Tissue distribution of S-adenosylmethionine and S-adenosylhomocysteine in the rat. Effect of age, sex and methionine administration on the metabolism of S-adenosylmethionine, S-adenosylhomocysteine and polyamines.
Tissue distribution of S-adenosylmethionine and S-adenosylhomocysteine in the rat. Effect of age, sex and methionine administration on the metabolism of S-adenosylmethionine, S-adenosylhomocysteine and polyamines.
复制标题
S-腺苷甲硫氨酸和S-腺苷高半胱氨酸在大鼠体内的组织分布。
作者：
T. Eloranta
本研究探讨了S-腺苷蛋氨酸、S-腺苷同型半胱氨酸、蛋氨酸腺苷转移酶和S-腺苷同型半胱氨酸水解酶在大鼠体内的组织分布。还研究了蛋氨酸给药对大鼠肝、脑和肾中S-腺苷蛋氨酸、S-腺苷高半胱氨酸和多胺蓄积的影响。S-腺苷甲硫氨酸、S-腺苷高半胱氨酸、甲硫氨酸腺苷转移酶和S-腺苷高半胱氨酸水解酶的组织分布在两性中相似，仅随年龄略有变化。S-腺苷高半胱氨酸水解酶的比活性大大超过蛋氨酸腺苷转移酶，并且在所有检测的组织中S-腺苷蛋氨酸的浓度高于S-腺苷高半胱氨酸。然而，肝S-腺苷甲硫氨酸/S-腺苷同型半胱氨酸的比例取决于食物供应和动物的年龄。甲硫氨酸腺苷转移酶的活性与腺苷化合物在不同组织中的浓度之间没有相关性。甲硫氨酸腹腔给药导致S-腺苷甲硫氨酸和S-腺苷高半胱氨酸的肝脏浓度显著但短暂增加。在注射蛋氨酸后的第一个2小时内，脑中S-腺苷甲硫氨酸的浓度也升高。甲硫氨酸处理后的S-腺苷甲硫氨酸浓度的上升可以通过同时施用甘氨酸来减少。结果支持了S-腺苷甲硫氨酸合成的限速因素是甲硫氨酸组织浓度的观点。他们进一步表明，甘氨酸N-甲基转移酶可能对肝脏中S-腺苷甲硫氨酸的利用具有调节作用。
The tissue distribution of S-adenosylmethionine, S-adenosylhomocysteine, methionine adenosyltransferase and S-adenosylhomocysteine hydrolase was explored in the rat. Also the effects of methionine administration on the accumulation of S-adenosylmethionine, S-adenosylhomocysteine and polyamines were studied in rat liver, brain and kidney. The tissue distribution of S-adenosylmethionine, S-adenosylhomocysteine, methionine adenosyltransferase and S-adenosylhomocysteine hydrolase was similar in both sexes, and was only slightly changed with age. The specific activity of S-adenosylhomocysteine hydrolase greatly exceeded that of methionine adenosyltransferase, and the concentration of S-adenosylmethionine was higher than that of S-adenosylhomocysteine in all tissues examined. However, the hepatic S-adenosylmethionine/S-adenosylhomocysteine ratio was dependent on food supply and on the age of the animal. No correlation was noticed between the activity of methionine adenosyltransferase and the concentrations of the adenosyl compounds in different tissues. Intraperitoneal administration of methionine resulted in a profound but transient increase in the hepatic concentrations of S-adenosylmethionine and S-adenosylhomocysteine. The concentration of S-adenosylmethionine was elevated also in the brain during the first 2h after methionine injection. The rise of S-adenosylmethionine concentration after methionine treatment could be diminished by simultaneous glycine administration. The results support the view that the rate-limiting factor of S-adenosylmethionine synthesis is the tissue concentration of methionine. They further suggest that glycine N-methyltransferase may have a regulatory role in the utilization of S-adenosylmethionine in the liver.