豚鼠内侧膝状体背侧核SP阳性神经元向下丘投射

Projection to inferior colliculus of substance P positive neurons in medial geniculate body or guinea pigs

目的：观察下丘（ＩＣ）至内侧膝状体（ＭＧＢ）神经纤维的投射方式，以及内侧膝状体ＳＰ阳性神经元向下丘中央核团的下行投射．方法：采用辣根过氧化物酶（ＨＲＰ）追踪和ＳＰ免疫组化染色．结果：内侧膝状体腹、背倒核均可见ＳＰ免疫反应阳性的神经元、神经纤维和终末．神经元多呈圆形、椭圆形、梭形或不规则形，大小不等，含二个或多个突起．左侧下丘中央核团注入ＨＲＰ后，同侧ＭＧＢ可见分布密集的标记终末．在背倒核，可见ＨＲＰ逆行标记的阳性神经元．免疫组化染色后，背侧核内可见数量较多的ＨＲＰ－ＳＰ双标神经元，含有少量ＳＰ，ＨＲＰ单标神经元．结论：下丘中央核（ＩＣＣ）的上行投射主要集中在同侧的内侧膝状体，而内侧膝状体背侧核有ＳＰ阳性神经元向ＩＣＣ投射．

AIM: To investigate the projection pattern ofnerve fibers between inferior colliculus (IC ) and medialgeniculate body (MGB) and observe the descending projection of substance P (SP) positive neurons from MGB toinferior colliculus central nucleus (ICC). METHODS: Horseradishperoxidase (HRP) tracing and SP immunohistochemical technique staining were used in this study. RESULTS: SP immunoreactive positive neurons, nerve fibers and terminalscould be seen in the ventral and dorsal nucleus of MGB. Thepositive neurons were showed in the shape of round, oval,fusiform or irregular appearance, were different in size, including two or more projections. HRP was injected into theleft ICC, the terminals labelled with HRP distributed denselyin the ipsilateral MGB. There were retrograde labelled HRPpositive neurons in the dorsal nucleus of MGB. After stainedby immunohistochemical technique, a lot of HRP--SP doublelabelled neurons were showed in the ipsilateral dorsal nucleusof MGB. There were also a few of SP, HRP mono--labelledneurons in the dorsal nucleus of MGB. CONCLUSION: Theascending fibers from ICC to MGB were mainly gathered inthe ipsilateral MGB. There were SP positive neurons in thedorsal nucleus of MGB descending projections to ICC.