Taurine and kynureninase

Abstract

i. In vitamin B6 deficient rats, xanthurenic acid shows a diabetogenic action. In diabetes induced by the Zn2+ chelating agent, 8-hydroxyquinoline oxine, proinsulin synthesis is inhibited. The cytosolic enzyme, kynureninase is inhibited, but not the mitochondrial enzyme, kynurenine aminotransferase. ii. Xanthurenic acid excretion increases in vitamin B6 deficiency, and xanthurenic acid also inhibits kynureninase. iii. In our experiments, taurine had a beneficial action in diabetes mellitus patients. iv. Zinc can improve the disturbance of taste in diabetes mellitus patients. Sometimes, zinc content in such patients is decreased. Zinc, in vitro, inhibits kynureninase activity. In vitamin B6 deficient rats, Zn2+ content in the brain stem is increased. In vivo, administration of Zn2+ inhibits DOPA decarboxylase activity in liver and brain stem. v. Hypertension and hypercholesterolemia develops in rats given excess methionine, but not in rats given excess taurine. vi. In STZ diabetic rats, vitamin B6 deficiency was not observed, but the formation of pyridoxal from pyridoxine decreased.