Ando S, Tanaka Y, Ono Y, Kon K
Adv Exp Med Biol. 1984;174:241-8. doi: 10.1007/978-1-4684-1200-0_20.
The turnover rate of GM1 ganglioside in myelin was examined reveal age-related alterations in the metabolic activity. Three different age groups of mice were given deuterium oxide, and myelin was prepared from cerebella at intervals of two weeks. GM1 was isolated from the total myelin gangliosides by high performance liquid chromatography. Deuterated sugar moieties of GM1 were determined by chemical ionization-mass spectrometry which provided prominent quasimolecular ions. This method made it possible to determine separately the incorporation of deuterium into internal and external galactoses as well as other components. The incorporation rate of GM1 into myelin was clearly shown to be decreased with advancing age. Lower incorporation of newly synthesized sialic acid into GM1 than that of other sugars may indicate reutilization of sialic acid at about 50%. The possibility of modification of the myelin metabolism by exogenous factors was examined by monitoring the incorporation rate of GM1 in animals treated with chemical agents. It was revealed that thyroxine enhanced the incorporation of GM1 into adult brain myelin, whereas propylthiouracil reduced the incorporation. Other chemicals, estradiol, S-adenosylmethionine and LM1 ganglioside, showed only minor effects on the myelin turnover.
对髓鞘中GM1神经节苷脂的周转率进行了检测，结果显示其代谢活性存在与年龄相关的变化。给三组不同年龄的小鼠注射重水，每隔两周从小脑制备髓鞘。通过高效液相色谱法从总髓鞘神经节苷脂中分离出GM1。GM1的氘代糖部分通过化学电离质谱法测定，该方法可提供显著的准分子离子。这种方法能够分别测定氘掺入内部和外部半乳糖以及其他成分的情况。结果清楚地表明，随着年龄的增长，GM1掺入髓鞘的速率降低。新合成的唾液酸掺入GM1的比例低于其他糖类，这可能表明约50%的唾液酸被再利用。通过监测化学试剂处理的动物中GM1的掺入率，研究了外源性因素对髓鞘代谢的影响。结果显示，甲状腺素可增强GM1掺入成年脑髓鞘的能力，而丙硫氧嘧啶则降低了掺入率。其他化学物质，如雌二醇、S-腺苷甲硫氨酸和LM1神经节苷脂，对髓鞘周转率的影响较小。
