Kohl R L, Quay W B
J Neurosci Res. 1979;4(3):189-96. doi: 10.1002/jnr.490040306.
In relation to concern for probable interrelations of cystathionine synthase (CS, EC 4.2.1.21) and methionine, one-carbon, and 5-hydroxytryptamine metabolism, we have investigated tissue and time-of-day differences in CS activity in the laboratory rat under standardized conditions. Liver, kidney, and pancreas had highest CS activities; nine regions of the CNS had mean activities ranging from 4.5% (lumbosacral cord) to 24.5% (hypothalamus) of mean hepatic activity; pituitary and adrenal glands lacked detectable CS activity. Although significantly lower CS activity occurred in liver (9%, P less than 0.050) and kidney (13%, P less than 0.025) during the interval two hours before to two hours after the daily onset of darkness, no significant changes were found in hypothalamus, cerebellum, or medulla oblongata. Regional CNS differences in CS activity appeared to be without correlation in relation to published data on relative contents of 5-hydroxytryptamine, tryptophan 5-hydroxylase (EC 1.14.16.4), 5,10-Methylene reductase (N5-methyltetrahydrofolate-NAD-oxidoreductase, (EC 1.1.1.78), or 5-methyltetrahydrofolate. Therefore, among CNS regions examined, a critical deficiency in ability to metabolize a homocysteine load is considered to be unlikely under normal conditions.
关于对胱硫醚合酶（CS，EC 4.2.1.21）与蛋氨酸、一碳代谢及5-羟色胺代谢之间可能存在的相互关系的关注，我们在标准化条件下研究了实验大鼠CS活性的组织差异和昼夜差异。肝脏、肾脏和胰腺的CS活性最高；中枢神经系统的九个区域的平均活性范围为肝脏平均活性的4.5%（腰骶脊髓）至24.5%（下丘脑）；垂体和肾上腺未检测到CS活性。尽管在每日黑暗开始前两小时至黑暗开始后两小时的时间段内，肝脏（9%，P<0.050）和肾脏（13%，P<0.025）的CS活性显著降低，但在下丘脑、小脑或延髓中未发现显著变化。CS活性的中枢神经系统区域差异似乎与已发表的关于5-羟色胺、色氨酸5-羟化酶（EC 1.14.16.4）、5,10-亚甲基还原酶（N5-甲基四氢叶酸-NAD氧化还原酶，（EC 1.1.1.78）或5-甲基四氢叶酸相对含量的数据无关。因此，在所检查的中枢神经系统区域中，在正常条件下不太可能存在代谢同型半胱氨酸负荷的关键能力缺陷。
