Bisphenol A Analogues Suppress Spheroid Attachment on Human Endometrial Epithelial Cells through Modulation of Steroid Hormone Receptors Signaling Pathway

One-step growth of Cu-doped carbon dots in amino-modified carbon nanotube-modified electrodes for sensitive electrochemical detection of BPA

Copper-doped carbon dots and aminated carbon nanotubes (Cu-CDs/NH2-CNTs) nanocomposites were synthesized by a one-step growth method, and the composites were characterized for their performance. An electrochemical sensor for sensitive detection of bisphenol A (BPA) was developed for using Cu-CDs/NH2-CNTs nanocomposites modified with glassy carbon electrodes (GCE). The sensor exhibited an excellent electrochemical response to BPA in 0.2 M PBS (pH 7.0) under optimally selected conditions. The linear range of the sensor for BPA detection was 0.5-160 μM, and the detection limit (S/N = 3) was 0.13 μM. Moreover, the sensor has good interference immunity, stability and reproducibility. In addition, the feasibility of the practical application of the sensor was demonstrated by the detection of BPA in bottled drinking water and Liu Yang River water.

Interacting with luteinizing hormone receptor provides a new elucidation of the mechanism of anti-androgenicity of bisphenol S

Bisphenol S (BPS) exhibited inhibitory effects on androgen synthesis, but its target of action remains unclear. We investigated the effects of BPS exposure at environmentally relevant concentrations (1 μg/L, 10 μg/L and 100 μg/L) for 48 h on androgen synthesis in rat ovarian theca cells and explored the underlying mechanisms, target site and target molecule. The results showed that BPS exposure inhibited the transcript levels of steroidogenic genes and reduced the contents of androgen precursors, testosterone and dihydrotestosterone. BPS exposure decreased the phosphorylation levels of extracellular signal-related kinase 1/2 (ERK1/2), and the inhibitory effects of BPS on testosterone content and steroidogenic gene expression were blocked by ERK1/2 agonist LY2828360, suggesting that ERK1/2 signaling pathway mediates the inhibitory effects of BPS on androgen synthesis. BPS mainly accumulated on the cell membrane, impermeable BPS-bovine serum albumin exposure still inhibited androgen synthesis, BPS interacted with rat luteinizing hormone receptor (LHR) via formation of hydrogen bonds in the transmembrane region, and the inhibitory effects of BPS on ERK1/2 phosphorylation were blocked by luteinizing hormone (the natural agonist of LHR), indicating that LHR located on the cell membrane is the target of action of BPS. This paper provides a new elucidation of the mechanism of anti-androgenicity of BPS, especially for the non-genomic pathways.

Reproductive toxicity of bisphenol A, at environmentally relevant concentrations, on ovarian redox balance, maturational response, and intra-oocyte signalling events in Labeo bata

Bisphenol A (BPA) is a widely used plastic monomer that potentially interferes with ovarian neuroendocrine, endocrine, and autocrine/paracrine factors, causing reproductive dysfunction. However, the influence of BPA on redox balance, estrogen receptor (ER) expression vis-à-vis meiotic cell cycle progression, and intra-oocyte signalling events has not been extensively investigated. The present study examines the impact of BPA on reproductive toxicity in female Labeo bata (Order Cypriniformes, Family Cyprinidae), a freshwater teleost preferred as a food fish in the Indian subcontinent. Our results show that while ovarian weight (gonadosomatic index, GSI) and dynamics of follicular growth undergo pronounced changes during the annual reproductive cycle, chronic BPA exposure at environmentally relevant concentrations promotes follicular atresia concomitant with reduced GSI during the spawning phase, the highest response being observed due to low-dose (0.1 μg/L, 0.438 nM) BPA exposure in vivo. Furthermore, BPA perturbation of ovarian StAR expression and ERα/ERβ homeostasis corroborates with elevated oxidative stress in BPA-treated ovary, FG follicles, and follicular cells. A sharp increase in ROS accumulation and nitric oxide (NO) levels in BPA-treated full-grown (FG) follicles coupled with loss of redox balance, elevated follicular cell death, and activation of apoptotic markers (caspase -8, -9, -3, Bax) indicate poor oocyte health and reproductive toxicity. Importantly, maturational steroid (MIS, 17,20β-P)-induced cyclin B-p34cdc2 activation and elevated GVBD (germinal vesicle breakdown) response require protein kinase A (PKA) inhibition and participation of Mos/MAPK- and cdc25-mediated signalling events. While the adenylate cyclase activator forskolin (FK) abrogates, priming with a PKA inhibitor (H89) promotes the meiotic G2-M1 transition, confirming the role of PKA in meiotic cell cycle progression in this species. Furthermore, the negative influence of BPA priming on 17,20β-P-induced oocyte maturation involves elevated PKAc phosphorylation (activation) and significant alteration in Mos/MAPK signalling, indicating derailed meiotic maturational competence and disrupted oocyte quality.

Toxic effects of bisphenol S on mice heart and human umbilical cord endothelial cells

Bisphenol S (BPS) exerts toxic effects on hippocampal HT22 cells, endocrine secretion, and reproductive capacity. However, whether BPS exerts toxic effects on the heart requires further investigation. Therefore, we investigated the effects of BPS on mouse heart tissues and predicted possible underlying molecular mechanisms of action. Our study showed that BPS induced apoptosis, increased oxidative stress response. Using electron microscopy, we found that BPS disrupted sarcomere arrangement in myocardial cells and caused reduction in the number of plasmalemmal vesicles in endothelial cells in the mouse heart tissues. Also, BPS increased expression levels of P-NF-κB in mouse heart tissues. Furthermore, we found that BPS induced reactive oxygen species (ROS) generation, NF-κB activation, promoted apoptosis, elevated expression of BAX and Caspase 3, and decreased expression of Bcl-2 in H9c2 cells and HUVECs. However, after the addition of n-acetylcysteine or pyrrolidinedithiocarbamate, ROS generation, NF-κB activation, apoptosis, and expression of BAX and Caspase 3 were reduced, whereas expression of Bcl-2 was elevated. Our results demonstrated that BPS induced apoptosis of myocardial and endothelial cells through oxidative stress by activation of NF-κB signaling pathway.

Adverse (geno)toxic effects of bisphenol A and its analogues in hepatic 3D cell model

Bisphenol A (BPA) is one of the most widely used and versatile chemical compounds in polymer additives and epoxy resins for manufacturing a range of products for human applications. It is known as endocrine disruptor, however, there is growing evidence that it is genotoxic. Because of its adverse effects, the European Union has restricted its use to protect human health and the environment. As a result, the industry has begun developing BPA analogues, but there are not yet sufficient toxicity data to claim that they are safe. We investigated the adverse toxic effects of BPA and its analogues (BPS, BPAP, BPAF, BPFL, and BPC) with emphasis on their cytotoxic and genotoxic activities after short (24-h) and prolonged (96-h) exposure in in vitro hepatic three-dimensional cell model developed from HepG2 cells. The results showed that BPFL and BPC (formed by an additional ring system) were the most cytotoxic analogues that affected cell viability, spheroid surface area and morphology, cell proliferation, and apoptotic cell death. BPA, BPAP, and BPAF induced DNA double-strand break formation (γH2AX assay), whereas BPAF and BPC increased the percentage of p-H3-positive cells, indicating their aneugenic activity. All BPs induced DNA single-strand break formation (comet assay), with BPAP (≥0.1 μM) being the most effective and BPA and BPC the least effective (≥1 μM) under conditions applied. The results indicate that not all of the analogues studied are safer alternatives to BPA and thus more in-depth research is urgently needed to adequately evaluate the risks of BPA analogues and assess their safety for humans.

Bisphenols A and F, but not S, induce apoptosis in bovine granulosa cells via the intrinsic mitochondrial pathway

With the gradual decline in global fertility rates, there is a need to identify potential contributing factors, their mechanisms of actions and investigate possible solutions to reverse the trend. Endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), are environmental toxicants that are known to negatively impact reproductive functions. As such, the use of BPA in the manufacturing industry has slowly been replaced by analogs, including bisphenol S (BPS) and bisphenol F (BPF), despite limited knowledge available regarding their impact on health and their safety. The following study investigates the effects of BPA, BPS and BPF at a concentration of 0.5 μg/mL and 50 μg/mL on bovine granulosa cell apoptosis, with the ultimate goal of determining how they may impact oocyte competence and, thus, overall fertility. The underlying hypothesis is that bisphenols disrupt the granulosa cell environment surrounding the oocyte inducing excessive apoptosis via the intrinsic mitochondrial pathway. To test this hypothesis, apoptosis was measured following a time- and dose-dependent exposure to all three bisphenols by flowcytometry paired with annexin V/PI staining as well as by quantification of key genes belonging to the intrinsic apoptotic pathway both at the mRNA and protein levels. The results of this study report that BPA and BPF reduce cell viability through reduced cell counts and increased apoptosis. This increase is due, in part, to the induction of apoptotic genes of the intrinsic pathway of apoptosis. Additionally, this study also suggests that BPS may not act on the intrinsic mitochondrial apoptotic pathway in bovine granulosa cells. Overall, this study allows us to establish potential apoptotic pathways activated by bisphenols as well as compare the relative apoptotic activities of BPA to its most widespread analogs.