Wong-Riley M, Anderson B, Liebl W, Huang Z
Department of Cellular Biology and Anatomy, Medical College of Wisconsin, Milwaukee 53226, USA.
Neuroscience. 1998 Apr;83(4):1025-45. doi: 10.1016/s0306-4522(97)00432-6.
Previously, we found that cytochrome oxidase-rich zones in the supragranular layers of the macaque striate cortex had more asymmetric, glutamate-immunoreactive synapses than the surrounding, cytochrome oxidase-poor regions. A major glutamate receptor family is N-methyl-D-aspartate, which is implicated in the stimulation of nitric oxide synthase and in the production of nitric oxide, a gaseous intra- and inter-cellular messenger. To determine if energy-generating and energy-utilizing enzymes bore any spatial relationship with neurochemicals associated with glutamatergic neurotransmission in the monkey visual cortex, serial cortical sections were processed histochemically for cytochrome oxidase and NADPH-diaphorase, and immunohistochemically for sodium/potassium-ATPase, nitric oxide synthase, and N-methyl-D-aspartate receptor subunit 1 protein, respectively. The general patterns were similar among the five neurochemicals, with layers 4C, 6 and supragranular puffs being labelled, although the intensity of labelling differed among them. Monocular impulse blockade with tetrodotoxin for two to four weeks induced a down-regulation of all five neurochemicals not only in deprived layer 4C ocular dominance columns, but also in deprived rows of puffs. Thus, the regulation of all five neurochemicals in the mature visual cortex is activity-dependent. Combined cytochrome oxidase histochemistry and nitric oxide synthase immunohistochemistry in the same sections revealed that double-labelled cells were primarily medium-sized non-pyramidals in various cortical layers. Likewise, those that were double-labelled by N-methyl-D-aspartate receptor subunit 1 immunohistochemistry and nitric oxide synthase immunogold silver staining in the same sections were of the medium-sized non-pyramidal neurons. At the ultrastructural level, combined cytochrome oxidase cytochemistry and postembedding immunogold labelling for nitric oxide synthase showed that immunogold particles for nitric oxide synthase were more heavily concentrated in cytochrome oxidase-rich type C cells. These medium-sized non-pyramidal cells were previously found to be gamma aminobutyric acid-immunoreactive and received both gamma aminobutyric acid- and glutamate-immunoreactive axosomatic synapses. Thus, our results are consistent with an enrichment of excitatory synaptic interactions in metabolically active regions of the primate visual cortex that involves glutamate-related neurochemicals, such as N-methyl-D-aspartate receptors and nitric oxide synthase. These interactions impose a higher energy demand under normal conditions and are down-regulated by retinal impulse blockade.
此前，我们发现猕猴纹状皮质颗粒上层中富含细胞色素氧化酶的区域比周围细胞色素氧化酶含量低的区域具有更多不对称的、谷氨酸免疫反应性突触。一个主要的谷氨酸受体家族是N-甲基-D-天冬氨酸，它与一氧化氮合酶的刺激以及一氧化氮的产生有关，一氧化氮是一种细胞内和细胞间的气态信使。为了确定能量产生和能量利用酶是否与猴视觉皮质中与谷氨酸能神经传递相关的神经化学物质存在任何空间关系，我们分别对连续的皮质切片进行了细胞色素氧化酶和NADPH-黄递酶的组织化学处理，以及钠/钾-ATP酶、一氧化氮合酶和N-甲基-D-天冬氨酸受体亚基1蛋白的免疫组织化学处理。这五种神经化学物质的总体模式相似，4C层、6层和颗粒上层的隆起区域都有标记，尽管它们之间的标记强度有所不同。用河豚毒素进行两到四周的单眼冲动阻断不仅会导致剥夺的4C层眼优势柱中所有五种神经化学物质下调，还会导致剥夺的隆起排中所有五种神经化学物质下调。因此，成熟视觉皮质中所有五种神经化学物质的调节都依赖于活动。在同一切片中进行细胞色素氧化酶组织化学和一氧化氮合酶免疫组织化学相结合的方法显示，双标记细胞主要是各皮质层中的中等大小的非锥体神经元。同样，在同一切片中通过N-甲基-D-天冬氨酸受体亚基1免疫组织化学和一氧化氮合酶免疫金银染色双标记的细胞也是中等大小的非锥体神经元。在超微结构水平上，细胞色素氧化酶细胞化学和一氧化氮合酶包埋后免疫金标记相结合的方法显示，一氧化氮合酶的免疫金颗粒更密集地集中在富含细胞色素氧化酶的C型细胞中。这些中等大小的非锥体细胞之前被发现是γ-氨基丁酸免疫反应性的，并接受γ-氨基丁酸和谷氨酸免疫反应性的轴体突触。因此，我们的结果与灵长类视觉皮质代谢活跃区域中涉及谷氨酸相关神经化学物质（如N-甲基-D-天冬氨酸受体和一氧化氮合酶）的兴奋性突触相互作用的富集一致。在正常情况下，这些相互作用会产生更高的能量需求，并通过视网膜冲动阻断而下调。
