大鼠囊泡膜谷氨酸转运体和5-羟色胺阳性终末与三叉神经中脑核神经元的联系

本研究应用免疫荧光组织化学三重染色技术和免疫电镜双重标记技术,对大鼠囊泡膜谷氨酸转运体 (VGluT1和VGluT2)和 5 -羟色胺(5- HT)阳性终末与三叉神经中脑核(Vme)神经元之间的联系进行了观察。在激光共聚焦显微镜下,Vme内可观察到许多磷酸激活的谷氨酰胺酶(PAG)阳性神经元,其中绝大多数为大的假单极神经元。VGluT1和VGluT2免疫阳性的神经纤维和终末广泛分布于Vme内,其中VGluT2阳性纤维和终末的分布密度高于VGluT1。在Vme内还可观察到相当数量的 5- HT阳性终末,其中部分终末同时呈VGluT2免疫阳性。一些VGluT1、VGluT2、5- HT及VGluT2 /5- HT双重标记的阳性终末与PAG阳性的Vme神经元胞体形成密切接触。在电镜下,分别用银加强的金颗粒和DAB反应产物显示VGluT1 /VGluT2和 5- HT阳性终末。在Vme内只观察到部分终末呈VGluT2和 5- HT双重免疫阳性,并且这些终末主要形成非对称性突触。以上结果提示,在口面部本体感觉信息向更高一级中枢传递过程中,谷氨酸能和 5 HT能神经终末可能通过Vme神经元对该信息进行复杂的调控。

ASSOCIATION OF VESTICULAR GLUTAMATE TRANSPORTERS-AND 5-HT-LIKE IMMUNOREACTIVE VARICOSITIES WITH MESENCEPHALIC TRIGEMINAL NUCLEUS NEURONS IN THE RAT

The possible relationship of vesicular glutamate transporters (VGluT1 and VGluT2)- and 5-HT-like immunoreactive (LI) terminals with mesencephalic trigeminal nucleus (Vme) neurons in the rat was examined by using triple-immunofluorescence histochemistry and double-labeled electron microscopic immunohistochemistry. Under confocal laser-scanning microscope, many neuronal cell bodies of Vme showed phosphate-activated glutaminase (PAG) -LI and the vast majority of them were large pseudounipolar neurons. A considerable number of VGluT1-LI and VGluT2-LI terminals were widely distributed in Vme, the density of VGluT2-LI terminals was higher than that of VGluT1-LI. 5-HT-LI axonal varicosities had dense distribution in Vme, and some 5-HT-LI terminals also showed immunoreactivity for VGluT2. Some VGluT1-LI, VGluT2-LI, 5-HT-LI and VGluT2/5-HT-LI terminals were frequently observed in close apposition to the cell bodies of Vme neurons showing PAG-LI. Under electron microscope, VGluT1/VGluT2-LI and 5-HT-LI were visualized with silver grains and peroxidase products, respectively. Some terminals in Vme showed both VGluT2- and 5-HT-LI, these dual labeled varicosities usually made asymmetric contact with Vme neurons. Synaptic terminals that showed VGluT1-LI was also observed, but no coexpression of VGluT1 and 5-HT was found in Vme. The present results suggest that in the transmission of the proprioceptive sensory information from the orofacial regions to the higher center, glutamate and 5-HT may play important roles on the regulation of Vme neurons through complicated integration.