Dávila J C, Megías M, Andreu M J, Real M A, Guirado S
Department of Cell Biology, University of Málaga, Spain.
Hippocampus. 1995;5(1):60-70. doi: 10.1002/hipo.450050108.
We analyzed the distribution and light-microscopic features of the NADPH diaphorase-containing structures in the lizard hippocampus, likely to correspond to nitric oxide synthase-containing cells and fibers, and thus likely to release nitric oxide. We also studied co-localization of NADPH diaphorase with the neurotransmitter GABA, the calcium-binding protein parvalbumin, and the neuropeptide somatostatin, in order to examine whether putative nitric oxide-synthesizing neurons represent a different subpopulation of GABA cells, on which the authors recently reported in lizards. We also studied co-localization of NADPH diaphorase with parvalbumin or somatostatin in mice to ascertain whether the characteristics of this population in reptiles parallel the situation in mammals. Most of the positive NADPH diaphorase neurons were stained in a Golgi-like manner and were in the plexiform layers of the lizard hippocampus with morphologies ranging from bipolar to multipolar. Co-localization with GABA was 100%, and NADPH diaphorase-positive neurons in the lizard hippocampus did not contain parvalbumin or somatostatin. The results indicate that putative nitric oxide-synthesizing neurons represent a distinct subpopulation of GABA interneurons in the lizard hippocampus. Two different types of fibers were described in the plexiform layers: one type bearing thick varicosities, and the other thinner ones. We discuss the possibility that at least part of the positive fibers arise from a hypothalamic aminergic nucleus contacting the third ventricle, the periventricular hypothalamic organ. Most radial glia were stained almost completely and formed typical end-feet both at the pia and around capillaries. The results of this study confirm that the capacity for synthesizing nitric oxide is linked to a determined set of neuronal markers depending on the specific brain region, and they provide new resemblances between hippocampal regions in different classes of vertebrates.
我们分析了蜥蜴海马体中含NADPH黄递酶结构的分布和光学显微镜特征，这些结构可能对应含一氧化氮合酶的细胞和纤维，因此可能释放一氧化氮。我们还研究了NADPH黄递酶与神经递质γ-氨基丁酸（GABA）、钙结合蛋白小白蛋白以及神经肽生长抑素的共定位情况，以检验假定的一氧化氮合成神经元是否代表了GABA细胞的一个不同亚群，作者最近在蜥蜴中报道了这一情况。我们还研究了NADPH黄递酶与小白蛋白或生长抑素在小鼠中的共定位情况，以确定爬行动物中这一群体的特征是否与哺乳动物中的情况相似。大多数NADPH黄递酶阳性神经元呈类似高尔基染色的方式，位于蜥蜴海马体的丛状层，形态从双极到多极不等。与GABA的共定位率为100%，蜥蜴海马体中的NADPH黄递酶阳性神经元不含小白蛋白或生长抑素。结果表明，假定的一氧化氮合成神经元代表了蜥蜴海马体中GABA中间神经元的一个独特亚群。在丛状层中描述了两种不同类型的纤维：一种带有粗大的膨体，另一种较细。我们讨论了至少部分阳性纤维起源于与第三脑室接触的下丘脑胺能核即室周下丘脑器官的可能性。大多数放射状胶质细胞几乎完全被染色，并在软脑膜和毛细血管周围形成典型的终足。这项研究的结果证实，一氧化氮的合成能力与一组特定的神经元标志物相关，这取决于特定的脑区，并且它们揭示了不同类脊椎动物海马区之间的新相似性。
