Nakamura S, Akiguchi I, Seriu N, Ohnishi K, Takemura M, Ueno M, Tomimoto H, Kawamata T, Kimura J, Hosokawa M
Department of Neurology, Faculty of Medicine, Kyoto University, Japan.
Acta Neuropathol. 1995;90(6):626-32. doi: 10.1007/BF00318576.
We examined the histochemical localization of monoamine oxidase in the hippocampus of young and old senescence-accelerated mouse (SAM). We found a monoamine oxidase-B-positive granular structure (MGS) in the hippocampus of old SAMP8, an accelerated senescence-prone line of SAM. The MGS was a round-shaped granular structure of 0.5 to 5 microns diameter and usually formed a cluster, the largest diameter of which ranged from 50 to 150 microns. No MGS were found in the hippocampus of young SAMP8 or of young SAMR1, an accelerated senescence resistant line of SAM, and only few, if any, were seen in old SAMR1. A monoamine oxidase-positive astrocyte was usually observed in the central area of each cluster of MGS. Furthermore, the MGS was in close anatomical relationship with monoamine oxidase-positive astrocytic processes. The enzyme inhibition experiments showed that monoamine oxidase activities localized in the MGS and astrocytes were both predominantly of type B. These findings suggest MGS occurs at least partly in monoamine oxidase-B-positive astrocytes. Furthermore, the MGS was similar to a periodic acid-Schiff-positive granular structure, a polyglucosan body previously documented in the brains of old SAMP8 and some other aged mice strains including C57BL/6 and nude mice, in terms of their size, morphological appearances and topographical distribution in the hippocampus. Thus, the present results suggest that monoamine oxidase type B is a proteinaceous component of the periodic acid-Schiff-positive granular structure in aged mice brains, and might provide some clues for clarifying the mechanisms of age-related occurrence of periodic acid-Schiff-positive granular structures in mice brains.
我们研究了年轻和老年加速衰老小鼠（SAM）海马中单胺氧化酶的组织化学定位。我们在老年SAMP8（SAM的一种易加速衰老品系）的海马中发现了一种单胺氧化酶B阳性颗粒结构（MGS）。MGS是一种直径为0.5至5微米的圆形颗粒结构，通常形成簇，其最大直径范围为50至150微米。在年轻SAMP8或年轻SAMR1（SAM的一种抗加速衰老品系）的海马中未发现MGS，在老年SAMR1中即使有也仅见少数。通常在每个MGS簇的中心区域观察到单胺氧化酶阳性星形胶质细胞。此外，MGS与单胺氧化酶阳性星形胶质细胞突起在解剖学上关系密切。酶抑制实验表明，位于MGS和星形胶质细胞中的单胺氧化酶活性主要都是B型。这些发现表明MGS至少部分存在于单胺氧化酶B阳性星形胶质细胞中。此外，就其大小、形态外观和在海马中的地形分布而言，MGS类似于过碘酸希夫阳性颗粒结构，一种先前在老年SAMP8和包括C57BL/6和裸鼠在内的其他一些老年小鼠品系的大脑中记录到的多葡聚糖体。因此，本研究结果表明，B型单胺氧化酶是老年小鼠大脑中过碘酸希夫阳性颗粒结构的一种蛋白质成分，可能为阐明小鼠大脑中与年龄相关的过碘酸希夫阳性颗粒结构出现机制提供一些线索。
