经络相关的脊髓前角运动神经元对交感节前神经元的树突投射

Dendritic Projections from Meridian-related Motoneurons to Sympathic Preganglion Neurons in the Spinal Cord of Rats

目的:探讨脊髓中与经络有关的运动神经元的树突在神经元之间和对交感节前神经元的投射特性。方法:用含有1.0%HRP的CB-HRP溶液分别注射于41只SD大鼠的足三阳经胸-腰段穴位肌肉,即胃经"承满""梁门"等,膀胱经"肝俞""胆俞"等,胆经"阳陵泉""阳关"等,以及腹腔神经节、肠系膜上神经节等部位。常规灌流后冰冻切片,HRP成色反应后,显微镜下观察运动神经元的树突联系和对交感节前神经元的投射特性。结果:CB-HRP逆行标记在脊髓前角显示每条经都有特定的运动神经元支配,同经的运动神经元通过相互之间的树突特异性投射,形成每条经所特有的神经柱,不同经的运动神经元柱中的树突不发生投射关系。在有脊髓交感节前神经元的胸-腰节段,标记的运动神经元发出树突束,向交感节前神经元区投射;而位于脊髓颈段无交感节前神经元结构的部位则没有此种运动神经元的树突投射。结论:每条足三阳经在脊髓前角都有它们特定的运动神经元支配,同经运动神经元的树突在神经元之间特异性相互投射而形成运动神经元柱状结构;在脊髓胸-腰段,运动神经元的树突对脊髓交感节前神经元发出定向投射。

Objective Previous studies indicated a close involvement of reflex activities of motoneurons in the spinal cord in the mechanism of meridian phenomena. The present study was designed to investigate the dendrite projections of meridian- related motoneurons among the motoneurons and sympathetic preganglionic neurons in the spinal cord. Methods A total of 41 Sprague-Dawley rats were used in the present study. Cholera toxin B-subunit conjugated horseradish peroxidase （CB-HRP） con- taining 1.0% HRP was respectively injected to acupoint ＂Chengman＂ （ST 20）, ＂Liangmen＂ （ST 21）, ＂Guanmen＂ （ST 22）, ＂Taiyi＂ （ST 23）, ＂Huaroumen＂ （ST 24）, ＂Tianshu＂ （ST 25） and ＂Wailing＂ （ST 26） of the Stomach Meridian, and ＂Ganshu＂ （BL 18）, ＂Danshu＂ （BL 19）, ＂Pishu＂ （BL 20）, ＂Weishu＂ （BL 21） and ＂Sanjiaoshu＂ （BL 22） of the Bladder Meridian, and ＂Dai- mai＂ （GB 26）, ＂Wushu＂ （GB 27）, ＂Weidao＂ （GB 28）, ＂Juliao＂ （GB 29）, ＂Huantiao＂ （GB 30）, ＂Fengshi＂ （GB 31）, ＂Zhong- du＂ （GB 32）, ＂Xiyangguan＂ （GB 33） and ＂Yanglingquan＂ （GB 34） of the Gallbladder Meridian （for labeling preganglionic neu- rons）, and the celiac ganglion and superior mesenteric ganglion for labeling sympathetic preganglionic neurons. Three days after injection, the animals anesthetized were transcardia-cally perfused with 1.5 % paraformaldehyde, the spinal cord was removed to be fixed routinely and then cut into sections for observing the labeled cells under microscope. Results In the ipsilateral ventral horn of the spinal cord, the motoneurons retrogradely labeled by CB-HRP formed dendritic projections oriented only to those motoneu- rons innervating the same meridian. In the longitudinal sections of spinal cord, the labeled motoneurons formed a bead-like column with a prominent network of longitudinal dendrites connecting the motoneurons innervating acupoints from the same meridian. In the transverse sections of spinal cord, two groups of dendrites from the labeled motoneurons projected to the identified sympatheticpreganglionic regions： one group exten-ded dorsolateraly to the intermediolateral gray, another group extended intermediolateraly toward the central canal. In rats with injection of CB-HRP into both acupoint regions and ipsilateral celiac ganglion, the dendrites originated from the labeled motoneurons projected directly to the labeled sympathetic preganglionic neurons. Cenc｜usien Each of the ST, BL and GB meridians is innervated by a specific group of motoneurons in the spinal cord. The motoneurons form a column with distinct border in the ventral horn of spinal cord, and the dendritic projections from the motoneurons oriented only to those innervating the same meridian. The dendrites from the meridian-related motoneurons can specifically project to the sympathetic preganglionic neurons at the theracolumbar level.