Bondareff W, Lin-liu S
Am J Anat. 1977 Jan;148(1):57-64. doi: 10.1002/aja.1001480106.
The volume of the extracellular space, which contributes to the microenvironment of neurons, is diminished in the brains of senescent (as compared to adult) rats and an age-related change in its composition has been hypothesized. To test this hypothesis we have compared the penetration of ruthenium red, a polyanion selectively distributed in the extracellular space, into the dentate gyri of young adult and senescent Fischer 344 rats. Slices of hoppocampal formation were fixed by immersion, first in a glutaraldehyde solution containing ruthenium red, then in a solution of osmium tetroxide containind examined by electron microscopy. Dense particles of ruthenium red reaction product were readily localized in intercellular channels and synaptic clefts and the depth of penetration of ruthenium red in 25-month-old rats, as compared with 3-month-old animals, was found. These data indicate an age-related change in the charge density of the intercellular channels in the dentate gyrus of 25-month-old rats. They suggest a primary age-related change in the charg density of extracellular macromoledules, presumed to be primarily glycosaminoglycans, with a consequent change in water binding capacity and volume of the extracellular space.
构成神经元微环境的细胞外空间体积在衰老（与成年相比）大鼠的大脑中减小，并且已假设其组成存在与年龄相关的变化。为了验证这一假设，我们比较了钌红（一种选择性分布于细胞外空间的聚阴离子）进入年轻成年和衰老的Fischer 344大鼠齿状回的情况。海马结构切片通过浸入固定，首先浸入含有钌红的戊二醛溶液中，然后浸入含有四氧化锇的溶液中，通过电子显微镜检查。钌红反应产物的致密颗粒很容易定位在细胞间通道和突触间隙中，并且发现与3个月大的动物相比，钌红在25个月大的大鼠中的渗透深度。这些数据表明25个月大的大鼠齿状回中细胞间通道电荷密度存在与年龄相关的变化。它们表明细胞外大分子（推测主要是糖胺聚糖）的电荷密度存在与年龄相关的原发性变化，从而导致水结合能力和细胞外空间体积的变化。
