Tappaz M L, Wassef M, Oertel W H, Paut L, Pujol J F
Neuroscience. 1983 Jun;9(2):271-87. doi: 10.1016/0306-4522(83)90293-2.
GABAergic cells and axon terminals were localized in the basal hypothalamus of differnet species (rat, mouse and cat), by means of an immunocytochemical approach using a specific and well-characterized antiserum to the GABA biosynthetic enzyme, glutamate decarboxylase. Light-microscopic visualization was performed with an indirect immunofluorescence method and electron-microscopic observations were made on material with pre-embedding staining and use of the peroxidase-antiperoxidase procedure. At the light-microscopic level, a dense immunofluorescent plexus was observed over both the medial and lateral parts of the external layer of the median eminence. The labelling extended from the rostal part of the median eminence up to the pituitary stalk. Over the subependymal and internal layers only a few immunoreactive dots were visible, except around the blood vessels where they appeared more concentrated. Immunoreactive varicosities could be found following the outlines of the capillary loops and lining tanycyte processes, especially in the median eminance midportion. At the electron-microscopic level, the immunolabelling was exclusively found over neuronal profiles in the median eminence. The latter represented a small fraction of the total number of varicosities visible on the same section. Labelled profiles typically contained numerous small clear synaptic vesicles and only a few or no dense-core vesicles. In the subependymal and internal layers, rare labelled endings were found close to ependymal cells or among transversally cut fibers, respectively. In the palisadic zone, elongated positive boutons were visible intermingled with bundles of unlabelled axons and glial or ependymal processes. In the neurohemal contact zone, immunoreactive endings were observed among unlabelled neurosecretory endings in close vicinity to fenestrated capillary perivascular space. Small moderately intense immunofluorescent varicosities were observed all over the hypothalamus. The density of the glutamate decarboxylase-positive network was higher than in most diencephalic regions. Intraventricular or topical injection of colchicine allowed the visualization of small lightly immunoreactive cells in the diffusion area of colchicine. In the arcuate nucleus labelled axonal endings containing small pleomorphic synaptic vesicles and sometimes a few dense-core vesicles were observed at the electron-microscopic level. Typical synaptic junctions were commonly found between positive endings and unlabelled perikarya, or more frequently, unlabelled dendrites. These findings show that glutamate decarboxylase-containing endings are localized ed in several strategic sites for potential GABAergic neuroendocrine regulations. The GABAergic endings found among neurosecretory endings in the neurohemal contact zone may provide the morphological support for the release of gamma-aminobutyrate into the portal blood flow as an hypothalamic hypophysiotropic hormone.
通过使用针对γ-氨基丁酸（GABA）生物合成酶谷氨酸脱羧酶的特异性且特性明确的抗血清，采用免疫细胞化学方法，在不同物种（大鼠、小鼠和猫）的下丘脑基部定位了GABA能细胞和轴突终末。利用间接免疫荧光法进行光学显微镜观察，并对经包埋前染色及使用过氧化物酶-抗过氧化物酶程序处理的材料进行电子显微镜观察。在光学显微镜水平，在正中隆起外层的内侧和外侧部分均观察到密集的免疫荧光丛。标记从正中隆起的嘴侧部分延伸至垂体柄。在室管膜下和内层，仅可见少数免疫反应性小点，但在血管周围它们更为密集。免疫反应性曲张可沿毛细血管袢轮廓及衬于伸展细胞突起处发现，尤其是在正中隆起中部。在电子显微镜水平，免疫标记仅见于正中隆起的神经元轮廓上。后者在同一切片上可见的曲张总数中占一小部分。标记的轮廓通常含有许多小而清亮的突触小泡，仅有少数或没有致密核心小泡。在室管膜下和内层，分别在靠近室管膜细胞处或横向切断的纤维中发现罕见的标记终末。在栅状带，可见细长的阳性终扣与未标记的轴突束以及神经胶质或室管膜突起交织在一起。在神经血接触区，在靠近有窗孔毛细血管血管周间隙的未标记神经分泌终末之间观察到免疫反应性终末。在下丘脑各处均观察到小的中等强度免疫荧光曲张。谷氨酸脱羧酶阳性网络的密度高于大多数间脑区域。脑室内或局部注射秋水仙碱可使秋水仙碱扩散区域内小的轻度免疫反应性细胞可视化。在电子显微镜水平，在弓状核观察到含有小的多形性突触小泡且有时有少数致密核心小泡的标记轴突终末。在阳性终末与未标记的核周体之间，或更常见地，在未标记的树突之间，通常可发现典型的突触连接。这些发现表明，含谷氨酸脱羧酶终末定位于几个潜在的GABA能神经内分泌调节的关键部位。在神经血接触区的神经分泌终末之间发现的GABA能终末可能为γ-氨基丁酸作为下丘脑促垂体激素释放至门静脉血流提供形态学支持。
