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Effects of oestrogen administration on vitamin B6 and tryptophan metabolism in the rat

Bender, DA; Tagoe, CE; Vale, JA; (1982) Effects of oestrogen administration on vitamin B6 and tryptophan metabolism in the rat. British Journal of Nutrition , 47 (3) 609 -614. 10.1079/BJN19820072. Green open access

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Abstract

1. In order to assess the effects of oestrogens on the metabolism of tryptophan and vitamin B6, ovariectomized rats have been maintained on diets providing known amounts of tryptophan, nicotinamide and vitamin B6. They received oestrone sulphate, 210 micrograms/kg body-wt per d, either incorporated in the diet for 8 weeks, or by daily intraperitoneal injection for periods of 1-3 d. 2. Oestrone sulphate administration caused a slight reduction in the concentration of pyridoxal phosphate in plasma. It had no effect on the concentration of pyridoxal phosphate in liver or kidney, the urinary excretion of 4-pyridoxic acid, the activation of erythrocyte aspartate aminotransferase (L-aspartate:2-oxo-glutarate aminotransferase, EC 2. 6. 1. 1) by incubation with added pyridoxal phosphate, or the activity of pyridoxal oxidase (aldehyde:oxygen oxido-reductase, EC 1.2.3.1) in the liver. 3. Oestrone sulphate administration caused an increase in the urinary excretion of kynurenine and a reduction in the activity of liver kynureninase (L-kynurenine hydrolase, EC 3.7.1.3). It had no effect on the urinary excretion of N1-methyl nicotinamide or the concentrations of nicotinamide nucleotides in blood, liver or kidney. 4. There was a considerable excess of the apoenzyme of kynureninase in the liver. Incubation of liver homogenates with added pyridoxal phosphate led to a 4- to 5-fold increase in activity. 5. We conclude that there is no evidence of any significant effect of oestrogens on vitamin B6. It is suggested that abnormalities of tryptophan metabolism in women receiving oestrogens, which have been widely attributed to drug-induced vitamin B6 depletion, can be accounted for by inhibition of kynureninase by oestrogen metabolites.

Type: Article
Title: Effects of oestrogen administration on vitamin B6 and tryptophan metabolism in the rat
Open access status: An open access version is available from UCL Discovery
DOI: 10.1079/BJN19820072
Publisher version: http://dx.doi.org/10.1079/BJN19820072
Language: English
Additional information: © 1982 Cambridge University Press
Keywords: Animals, Estrogens, Conjugated (USP), pharmacology, Estrone, analogs & derivatives, Female, Hydrolases, metabolism, Pyridoxal Phosphate, Pyridoxine, Rats, Inbred Strains, Tissue Distribution, Tryptophan
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: http://discovery.ucl.ac.uk/id/eprint/137527
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