CONVERGENT SYNAPTIC INPUT FROM THE NEOSTRIATUM AND THE SUBTHALAMUS ONTO IDENTIFIED NIGROTHALAMIC NEURONS IN THE RAT
CONVERGENT SYNAPTIC INPUT FROM THE NEOSTRIATUM AND THE SUBTHALAMUS ONTO IDENTIFIED NIGROTHALAMIC NEURONS IN THE RAT
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DOI：
10.1111/j.1460-9568.1994.tb00275.x
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发表时间：
1994-03-01
影响因子：
3.4
通讯作者：
CROSSMAN, AR
中科院分区：
文献类型：
--
作者：
BEVAN, MD;BOLAM, JP;CROSSMAN, AR
黑质网状部的两个主要传入是丘脑底核和纹状体。刺激这些传入神经对黑质网状部的输出神经元具有相反的生理效应。为了更好地了解这些传入的信息流通过基底神经节的作用，并更好地了解他们可能相互作用的方式，实验已经进行了测试的可能性，黑质网状部的单输出神经元接受会聚的突触输入从丘脑底核和新纹状体。为了解决这一问题，大鼠接受离子电渗沉积的顺行示踪剂菜豆leucoagglutinin丘脑底核，注射顺行示踪剂biocytin在新纹状体和注射逆行示踪剂辣根过氧化物酶共轭小麦胚芽凝集素在丘脑腹内侧核。在适当的存活时间后，对动物进行灌注固定，并对黑质切片进行处理，以显示运输的示踪剂，并制备用于电子显微镜检查。光镜检查发现，黑质含有丰富的丛顺行标记的底丘脑和纹状体终端，以及许多逆行标记的黑丘脑神经元。顺行标记的终末常与逆行标记的神经元并列。在电子显微镜下，底丘脑终末与黑丘脑神经元以及未标记的胞体和近端和远端树突形成不对称的突触接触（底丘脑1型）。在确认以前的研究结果，纹状体终末与黑丘脑神经元以及未标记的神经元对称的突触接触。在这两类终端之间的重叠领域，确定nigrothalamic神经元和未标记的黑质神经元被发现接受会聚的突触输入从丘脑底核和新纹状体。除了形成不对称的突触专业化的顺行标记的丘脑底神经末梢，第二，更罕见的类也观察到（丘脑底神经2型）。这些终末大得多，形成对称的突触;几条证据表明，它们不是起源于丘脑底核，而是起源于苍白球。发现这些终末与已识别的黑丘脑神经元和未标记的神经元形成突触接触，并与底丘脑1型终末和纹状体终末形成会聚的突触接触。得出的结论是，通过基底神经节的信息流的所谓直接（纹状体至黑质网状部）和间接通路（即涉及丘脑底核和/或苍白球的通路）的地形和突触组织是抑制和兴奋的基础刺激纹状体后发生的黑质网状部的输出神经元。
The two major afferents of the substantia nigra pars reticulata are the subthalamic nucleus and the striatum. Stimulation of these afferents has opposing physiological effects on the output neurons of the substantia nigra pars reticulata. In order to better understand the role of these afferents in the flow of information through the basal ganglia and to better understand the ways in which they might interact, experiments have been performed to test the possibility that single-output neurons of the substantia nigra pars reticulata receive convergent synaptic input from the subthalamic nucleus and the neostriatum. To address this, rats received iontophoretic deposits of the anterograde tracer Phaseolus vulgaris leucoagglutinin in the subthalamic nucleus, injections of the anterograde tracer biocytin in the neostriatum and injections of the retrograde tracer horseradish peroxidase conjugated to wheat-germ agglutinin in the ventral medial nucleus of the thalamus. Following appropriate survival times the animals were perfusion-fixed and sections of the substantia nigra were processed to reveal the transported tracers and prepared for electron microscopy. Light microscopic examination revealed that the substantia nigra contained rich plexuses of anterogradely labelled subthalamic and striatal terminals, as well as many retrogradely labelled nigrothalamic neurons. The anterogradely labelled terminals were often seen apposed to the retrogradely labelled neurons. In the electron microscope the subthalamic terminals were seen to form asymmetrical synaptic contacts (subthalamic type 1) with the identified nigrothalamic neurons as well as unlabelled perikarya and both proximal and distal dendrites. In confirmation of previous findings, the striatal terminals made symmetrical synaptic contact with the nigrothalamic neurons as well as unlabelled neurons. In areas of overlap between the two classes of terminals, identified nigrothalamic neurons and unlabelled nigral neurons were found to receive convergent synaptic input from the subthalamic nucleus and the neostriatum. In addition to the anterogradely labelled subthalamic terminals that formed asymmetrical synaptic specializations, a second, much rarer class was also observed (subthalamic type 2). These terminals were much larger and formed symmetrical synapses; several lines of evidence suggest that they originated not in the subthalamic nucleus but in the globus pallidus. These terminals were found to make synaptic contacts with identified nigrothalamic neurons and non-labelled neurons and to form convergent synaptic contacts with subthalamic type 1 terminals and striatal terminals. It is concluded that the topographical and synaptic organization of the so-called direct (striatum to substantia nigra pars reticulata) and indirect pathways (i.e. pathways involving the subthalamic nucleus and/or the globus pallidus) of information flow through the basal ganglia underlies the inhibition and excitation of the output neurons of the substantia nigra pars reticulata that occur following stimulation of the striatum.