大鼠中脑导水管周围灰质向下丘脑orexin神经元的纤维投射  

Projections from the periaqueductal gray to orexin neurons in the hypothalamus in rats

作　　者：韩怀钦[1,2] 张博闻[1,2] 顾金海[1] 赵奇[1,2] 和祯泉[1] 任双来[1] 何仲义[1,2] 牛建国[1,2] 

机构地区：[1]宁夏医科大学宁夏颅脑疾病重点实验室,银川750004 [2]宁夏医科大学基础医学院人体解剖学与组织胚胎学系,银川750004

出　　处：《神经解剖学杂志》2016年第3期321-327,共7页Chinese Journal of Neuroanatomy

基　　金：科技部973计划前期研究专项课题(2014CB560711);国家自然科学基金项目(81460207);宁夏自然科学基金项目(NZ13059;NZ12183)

摘　　要：目的:明确中脑导水管周围灰质(PAG)神经元调节下丘脑orexin神经元的解剖学基础。方法:首先采用逆行示踪技术,将霍乱毒素B亚单位(CTb)作为逆行示踪剂注射到下丘脑orexin神经元胞体分布的区域,免疫组织化学方法染色观察PAG内CTb逆行标记细胞的分布特点;接着采用顺行示踪技术和免疫组化相结合的方法,将生物素化葡聚糖胺(BDA)作为顺行示踪剂注射到PAG,观察下丘脑内BDA标记的神经纤维与orexin神经元的重叠分布特点;最后运用免疫电镜技术观察BDA标记轴突终末与orexin神经元之间的突触联系。结果:CTb注射到单侧下丘脑orexin神经元区域后,在PAG观察到大量CTb标记神经元,注射点同侧标记细胞数明显占优,其中PAG外侧区(lPAG)和腹外侧区(vlPAG)可见大量CTb逆标神经元,背外侧区(dlPAG)和背内侧区(dm PAG)可见少量标记神经元;注射点对侧lPAG及vlPAG区域也观察到少量CTb标记神经元。BDA注射到单侧lPAG后,下丘脑内双侧均可观察到BDA标记的神经纤维,但注射点同侧标记神经纤维数量明显占优。BDA标记纤维与orexin神经元胞体在穹窿背侧接近不定带(ZI)的区域(本文中将此区域称作"穹窿上区")形成显著的重叠分布。透射电镜下观察到BDA标记的轴突终末与orexin神经元之间形成突触联系,且多为非对称性类型。结论:lPAG投射到下丘脑的神经纤维在穹窿上区与orexin神经元形成优势重叠分布、并与orexin神经元的胞体或树突形成以非对称性为主的突触联系,提示orexin神经元可能在lPAG的直接支配下发挥其调节觉醒状态、摄食行为等功能。Objective： The present study was performed to understand the anatomicalsubstrates of periaqueductalgray（ PAG） modulation of orexin-containing neurons in the hypothalamus. Methods： Firstly,cholera toxin B subunit（ CTb）was injected into the orexin field dorsalto the fornix in the hypothalamus in rats and the distributions of CTb-immunoreactive（ ir） neurons in the PAG were observed under a light microscope. And then,after a combination of biotinylated dextran amine（ BDA） injection into PAG and immunostaining of orexin-containing neurons was performed,the distribution of BDA-labeled fibers and that of orexin-positive neurons were observed in hypothalamus. Furthermore,synaptic connections between those BDA-labeled axon terminals and orexin-ir neurons were examined under a transmission electron microscopy.Results： After CTb injection into the orexin field in the hypothalamus,a large number of CTb-labeled neurons were found in the PAG bilaterally with an ipsilateralpredominance. Among the subregions of PAG,ipsilaterallateralPAG（ lPAG）and ventrolateralPAG（ vlPAG） contain numerous CTb-labeled neurons,while dorsolateralPAG（ dlPAG） and dorsomedialPAG（ dm PAG） contain rare labeled neurons. Within the contralateralsubregions,only a smallnumber of CTb-labeled neurons were found in lPAG and vlPAG. After BDA injection into lPAG,BDA-labeled fibers were found in hypothalamus bilaterally with an ipsilateralpredominance. A prominent overlap of the distribution field of the BDA-labeled fibers and that of the orexin-positive neurons was found in region that is dorsalto the fornix and close to the zona incerta（ this overlapping field was referred to as＂suprafornicalarea＂in the present study）. Under transmission electron microscopy,the synapse between BDA-labeled axon terminals and the somata and dendrites of orexin-positive neurons were observed and most of them were asymmetricaltype. Conclusion： Orexin positive neurons form synaptic connections with axon terminals originated from the lPA

关 键 词：OREXIN 中脑水管周围灰质 下丘脑 突触联系 大鼠 

分 类 号：R741[医药卫生—神经病学与精神病学]