大鼠内侧视前区支配Barrington核内骶髓投射神经元的光,电镜研究

采用光镜及电镜双标记技术，对大鼠内侧视前区（ＭＰＯ）神经元发出的投射到脑桥Ｂａｒｉｎｇｔｏｎ核的轴突与其内投射到骶髓的神经元的胞体和树突之间的突触关系进行了探讨。将顺行追踪剂结合生物素的葡聚糖胺（ＢＤＡ）注射于ＭＰＯ用来标记它发出的轴突终末；将逆行追踪剂辣根过氧化物酶（ＨＲＰ）注射于脊髓腰骶段，以此标记Ｂａｒｉｎｇｔｏｎ核内投射至腰骶髓的神经元。光镜观察发现Ｂａｒｉｎｇｔｏｎ核内含有大量ＢＤＡ顺行标记的终末及ＨＲＰ逆行标记的树突和胞体，电镜观察确证了ＢＤＡ标记的轴突终末与ＨＲＰ标记的树突和胞体间存在直接的突触联系，且均为对称性突触。此结果提示ＭＰＯ可能通过这一直接的纤维联系调节排尿反射活动。

MEDIAL PREOPTIC AREA INNERVATING SACRAL SPINAL CORDPROJECTING NEURONS IN BARRINGTON NUCLEUS: LIGHT AND ELECTRON MICROSCOPE STUDY IN THE RAT

Direct projections from the medial preoptic area (MPO) to sacral spinal cordprojecting neurons of Barrington nucleus were revealed in the rat by a double labeling method with light and electron microscopy. Biotinylated dextran amine (BDA), an anterograde tracer, was injected into the MPO to label projection axon terminals originating from the MPO and horseradish peroxidase (HRP), a retrograde tracer, was injected into the lumbosacral cord segments to label neurons projecting to the lumbosacral spinal cord in Barrington nucleus. At light microscope level, a large number of BDAlabeled presumptive axon terminals and HRPlabeled neurons were seen in Barrington nucleus. Electron microscopic observation showed that some BDAlabeled axon terminals made symmetric synaptic contacts with dendrites and somata of HRPlabeled neurons in Barrington nucleus. The present results provided evidence for involvement of MPO in the neuronal mechanisms of the rat micturition reflex.