Effects of the synthetic progestin levonorgestrel on some aspects of thyroid physiology in common carp (Cyprinus carpio)

Progestin Pollution in Surface Waters of a Major Southwestern European Estuary: The Douro River Estuary (Iberian Peninsula)

The concentrations and spreading of eight synthetic and two natural progestins (PGs) were investigated in surface waters from ten sites at the Douro River Estuary. Samples were filtrated and subjected to solid-phase extraction (SPE) to isolate and concentrate the target PGs. The extracts were cleaned by silica cartridges and analyzed by LC-MS/MS. The finding of biologically relevant amounts of gonanes (22.3 ± 2.7 ng/L), progesterone derivatives (12.2 ± 0.5 ng/L), drospirenone (4.1 ± 0.8 ng/L), and natural PGs (9.4 ± 0.9 ng/L) support the possibility of these compounds acting as endocrine disruptors. Despite the absence of significant differences amongst sampling sites and seasons, the principal component analysis (PCA) and the linear discriminant analysis (LDA) approaches reveal that spring and summer have different patterns of PG distribution compared to autumn and winter. The assessment of risk coefficients (RQs) and the potential concentrations of synthetic progestins in fish blood sustains that all tested compounds pose a significant risk to local biota (RQs > 1). Additionally, three progestins-norethindrone, norethindrone acetate, and medroxyprogesterone acetate-should reach human-equivalent therapeutic levels in fish plasma. Overall, the current data show PGs' presence and potential impacts in one of the most important estuaries of the Iberian Peninsula.

Outdoor light at night exposure was associated with hypothyroidism in pregnant women: A national study in China

BACKGROUND

Evidence on the influence of outdoor artificial light at night (ALAN) on hypothyroidism in pregnant women is scarce. We aimed to investigate the association between outdoor ALAN exposure and hypothyroidism in pregnancy.

METHODS

81,820 pregnant women from the China Birth Cohort Study (CBCS) were analyzed, which recruited from 18 provinces and autonomous regions in China between February 2018 and December 2020. Hypothyroidism was defined based on clinical diagnosis by physicians. Outdoor ALAN exposure (nW/cm2/sr) within 1500 m was estimated using VIIRS/DNB satellite data based on the participants' residential address. The Outdoor ALAN was divided in quartiles, with the lowest quartile (Q1) serving as the reference group. Generalized linear mixed models were employed to estimate the association between ALAN exposure and hypothyroidism.

RESULTS

Among the 81,120 pregnant women, 3902 (4.77 %) were diagnosed hypothyroidism. Pregnant women with hypothyroidism had significantly higher median (IQR, interquartile range) outdoor ALAN levels during pregnancy compared to those without hypothyroidism (30.97 (18.15) vs. 29.14 (20.21) nW/cm2/sr, p < 0.01). After adjusting for covariates, we found that each quartile increment of outdoor ALAN exposure was associated with an adjusted Odds Ratio (aOR of 1.15 (95 % Confidence Interval [95 % CI]: 1.03-1.27), 1.15 (1.05-1.28), and 1.12 (1.00-1.25) for hypothyroidism, respectively from Q2 to Q4. Additionally, stratified analyses revealed that pre-pregnancy BMI was a significant modifier in the association between outdoor ALAN and hypothyroidism in pregnancy, with stronger effects observed among those who were overweight before pregnancy (1.21 [95 % CI, 1.05-1.39] vs. 1.03 [95 % CI, 0.97-1.10], p for interaction = 0.01).

CONCLUSIONS

Outdoor ALAN exposure is positively associated with hypothyroidism in pregnancy. To benefit maternal and infant health and well-being, recommendations for mitigating ALAN pollution and effective measures to avoid excessive light exposure should be developed.

Effects of mifepristone, a model compound with anti-progestogenic activity, on the reproduction of African clawed frog (Xenopus laevis)

This is the first study on how a substance with anti-progestogenic activity affects amphibian reproduction. Mifepristone, a synthetic anti-progestin used in abortion pills, was chosen as model compound. African clawed frog (Xenopus laevis) females were exposed to four mifepristone concentrations (0.7, 9, 120, and 1380 ng∙L-1) for 30 days. A control group was also included. Egg-laying during the experiment was significantly less at the highest concentration. At the experiment's end, mifepristone-exposed and control females were randomly mated with sexually mature males. Breeding rate for females exposed to 1380 ng∙L-1 mifepristone was only 50 %. Histology revealed no significant changes in gonads, thyroid, or liver. Females exposed to 1380 ng∙L-1 mifepristone had lower estradiol levels in plasma, lower mRNA expression of lh and fsh in brain-pituitary complex, and p450scc in ovaries. In liver, mRNA level of npr was significantly increased in females exposed to 120 ng∙L-1 mifepristone. mRNA expression of mpr, erβ, dio2, and dio3 were upregulated in animals exposed to 9 ng∙L-1 and 120 ng∙L-1 mifepristone, whereas vtg expression was significantly downregulated in females exposed to 1380 ng∙L-1 mifepristone. All these findings show that exposure to compounds with anti-progestogenic activity affects the hypothalamus-pituitary-gonad axis and decreases reproductive success.

The long-term effects of norgestrel on the reproductive and thyroid systems in adult zebrafish at environmentally relevant concentrations

Progestins are crucial steroid hormones that have attracted wide attention due to their endocrine disrupting effects in fish. The aim of this study is to investigate the effects of long-term exposure to low concentrations of norgestrel (NGT) on the reproductive and thyroid endocrine systems of adult zebrafish. Adult zebrafish were exposed to 7 and 39 ng/L NGT for a duration of 90 days. The results revealed that exposure to 39 ng/L NGT led to a significant up-regulation of 3β-hydroxysteroid dehydrogenase (hsd3b) and 20β-hydroxysteroid dehydrogenase (hsd20b) genes in the ovary of female zebrafish. Additionally, there was a significant up-regulation of 11β-hydroxysteroid dehydrogenase 2 (hsd11b2) gene in the testis of male zebrafish. Furthermore, egg production decreased significantly, accompanied by notable alterations in the proportion of ovarian development stages, as well as reductions of sex hormone levels (E2, 11-KT, and T) in both females and males. However, long-term exposure to low concentrations of NGT did not lead to changes in thyroid hormone levels and thyroid histopathology in adult zebrafish. The overall results imply that environmental concentrations of NGT have a strong endocrine disrupting effect on the reproductive system of zebrafish, while the thyroid system is not sensitive to NGT exposure. The present study underscores the reproductive endocrine impacts of NGT and emphasizes the necessity for prolonged exposure at environmental concentrations.

Identification of hot spots and co-occurrence patterns of activities on thyroid hormone receptor and transthyretin binding in passive samplers from Czech surface waters

One of the less studied in vitro biological activities in the aquatic environment are thyroid hormone receptor beta (TRβ)-mediated agonistic and antagonistic activities and transthyretin (TTR) binding activity. They were measured mostly using active sampling methods, but rarely found. It is unclear if these activities co-occur, and the drivers of the (anti-)TRβ activity are mostly unknown. Therefore, the main aim of the study was to determine (anti-)TRβ activities as well as transthyretin (TTR) binding activity in passive samplers from Czech surface waters in combination with the search for the effect drivers based on liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis by applying suspect screening. Passive samplers (polar organic chemical integrative samplers, POCIS) were deployed at twenty-one sites (all ends of watersheds and other important sites in Elbe River) in the Czech rivers. The (anti-)TRβ and TTR binding activity were measured using (anti-)TRβ-CALUX and TTR-TRβ-CALUX bioassays. Anti-TRβ activity was found at eight sites, and TTR binding activity co-occurred there at six of these sites. The co-occurrence of TRβ-mediated antagonistic activity and TTR binding indicate that they may have common effect drivers. No sample exhibited TRβ agonistic activity. The extract from the site Bílina River, the most burdened with anti-TRβ activity, was further successfully fractionated, and this activity was revealed in the fraction, where mid-polar compounds prevailed. However, the suspect LC-HRMS analysis did not reveal the chemical effect drivers. Our results showed that anti-TRβ activity can be found in surface waters by employing passive sampling and frequently co-occurs with TTR binding activity. Overall, the fractionation procedure and non-target data acquisition used in this study can serve as a basis for searching the effect drivers in future research.

Application of a robust analytical method for quantifying progestins in environmental samples from three Portuguese Estuaries

In the last years, progestins have raised special concerns for their documented negative effects on aquatic species, yet little is known about their environmental levels in surface waters and bioaccumulation in the trophic web. This study aimed to 1) adapt an extraction method for quantifying progestins in freeze-dried matrices, 2) validate the analytical procedure for three matrices: bivalve, polychaete, and crustacean, and 3) characterize levels of the four most prescribed synthetic progestins in key species across three Portuguese estuaries. Through the validated method, progestins were only quantifiable for the crustacean. Values were generally low, peaking with drospirenone values in Ria de Aveiro (1.33 ± 0.26 ng/g ww) and Tagus estuary (1.42 ± 0.55 ng/g ww), while Ria Formosa exhibited the lowest progestin concentrations (< 1 ng/g ww). This study enabled the development of a precise extraction and analytical method for quantifying steroid hormones in three distinct biological matrices.

Effects of mifepristone, a model compound with anti-progestogenic activity, on the development of African clawed frog (Xenopus laevis)

The objective of this study was to assess the effects of a model substance with anti-progestogenic activity on development of African clawed frog (Xenopus laevis) from tadpole to juvenile stage. Mifepristone, a synthetic progesterone receptor-blocking steroid hormone used in medicine as an abortifacient, was chosen as a model compound with anti-progestogenic activity. In the experiment, African clawed frog tadpoles were exposed to mifepristone at three concentrations (2, 21, and 215 ng L-1). A control group was exposed to dimethyl sulfoxide (DMSO; 0.001 %). The experiment started when tadpoles reached stages 47-48 according to Nieuwkoop and Faber (NF; 1994) and continued until stage NF 66, when metamorphosis was complete. Exposure to mifepristone had no significant effect on the rate of tadpole development, occurrence of morphological anomalies, weight, body length, or sex ratio. Mortality was within an acceptable range of 0-3.6 % throughout the test and did not differ among the groups. Histopathological examination of the gonads and thyroid gland revealed no significant changes. Therefore, we can conclude that mifepristone had no negative effect on development of the African clawed frog up to juvenile stage. Nevertheless, at the highest tested mifepristone concentration (215 ng L-1), gene expression analysis revealed up-regulation of mRNA expression of nuclear progesterone receptor (npr), membrane progesterone receptor (mpr), estrogen receptor beta (esrβ), and luteinizing hormone (lh) in the brain-pituitary complex of exposed frogs at stage NF 66. Higher mRNA expression of npr was also found in frogs exposed to 22 ng L-1 mifepristone compared to the solvent control. These findings confirmed the anti-progestogenic activity of mifepristone in frogs because the up-regulation of progesterone receptors occurs if progesterone availability in the body is reduced. All the observed changes in combination may have negative consequences for reproduction and reproductive behavior later in life.

Exploring the underlying molecular mechanism of tri(1,3-dichloropropyl) phosphate-induced neurodevelopmental toxicity via thyroid hormone disruption in zebrafish by multi-omics analysis

Tri(1,3-dichloropropyl) phosphate (TDCPP) is widespread in the environment as a typical thyroid hormone-disrupting chemical. Here, we aimed to explore the toxicological mechanisms of the thyroid hormone-disrupting effects induced by TDCPP in zebrafish embryos/larvae using multi-omics analysis. The results showed that TDCPP (400 and 600 µg/L) induced phenotypic alteration and thyroid hormone imbalance in zebrafish larvae. It resulted in behavioral abnormalities during zebrafish embryonic development, suggesting that this chemical might exhibit neurodevelopmental toxicity. Transcriptomic and proteomic analysis provided consistent evidence at the gene and protein levels that neurodevelopmental disorders were significantly enhanced by TDCPP exposure (p < 0.05). Additionally, multi-omics data indicated that membrane thyroid hormone receptor (mTR)-mediated non-genomic pathways, including cell communication (ECM-receptor interactions, focal adhesion, etc.) and signal transduction pathways (MAPK signaling pathway, calcium signaling pathway, neuroactive ligand-receptor interaction pathway, etc.), were significantly disturbed (p < 0.05) and might contribute to the neurodevelopmental toxicity induced by TDCPP. Therefore, behavioral abnormalities and neurodevelopmental disorders might be important phenotypic characteristics of TDCPP-induced thyroid hormone disruption, and mTR-mediated non-genomic networks might participate in the disruptive effects of this chemical. This study provides new insights into the toxicological mechanisms of TDCPP-induced thyroid hormone disruption and proposes a theoretical basis for risk management of this chemical.