Disturbances of Tryptophan Metabolism in Mice Acutely Deprived of Tryptophan
作者:
Michael.L. Jones,
Daniel Kimbrough,
L.B. Weekley,
期刊:
Annals of Nutrition and Metabolism
(Karger Available online 1985)
卷期:
Volume 29,
issue 4
页码: 209-215
ISSN:0250-6807
年代: 1985
DOI:10.1159/000176972
出版商: S. Karger AG
关键词: Dietary tryptophan;Brain indoleamines;Tryptophan metabolism;systemic
数据来源: Karger
摘要:
The effect of a dietary tryptophan deficiency on tissue serotonin (5-hydroxytryptamine) synthesis rates, systemic tryptophan metabolism and its response to steroid or cycloheximide treatment was investigated. Brain serotonin synthesis was depressed in tryptophan-deprived (TD) mice while duodenal serotonin synthesis was enhanced following a tryptophan load. Liver total protein content was initially depressed in TD mice but increased following a tryptophan load. Blood tryptophan and albumin were depressed in TD mice while the percentage of albumin-bound tryptophan significantly increased in TD mice. Serum-free fatty acids were not significantly altered. Furthermore, enzyme kinetics studies indicated that in TD mice, tryptophan-5-hydroxylase has a reduced Vmax, while the Km for both tryptophan and the pteridine cofactor was significantly lowered. The tryptophan hydroxylase response to tryptophan or hydrocortisone injection was accentuated in TD mice while the tryptophan-2,3-dioxygenase response to tryptophan or hydrocortisone injection was blunted in TD mice. Finally, injection of tryptophan and cycloheximide blocked the tryptophan-2,3-dioxygenase response while the tryptophan hydroxylase response was unaltered in both control and TD diet mice.
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