Activities of tryptophan-metabolizing enzymes in liver and brain of rats treated with aflatoxins
| Autor: | G.C. Llewellyn, L.B. Weekley |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
Male
medicine.medical_specialty Aflatoxin In Vitro Techniques Tryptophan Hydroxylase Toxicology Cofactor Aflatoxins In vivo Internal medicine medicine Animals 5-HT receptor Hydrocortisone chemistry.chemical_classification biology Chemistry Tryptophan Brain Rats Inbred Strains General Medicine In vitro Tryptophan Oxygenase Rats Kinetics Enzyme Endocrinology Liver biology.protein Food Science medicine.drug |
| Zdroj: | Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association. 22(1) |
| ISSN: | 0278-6915 |
| Popis: | Male Sprague-Dawley rats were treated ip twice daily for 10 days with mixed aflatoxins (10 μg/kg body weight) and then the activities of liver tryptophan 2,3-dioxygenase and brainstem tryptophan 5-hydroxylase were determined in vitro . Total tryptophan 2,3-dioxygenase activity was reduced by aflatoxin treatment while holoenzyme activity was not. Induction of tryptophan 2,3-dioxygenase activity by l -tryptophan was not altered by the treatment though induction by hydrocortisone was blocked. It is suggested that aflatoxin may alter the tryptophan 2,3-dioxygenase-haem bond in vivo rather than affect enzyme or cofactor synthesis. Kinetics studies performed in vitro on brain tryptophan 5-hydroxylase showed that aflatoxin treatment in vivo increased the K m of the hydroxylase when l -trytophan and synthetic 6,7-dimethyl-5,6,7,8-tetrahydrobiopterin were used as the substrate and cofactor, respectively. However, aflatoxin treatment did not alter the V max of tryptophan-5-hydroxylase. |
| Databáze: | OpenAIRE |
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