Isaacson L G, Tanaka D
Department of Anatomy, Michigan State University, East Lansing 48824.
J Comp Neurol. 1988 Nov 22;277(4):529-40. doi: 10.1002/cne.902770406.
Choline acetyltransferase (ChAT) immunocytochemistry and lectin-conjugated horseradish peroxidase (WGA-HRP) histochemistry were combined at the electron microscopic level to examine the morphology of cholinergic terminals in the canine centrum medianum-parafascicular complex (CM-Pf) and to localize cholinergic terminals making synaptic contact with retrogradely labeled CM-Pf thalamostriatal projection neurons. Following WGA-HRP injections into the caudate nucleus, CM-Pf neurons were heavily labeled with WGA-HRP reaction product. Examination with the electron microscope revealed retrogradely labeled neurons characterized by a large nucleus with deep infoldings of the nuclear envelope. ChAT-positive terminals were observed arising from small-diameter nonmyelinated axonal profiles. These terminals varied in size from 0.5 to 1.4 micron in long diameter. The smaller terminals (0.5-0.7 micron) were seen most frequently and established symmetrical or slightly asymmetrical synaptic contacts with small dendritic profiles. The larger ChAT-positive terminals (1.0-1.4 micron) were less frequently observed, contained several mitochondria and small clusters of pleomorphic vesicles, and contacted large dendritic shafts and cell somata. Some of the postsynaptic targets of both smaller and larger ChAT-positive terminals were identified as belonging to retrogradely HRP-labeled thalamostriatal neurons. These observations indicate that at least some thalamostriatal neurons within the CM-Pf complex are innervated by cholinergic terminals which probably arise from ChAT-positive cell bodies located within the pontomesencephalic tegmentum, particularly within the nucleus tegmenti pedunculopontinus and the laterodorsal tegmental nucleus. These findings provide evidence for direct influence by cholinergic brainstem nuclei over activities of thalamostriatal neurons.
胆碱乙酰转移酶（ChAT）免疫细胞化学和凝集素结合辣根过氧化物酶（WGA-HRP）组织化学在电子显微镜水平上相结合，以检查犬中脑中央核-束旁复合体（CM-Pf）中胆碱能终末的形态，并定位与逆行标记的CM-Pf丘脑纹状体投射神经元形成突触联系的胆碱能终末。将WGA-HRP注入尾状核后，CM-Pf神经元被WGA-HRP反应产物大量标记。电子显微镜检查显示逆行标记的神经元，其特征为细胞核大，核膜有深陷褶。观察到ChAT阳性终末起源于小直径无髓轴突轮廓。这些终末长径大小在0.5至1.4微米之间变化。较小的终末（0.5-0.7微米）最常见，与小的树突轮廓建立对称或稍不对称的突触联系。较大的ChAT阳性终末（1.0-1.4微米）较少观察到，含有几个线粒体和小的多形性囊泡簇，并与大树突干和细胞体接触。较小和较大的ChAT阳性终末的一些突触后靶点被确定为属于逆行HRP标记的丘脑纹状体神经元。这些观察结果表明，CM-Pf复合体内至少一些丘脑纹状体神经元由胆碱能终末支配，这些终末可能起源于位于脑桥中脑被盖部，特别是脚桥被盖核和外侧背侧被盖核内的ChAT阳性细胞体。这些发现为胆碱能脑干核直接影响丘脑纹状体神经元的活动提供了证据。
