XANTHURENIC ACID, AN ABNORMAL METABOLITE OF TRYPTOPHAN AND THE DIABETIC SYMPTOMS CAUSED IN ALBINO RATS BY ITS PRODUCTION
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概要
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1. After administering tryptophan to albino rats fed on a B6 deficient diet containing casein, xanthurenic acid is excreted in the urine.2. Feeding rats on a diet containing much fatty acid salt and tryptophan, they become deficient in vitamin B6 and a remarkable amount of xanthurenic acid is excreted in the urine, which was isolated and identified. After the administration of pyridoxine, the urinary excretion of xanthurenic acid remarkably decreased but never completely disappeared.3. After administering orally both sodium butyrate and tryptophan to albino rats, the blood sugar curve show primary hyperglycemia, followed by temporary hypoglycemia, and finally definite hyperglycemia, accompanied by glycosuria owing to the production of xanthurenic acid.4. Administration of xanthurenic acid to albino rat leads also to the development of diabetic symptoms.5. Xanthurenic acid, when given continuously, shows an accumulative effect on diabetic symptoms. In the urine of the rats in hyperglycemia and vitamin B6 deficiency, a definite increase of acetone bodies is detected.6. The pancreas of rat showing hyperglycemia after feeding for a long period on high fat and casein diet or vitamin B6 deficient one, showed histologically degenerative changes of β-cells of Langerhans islets. It was especially conspicuous in vitamin B6 deficiency.7. In the urines of diabetic patients, the spot corresponding to free form of xanthurenic acid was detected by paper chromatography, contrary to the healthy subjects.8 Insulin was found to prevent the urinary excretion of xanthurenic acid of experimental animals as detected by paper chromatography. The product excreted in the urine instead of xanthurenic acid was proved to be kynurenic acid.9. Methionine inhibit the formation of xanthurenic acid. By simultaneous application of methionine and pyridoxine to rats, the urinary xanthurenic acid disappeared completely.10. The xanthurenic acid injected to rat is readily excreted in the urine. An enzyme, xanthurenicase, was found in rabbit liver.11. The injected xanthurenic acid is excreted in conjugated forms as non-toxic substances.
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