Regulation of tryptophan-niacin metabolism by hormones.
Regulation of tryptophan-niacin metabolism by hormones.
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激素对色氨酸-烟酸代谢的调节。
DOI：
10.3177/jnsv.26.617
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发表时间：
1980
影响因子：
1.6
通讯作者：
M. Miyazaki
中科院分区：
文献类型：
--
作者：
H. Sanada;M. Miyazaki
本文研究了垂体和肾上腺皮质激素对豚鼠体内烟碱代谢的调节作用。垂体切除大鼠喂养的烟酸免费纯化的饮食注射牛生长激素，醋酸泼尼松或两者兼而有之。然后比较激素治疗前后口服色氨酸后尿中N-甲基烟酰胺（MNA）和N-甲基-2-吡啶酮-5-甲酰胺（2-Py）的排泄量。注射生长激素后尿MNA含量增加，而注射强的松后尿MNA含量减少。另一方面，在给予两种激素的大鼠中未观察到尿MNA的变化。2-Py的量似乎减少泼尼松治疗，但不受生长激素注射。肝脏α-氨基-β-羧基粘康酸-ε-半醛脱羧酶（吡啶羧化酶）的活性与（口服色氨酸）/（尿MNA）比值成正比。此外，酶活性似乎与肝脏中烟酸的浓度成反比。此外，尿中MNA的含量也受体重增加的影响。给药垂体激素和胰岛素未能使糖尿病大鼠尿MNA排泄量减少正常化，表明垂体激素的任何变化都不是糖尿病中异常的β-烟酸代谢的原因。
The regulation of tryptophan-niacin metabolism by pituitary and adrenocortical hormones was investigated. Hypophysectomized rats fed on a niacin-free purified diet were injected with bovine somatotropin, predonine acetate or both. The urinary excretion of N-methylnicotinamide (MNA) and N-methyl-2-pyridone-5-carboxamide (2-Py) after oral administration of tryptophan was then compared before and after the hormone treatment. The amount of urinary MNA was found to be increased after the injection of somatotropin, but decreased after the predonine injection. On the other hand, no change in urinary MNA was observed in the rats administered with both hormones. The amount of 2-Py appeared to be reduced by the predonine treatment, but was not affected by somatotropin injection. The activity of liver alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (picolinic carboxylase) was shown to be directly proportional to the ratio (oral tryptophan)/(urinary MNA). Moreover, the enzyme activity appeared to be inversely proportional to the concentration of niacin in liver. In addition, the amount of urinary MNA was suggested to be affected by the change of body weight gain. The administration of both pituitary hormone and insulin failed to normalize the reduced urinary MNA excretion in diabetic rats, suggesting that any change in pituitary hormone was not responsible for the abnormal tryptophan-niacin metabolism in diabetes.