Bisphenol S affects in vitro early developmental oocyte competence in ewes

International audienceIn the plastics industry, bisphenol S (BPS) replaces sisphenol A reported to be an oestrogen mimetic endocrine disruptor damaging oocyte meiosis and maturation (Machtinger 2014 Reprod. Biomed. Online 29, 404). Studies on fish and rodents reported that BPS affects reproduction similarly to BPA (Uzumcu 2007 Reprod. Toxicol. 23, 337; Giulivo 2016 Environ. Res. 151, 251; Ullah 2016 Chemosphere 152, 353). Bisphenol S is detected in human urine at nanomolar concentrations (Liao 2012 Environ. Sci. Technol 46, 6860) and in some laboratory supplies (tips and tubes; unpublished data). Therefore, in this study, we assessed effects of BPS at low doses during in vitro maturation (IVM) on oocyte developmental competence in ewes. Cumulus-oocyte complexes (COC) collected from ovine follicles >2 mm underwent 24-h IVM, in the absence or presence of BPS at 1, 10, and 100 nM and 1 and 10 µM (Sigma Chemical Co.). Nuclear oocyte maturation rate was evaluated by MII oocyte count after chromatin Hoechst staining [n = 3 replicates (R), 1159 oocytes]. At 6 h of IVM, BPS effects on mRNA expression of oestrogen (E2) and progesterone (P4) receptors in cumulus cells (CC) were assessed by real-time quantitative PCR. After 24 h of IVM, The effect of BPS on P4 level was assessed in spent medium by enzyme-linked immunosorbent assay (n = 6 R, 40 COC/condition). Transcript expression level and P4 concentration were analysed using nonparametric one-way ANOVA, with Tukey post hoc test (Rcmdr, R version 3.5.3). After 24 h of IVM, matured COC underwent IVF and in vitro culture (IVC) for 7 days. Cleavage and blastocyst rates were assessed on Days 2 and 7, respectively, after IVF (8 experiments, 300 COC/condition). Data were analysed using logistic regression and linear model (R version 3.5.3). Our results showed a decreased oocyte maturation rate with 10 µM BPS (76.6%, n = 171; P = 0.0008) compared with control (88%, n = 152), with no effect on cell viability. The concentration of P4 decreased with 1 µM BPS (0.02 ng mL−1 per COC) compared with control (0.034 ng mL−1 per COC; P < 0.001). At 6 h IVM, BPS had no significant effect on oestrogen receptors (ESR1, ESR2, GPER) transcripts in CC but 10 nM BPS decreased mRNA expression of P4 receptor (PR) (0.00647 ± 0.00145; P = 0,005) compared with control (0.01165 ± 0.00196). Within fertilized COC, 1 µM BPS decreased cleavage rate (47.6%, n = 152) compared with control (54.6%; P = 0.004). Among cleaved embryos, blastocyst rate decreased to 14.2% and 12.5% with 10 nM and 1 µM BPS respectively (n = 26, P = 0.046; and n = 19, P = 0.017), compared with control (21.8%, n = 44). Bisphenol S at a low dose during ovine IVM reduced COC P4 secretion, PR transcript in CC, and cleavage and blastocyst rates. Our data suggest that BPS at an environmental dose (10 nM) negatively affects early developmental oocyte competence. Studies are ongoing to investigate the effect of BPS on Day 6 embryo cell number and on the ERK1/2 signalling pathway in oocyte

Bisphenol S affects In Vitro Ovine Early Developmental Oocyte Competence

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In vitro Bisphenol S affects in vitro early developmental oocyte competence in ewe

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Le Bisphenol S altère la compétence ovocytaire in vitro chez la brebis

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Bisphenol S Impairs In Vitro Ovine Early Developmental Oocyte Competence

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Bisphenol S versus Bisphénol A et la fonction de reproduction femelle : effets sur les cellules de granulosa ovines primaires in vitro

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Effects of bisphenol S on ovine primary granulosa cells in vitro

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Bisphenol A and S impaired ovine granulosa cell steroidogenesis

International audienceBisphenols, plasticisers used in food containers, can transfer to food. Bisphenol A (BPA) has been described as an endocrine disruptor and consequently banned from the food industry in several countries. It was replaced by a structural analogue, Bisphenol S (BPS). BPA action on the steroidogenesis is one of the mechanisms underlying its adverse effects on the efficiency of female reproduction. This study aimed to determine whether BPS is a safe alternative to BPA regarding GC functions. Antral follicles (2–6 mm), of approximatively 1000 adult ewe ovaries, were aspired and GC purified. For 48 h, ovine GC were treated with BPA or BPS (from 1 nM to 200 μM) and the effects on cell viability, proliferation, steroid production, steroidogenic enzyme expression and signalling pathways were investigated. Dosages at and greater than 100 μM BPA and 10 μM BPS decreased progesterone secretion by 39% (P< 0.001) and 22% (P = 0.040), respectively. BPA and BPS 10 μM and previously mentioned concentrations increased oestradiol secretion two-fold (P< 0.001 and P = 0.082, respectively). Only 100 μM BPA induced a decrease (P< 0.001) in gene expression of the enzymes of steroidogenesis involved in the production of progesterone. BPA reduced MAPK3/1 phosphorylation and ESR1 and ESR2gene expression, effects that were not observed with BPS. BPA and BPS altered steroidogenesis of ovine GC. Thus, BPS does not appear to be a safe alternative for BPA. Further investigations are required to elucidate BPA and BPS mechanisms of actio

Bisphenol S chronic exposure interacted with ewe metabolic status to impair female reproduction

International audienceBisphenol A (BPA), a plasticizer used in the food industry, is reported to be an estrogenomimetic endocrine disruptor, involved in deleterious effects on oocyte meiosis and maturation as well as in steroigegenesis impairment. BPA being regulated, structural analogs emerged including bisphenol S (BPS). Studies on fish and rodent species reported that BPS affects reproduction similarly to BPA. Moreover, because metabolism affects the ovarian functionning, we hypothesized that the metabolic status could interact with the effects of environmental factors. Therefore, this study assessed BPS chronic effects at dose corresponding to the tolerable daily intake defined for the BPA, on oocyte quality, steroidogenesis and granulosa cell proteomic data. Groups of 20 ewes were subjected to either a restricted (R) or well-fed (WF) diet and to a bisphenoldaily exposure (0, 4 or 50 µg/kg/day) for more than 3 months, thus generating 6 groups : R0, R4, R50, WF0, WF4 and WF50. After hormonal oestrus synchronization and ovarian stimulation, oocytes were surgically recovered (OPU sessions) and underwent in vitro maturation (IVM), fecundation and development. Developmental rates were analyzed at day 2 and 7 after IVM. At the time of slaughter, after 5 month of daily exposure to bisphenol, After hormonal oestrus synchronization, the follicular fluid and granulosa cells of the preovulotary follicle were collected. The follicular fluid underwent a steroidomic analysis while the granulosa cells underwent a proteomic analysis. Body weight was higher in well-fed compared to restricted ewes at the time of oocyte punctures (diet effect, p&lt;0.0001, 64.3 ± 1.2 kg vs 54.1 ± 1.2 kg, respectively) whichwas also the case for body condition score (diet effect, p&lt;0.0001, 2.92 ± 0.02 vs 2.18 ± 0.02, respectively). Regarding embryo production data, the most interesting finding was a significant diet x BPS dose interaction that was reported for cleaved embryos, &gt;4-cell embryos, blastocyst and early blastocyst numbers. Moreover, steroidomic analysis of the preovulatory follicle showed a significant interaction between metabolic status and BPS exposure for seven steroids, including estradiol. Indeed, while exposure to BPS impaired estradiol concentrations in follicular fluid of well-fed ewes, this was not reported in restricted ewes. Granulosa cell proteomic analysis of the preovulatory follicle confirmed the interaction between metabolic status and BPS exposure as most of the proteins corresponding to the diet effect (21 and 30 proteins) differ depending on the BPS exposure. Lastly, among the proteins that varied after BPS exposure, the most interesting one is the beta-glucuronidase. Bisphenols, with oestrogenic properties, are metabolized into glucuronide bisphenols, without glucuronide properties. Nevertheless, the beta-glucuronidase has been reported to be able to remove the glucuronide part of BPA glucuronide and therefore to turn it back into BPA with oestrogenic properties. This protein that is expressed at the follicular level, is also overabundant after BPS exposure and could therefore prolonged the BPS effects at the ovarian level. Moreover, according to both the literature and our data, the beta-glucuronidase expression increases with adiposity. To conclude, our data highlighted the deleterious effects of BPS and its interaction with the metabolic status, indicating that its use in food packaging should be regulated. Our data also suggested that individuals with higher adiposity might be more sensitive to bisphenols effects

Bisphenol s impaired in vitro ovine early developmental oocyte competence

International audienceIntroduction: Bisphenol A (BPA) is a widespread compound in the plastic industry that is especially used to produce baby bottles, food packaging and metal cans. BPA, an endocrine disruptor, leads to alterations in reproductive function and therefore has been banned from the food industry. Unregulated BPA analogues, particularly Bisphenol S (BPS), have emerged and are now used in the plastic industry. Thus, this study aimed to examine the acute effects of low and environmental doses of BPS on ewe oocyte quality and developmental competence, and its mechanism of action, during in vitro maturation. Methods: Ewe cumulus-oocyte complexes underwent in vitro maturation in the presence or absence of BPS (1 nM, 10 nM, 100 nM, 1 μM or 10 μM). Oocytes were then subjected to in vitro fertilisation and development. Results:1 μM BPS induced a 12.7% decrease in the cleavage rate (p= 0.004) and a 42.6% decrease in the blastocyst rate (p= 0.017) compared to control. The blastocyst rate reduction was also observed with 10 nM BPS. Furthermore, 10 μM BPS reduced the oocyte maturation rate,and 1 μM BPS decreased cumulus cell progesterone secretion. PRand AMHgene expression were reduced in cumulus cells. BPS induced a 5-fold increase in MAPK 3/1 activation (p= 0.04). Conclusions:BPS impaired ewe oocyte developmental competence. The data suggest that BPS might not be a safe BPA analogue. Further studies are required to elucidate its detailed mechanism of actio