Functional capacity of the tryptophan-niacin pathway in the premenarchial phase and in the menopausal age.
Studies on the interrelationship between female hormones associated with reproduction and the  vitamin B6-dependent enzymes along the kynurenin pathway of trytophan metabolism were carried out in girls with an age less, and more than 10 years (just before the onset of the first menstrual cycle), and in postmenapausal women with and without relative (excess) production of estradioll from the adrenal cortex. It is found that most of the determined metabolites are retained by the girls with age less than 10 years after tryptophan loading without and with vitamin B6 supplementation. Estradiol from either the ovaries (in girls just before menarch), or the adrenal cortex-in postmenopausal women with relative (excess) production of this hormone-interferes with the further degradation of 3-hydroxyanthranilic acid. However, this interference could be completely restored by vitamin B6 supplementation. The extra presence of a partial impairment in the kynureninase enzyme is also suggested in these postmenopausal women. In the latter case, this enzymatic activity could be partially resored by vitamin B6 supplementation. On the contrary, the enzymes: kynureninases and adrenocortical estradio. Pyridoxine supplementation partially corrected the inhibition especially that of 3-hydroxykynurenine transaminase enzyme.
D000328:Adult; D002648:Child; D004958:Estradiol / Q000502:physiology; D005260:Female; D006801:Humans; D007737:Kynurenine / Q000378:metabolism; D008297:Male; D008572:Menarche; D008593:Menopause; D008875:Middle Aged; D009539:Nicotinic Acids / Q000378:metabolism*; D011736:Pyridoxine / Q000494:pharmacology; D014364:Tryptophan / Q000378:metabolism*
D009539:Nicotinic Acids; D007737:Kynurenine; D004958:Estradiol; D014364:Tryptophan; D011736:Pyridoxine