大鼠囊泡膜谷氨酸转运体样和P物质样阳性终末与三叉神经中脑核神经元的联系

最近在哺乳类动物脑内克隆出两种囊泡膜谷氨酸转运体— VGlu T1和 VGlu T2 ,目前人们已将两者作为脑内谷氨酸能终末的特异性标记物。本研究应用免疫荧光组织化学三重染色技术 ,在激光共聚焦显微镜下对大鼠三叉神经中脑核 (Vme)内VGlu T1/VGlu T2样和 P物质 (SP)样阳性终末与磷酸激活的谷氨酰胺酶 (PAG)样阳性神经元之间的联系进行了观察。结果显示 :(1) Vme内有较多的 PAG样阳性神经元 ,在吻尾方向上亘其全长出现 ,这些神经元绝大多数为大的假单极神经元 ,直径为2 5～ 5 0 μm。(2 )大量的 VGlu T1样、VGlu T2样和 SP样免疫阳性的神经纤维和终末广泛分布于 Vme内 ,其中 VGlu T2样阳性纤维和终末的分布密度高于 VGlu T1;部分 SP样阳性纤维和终末同时呈 VGlu T1样或 VGlu T2样免疫阳性。 (3 )一些 VGlu T1/VGlu T2样、SP样或 VGlu T1/VGlu T2和 SP双重标记的免疫阳性终扣分别包绕在 PAG样阳性的 Vm e神经元胞体周围 ,并与之形成密切接触。以上结果提示 :Vme神经元在将口面部本体感觉信息向更高一级中枢传递过程中 ,可能接受中枢其它来源的谷氨酸能和 SP能终末的调控 ,其中谷氨酸能的投射末梢可能通过与突触后膜上的相应受体结合而发挥作用而 SP则可能在突触前发挥间接的调控作用

ASSOCIATION OF VESTICULAR GLUTAMATE TRANSPORTERS-AND SUBSTANCE P-LIKE IMMUNOREACTIVE TERMINALS WITH PAG-LIKE POSITIVE NEURONS IN THE MESENCEPHALIC TRIGEMINAL NUCLEUS OF THE RAT

Two vesicular glutamate transporters(VGluTs), VGluT1 and VGluT2, have recently been identified in brains of mammals, and it is now generally accepted that they are the specific markers for glutamatergic terminals. To observe the relationships between VGluTs , substance P (SP) like immunoreactive ( LI) terminals and phosphate activated gluataminase (PAG) LI neurons in the mesencephalic trigeminal nucleus (Vme) of the rat, the triple immunofluorescence histochemical staining techniques were used in the present study. The results demonstrated that: (1) many neuronal cell bodies through the whole rostrocaudal levels of the Vme were showed PAG LI and the vast majority of them were large pseudounipolar neurons (diameter 25～50 μm); (2) a large number of VGluT1 , VGluT2 , SP LI fibers and terminals were widely distributed in Vme, and the density of distribution of VGluT2 LI terminals was higher than that of VGluT1 LI. In addition, some SP LI terminals also showed immunoreactivity for VGluT1 or VGluT2; (3) some VGluT1/VGluT2 LI, SP LI or double labeled axonal varicosities surrounded the cell bodies of Vme neurons showing PAG LI and formed close contact with them. The present results suggest that Vme neurons may receive both glutaminergic and SPergic inputs from other brain area in the transmission of proprioceptive sensory information from the orofacial region to the higher centres. Glutaminergic terminals projecting to Vme might play an important role of regulation via postsynaptic glutamate receptors, whereas SP might exert indirect modulation through presynaptic effect.