BACKGROUND: Lipophilic estradiol derivatives carried by lipoprotein particles in blood may mediate antioxidant or endocrine effects. We developed a new quantitative method to determine the concentration of circulating lipophilic estradiol fatty acid esters in human early- and late-pregnancy serum and in ovarian follicular fluid. METHODS: After extraction from serum or follicular fluid, estradiol fatty acid esters were separated from nonesterified estradiol by Sephadex LH-20 column chromatography. The estradiol ester fraction was hydrolyzed by saponification and further purified by several chromatographic steps. The hydrolyzed estradiol esters were measured by time-resolved fluoroimmunoassay. RESULTS: The average estradiol fatty acid ester concentration in serum increased 10-fold during pregnancy, from 40.4 pmol/L (expressed as pmol/L estradiol; range, 25.0-64.2 pmol/L) in early pregnancy (n = 8) to 404 pmol/L (196-731 pmol/L) in late pregnancy (n = 10). The ratio of estradiol ester to nonesterified estradiol remained relatively constant during pregnancy, at 0.4-0.6%. In 10 follicular fluid samples, the mean estradiol ester concentration was 106 nmol/L (56.9-262 nmol/L). Compared with serum, a greater proportion of estradiol in follicular fluid (3.0-10%) was in the esterified form. CONCLUSION: The new method provides a means to measure circulating estradiol fatty acid ester concentrations in human pregnancy serum.
BACKGROUND: Lipophilic estradiol derivatives carried by lipoprotein particles in blood may mediate antioxidant or endocrine effects. We developed a new quantitative method to determine the concentration of circulating lipophilic estradiol fatty acid esters in human early- and late-pregnancy serum and in ovarian follicular fluid. METHODS: After extraction from serum or follicular fluid, estradiol fatty acid esters were separated from nonesterified estradiol by Sephadex LH-20 column chromatography. The estradiol ester fraction was hydrolyzed by saponification and further purified by several chromatographic steps. The hydrolyzed estradiol esters were measured by time-resolved fluoroimmunoassay. RESULTS: The average estradiol fatty acid ester concentration in serum increased 10-fold during pregnancy, from 40.4 pmol/L (expressed as pmol/L estradiol; range, 25.0-64.2 pmol/L) in early pregnancy (n = 8) to 404 pmol/L (196-731 pmol/L) in late pregnancy (n = 10). The ratio of estradiol ester to nonesterified estradiol remained relatively constant during pregnancy, at 0.4-0.6%. In 10 follicular fluid samples, the mean estradiol ester concentration was 106 nmol/L (56.9-262 nmol/L). Compared with serum, a greater proportion of estradiol in follicular fluid (3.0-10%) was in the esterified form. CONCLUSION: The new method provides a means to measure circulating estradiol fatty acid ester concentrations in human pregnancy serum.
Authors: Thomas Høj Rasmussen; Flemming Nielsen; Helle Raun Andersen; Jesper Bo Nielsen; Pal Weihe; Philippe Grandjean Journal: Environ Health Date: 2003-10-15 Impact factor: 5.984