Horn A K, Büttner-Ennever J A, Wahle P, Reichenberger I
Institute of Neuropathology, University of Munich, Germany.
J Neurosci. 1994 Apr;14(4):2032-46. doi: 10.1523/JNEUROSCI.14-04-02032.1994.
Saccadic omnipause neurons (OPNs) are essential for the generation of saccadic eye movements. In primates OPNs are located near the midline within the nucleus raphe interpositus (rip). In the present study we used several different neuroanatomical methods to investigate the transmitters associated with OPNs in the monkey. Immunolabeling for the calcium-binding protein parvalbumin was employed to mark OPNs in the monkey and define the homologous cell group in cat and human. The use of antibodies against GABA, glycine (GLY), glutamate (GLU), serotonin (5-HT), and tyrosine hydroxylase revealed that the somata of OPNs are GLY immunoreactive, but they are devoid of GABA and 5-HT immunostaining. In situ hybridization with the GAD67 mRNA probe confirmed the negative GABA immunostaining of OPNs. 3H-GLY was injected into a projection field of OPNs, the rostral interstitial nucleus of the medial longitudinal fascicle (riMLF)--the vertical saccadic burst neuron area. This resulted in selective retrograde labeling of the OPNs in rip, while no labeling was found in the superior colliculus, which sends an excitatory projection to the riMLF. The somata and dendrites of putative burst neurons in the riMLF were contacted by numerous GLY-immunoreactive terminals. The quantitative analysis of immunoreactive terminal-like structures contacting OPNs revealed a strong input from GLY- and GABA-positive terminals on somata and dendrites, whereas GLU-positive puncta were mainly confined to the dendrites. Very few 5-HT and catecholaminergic terminals contacted OPN somata. Our findings suggest that OPNs use GLY as a neurotransmitter, and they receive numerous contacts from GABAergic, glycinergic, and glutaminergic afferents, and significantly fewer from monoaminergic inputs.
扫视性全暂停神经元（OPNs）对于扫视性眼球运动的产生至关重要。在灵长类动物中，OPNs位于中缝间核（rip）内靠近中线的位置。在本研究中，我们使用了几种不同的神经解剖学方法来研究与猴子OPNs相关的神经递质。利用针对钙结合蛋白小白蛋白的免疫标记来标记猴子的OPNs，并确定猫和人类中的同源细胞群。使用针对γ-氨基丁酸（GABA）、甘氨酸（GLY）、谷氨酸（GLU）、5-羟色胺（5-HT）和酪氨酸羟化酶的抗体显示，OPNs的胞体具有GLY免疫反应性，但缺乏GABA和5-HT免疫染色。用GAD67 mRNA探针进行原位杂交证实了OPNs的GABA免疫染色呈阴性。将3H-GLY注入OPNs的一个投射区域，即内侧纵束的嘴侧间质核（riMLF）——垂直扫视爆发神经元区域。这导致rip中的OPNs出现选择性逆行标记，而上丘未发现标记，上丘向riMLF发送兴奋性投射。riMLF中假定的爆发神经元的胞体和树突与许多GLY免疫反应性终末接触。对与OPNs接触的免疫反应性终末样结构的定量分析显示，GLY和GABA阳性终末对胞体和树突有强烈输入，而GLU阳性斑点主要局限于树突。很少有5-HT和儿茶酚胺能终末接触OPNs的胞体。我们的研究结果表明，OPNs使用GLY作为神经递质，它们接收来自GABA能、甘氨酸能和谷氨酸能传入神经的大量接触，而单胺能输入的接触则明显较少。
