大鼠GAD样阳性终末与三叉神经中脑核内GABA_B受体和PAG共存神经元的联系

本研究应用免疫荧光组织化学双重和三重反应技术 ,在激光共聚焦显微镜下观察了大鼠三叉神经中脑核神经元内GABAB受体和磷酸激活的谷氨酰胺酶 (PAG)的共存关系 ,以及谷氨酸脱羧酶 (GAD)样阳性终末与此二者共存的神经元之间的联系。结果证明 :在三叉神经中脑核内可见大量 GABAB受体样和谷氨酰胺酶样免疫阳性神经元 ,在吻尾方向上几乎亘其全长出现 ,多为大的假单极神经元。许多谷氨酰胺酶样阳性神经元同时呈 GABAB受体样免疫阳性 ,这种双重阳性的细胞约占磷酸激活的谷氨酰胺酶样阳性细胞的 85 %。在激光共聚焦显微镜下观察到密集分布的谷氨酸脱羧酶样阳性终末聚集于 GABAB受体样和磷酸激活的谷氨酰胺酶样双重阳性的三叉神经中脑核神经元胞体周围 ,并与之形成密切接触。以上结果提示 ,GABA能投射至三叉神经中脑核的神经终末可能通过 GABAB受体对谷氨酸介导的口面部本体觉信息的传递发挥抑制性调控作用

CONNECTIONS BETWEEN GAD-LIKE IMMUNOREACTIVE TERMINALS AND CO-EXISTENT NEURONS OF GABAB RECEPTOR AND PHOSPHATE ACTIVATED GLUTAMINASE IN THE MESENCEPHALIC TRIGEMINAL NUCLEUS OF THE RAT

In the present study, double and triple immunofluorescence histochemical staining techniques were used to examine co localization of GABA B receptor and phosphate activated glutaminase (PAG) in the mesencephalic trigeminal nucleus (Vme) of the rat, and the connections between the glutamic acid decarboxylase like immunoreactive (GAD LI) terminals and co existent Vme neurons of GABA B receptor LI and PAG LI with confocal laser scanning microscopy. The results demonstrated that many neuronal cell bodies through the whole rostrocaudal extent of the Vme showed GABA B receptor LI and PAG LI, and the majority of them were the large pseudounipolar neurons. A considerable number of PAG LI neurons expressed GABA B receptor LI, cell counts demonstrated that about 85% of PAG LI neurons were immunostained with GABA B receptor LI. Confocal laser scanning microscope further revealed that dense GAD LI terminals surrounded the somata of the Vme neurons showing both GABA B receptor LI and PAG LI, and formed the close contact between them. The present results indicated that the GABAergic terminals to the Vme might exert inhibitory regulation and control effects through GABA B receptor on the transmission of the orofacial region proprioceptive sensory signals mediated by glutamate.