Ishida K, Shimizu H, Hida H, Urakawa S, Ida K, Nishino H
Core Laboratory, Nagoya City University Graduate School of Medical Sciences, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
Neuroscience. 2004;125(3):633-44. doi: 10.1016/j.neuroscience.2004.02.002.
Argyrophilic dark neurons (DNs) reflect the early histopathological state of neurons following various brain insults. We examined the fate of DNs, about to either die or recover, following two types (heavy and light damage) of brain insult. Wistar rats were injected ibotenic acid unilaterally into the hippocampal CA1 region (ibotenic acid [IA] injection) or were forced to swim (SWIM). Argyrophil III (DNs)-, activated caspase-3 immuno-, TUNEL- and hematoxylin-eosin (H-E)-staining and ultrastructural examinations were then performed. One to three hours after IA injection, typical DNs (argyrophilic both in somata and dendrites) with corkscrew-like dendrites were densely packed in the pyramidal cell layer of hippocampal CA1 around the injection site. After 12-24 h, DNs were argyrophilic only in the somata and proximal dendrites but absent in distal dendrites in the CA1 region. However, at this time typical DNs were found in remote areas. At 3 h, caspase-3 activation was detected at the injection site, which increased to a peak level after 12 h. Three to 7 days after injection, TUNEL positive cells were detected in the CA1 pyramidal cell layer. Immediately following SWIM, "brown" rather than "dark" neurons were detected in the various areas and most frequently in the CA1 pyramidal cell layer. No typical DNs were detected over the first 3 days. Some activation of caspase-3 was detected in a few CA3 pyramidal cells but no TUNEL-positive cells were detected. Ultrastructural examination revealed a diffuse distribution of aggregated silver particles in the dendrites and cytoplasm of pyramidal cells at the sites of IA injection. After SWIM, silver particles were detected mainly on mitochondria of affected cells. These data suggest that DNs provide a measure of neuronal damage: typically dark neurons with broad damage to the cytoskeleton of dendrites would die, while non-typical brown neurons, that may have a disturbance in mitochondria, predominantly survive.
嗜银性暗神经元（DNs）反映了各种脑损伤后神经元的早期组织病理学状态。我们研究了在两种类型（重度和轻度损伤）的脑损伤后，即将死亡或恢复的DNs的命运。将鹅膏蕈氨酸单侧注射到Wistar大鼠海马CA1区（鹅膏蕈氨酸[IA]注射）或使其被迫游泳（SWIM）。然后进行嗜银性III（DNs）、活化的半胱天冬酶-3免疫、TUNEL和苏木精-伊红（H-E）染色以及超微结构检查。IA注射后1至3小时，具有螺旋状树突的典型DNs（胞体和树突均嗜银）密集地聚集在注射部位周围海马CA1区的锥体细胞层中。12至24小时后，DNs仅在胞体和近端树突中嗜银，而在CA1区的远端树突中不存在。然而，此时在远处区域发现了典型的DNs。在3小时时，在注射部位检测到半胱天冬酶-3激活，12小时后增加到峰值水平。注射后3至7天，在CA1锥体细胞层中检测到TUNEL阳性细胞。游泳后立即在各个区域检测到“棕色”而非“暗”神经元，最常见于CA1锥体细胞层。在最初3天未检测到典型的DNs。在少数CA3锥体细胞中检测到一些半胱天冬酶-3激活，但未检测到TUNEL阳性细胞。超微结构检查显示，IA注射部位锥体细胞的树突和细胞质中聚集的银颗粒呈弥漫性分布。游泳后，银颗粒主要在受影响细胞的线粒体上检测到。这些数据表明，DNs提供了一种神经元损伤的衡量标准：通常对树突细胞骨架有广泛损伤的暗神经元会死亡，而可能线粒体有紊乱的非典型棕色神经元主要存活。
