MAMILLARY BODY IN THE RAT - TOPOGRAPHY AND SYNAPTOLOGY OF PROJECTIONS FROM THE SUBICULAR COMPLEX, PREFRONTAL CORTEX, AND MIDBRAIN TEGMENTUM
MAMILLARY BODY IN THE RAT - TOPOGRAPHY AND SYNAPTOLOGY OF PROJECTIONS FROM THE SUBICULAR COMPLEX, PREFRONTAL CORTEX, AND MIDBRAIN TEGMENTUM
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DOI：
10.1002/cne.902860303
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发表时间：
1989-08-15
影响因子：
2.5
通讯作者：
HOPKINS, DA
中科院分区：
文献类型：
--
作者：
ALLEN, GV;HOPKINS, DA
利用与小麦胚芽凝集素（WGA-HRP）结合的辣根过氧化物酶的逆行和顺行转运，在光镜和电镜水平上追踪了大鼠乳状体（MB）的传入连接。将WGA-HRP注射到MB的不同部位，可在丘下复合体、内侧前额皮质、背侧和腹侧被盖核中产生大量逆行标记。将WGA-HRP分别注射到这两个脑区，在MB中产生了具有特定分布和特征突触组织的顺行标记。来自丘背侧和尾腹侧的投射在两侧的内侧乳状核中以有地形组织的层流方式终止，而来自丘前和副丘的传入投射仅在外侧乳状核中终止。标记轴突末梢起源于丘下复合体，其特征为圆形囊泡，在乳状核内侧和外侧形成小直径树突和树突棘的不对称突触连接。前额叶皮层的投射主要来自边缘下区域，在较小程度上来自边缘前和前扣带区域。向这些脑区注射示踪剂可在内侧乳状核、内侧部和内侧部前背内侧部分产生密集的轴突终末标记。标记的末端以圆形囊泡为特征，与小直径的树突和树突棘形成不对称的突触连接。背侧被盖核的投射终止于同侧外侧乳状核，而腹侧被盖核的前、后亚核的传入投射在地形上终止于内侧乳状核。腹侧被盖核，前部投射到内侧核的中线区域，后部的背外侧和腹内侧分支分别投射到内侧核的内侧和外侧部分。与小脑丘下复合体和内侧前额叶皮层轴突末梢的突触形态不同，起源于中脑被盖的小脑标记轴突末梢以多形性囊泡为特征，与神经元体、近端树突、远端树突和树突棘形成对称的突触连接。与来自中脑被盖的轴突末梢相比，来自丘下复合体和内侧前额叶皮层的传入投射的轴突末梢在形态学上的差异表明，输入对MB神经元的兴奋或抑制作用不同。研究人员提出，MB的皮层、皮层下和脑干连接形成了三种不同的神经回路，这可能代表了不同功能活动的解剖学基础。
The retrograde and anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) has been used to trace afferent connections of the rat mamillary body (MB) at the light and electron microscopic levels. Injections of WGA-HRP into different parts of the MB resulted in heavy retrograde labeling in the subicular complex, medial prefrontal cortex, and dorsal and ventral tegmental nuclei. Injections of WGA-HRP into each of these brain regions, respectively, resulted in anterograde labeling with specific distributions and characteristic synaptic organizations in the MB. Projections from the rostrodorsal and caudoventral subiculum terminated in a topographically organized laminar fashion in the medial mamillary nucleus bilaterally, whereas afferent projections from the presubiculum and parasubiculum terminated only in the lateral mamillary nucleus. Labeled axon terminals which originated from the subicular complex were characterized by round vesicles and formed asymmetric synaptic junctions with small-diameter dendrites and dendritic spines in the medial and lateral mamillary nuclei. Projections from the prefrontal cortex originated mainly in the infralimbic area and to a lesser degree in the prelimbic and anterior cingulate areas. Injections of tracer into these brain regions gave rise to dense labeling of axon terminals in the medial mamillary nucleus, pars medianus, and in the anterior dorsomedial portion of the pars medialis. The labeled terminals were characterized by round vesicles and formed asymmetric synaptic junctions with small-diameter dendrites and dendritic spines. Projections from the dorsal tegmental nucleus terminated in the ipsilateral lateral mamillary nucleus, whereas afferent projections from the anterior and posterior subnuclei of the ventral tegmental nucleus terminated topographically in the medial mamillary nucleus. The ventral tegmental nucleus, pars anterior projected to the midline region of the medial nucleus and the dorsolateral and ventromedial subdivisions of the pars posterior projected to medial and lateral parts of the medial nucleus, respectively. In contrast to the synaptic morphology of subicular complex and medial prefrontal cortex axon terminals in the MB, labeled axon terminals in the MB which originated from the midbrain tegmentum were characterized by pleomorphic vesicles and formed symmetric synaptic junctions with neuronal somata and proximal dendrites as well as distal dendrites and dendritic spines. The morphological differences among axon terminals of afferent projections from the subicular complex and the medial prefrontal cortex compared to those from the midbrain tegmentum suggest that the inputs differ in terms of excitatory or inhibitory effects on MB neurons. It is proposed that cortical, subcortical, and brainstem connections of the MB form three distinct neural circuits which may represent anatomical substrates for different functional activities.