梢分布于同侧INV内,在其膨大部较为集中;大量的CB和Fos免疫反应阳性神经元分布于双侧INV内,并与BDA注射侧的BDA标记末梢区相重叠：共聚焦显微镜观察显示,约半数CB免疫反应阳性的神经元同时呈Fos阳性的双标记神经元(74／153),其中部分双标神经元与IAN末梢形成紧密接触状。(2)辣根过氧化物酶(horseradish peroxidase,HRP)注射到IAN后,HRP跨节标记的纤维和末梢的分布与BDA标记的分布相似;电镜下观察到,INV内有大量CB免疫反应阳性神经元的树突和少量胞体,以及HRP标记的传入末梢,其中一些HRP标记的轴突终末分别与CB免疫反应阳性树突和胞体形成非对称型轴-树或轴-体突触。结果提示口面部躯体初级传入信息和内脏伤害性信息汇聚于INV内含CB的神经元上,可能在躯体传入信息对内脏伤害性信息的调制和内脏心血管活动中发挥重要作用。

Somatic and visceral nociceptive inputs from the orofacial area and the upper alimentary tract converge onto CB-containing neurons in interstitial nucleus of the spinal trigeminal tract in rats

The interstitial nucleus of the spinal trigeminal tract (INV) contains many calbindin-D28k-containing neurons (CB-neurons) receiving convergence information from the somatic and visceral structures. The purpose of the present study was to confirm whether the primary afferent terminals from the inferior alveolar nerve (IAN) make close contact and synaptic connections with the same CB-neurons receiving visceral nociceptive signals in INV. Biotinylated dextran amine (BDA) and horseradish peroxidase (HRP) tracing combined with CB and Fos proteins immunohistochemistry were used. After injections of BDA and formalin into unilateral IAN and upper alimentary tract, respectively, the transganglionic labeled afferent fibers and terminals from IAN were observed in the ipsilateral INV, especially in its enlarged part. A large number of CB- and Fos-like immunoreactive (LI) neurons were found in bilateral INV. These CB- and Fos-LI neurons mostly overlapped with BDA-labeled terminals in the enlarged part of INV. About one half of the CB-LI neurons were double labeled with Fos-LI nuclei (74/153). The terminals from IAN were to made close contacts with many CB/Fos-double labeled or CB-single labeled neurons. After injection of HRP into IAN, HRP-labeled fibers and terminals in INV were similar to that labeled with BDA. Under the electron microscope, a large number of CB-LI dendrites and a few soma in the enlarged part of INV were found to form asymmetrical axo-dendritic and axo-somal synapses with the HRP-labeled axon terminals. These results indicate that the orofacial somatic inputs from IAN and the visceral nociceptive inputs from the upper alimentary tract converge onto the same CB-containing neurons in INV. These CB-containing neurons in INV probably play an important role in information integration as well as visceral and cardiovascular activity.