SELECTIVE RETROGRADE LABELING OF LATERAL OLIVOCOCHLEAR NEURONS IN THE BRAIN-STEM BASED ON PREFERENTIAL UPTAKE OF H-3 D-ASPARTIC ACID IN THE COCHLEA
SELECTIVE RETROGRADE LABELING OF LATERAL OLIVOCOCHLEAR NEURONS IN THE BRAIN-STEM BASED ON PREFERENTIAL UPTAKE OF H-3 D-ASPARTIC ACID IN THE COCHLEA
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DOI：
10.1002/cne.902550411
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发表时间：
1987-01-22
影响因子：
2.5
通讯作者：
WANG, ZX
中科院分区：
文献类型：
--
作者：
RYAN, AF;SCHWARTZ, IR;WANG, ZX
我们之前已经证明，用探针浓度的 3H-D-天冬氨酸 (D-ASP) 灌注沙鼠耳蜗会导致内毛细胞下 50-60% 的传出末梢立即选择性标记，推测是通过高亲和力摄取。本研究的目的是确定这些结局的起源。用 D-ASP 进行耳蜗灌注 24 小时后，在同侧观察到标记的神经元，在对侧、外侧上橄榄核 (LSO) 中观察到标记的神经元，程度要小得多。这些细胞很小，主要呈梭形，并且比其他 LSO 细胞显示出更少的突触接触。 D-ASP 和辣根过氧化物酶的联合转运表明，LSO 内投射到注射耳蜗的所有橄榄耳蜗神经元都被 D-ASP 标记。标记的纤维从 LSO 向背侧走行，与穿过第四脑室底部的对侧纤维连接，并在其腹内侧边缘进入第八神经根。 邻近耳蜗腹核（VCN），密集标记的侧支纤维穿过神经根进入 VCN。标记的光纤和终端在中央 VCN 中很明显。没有观察到内侧橄榄耳蜗和前庭传出神经对 D-ASP 的逆行转运，也没有观察到第 8 神经传入神经对 D-ASP 的顺行转运。 D-ASP 标记的细胞和纤维显然是侧橄榄耳蜗传出神经。因此，D-ASP 的逆行运输使得侧橄榄耳蜗系统的细胞、轴突和侧枝能够在形态学上与投射到耳蜗的其他细胞分开进行研究。由于橄榄耳蜗神经元几乎肯定是胆碱能的，逆行氨基酸转运不一定能识别神经元的主要神经递质。相反，它表明氨基酸注射部位的神经元过程存在选择性摄取。通过使用代谢惰性化合物（例如 D 异构体氨基酸），逆行标记似乎得到显着增强。
We have previously shown that perfusion of the gerbil cochlea with probe concentrations of 3H-D-aspartic acid (D-ASP) results in immediate, selective labeling of 50-60% of the efferent terminals under the inner hair cells, presumably by high-affinity uptake. The present study was undertaken to determine the origin of these endings. Twenty-four hours after cochlear perfusion with D-ASP, labeled neurons were observed in the ipsilateral, and to a much lesser extent in the contralateral, lateral superior olivary nucleus (LSO). The cells were small, primarily fusiform, and showed fewer synaptic contacts than other LSO cells. Combined transport of D-ASP and horseradish peroxidase indicated that all olivocochlear neurons within the LSO that projected to the injected cochlea were labeled by D-ASP. Labeled fibers coursed dorsally from the LSO, joined contralateral fibers that had passed under the floor of the fourth ventricle, and entered the VIIIth nerve root at its ventromedial edge. Adjacent to the ventral cochlear nucleus (VCN), densely labeled collateral fibers crossed the nerve root to enter the VCN. Labeled fibers and terminals were prominent in the central VCN. Neither retrograde transport of D-ASP by medial olivocochlear and vestibular efferents nor anterograde transport by VIIIth nerve afferents was observed. The D-ASP-labeled cells and fibers are clearly lateral olivocochlear efferents. Retrograde transport of D-ASP thus allows the cells, axons, and collaterals of the lateral olivocochlear system to be studied, morphologically, in isolation from other cells that project to the cochlea. Since the olivocochlear neurons are almost certainly cholinergic, retrograde amino acid transport does not necessarily identify the primary neurotransmitter of a neuron. Rather, it indicates the presence of selective uptake by the processes of that neuron at the site of amino acid injection. Retrograde labeling appears to be markedly enhanced by the use of metabolically inert compounds such as d-isomer amino acids.