大鼠三叉神经脊束核尾侧亚核和脊髓向丘脑和臂旁核的谷氨酸能投射

GLUTAMATERGIC PROJECTIONS FROM THE CAUDAL SUBNUCLEUS OF THE SPINAL TRIGEMINAL NUCLEUS AND SPINAL CORD TO THE THALAMUS AND PARABRACHIAL NUCLEUS IN THE RAT

本研究用荧光金逆行追踪与免疫荧光组比技术相结合的方法，对大鼠三叉神经脊束核尾侧亚核和脊髓向丘脑和臂旁核的谷氨酸能投射进行了观察。磷酸激活的谷氨酸胺酶（PAG）是谷氨酸能神经元的特异性标识物。PAG样阳性胞体主要位于三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层，少量PAG样阳性胞体也见于它们的Ⅱ层外侧部及外侧网状核。将荧光金注入丘脑腹基底复合体后．荧光金逆标神经元主要见于对侧三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层及外侧网状核；将荧光金注入臂旁核后，荧光金逆标神经元也主要见于对侧三叉神经脊束核尾侧亚核和颈髓背角的Ⅰ层及外侧网状核。三叉神经脊束核尾侧亚核向丘脑腹基底复合体投射神经元的12．4％，向臂旁核投射神经元的13．2％呈PAG样阳性；颈髓背角浅层向丘脑瓜基底复合体投射神经元的12．7％，向臂旁核投射神经元的14．3％呈PAG样阳性。向丘脑腹基底复合体和臂旁核投射的PAG／荧光金双标神经元分别占三叉神经脊束核尾侧亚核浅层内PAG样阳性神经元总数的13％和24．6％，向丘脑腹基底复合体和臂旁核投射的PAG／荧光金双标神经元分别占颈髓背角浅层内PAG样阳性神经元总数的11．6％和30．1％。外侧网状核内的部分PAG样阳性神经元也向丘脑腹基底复合体或臂旁核投射。Ⅰ层内的双?

A combination of fluoro-gold (FG) retrograde tracing with the immunofluorescent histochemical staining for phosphate-activated glutaminase (PAG), a specific marker for glutamatergic neurons within the central nervous system, was employed in the present study to investigate the glutamatergic projections from the caudal subnucleus of the spinal trigeminal nucleus (Vc) and spinal cord to thalamus and parabrachial nucleus (PBN). PAG-like immunoreactive (PAG-LI) neurons were mainlyobserved in lamina Ⅰ of the Vc and dorsal horn of the cervical cord. Some of the PAG-LI neurons were also found in the outerpart of lamina Ⅱ (Ⅱ o) and lateral reticular nucleus (LRt). After injecting FG into the ventrobasal complex (VBC) of the thaiamus on one side, which is composed of ventral posteromedial nucleus and ventral posterolateral nucleus, FG retrogradely labeledneurons were mainly encountered in contralaleral lamina Ⅰ of the Vc and cervical dorsal horn and in the LRt. After injecting FGinto the PBN on one side. FG retrogradely labeled neurons were also mainly seen in the contralateral lamina Ⅰ of the Vc and cervical dorsal horn, some FG labeled neurons were also found in the Ⅱ o and in the LRt. In the Vc, 12. 4% and 13. 2% of the neurons which projected to the VBC and the PBN exhibited PAG-LI. in the dorsal horn of the cervical cord. 12. 7% and 14. 3% ofthe neurons which projected to the VBC and PBN showed PAG-LI. respectively. Of the PAG-LI neurons in the Vc, 13% and24. 6% were labeled by FG. of the PAG-LI neurons in the cervical dorsal horn. 11. 6 % and 30. 1 % of the neurons were labeledBy FG, respectively. A few PAG-LI neurons in the LRt also projected to the VBC and PBN. In the lamina Ⅰ of the Vc and cervical dorsal horn, most of the PAG/FG double-labeled neurons were large and medium sized fusiform and round neurons. Thepresent results indicate that glutamate might play an important role in the transmission of noxious stimulation information fromVc and spinal cord to thalamus and PBN.