Vigh-Teichmann I, Vigh B
Neuroendocrine Laboratory, Hungarian Academy of Sciences-Semmelweis Medical University Joint Research Organization, Budapest.
Arch Histol Cytol. 1989;52 Suppl:195-207. doi: 10.1679/aohc.52.suppl_195.
Cerebrospinal fluid (CSF)-contacting neurons are located periventricularly or inside the brain ventricles; they contact the CSF via their dendrites, perikarya or axons. Most of these neurons form ciliated dendrite terminals in the internal CSF as do retinal and pineal photoreceptors in the optic ventricle and pineal recess. The peculiar localization, polarization and synaptic connections of the CSF-contacting neuronal elements suggest receptor and integrative functions. The present review pays special attention to vitamin A (retinoids) immunoreactivity in CSF-contacting neurons as compared with that present in retinal and pineal photoreceptor cells, common neurons, glial and adenohypophysial cells. The immunoreactivity of the dark-adapted photoreceptor outer segments was strong, but decreased after illumination, suggesting the functioning of vitamin A as the chromophore of the retinal and pineal photopigments. Retinoid immunoreaction was also found in the endoplasmic reticulum, nuclei, nucleoli and mitochondria of the cell types studied. This cytological localization suggests that vitamin A compounds may be involved in the function of these organelles. The CSF-contacting neurons contain varying amounts of bioactive materials. The intracellular distribution of immunoreactive serotonin (5-HT), substance P (SP) and gamma-aminobutyric acid (GABA) is compared with that of immunoreactive vitamin A. Immunogold labeling for SP was demonstrated in dense-core vesicles of preoptic neurons; 5-HT marking was found on the dense-core vesicles of subependymal CSF-contacting neurons of the paraventricular organ, while GABA immunoreaction was localized in the cytoplasm of distal infundibular CSF-contacting neurons. The CSF-contacting neurons are considered to synthesize and release their bioactive substances at transmitter synapses, and/or at neurohormonal terminals into the external CSF in accord with information received by their dendrites from the internal CSF and by afferent fiber connections from various brain areas.
脑脊液（CSF）接触神经元位于脑室周围或脑室内；它们通过树突、胞体或轴突与脑脊液接触。这些神经元中的大多数在脑室内形成纤毛树突终末，就像视脑室和松果体隐窝中的视网膜和松果体光感受器一样。脑脊液接触神经元成分独特的定位、极化和突触连接提示了其受体和整合功能。本综述特别关注脑脊液接触神经元中维生素A（视黄醇）的免疫反应性，并将其与视网膜和松果体光感受器细胞、普通神经元、神经胶质细胞和腺垂体细胞中的情况进行比较。暗适应光感受器外段的免疫反应性很强，但光照后减弱，这表明维生素A作为视网膜和松果体光色素的发色团发挥作用。在所研究的细胞类型的内质网、细胞核、核仁和线粒体中也发现了视黄醇免疫反应。这种细胞学定位表明维生素A化合物可能参与这些细胞器的功能。脑脊液接触神经元含有不同数量的生物活性物质。将免疫反应性5-羟色胺（5-HT）、P物质（SP）和γ-氨基丁酸（GABA）的细胞内分布与免疫反应性维生素A的分布进行比较。视前神经元的致密核心囊泡中显示有SP的免疫金标记；室旁器官室管膜下脑脊液接触神经元的致密核心囊泡上发现5-HT标记，而GABA免疫反应定位于漏斗柄远端脑脊液接触神经元的细胞质中。脑脊液接触神经元被认为在递质突触处和/或在神经激素终末合成并释放其生物活性物质，释放到外部脑脊液中，这与它们的树突从内部脑脊液以及来自各个脑区的传入纤维连接所接收的信息一致。
