Frederik Knud Nielsen

Mixture effects of 3 model endocrine disruptors, prochloraz, ketoconazole, and genistein, on steroidogenesis were tested in the adrenocortical H295R cell line. Seven key steroid hormones (pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, estrone, and 17β-estradiol) were analyzed using gas chromatography and tandem mass spectrometry (GC-MS/MS) to investigate the effects throughout the steroidogenic pathway. Current modeling approaches often rely on models… Vis mere

Mixture effects of 3 model endocrine disruptors, prochloraz, ketoconazole, and genistein, on steroidogenesis were tested in the adrenocortical H295R cell line. Seven key steroid hormones (pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, estrone, and 17β-estradiol) were analyzed using gas chromatography and tandem mass spectrometry (GC-MS/MS) to investigate the effects throughout the steroidogenic pathway. Current modeling approaches often rely on models assuming compounds acting independently and that the individual effects in some way can be summarized to predict a mixture effect. In H295R cells with an intact steroidogenic pathway, such assumptions may not be feasible. The purpose of this study was therefore to evaluate whether effects of a mixture with differing modes of action followed or deviated from additivity (concentration addition) and whether the H295R cell line was suitable for evaluating mixture toxicity of endocrine disruptors with different modes of action. The compounds were chosen because they interfere with steroidogenesis in different ways. They all individually decrease the concentrations of the main sex steroids downstream but exert different effects upstream in the steroidogenic pathway. Throughout the study, we observed lowest observed effect concentrations of mixtures at levels 2 to 10 times higher than the predicted EC50, strongly indicating antagonistic effects. The results demonstrate that chemical analysis combined with the H295R cell assay is a useful tool also for studying how mixtures of endocrine disruptors with differing modes of action interfere with the steroidogenic pathway and that existing models like concentration addition are insufficient in such cases. Furthermore, for end points where compounds exert opposite effects, no relevant models are available. Vis mindre

The adrenocortical human cell line H295R is a valuable tool for screening endocrine disrupting compounds. In general, previous research focus has been on the production of the 2 sex steroids, 17β-estradiol and testosterone, and less attention has been paid to other important steroid end points in the steroidogenesis with a wide range of physiological functions, such as the glucocorticoids (corticosterone and cortisol). A newly developed and validated solid phase extraction (SPE) liquid… Vis mere

The adrenocortical human cell line H295R is a valuable tool for screening endocrine disrupting compounds. In general, previous research focus has been on the production of the 2 sex steroids, 17β-estradiol and testosterone, and less attention has been paid to other important steroid end points in the steroidogenesis with a wide range of physiological functions, such as the glucocorticoids (corticosterone and cortisol). A newly developed and validated solid phase extraction (SPE) liquid chromatography–mass spectroscopy (LC-MS/MS) method was used to measure the production of cortisol and corticosterone in the H295R cell line. The method was applied by studying the effects of 2 model endocrine disrupters, ketoconazole and prochloraz, the pharmaceutical budesonide, and the inducer forskolin on the steroid production in this cell line. Dose–response curves were obtained for the correlation between hormone concentrations and the concentration of the individual disruptors. Exposing cells to ketoconazole resulted in a decrease in cortisol and corticosterone concentrations in a dose-dependent manner with EC50 values of 0.24 and 0.40 μmol/L, respectively. The same applied for cells exposed to prochloraz with EC50 values of 0.06 and 0.09 μmol/L for cortisol and corticosterone, respectively. Budesonide also inhibited glucocorticoid secretion. The EC50 value for cortisol was 19.50 μmol/L, whereas the EC50 value for corticosterone was 71.42 μmol/L. Forskolin induced the secretion of both cortisol (EC50 = 4.09 μmol/L) and corticosterone (EC50 = 0.28 μmol/L). The results obtained demonstrated the validity of the method. Based on these findings, quality criteria for the production of these steroids in this cell line were suggested. Vis mindre

The effects of three model endocrine disruptors, prochloraz, ketoconazole and genistein on steroidogenesis were tested in the adrenocortical H295R cell line to demonstrate that a broader mechanistic understanding can be achieved in one assay by applying chemical analysis to the H295R assay. Seven key steroid hormones (pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, estrone and 17β-estradiol) were analyzed using a novel and thoroughly validated GC-MS/MS… Vis mere

The effects of three model endocrine disruptors, prochloraz, ketoconazole and genistein on steroidogenesis were tested in the adrenocortical H295R cell line to demonstrate that a broader mechanistic understanding can be achieved in one assay by applying chemical analysis to the H295R assay. Seven key steroid hormones (pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, estrone and 17β-estradiol) were analyzed using a novel and thoroughly validated GC-MS/MS method. In addition to the simultaneous quantification of 7 steroid hormones, the present method also negates the potential problems of cross-reactivity that can be encountered in some immunoassays. Although all 3 test compounds decrease the concentrations of the main sex steroids, the chemicals exerted different effects upstream in the pathway. Exposure to prochloraz resulted in increased hormone levels upstream of steroid 17 alpha-hydroxylase/17,20 lyase (P450c17) and decreases downstream. Ketoconazole inhibited the entire pathway, while exposure to genistein resulted in increased hormone levels upstream of 3-β-hydroxysteroid dehydrogenase (3β-HSD) and decreases downstream. The results demonstrate that chemical analysis combined with the H295R cell assay is a useful tool for studying the mechanisms by which endocrine disruptors interfere with the steroidogenic pathway. Vis mindre

This paper presents the development, optimization and validation of a methodology to determine nine key steroid hormones (viz. pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, estrone, 17α-estradiol and 17β-estradiol) expressed in the steroidogenesis in biological fluids. The analytical method allows for the determination of steroid hormones in blood plasma and serum down to 0.08–0.16 ng/mL for estrogens, 0.20–0.36 ng/mL for androgens and… Vis mere

This paper presents the development, optimization and validation of a methodology to determine nine key steroid hormones (viz. pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, estrone, 17α-estradiol and 17β-estradiol) expressed in the steroidogenesis in biological fluids. The analytical method allows for the determination of steroid hormones in blood plasma and serum down to 0.08–0.16 ng/mL for estrogens, 0.20–0.36 ng/mL for androgens and 0.36–0.43 ng/mL for progestagens. These limits of
detection were obtainable using a two-step solid-phase clean-up for fractionation and elimination of interfering lipids (fatty acids, phospholipids, glycerides and sterols) from the steroid hormones. The accuracy of the method was 50–112% in the range 0.10 to 2.00 ng/mL Vis mindre