title: 17beta-estradiol inhibition of ascorbic acid accumulation in human intestinal Caco-2 cells.
abstract: We investigated the effect of estrogen on the accumulation of ascorbic acid by human intestinal Caco-2 cells. 17beta-estradiol, synthetic estrogen diethylstilbestrol, and partial agonist tamoxifen were found to inhibit ascorbic acid accumulation in a dose-dependent fashion. The inhibitory effect of estrogens can be observed at as short as 5 min of incubation. An additive effect was observed when they were used in combination. Similar to dietary flavonoids, inhibition was also observed in two other intestinal cell lines, HT-29 and IEC-6. These chemicals affected both Na+ -dependent and Na+ -independent(K+ substituting Na+) accumulation of ascorbic acid and did not affect the efflux of accumulated ascorbic acid. Kinetic analysis of diethylstilbestrol showed a non-competitive inhibition with an apparent Ki of 23 microM. The hormone-ascorbic acid interaction in the intestinal cell could help to explain the known reduction in blood ascorbic acid level among oral contraceptive users and female guinea pigs given contraceptive hormones.
authors.affiliation: Department of Physical Therapy, Exercise and Nutrition Sciences, State University of New York at Buffalo, 14214, USA. smkuo@acsu.buffalo.edu
authors.forename: S M
authors.initials: SM
authors.lastname: Kuo
authors.forename: C P
authors.initials: CP
authors.lastname: Lin
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism*; D001692:Biological Transport; D018938:Caco-2 Cells; D004054:Diethylstilbestrol / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000138:chemical synthesis / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D007700:Kinetics; D012964:Sodium / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology; D013997:Time Factors
chemical_list: D004965:Estrogen Antagonists; D004967:Estrogens; D004968:Estrogens, Non-Steroidal; D013629:Tamoxifen; D004958:Estradiol; D004054:Diethylstilbestrol; D012964:Sodium; D001205:Ascorbic Acid