Elucidation of the mechanism of membrane transport of metal ions in the central nervous system and the relation to brain function

本研究旨在探讨金属离子在中枢神经系统的膜转运机制及其与脑功能的关系。研究结果如下：1.应用免疫组织化学技术，观察了Wilson病基因产物铜转运P型ATP酶（ATP 7 B）在Long-Evans免疫大鼠脑、肾、小肠和肝中的定位。在大鼠脑的海马结构、嗅球、小脑、大脑皮质和脑干的核、肾脏的皮质和外髓质的外条纹、小肠的潘氏细胞和肝细胞的神经元细胞中强烈检测到ATP 7 B。ATP 7 B主要观察到的区域中，其中大量的铜和铜结合蛋白，如Cu-ZnSOD和金属硫蛋白和NO合酶的检测。因此，在正常组织中，ATP 7 B不仅调节CNS中铜稳态和全铜结合蛋白的生物合成，而且还调节CNS中NO的合成。测定了衰老加速小鼠P10（SAMP 10）脑中微量元素和神经递质浓度随衰老的变化，该小鼠表现出脑萎缩和学习记忆缺陷。SAM-P10大部分区域的Zn、Cu、Mn含量均显著低于对照组。SAM-P10脑组织钼含量显著高于对照组。与对照组相比，12月龄SAM-P10海马CA 3区谷氨酸和甘氨酸释放量过量。这些结果表明，异常的金属离子在中枢神经系统的膜转运诱导SAMP 10的脑衰老加速。

In the present study, we intended to evaluate the mechanism of membrane transport of metal ions in the central nervous system and its relation to the brain function. Results obtained in the present investigations are as follows;1. Localization of copper-transporting P-type ATPase (ATP7B), a gene product responsible for Wilson disease, was visualized in the brain, kidney, small intestine and liver of the Long-Evans agouti rat using immunohistochemical technique. The ATP7B was intensely detected in neuronal cells of the hippocampal formation, olfactory bulbs, cerebellum, cerebral cortex and nuclei in the brain stem of the rat brain, the cortex and the outer stripe of the outer medulla in the kidney, Paneth cells of the small intestine, and hepatocytes. ATP7B was observed predominantly in the regions in which high amounts of copper and copper-binding proteins such as Cu-ZnSOD and metallothionein and NO synthase were detected. Thus, in normal tissue, ATP7B was considered to regulate not only copper homeostasis and biosynthesis of holo copper-binding proteins but also NO synthesis in CNS.2.. Changes in concentrations of trace elements and neurotransmitters by aging were determined in the brain of Senescence-Accelerated Mouse P10(SAMP10), which showed brain atrophy and deficits in learning and memory. Zn, Cu and Mn concentrations in most regions of SAM-P10, were significantly lower than those in the control rat. Mo concentration in the brain of SAM-P10 was significantly higher than that in the control. The excess amount of glutamate and glycine release from the hippocampal CA3 regions of SAM-P10 aged 12 months was observed as compared to that in the control. These results suggest that abnormal membrane transports of metal ions in CNS induce senescence-acceleration of the brain of SAMP10.