Tamoxifen, esterified estradiol, and physiologic concentrations of estradiol inhibit oxidation of low-density lipoprotein by endothelial cells.
OBJECTIVE
We investigated the antioxidant effect of tamoxifen, esterified estradiol, and physiologic concentrations of 17beta-estradiol on endothelial cell-mediated oxidation of low-density lipoprotein.


METHODS
Human umbilical vein endothelial cells were preincubated with nanomolar concentrations of estradiol, estradiol stearate, and tamoxifen. Low-density lipoprotein was isolated and incubated with cells in serum-free medium. Oxidation of low-density lipoprotein was quantified after 8, 16, and 24 hours of incubation as the formation of thiobarbituric acid-reactive substances.


RESULTS
Compared with control, preincubation of human umbilical vein endothelial cells with 1- or 10-nmol/L estradiol resulted in a 12% reduction in the formation of thiobarbituric acid-reactive substances at 24 hours. Preincubation of human umbilical vein endothelial cells with either 10-nmol/L estradiol 17-stearate or 10-nmol/L tamoxifen resulted in 26% and 20% decreases, respectively, in formation of thiobarbituric acid-reactive substances at 24 hours. The difference in the reduction in thiobarbituric acid-reactive substances between control and treatment wells became more pronounced over time.


CONCLUSIONS
Under these experimental conditions, tamoxifen, esterified estradiol, and physiologic concentrations of exogenous estradiol inhibit oxidation of low-density lipoprotein by human umbilical vein endothelial cells.
Kuohung
W
W
Department of Obstetrics and Gynecology and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Massachusetts, USA.
Shwaery
G T
GT
Keaney
J F
JF
D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004951:Esterification; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction / Q000187:drug effects; D013629:Tamoxifen / Q000494:pharmacology*
D004965:Estrogen Antagonists; D008077:Lipoproteins, LDL; D013629:Tamoxifen; D004958:Estradiol