H295R cells as a model for steroidogenic disruption: A broader perspective using simultaneous chemical analysis of 7 key steroid hormones

Trace elements alone or in mixtures associated with unconventional natural gas exploitation affect rat fetal steroidogenesis and testicular development in vitro

Biomonitoring studies have shown that pregnant women living in regions of unconventional natural gas (UNG) exploitation have higher levels of trace elements. Whether developmental endocrine disruption can be expected at these exposure levels during pregnancy is unclear. In this study, we aimed to test the impact of five trace elements alone or in mixtures using in vitro cell- and tissue-based assays relevant to endocrine disruption and development. Manganese, aluminum, strontium, barium, and cobalt were tested at concentrations including those representatives of human fetal exposure. Using transactivation assays, none of the tested elements nor their mixture altered the human estrogen receptor 1 or androgen receptor genomic signalling. In the rat fetal testis assay, an organ culture system, cobalt (5 μg/l), barium (500 μg/l) and strontium (500 μg/l) significantly increased testosterone secretion. Cobalt and strontium were associated with hyperplasia and/or hypertrophy of fetal Leydig cells. Mixing the five elements at concentrations where none had an effect individually stimulated testosterone secretion by the rat fetal testis paralleled by the significant increase of 3β-hydroxysteroid dehydrogenase protein level in comparison to the vehicle control. The mechanisms involved may be specific to the fetal testis as no effect was observed in the steroidogenic H295R cells. Our data suggest that some trace elements in mixture at concentrations representative of human fetal exposure can impact testis development and function. This study highlights the potential risk posed by UNG operations, especially for the most vulnerable populations, pregnant individuals, and their fetus.

Aging induces region-specific dysregulation of hormone synthesis in the primate adrenal gland

Adrenal glands, vital for steroid secretion and the regulation of metabolism, stress responses and immune activation, experience age-related decline, impacting systemic health. However, the regulatory mechanisms underlying adrenal aging remain largely uninvestigated. Here we established a single-nucleus transcriptomic atlas of both young and aged primate suprarenal glands, identifying lipid metabolism and steroidogenic pathways as core processes impacted by aging. We found dysregulation in centripetal adrenocortical differentiation in aged adrenal tissues and cells in the zona reticularis region, responsible for producing dehydroepiandrosterone sulfate (DHEA-S), were highly susceptible to aging, reflected by senescence, exhaustion and disturbed hormone production. Remarkably, LDLR was downregulated in all cell types of the outer cortex, and its targeted inactivation in human adrenal cells compromised cholesterol uptake and secretion of dehydroepiandrosterone sulfate, as observed in aged primate adrenal glands. Our study provides crucial insights into endocrine physiology, holding therapeutic promise for addressing aging-related adrenal insufficiency and delaying systemic aging.

Towards a microfluidic H295R steroidogenesis assay-biocompatibility study and steroid detection on a thiol-ene-based chip

The development of cell-based microfluidic assays offers exciting new opportunities in toxicity testing, allowing for integration of new functionalities, automation, and high throughput in comparison to traditional well-plate assays. As endocrine disruption caused by environmental chemicals and pharmaceuticals represents a growing global health burden, the purpose of the current study was to contribute towards the miniaturization of the H295R steroidogenesis assay, from the well-plate to the microfluidic format. Microfluidic chip fabrication with the established well-plate material polystyrene (PS) is expensive and complicated; PDMS and thiol-ene were therefore tested as potential chip materials for microfluidic H295R cell culture, and evaluated in terms of cell attachment, cell viability, and steroid synthesis in the absence and presence of collagen surface modification. Additionally, spike-recovery experiments were performed, to investigate potential steroid adsorption to chip materials. Cell aggregation with poor steroid recoveries was observed for PDMS, while cells formed monolayer cultures on the thiol-ene chip material, with cell viability and steroid synthesis comparable to cells grown on a PS surface. As thiol-ene overall displayed more favorable properties for H295R cell culture, a microfluidic chip design and corresponding cell seeding procedure were successfully developed, achieving repeatable and uniform cell distribution in microfluidic channels. Finally, H295R perfusion culture on thiol-ene chips was investigated at different flow rates (20, 10, and 2.5 µL/min), and 13 steroids were detected in eluting cell medium over 48 h at the lowest flow rate. The presented work and results pave the way for a time-resolved microfluidic H295R steroidogenesis assay.

Human adrenocortical carcinoma cell line (NCI-H295R): An in vitro screening model for the assessment of endocrine disruptors' actions on steroidogenesis with an emphasis on cell ultrastructural features

Cell lines as an in vitro model for xenobiotic screening and toxicity studies provide a very important tool in the field of scientific research at the level of molecular pathways and gene expression. Good cell culture practice and intracellular characterization, as well as physiological properties of the cell line are of critical importance for in vitro reproductive toxicity testing of various endocrine-disrupting chemicals. The NCI-H295R, human adrenocarcinoma cell line, is the most widely used in vitro cellular system to study the human adrenal steroidogenic pathway at the level of hormone production and gene expression, as it expresses genes that encode for all the key enzymes for steroidogenesis. In this review, we aim to highlight the information considering the origin, development, physiological and ultrastructural characteristics of the NCI-H295R cell line. The review also creates a broad overview of the cell line usage in various range of studies related to the steroidogenesis issues. To our best knowledge, the paper provides the first report of quantitative data (ex novo) from stereological estimates of component (volume, surface) densities of nuclei, mitochondria, and lipid droplets of the NCI-H295R cells. Such ultrastructural measurements can be valuable in the assessment of underlying mechanisms of changes in the cell steroid hormone production induced by the action of diverse endocrine disruptors. Thus, they can significantly contribute to complexity of structure-function relationships in association with steroidogenesis.

Development of a Liquid Chromatography-Mass Spectrometry-Based In Vitro Assay to Assess Changes in Steroid Hormones Due to Exposure to Per- and Polyfluoroalkyl Substances

Per- and poly-fluorinated substances (PFASs) are organic pollutants that have been linked to numerous health effects, including diabetes, cancers, and dysregulation of the endocrine system. This study aims to develop a liquid chromatography with tandem mass spectrometry (LC-MS/MS) assay to measure changes in 17 hormones in H295R cell line (a steroid producing adrenocortical cells) upon exposure to PFASs. Due to the challenges in the analysis of steroid hormones using electrospray ionization MS, a chemical derivatization method was employed to achieve 0.07-2 μg/L detection limits in LC-MS/MS. Furthermore, a 10-fold concentration factor through solid-phase extraction (SPE) allows for consistent sub-parts per billion detections. Optimization of the derivatization conditions showed doubly-derivatized products in some hormone analytes, including progesterone, corticosterone, and cortisol, and gave improved ionization efficiency up to 20-fold higher signal than the singly-derivatized product. The use of SPE for sample cleanup to analyze hormones from cellular media using weak anion exchange sorbent yielded 80-100% recovery for the 17 targeted hormones. The method was validated by exposing H295R cells to two known endocrine disruptors, forskolin and prochloraz, which showed expected changes in hormones. An initial exposure of H295R cells with various PFAS standards and their mixtures at 1 μM showed significant increases in progestogens with some PFAS treatments, which include PFBS, PFHxA, PFOS, PFDA, and PFDS. In addition, modest changes in hormone levels were observed in cells treated with other sulfonated or carboxylated headgroup PFASs. This sensitive LC-MS/MS method for hormone analysis in H295R cells will allow for the investigations of the alterations in the hormone production caused by exposure to various environmental insults in cell-based assays and other in vitro models.

Discovery of Soticlestat, a Potent and Selective Inhibitor for Cholesterol 24-Hydroxylase (CH24H)

Cholesterol 24-hydroxylase (CH24H, CYP46A1), a brain-specific cytochrome P450 (CYP) family enzyme, plays a role in the homeostasis of brain cholesterol by converting cholesterol to 24S-hydroxycholesterol (24HC). Despite a wide range of potential of CH24H as a drug target, no potent and selective inhibitors have been identified. Here, we report on the structure-based drug design (SBDD) of novel 4-arylpyridine derivatives based on the X-ray co-crystal structure of hit derivative 1b. Optimization of 4-arylpyridine derivatives led us to identify 3v ((4-benzyl-4-hydroxypiperidin-1-yl)(2,4'-bipyridin-3-yl)methanone, IC50 = 7.4 nM) as a highly potent, selective, and brain-penetrant CH24H inhibitor. Following oral administration to mice, 3v resulted in a dose-dependent reduction of 24HC levels in the brain (1, 3, and 10 mg/kg). Compound 3v (soticlestat, also known as TAK-935) is currently under clinical investigation for the treatment of Dravet syndrome and Lennox-Gastaut syndrome as a novel drug class for epilepsies.

Effect of dietary supplementation with nettle or fenugreek on folliculogenesis and steroidogenesis in the rabbit ovary - An in vivo study

The objective of the study was to investigate the effect of dietary supplementation with nettle or fenugreek on folliculogenesis and steroidogenesis in the juvenile rabbit ovary. To gain insight into the mechanism of action of these herbs, we examined follicle formation, ovarian cell proliferation and apoptosis, steroidogenic enzyme abundance and steroid concentrations in ovarian tissue and plasma. Animals were fed with control, 1% nettle- or 1% fenugreek-supplemented pellets from 5 to 12 weeks of age (n = 10 per each group), when animals were slaughtered for ovary and blood collection. The addition of nettle decreased the numbers of primordial (P = 0.015) and early antral (P = 0.02) follicles and increased the number of primary (P = 0.04) ones when compared with the control group. Following fenugreek supplementation, the numbers of primary (P = 0.008) and antral (P = 0.027) follicles were greater, while the number of early antral (P = 0.003) follicles was lower in comparison with the control group. Nettle revealed apoptotic activity through activation of caspases 9 (P = 0.047), 8 (P = 0.022) and 3 (P = 0.004), whereas fenugreek increased (P = 0.042) follicular cell proliferation marked by PCNA protein abundance. Furthermore, only fenugreek targeted steroidogenic enzymes, decreasing CYP17A1 (P = 0.043) and increasing CYP19A1 (P = 0.048) protein abundances that resulted in enhanced estradiol biosynthesis and its elevated (P = 0.006) plasma concentration. In conclusion, both herbs affected follicle development in the rabbit ovary in a stage specific manner. Additionally, fenugreek altered ovarian steroidogenesis in a way that might affect sexual maturation in rabbits.

An in vitro assay approach to investigate the potential impact of different doping agents on the steroid profile

The steroid profile, that is, the urinary concentrations and concentration ratios of selected steroids, is used in sports drug testing to detect the misuse of endogenous steroids such as testosterone. Since several years, not only population-based thresholds are applied but also the steroid profile is monitored via the Athlete Biological Passport whereby the individual reference ranges derived from multiple test results of the same athlete are compared to population-based thresholds. In order to maintain a high probative force of the passport, samples collected or analyzed under suboptimal conditions should not be included in the longitudinal review. This applies to biologically affected or degraded samples and to samples excluded owing to the presence of other substances potentially (or evidently) altering the steroid profile. Nineteen different doping agents comprising anabolic steroids, selective androgen receptor modulators, selective estrogen receptor modulators, ibutamoren, and tibolone were investigated for their effect on the steroid profile using an androgen receptor activation test, an androgen receptor binding assay, an aromatase assay, and a steroidogenesis assay. The in vitro tests were coupled with well-established liquid chromatography/mass spectrometry-based analytical approaches and for a subset of steroidal analytes by gas chromatography/mass spectrometry. The variety of tests employed should produce a comprehensive data set to better understand how a compound under investigation may impact the steroid profile. Although our data set may allow an estimate of whether or not a substance will have an impact on the overall steroid metabolism, predicting which parameter in particular may be influenced remains difficult.

Range of SHH signaling in adrenal gland is limited by membrane contact to cells with primary cilia

The signaling protein Sonic Hedgehog (SHH) is crucial for the development and function of many vertebrate tissues. It remains largely unclear, however, what defines the range and specificity of pathway activation. The adrenal gland represents a useful model to address this question, where the SHH pathway is activated in a very specific subset of cells lying near the SHH-producing cells, even though there is an abundance of lipoproteins that would allow SHH to travel and signal long-range. We determine that, whereas adrenal cells can secrete SHH on lipoproteins, this form of SHH is inactive due to the presence of cosecreted inhibitors, potentially explaining the absence of long-range signaling. Instead, we find that SHH-producing cells signal at short range via membrane-bound SHH, only to receiving cells with primary cilia. Finally, our data from NCI-H295R adrenocortical carcinoma cells suggest that adrenocortical tumors may evade these regulatory control mechanisms by acquiring the ability to activate SHH target genes in response to TGF-β.

Oral anti-diabetic drugs as endocrine disruptors in vitro - No evidence for additive effects in binary mixtures

Diabetes is one of the World's most concerning health problems and millions of patients are using anti-diabetic drugs (ADDs) in order to control blood glucose. The in vitro H295R steroidogenesis assay was implemented to investigate endocrine effects of three ADDs, metformin (MET), glimepiride (GLIM), sitagliptin (SIT) and the cholesterol-lowering drug simvastatin (SIM) individually and in three binary mixtures. Steroid hormones were analyzed using LC-MS/MS. Mixture effects were assessed by applying the Concentration Addition (CA) model. All tested drugs and binary mixtures interrupted the H295R steroidogenesis with different potency. The effects of MET:GLIM on the steroidogenesis were overall similar to the steroidogenic profile of GLIM, however effects were less pronounced. The binary mixture of MET:SIT showed overall minor effects on steroid production and only at very high concentrations. The SIM:SIT mixture showed inhibition downstream from cholesterol, which was attributed to the effects of SIM. The CA model partly predicted the effect of MET:SIT on some steroids but significantly overestimated the effects of MET:GLIM and SIM:SIT. Thus, the applicability of the CA model was limited and cocktail effects appeared to be intermediate responses of individual drugs, rather than additive. The complexity of dynamic pathways such as steroidogenesis appears to significantly reduce the use of the CA model. In conclusion, more dynamic models are needed to predict mixture effects in complex systems.

Refinement of an OECD test guideline for evaluating the effects of endocrine disrupting chemicals on aromatase gene expression and reproduction using novel transgenic cyp19a1a-eGFP zebrafish

Transgenic fish are powerful models that can provide mechanistic information regarding the endocrine activity of test chemicals. In this study, our objective was to use a newly developed transgenic zebrafish line expressing eGFP under the control of the cyp19a1a promoter in the OECD Fish Short Term Reproduction Assay (TG 229) to provide additional mechanistic information on tested substances. For this purpose, we exposed adult transgenic zebrafish to a reference substance of the TG 229, i.e. prochloraz (PCZ; 1.7, 17.2 and 172.6 μg/L). In addition to "classical" endpoints used in the TG 229 (reproductive outputs, vitellogenin), the fluorescence intensity of the ovaries was monitored at 4 different times of exposure using in vivo imaging. Our data revealed that 172.6 μg/L PCZ significantly decreased the number of eggs laid per female per day and the concentrations of vitellogenin in females, reflecting the decreasing E2 synthesis due to the inhibition of the ovarian aromatase activities. At 7 and 14 days, GFP intensities in ovaries were similar over the treatment groups but significantly increased after 21 days at 17.2 and 172.6 μg/L. A similar profile was observed for the endogenous cyp19a1a expression measured by qPCR thereby confirming the reliability of the GFP measurement for assessing aromatase gene expression. The overexpression of the cyp19a1a gene likely reflects a compensatory response to the inhibitory action of PCZ on aromatase enzymatic activities. Overall, this study illustrates the feasibility of using the cyp19a1a-eGFP transgenic line for assessing the effect of PCZ in an OECD test guideline while providing complementary information on the time- and concentration-dependent effects of the compound, without disturbing reproduction of fish. The acquisition of this additional mechanistic information on a key target gene through in vivo fluorescence imaging of the ovaries was realized without increasing the number of individuals.

Development of a prioritization method for chemical-mediated effects on steroidogenesis using an integrated statistical analysis of high-throughput H295R data

Synthesis of 11 steroid hormones in human adrenocortical carcinoma cells (H295R) was measured in a high-throughput steroidogenesis assay (HT-H295R) for 656 chemicals in concentration-response as part of the US Environmental Protection Agency's ToxCast program. This work extends previous analysis of the HT-H295R dataset and model by examining the utility of a novel prioritization metric based on the Mahalanobis distance that reduced these 11-dimensional data to 1-dimension via calculation of a mean Mahalanobis distance (mMd) at each chemical concentration screened for all hormone measures available. Herein, we evaluated the robustness of mMd values, and demonstrate that covariance and variance of the hormones measured appear independent of the chemicals screened and are inherent to the assay; the Type I error rate of the mMd method is less than 1%; and, absolute fold changes (up or down) of 1.5 to 2-fold have sufficient power for statistical significance. As a case study, we examined hormone responses for aromatase inhibitors in the HT-H295R assay and found high concordance with other ToxCast assays for known aromatase inhibitors. Finally, we used mMd and other ToxCast cytotoxicity data to demonstrate prioritization of the most selective and active chemicals as candidates for further in vitro or in silico screening.

The anti-epileptic drug lamotrigine inhibits the CYP17A1 lyase reaction in vitro

The potential endocrine disrupting effects of the commonly prescribed anti-epileptic drug lamotrigine (LAM) were investigated using the H295R steroidogenic in vitro assay and computational chemistry methods. The H295R cells were exposed to different concentrations of LAM, and a multi-steroid LC-MS/MS method was applied to quantify the amount of secreted steroid hormones. LAM affected several steroid hormones in the steroidogenesis at therapeutic concentrations. All progestagens as well as 11-deoxycorticosterone and corticosterone increased 100-200% with increasing concentrations of LAM suggesting a selective inhibitory effect of LAM on CYP17A1, in particular on the lyase reaction. Recombinant CYP17A1 assay confirmed the competitive inhibition of LAM toward the enzyme with IC50 values of 619 and 764 μM for the lyase and the hydroxylase reaction, respectively. Levels of androstenedione and testosterone decreased at LAM concentrations above the therapeutic concentration range. The ability of LAM to bind to CYP17A1, CYP19A1, and CYP21A2 was investigated using docking and molecular dynamics simulations. This in silico study showed that LAM was able to bind directly to the heme iron in the active site of CYP17A1, but not CYP21A2, thus supporting the results of the in vitro studies. The molecular dynamics simulations also suggested binding of LAM to the heme iron in the CYP19A1 active site. No inhibition of the aromatase enzyme was, however, observed in the H295R assay. This could be due to a sequential effect within the steroidogenesis caused by the inhibition of CYP17A1, which reduced the amounts of androgens available for CYP19A1.

180 Day Repeated-Dose Toxicity Study on Forchlorfenuron in Sprague-Dawley Rats and Its Effects on the Production of Steroid Hormones

Forchlorfenuron (FCF) is a synthetic plant cytokine-like growth regulator that is massively used in agriculture to increase fruit size and weight. There is an insufficiency of published data on the safety profile of FCF, especially as it is involved in ovarian function. In our study, a chronic toxicity study on FCF was conducted and designed by feeding at dosage levels of 0, 0.6, and 60 mg/kg body weight in Sprague-Dawley rats for 180 days. During the 180 day FCF administration, no biologically relevant changes were observed in the body weight, clinical signs, food consumption, organ weight, hematology, and clinical biochemistry of the tested animals. However, macroscopic and microscopic evaluations revealed the presence of severe hydrometra in the uterus and pathological changes in the ovaries. In addition, it was found that FCF inhibited the proliferation of granulosa cells (GCs) and H295R cells, as well as downregulated the expression of CYP17A1 and CYP19A1 in estradiol and progesterone production, resulting in decreased steroidogenesis in GCs and H295R cells. Taken together, our findings suggest that FCF has potential adverse effects on the ovaries and on steroidogenesis.

Effects of defined mixtures of POPs and endocrine disruptors on the steroid metabolome of the human H295R adrenocortical cell line

The presence of environmental pollutants in our ecosystem may impose harmful health effects to wildlife and humans. Several of these toxic chemicals have a potential to interfere with the endocrine system. The adrenal cortex has been identified as the main target organ affected by endocrine disrupting chemicals. The aim of this work was to assess exposure effects of defined and environmentally relevant mixtures of chlorinated, brominated and perfluorinated chemicals on steroidogenesis, using the H295R adrenocortical cell line model in combination with a newly developed liquid chromatography tandem mass spectrometry (LC-MS/MS) method. By using this approach, we could simultaneously analyze 19 of the steroids in the steroid biosynthesis pathway, revealing a deeper insight into possible disruption of steroidogenesis. Our results showed a noticeable down-regulation in steroid production when cells were exposed to the highest concentration of a mixture of brominated and fluorinated compounds (10,000-times human blood values). In contrast, up-regulation was observed with estrone under the same experimental condition, as well as with some other steroids when cells were exposed to a perfluorinated mixture (1000-times human blood values), and the mixture of chlorinated and fluorinated compounds. Interestingly, the low concentration of the perfluorinated mixture alone produced a significant, albeit small, down-regulation of pregnenolone, and the total mixture a similar effect on 17-hydroxypregnenolone. Other mixtures resulted in only slight deviations from the control. Indication of synergistic effects were noted when we used a statistical model to improve data interpretation. A potential for adverse outcomes of human exposures is indicated, pointing to the need for further investigation into these mixtures.

High-Throughput H295R Steroidogenesis Assay: Utility as an Alternative and a Statistical Approach to Characterize Effects on Steroidogenesis

The U.S. Environmental Protection Agency Endocrine Disruptor Screening Program and the Organization for Economic Co-operation and Development (OECD) have used the human adrenocarcinoma (H295R) cell-based assay to predict chemical perturbation of androgen and estrogen production. Recently, a high-throughput H295R (HT-H295R) assay was developed as part of the ToxCast program that includes measurement of 11 hormones, including progestagens, corticosteroids, androgens, and estrogens. To date, 2012 chemicals have been screened at 1 concentration; of these, 656 chemicals have been screened in concentration-response. The objectives of this work were to: (1) develop an integrated analysis of chemical-mediated effects on steroidogenesis in the HT-H295R assay and (2) evaluate whether the HT-H295R assay predicts estrogen and androgen production specifically via comparison with the OECD-validated H295R assay. To support application of HT-H295R assay data to weight-of-evidence and prioritization tasks, a single numeric value based on Mahalanobis distances was computed for 654 chemicals to indicate the magnitude of effects on the synthesis of 11 hormones. The maximum mean Mahalanobis distance (maxmMd) values were high for strong modulators (prochloraz, mifepristone) and lower for moderate modulators (atrazine, molinate). Twenty-five of 28 reference chemicals used for OECD validation were screened in the HT-H295R assay, and produced qualitatively similar results, with accuracies of 0.90/0.75 and 0.81/0.91 for increased/decreased testosterone and estradiol production, respectively. The HT-H295R assay provides robust information regarding estrogen and androgen production, as well as additional hormones. The maxmMd from this integrated analysis may provide a data-driven approach to prioritizing lists of chemicals for putative effects on steroidogenesis.

Effects of antihistamines on the H295R steroidogenesis - Autocrine up-regulation following 3β-HSD inhibition

Millions of people of all ages suffer from allergies worldwide and as a consequence antihistamines are among the most commonly prescribed pharmaceuticals in the world. We investigated the disruptive effects of three antihistamines, promethazine (PMZ), cetirizine (CET) and fexofenadine (FEX) on the H295R steroidogenesis. A multi-steroid LC-MS/MS method was used to quantify 13 steroid hormones in the steroidogenesis. In addition, real-time RT-PCR was used to determine if exposure to antihistamines altered gene expression in the cell line. When exposing the H295R cells to PMZ and CET, significant increases in Δ⁵-steroids and significant decreases in Δ⁴-steroids were observed, indicating an inhibition of 3β-hydroxysteroid dehydrogenase (3β-HSD). A sequential decrease in corticosteroids, androgens and estrogens were also observed. Overall, FEX had no effect on the steroidogenesis even though minor effects were observed at the highest concentrations. Real-time RT-PCR showed that PMZ resulted in significant up-regulation of 3β-HSD and 17β-HSD, whereas CET only resulted in up-regulation of 3β-HSD. This indicated that the decrease in steroids downstream from 3β-HSD following PMZ and CT exposure induced a compensatory autocrine response in 3β-HSD gene expression. The effects on the steroidogenesis were observed at concentrations 30-50 times higher than the therapeutic plasma concentrations. However, antihistamines are lipophilic and may accumulate in adrenals and gonads. Thus, disruptive effects of PMZ and CET on human steroidogenesis cannot be excluded.

Modulation of estrogen synthesis and metabolism by phytoestrogens in vitro and the implications for women's health

Phytoestrogens are increasingly used as dietary supplements due to their suggested health promoting properties, but also by women for breast enhancement and relief of menopausal symptoms. Generally, phytoestrogens are considered to exert estrogenic activity via estrogen receptors (ERs), but they may also affect estrogen synthesis and metabolism locally in breast, endometrial and ovarian tissues. Considering that accurate regulation of local hormone levels is crucial for normal physiology, it is not surprising that interference with hormonal synthesis and metabolism is associated with a wide variety of women's health problems, varying from altered menstrual cycle to hormone-dependent cancers. Yet, studies on phytoestrogens have mainly focused on ER-mediated effects of soy-derived phytoestrogens, with less attention paid to steroid synthesis and metabolism or other phytoestrogens. This review aims to evaluate the potential of phytoestrogens to modulate local estrogen levels and the implications for women's health. For that, an overview is provided of the effects of commonly used phytoestrogens, i.e. 8-prenylnaringenin, biochanin A, daidzein, genistein, naringenin, resveratrol and quercetin, on estrogen synthesizing and metabolizing enzymes in vitro. The potential implications for women's health are assessed by comparing the in vitro effect concentrations with blood concentrations that can be found after intake of these phytoestrogens. Based on this evaluation, it can be concluded that high-dose supplements with phytoestrogens might affect breast and endometrial health or fertility in women via the modulation of steroid hormone levels. However, more data regarding the tissue levels of phytoestrogens and effect data from dedicated, tissue-specific assays are needed for a better understanding of potential risks. At least until more certainty regarding the safety has been established, especially young women would better avoid using supplements containing high doses of phytoestrogens.

Incorporation of 14C-cholesterol in human adrenal corticocarcinoma H295R cell line and online-radiodetection of produced 14C-steroid hormone metabolites

This study demonstrates the addition of ¹⁴C-cholesterol to the human cell line H295R will in-situ form radiolabeled steroid hormones allowing for new mechanistic and metabolic insights. The aim of the present study was to in-situ radiolabel steroid hormones from cell line-incorporated ¹⁴C-cholesterol using the OECD guideline 456, H295R steroidogenesis in-vitro assay. Radiodetection of the steroid metabolites of the steroidogenic pathway allows for an improved understanding of the various enzymatic mechanisms involved without necessarily being dependent on quantification. Generated radiolabeled steroids were analyzed using HPLC hyphenated with a Flow Scintillation Analyzer (FSA). H295R cells were incubated with radiolabeled cholesterol and cell media were collected and prepared by solid phase extraction and analyzed with HPLC-FSA. For successful radiolabeling of the steroids in the steroidogenesis of H295R cells, radioactive cholesterol may potentially only need to be added just before the cells are incubated for 72h in well plates. Based on the obtained HPLC-FSA chromatograms, and confirmation of the observations by studies in the literature, a qualitative time profile for the production of steroid hormones was estimated. Multiple radiolabeled steroid hormones were identified by means of analytical standards and UV (ultraviolet) co-chromatography, though the elucidation of multiple metabolites remains unresolved. Although online radiodetection proved to suffer from suboptimal sensitivity, the concept of radiolabeling the steroidogenesis in H295R cells with ¹⁴C-cholesterol and detecting the radiolabeled steroid hormones online was proved and may assist in further toxicological studies.

Simultaneous profiling of 17 steroid hormones for the evaluation of endocrine-disrupting chemicals in H295R cells

Aim: There is urgent need to develop a new protocol for the evaluation of chemical substances to potentially interact with the endocrine system and induce numerous pathological issues. The recently validated in vitro screening assay is limited on monitoring two steroid hormones. Methodology & results: The H295R model cell was exposed to seven endocrine disrupting chemicals (EDCs). The levels of 17 steroid hormones in cell extracts were subsequently determined by a quantitative targeted GC/MS/MS method. Through wide coverage, this system managed to capture the effects of exposure to increasing EDCs concentrations in the entire steroidogenic pathways. Conclusion: The developed approach could be beneficial for the mechanistic investigation of EDCs.

Structure-based optimisation of non-steroidal cytochrome P450 17A1 inhibitors

Five new non-steroidal inhibitors for cytochrome P450 17A1 were identified by structure-based optimisation.

Assessment of the endocrine-disrupting effects of short-chain chlorinated paraffins in in vitro models

Short-chain chlorinated paraffins (SCCPs), which are candidate persistent organic pollutants (POPs) according to the Stockholm Convention, are of great concern because of their persistent bioaccumulation, long-range transport and potential adverse health effects. However, data on the endocrine-disrupting effects of SCCPs remain scarce. In this study, we first adopted two in vitro models (reporter gene assays and H295R cell line) to investigate the endocrine-disrupting effects of three SCCPs (C10-40.40%, C10-66.10% and C11-43.20%) via receptor mediated and non-receptor mediated pathway. The dual-luciferase reporter gene assay revealed that all test chemicals significantly induced estrogenic effects, which were mediated by estrogen receptor α (ERα), in the following order: C11-43.20%>C10-66.10%>C10-40.40%. Notably, C10-40.40% and C10-66.10% also demonstrated remarkable anti-estrogenic activities. Only C11-43.20% showed glucocorticoid receptor-mediated (GR) antagonistic activity, with a RIC20 value of 2.6×10(-8)mol/L. None of the SCCPs showed any agonistic or antagonistic activities against thyroid receptor β (TRβ). Meanwhile, all test SCCPs stimulated the secretion of 17β-estradiol (E2). Both C10-66.10% and C11-43.20% increased the production of cortisol at a high level in H295R cell lines. In order to explore the possible mechanism underlying the endocrine-disrupting effects of SCCPs through the non-receptor pathway, the mRNA levels of 9 steroidogenic genes were measured by real-time polymerase chain reaction (RT-PCR). StAR, 17βHSD, CYP11A1, CYP11B1, CYP19 and CYP21 were upregulated in a concentration-dependent manner by all chemicals. The data provided here emphasized that comprehensive assessments of the health and ecological risks of emerging contaminants, such as SCCPs, are of great concern and should be investigated further.

Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors

Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC50 values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells.

Two simple cleanup methods combined with LC-MS/MS for quantification of steroid hormones in in vivo and in vitro assays

Measuring both progestagens, androgens, corticosteroids as well as estrogens with a single method makes it possible to investigate the effects of endocrine-disrupting chemicals (EDCs) on the main pathways in the mammalian steroidogenesis. This paper presents two simple methods for the determination of the major steroid hormones in biological matrixes using liquid chromatography tandem mass spectrometry (LC-MS(2)). A novel method was developed for the determination of 14 steroids in the H295R in vitro assay without the need for solid phase extraction (SPE) purification prior to LC-MS(2) analysis. The in vitro assay was validated by exposing H295R cells to prochloraz for inhibiting steroid hormone secretion and by exposing cells to forskolin for inducing steroid hormone secretion. The developed method fulfills the recommendations for the H295R assay suggested by the OECD. Furthermore, a simple off-line SPE methodology was developed for the necessary clean-up of in vivo assays. Samples, such as gonad tissue, plasma and serum, are complex biological matrixes, and the SPE methodology was optimized to remove salts and proteins prior to elution of target analytes. At the same time, lipophilic compounds were retained on the SPE cartridge during elution. This, combined with the multi-steroid LC-MS(2) method, made it possible to determine 10 steroids in male Sprague-Dawley rat gonad tissue. Furthermore, it was possible to quantify 6 steroids in the plasma. In general, the observed concentration of steroid hormones in plasma, testes, and H295R cell medium corresponded well with previous studies. The off-line SPE method was validated using spiked charcoal-stripped serum. Method recovery, accuracy, precision and robustness were all good. Instrument sensitivity was in the range of 55-530 pg/mL (LLOQ).

Disruption of steroidogenesis: Cell models for mechanistic investigations and as screening tools

In the modern world, humans are exposed during their whole life to a large number of synthetic chemicals. Some of these chemicals have the potential to disrupt endocrine functions and contribute to the development and/or progression of major diseases. Every year approximately 1000 novel chemicals, used in industrial production, agriculture, consumer products or as pharmaceuticals, are reaching the market, often with limited safety assessment regarding potential endocrine activities. Steroids are essential endocrine hormones, and the importance of the steroidogenesis pathway as a target for endocrine disrupting chemicals (EDCs) has been recognized by leading scientists and authorities. Cell lines have a prominent role in the initial stages of toxicity assessment, i.e. for mechanistic investigations and for the medium to high throughput analysis of chemicals for potential steroidogenesis disrupting activities. Nevertheless, the users have to be aware of the limitations of the existing cell models in order to apply them properly, and there is a great demand for improved cell-based testing systems and protocols. This review intends to provide an overview of the available cell lines for studying effects of chemicals on gonadal and adrenal steroidogenesis, their use and limitations, as well as the need for future improvements of cell-based testing systems and protocols.

Enantioselective endocrine disrupting effects of omeprazole studied in the H295R cell assay and by molecular modeling

Enantiomers possess different pharmacokinetic and pharmacodynamic properties and this may not only influence the therapeutic effect of a drug but also its toxicological effects. In the present work we investigated the potential enantioselective endocrine disrupting effects of omeprazole (OME) and its two enantiomers on the human steroidogenesis using the H295R cell line. Differences in production of 16 steroid hormones were analyzed using LC-MS/MS. Additionally, to evaluate the differences in binding modes of these enantiomers, docking and molecular dynamics (MD) simulations of S-omeprazole (S-OME) and R-omeprazole (R-OME) in CYP17A1, CYP19A1 and CYP21A2 were carried out. Exposing H295R cells to OME and its enantiomers resulted in an increase of progesterone (PRO) and 17α-hydroxy-progesterone (OH-PRO) levels. At the same time, a decrease in the corticosteroid and androgen synthesis was observed, indicating inhibition of CYP21A2 and CYP17A1. In both cases, the effect of R-OME was smaller compared to that of the S-OME and a certain degree of enantioselectivity of CYP17A1 and CYP21A2 was suggested. Docking indicated that the N-containing rings of OME possibly could interact with the iron atom of the heme for S-OME in CYP17A1 and S- and R-OME in CYP21A2. However, density functional theory calculations suggest that the direct N-Fe interaction is weak. The study demonstrates enantioselective differences in the endocrine disrupting potential of chiral drugs such as omeprazole. These findings may have potential implications for drug safety and drug design.

Steroids in house sparrows (Passer domesticus): Effects of POPs and male quality signalling

At high trophic levels, environmental contaminants have been found to affect endocrinological processes. Less attention has been paid to species at lower trophic levels. The house sparrow (Passer domesticus) may be a useful model for investigating effects of POPs in mid-range trophic level species. In male house sparrows, ornamental traits involved in male quality signalling are important for female selection. These traits are governed by endocrinological systems, and POPs may therefore interfere with male quality signalling. The aim of the present study was to use the house sparrow as a mid-range trophic level model species to study the effects of environmental contaminants on endocrinology and male quality signalling. We analysed the levels of selected PCBs, PBDEs and OCPs and investigated the possible effects of these contaminants on circulating levels of steroid hormones (4 progestagens, 4 androgens and 3 estrogens) in male and female adult house sparrows from a population on the island Leka, Norway. Plasma samples were analysed for steroid hormones by GC-MS and liver samples were analysed for environmental contaminants by GC-ECD and GC-MS. In males, we also quantified ornament traits. It was hypothesised that POPs may have endocrine disrupting effects on the local house sparrow population and can thus interfere with the steroid hormone homeostasis. Among female house sparrows, bivariate correlations revealed negative relationships between POPs and estrogens. Among male sparrows, positive relationships between dihydrotestosterone levels and PCBs were observed. In males, positive relationships were also found between steroids and beak length, and between steroids and ornamental traits such as total badge size. This was confirmed by a significant OPLS model between beak length and steroids. Although sparrows are in the mid-range trophic levels, the present study indicates that POPs may affect steroid homeostasis in house sparrows, in particular for females. For males, circulating steroid levels appears to be more associated with biometric parameters related to ornamental traits.

Estimation of the Mechanism of Adrenal Action of Endocrine-Disrupting Compounds Using a Computational Model of Adrenal Steroidogenesis in NCI-H295R Cells

Adrenal toxicity is one of the major concerns in drug development. To quantitatively understand the effect of endocrine-active compounds on adrenal steroidogenesis and to assess the human adrenal toxicity of novel pharmaceutical drugs, we developed a mathematical model of steroidogenesis in human adrenocortical carcinoma NCI-H295R cells. The model includes cellular proliferation, intracellular cholesterol translocation, diffusional transport of steroids, and metabolic pathways of adrenal steroidogenesis, which serially involve steroidogenic proteins and enzymes such as StAR, CYP11A1, CYP17A1, HSD3B2, CYP21A2, CYP11B1, CYP11B2, HSD17B3, and CYP19A1. It was reconstructed in an experimental dynamics of cholesterol and 14 steroids from an in vitro steroidogenesis assay using NCI-H295R cells. Results of dynamic sensitivity analysis suggested that HSD3B2 plays the most important role in the metabolic balance of adrenal steroidogenesis. Based on differential metabolic profiling of 12 steroid hormones and 11 adrenal toxic compounds, we could estimate which steroidogenic enzymes were affected in this mathematical model. In terms of adrenal steroidogenic inhibitors, the predicted action sites were approximately matched to reported target enzymes. Thus, our computer-aided system based on systems biological approach may be useful to understand the mechanism of action of endocrine-active compounds and to assess the human adrenal toxicity of novel pharmaceutical drugs.

High-Throughput Screening of Chemical Effects on Steroidogenesis Using H295R Human Adrenocortical Carcinoma Cells

Disruption of steroidogenesis by environmental chemicals can result in altered hormone levels causing adverse reproductive and developmental effects. A high-throughput assay using H295R human adrenocortical carcinoma cells was used to evaluate the effect of 2060 chemical samples on steroidogenesis via high-performance liquid chromatography followed by tandem mass spectrometry quantification of 10 steroid hormones, including progestagens, glucocorticoids, androgens, and estrogens. The study employed a 3 stage screening strategy. The first stage established the maximum tolerated concentration (MTC; ≥ 70% viability) per sample. The second stage quantified changes in hormone levels at the MTC whereas the third stage performed concentration-response (CR) on a subset of samples. At all stages, cells were prestimulated with 10 µM forskolin for 48 h to induce steroidogenesis followed by chemical treatment for 48 h. Of the 2060 chemical samples evaluated, 524 samples were selected for 6-point CR screening, based in part on significantly altering at least 4 hormones at the MTC. CR screening identified 232 chemical samples with concentration-dependent effects on 17β-estradiol and/or testosterone, with 411 chemical samples showing an effect on at least one hormone across the steroidogenesis pathway. Clustering of the concentration-dependent chemical-mediated steroid hormone effects grouped chemical samples into 5 distinct profiles generally representing putative mechanisms of action, including CYP17A1 and HSD3B inhibition. A distinct pattern was observed between imidazole and triazole fungicides suggesting potentially distinct mechanisms of action. From a chemical testing and prioritization perspective, this assay platform provides a robust model for high-throughput screening of chemicals for effects on steroidogenesis.

Modulation of glucocorticoid, mineralocorticoid and androgen production in H295 cells by Trimesemine™, a mesembrine-rich Sceletium extract

ETHNOPHARMACOLOGICAL RELEVANCE

Stress-related illnesses rate among the most prevalent non-fatal diseases globally. With the global trend for consumer bias towards natural medicine, the Sceletium plant has become more prominent in the field of natural products. Although potentially useful effects of Sceletium tortuosum on the central nervous system have been reported, limited data is available on effects of the plant in the peripheral compartment.

AIM OF THE STUDY

The current study aimed to elucidate the effect(s) of a Sceletium extract (TRI) rich in mesembrine (1% of plant extract w/w), on adrenal steroid biosynthesis.

MATERIALS AND METHODS

Steroidogenesis was assessed basally and in response to stimuli (forskolin, angiotensin II, KCl), in human adrenocortical carcinoma cells (H295R). Steroid hormone levels were assessed using UPLC-MS/MS. UPLC-MS analyses of TRI identified major alkaloids Δ7-mesembrenone, mesembrenone and mesembrine.

RESULTS

Highest dose TRI treatment (1 mg/ml, 34.5 μM mesembrine) increased pregnenolone and decreased 16-hydroxyprogesterone levels (both P<0.00001) in forskolin-stimulated conditions only, suggesting CYP17 enzyme inhibition. This led to significant inhibition of forskolin-associated increases in cortisol levels at the highest dose (P<0.001) and basal cortisol levels across all doses (P<0.0001). Independently of forskolin, TRI inhibited androstenedione and testosterone production across all doses (both P<0.00001), suggesting inhibition of 3βHSD and 17βHSD respectively. TRI decreased both the angiotensin II- (P<0.05) and forskolin-induced (P<0.0001) increases in aldosterone production.

CONCLUSIONS

Our data suggest potentially beneficial effects of TRI in the context of stress and hypertension. These should be further investigated in a whole organism model, while the effects on the androgenic pathway should also be further elucidated.

Simvastatin decreases steroid production in the H295R cell line and decreases steroids and FSH in female rats

Endocrine modulating effects of Simvastatin (SV) and its metabolite, Simvastatin β-hydroxy acid (SVA), were investigated in H295R cells and in female Sprague-Dawley (SPRD) rats. H295R cells were exposed to SV and SVA concentrations from 0 to 10μM for 48h. Four groups of SPRD rats received 0 (CT), 1.3 (L), 5.0 (M), and 20.0 (H)mg SV/kg bw/day for 14 days. 10 Steroids were investigated in H295R growth media, and in tissues and plasma from rats using GC-MS/MS. Plasma LH and FSH were quantified by ELISA. In the H295R assay, SV and SVA particularly decreased progestagens with IC50-values from 0.10-0.13μM for SV and from 0.019-0.055μM for SVA. In rats, SV decreased progestagens in ovaries, brain and plasma, and plasma FSH in the M (72.4% decrease) and H group (76.6% decrease). Because progestagens and gonadotropins are major players in fertility, administration of SV might exert negative effects on female reproduction.

Advances in the analytical methodologies: Profiling steroids in familiar pathways-challenging dogmas

The comprehensive evaluation of the adrenal steroidogenic pathway, given its complexity, requires methodology beyond the standard techniques currently employed. Advances in LC-MS/MS, coupled with in vitro cell models that produce all the steroid metabolites of the mineralo-, glucocorticoid and androgen arms, present a powerful approach for the comprehensive evaluation of adrenal steroidogenesis in response to compounds of interest including bioactives, drug treatments and endocrine disrupting compounds. UHPLC-MS/MS analysis of steroid panels in forskolin, angiotensin II and K(+) stimulated H295R cells provides a snapshot of their effect on intermediates and end products of adrenal steroidogenesis. The impact of full steroid panel evaluations by LC- and GC-MS/MS extends to clinical profiling with the characterization of normal pediatric steroid reference ranges in sexual development and of disease-specific profiles improving diagnosis and sub classification. Comprehensive analyses of steroid profiles may potentially improve patient outcomes together with the application of treatments specifically suited to clinical subgroups. LC-MS/MS and GC-MS/MS applications in the analyses of comprehensive steroid panels are demonstrated in clinical conditions such as congenital adrenal hyperplasia in newborns requiring accurate diagnoses and in predicting metabolic risk in polycystic ovary syndrome patients. Most notable perhaps is the impact of LC-MS/MS evaluations on our understanding of the basic biochemistry of steroidogenesis with the detection of the long forgotten adrenal steroid, 11β-hydroxyandrostenedione, at significant levels. The characterization of its metabolism to androgen receptor ligands in the LNCaP prostate cancel cell model, specifically within the context of recurring prostate cancer, lends new perspectives to old dogmas. We demonstrate that UHPLC-MS/MS has enabled the analyses of novel metabolites of the enzymes, SRD5A, 11βHSD and 17βHSD, in LNCaP cells. Undoubtedly, the continuous advances in the analytical methodologies used for steroid profiling and quantification will give impetus to the unraveling of the remaining enigmas, old and new, of both hormone biosynthesis and metabolism.

Mixture Effects of 3 Mechanistically Different Steroidogenic Disruptors (Prochloraz, Genistein, and Ketoconazole) in the H295R Cell Assay

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.

Effects of selective serotonin reuptake inhibitors on three sex steroids in two versions of the aromatase enzyme inhibition assay and in the H295R cell assay

Selective serotonin reuptake inhibitors are known to have a range of disorders that are often linked to the endocrine system e.g. hormonal imbalances, breast enlargement, sexual dysfunction, and menstrual cycle disorders. The mechanisms behind most of these disorders are not known in details. In this study we investigated whether the endocrine effect due to SSRI exposure could be detected in well adopted in vitro steroidogenesis assays, two versions of the aromatase enzyme inhibition assay and the H295R cell assay. The five drugs citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline, were shown to inhibit the aromatase enzyme in both types of aromatase assays. The IC50 values ranged from 3 to 600 μM. All five SSRIs, were further investigated in the H295R cell line. All compounds altered the steroid secretion from the cells, the lowest observed effect levels were 0.9 μM and 3.1 μM for sertraline and fluvoxamine, respectively. In general the H295R cell assay was more sensitive to SSRI exposure than the two aromatase assays, up to 20 times more sensitive. This indicates that the H295R cell line is a better tool for screening endocrine disrupting effects. Our findings show that the endocrine effects of SSRIs may, at least in part, be due to interference with the steroidogenesis.

Evaluation of steroidomics by liquid chromatography hyphenated to mass spectrometry as a powerful analytical strategy for measuring human steroid perturbations

This review presents the evolution of steroid analytical techniques, including gas chromatography coupled to mass spectrometry (GC-MS), immunoassay (IA) and targeted liquid chromatography coupled to mass spectrometry (LC-MS), and it evaluates the potential of extended steroid profiles by a metabolomics-based approach, namely steroidomics. Steroids regulate essential biological functions including growth and reproduction, and perturbations of the steroid homeostasis can generate serious physiological issues; therefore, specific and sensitive methods have been developed to measure steroid concentrations. GC-MS measuring several steroids simultaneously was considered the first historical standard method for analysis. Steroids were then quantified by immunoassay, allowing a higher throughput; however, major drawbacks included the measurement of a single compound instead of a panel and cross-reactivity reactions. Targeted LC-MS methods with selected reaction monitoring (SRM) were then introduced for quantifying a small steroid subset without the problems of cross-reactivity. The next step was the integration of metabolomic approaches in the context of steroid analyses. As metabolomics tends to identify and quantify all the metabolites (i.e., the metabolome) in a specific system, appropriate strategies were proposed for discovering new biomarkers. Steroidomics, defined as the untargeted analysis of the steroid content in a sample, was implemented in several fields, including doping analysis, clinical studies, in vivo or in vitro toxicology assays, and more. This review discusses the current analytical methods for assessing steroid changes and compares them to steroidomics. Steroids, their pathways, their implications in diseases and the biological matrices in which they are analysed will first be described. Then, the different analytical strategies will be presented with a focus on their ability to obtain relevant information on the steroid pattern. The future technical requirements for improving steroid analysis will also be presented.

Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus)

As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA), androstenedione (AN), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (βE2), pregnenolone (PRE) and progesterone (PRO) were determined. The aim of the study was to investigate associations among circulating levels of specific POP compounds and POP-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid concentrations and other analyzed POPs or the variables capture date and capture location (latitude and longitude), lipid content, condition and body mass. Although statistical associations do not necessarily represent direct cause-effect relationships, the present study indicate that OH-PCBs may affect the circulating levels of AN and PRE in female polar bears and that OH-PCBs thus may interfere with the steroid homeostasis. Increase in PRO and a decrease in AN concentrations suggest that the enzyme CYP17 may be a potential target for OH-PCBs. In combination with natural stressors, ongoing climate change and contaminant exposure, it is possible that OH-PCBs may disturb the reproductive potential of polar bears.

Accumulation and potential health effects of organohalogenated compounds in the arctic fox (Vulpes lagopus)--a review

This review addresses biological effects of anthropogenic organohalogenated compounds in the arctic fox (Vulpes lagopus). When considering the current levels, spatial and tissue distributions of selected organic pollutants in arctic fox subpopulations, especially the Svalbard based populations accumulate high levels. The dominating contaminant groups are the polychlorinated biphenyls (PCBs) and chlordanes (CHLs), which reach high levels in adipose tissues, adrenals and liver. Recent controlled exposure studies on domesticated arctic fox and Greenland sledge dogs, show adverse health effects associated with OC concentrations lower than those measured in free-ranging populations. This indicates that especially populations at Svalbard may be at risk of experiencing OC related effects. The arctic fox as such may be an overlooked species in the Arctic Monitoring and Assessment Programs and it would add further information about pollution in the Arctic to include this species in the monitoring program.