Long-term exposure to low doses of bisphenol S has hypoglycaemic effect in adult male mice by promoting insulin sensitivity and repressing gluconeogenesis

Long-term Bisphenol S exposure induced gut microbiota dysbiosis, obesity, hepatic lipid accumulation, intestinal lesions and dyslipidemia in mice

Bisphenol S (BPS) is a commonly detected chemical raw material in water, which poses significant threats to both the ecological environment and human health. Despite being recognized as a typical endocrine disruptor and a substitute for Bisphenol A, the toxicological effects of BPS remain nonnegligible. In order to comprehensively understand the health impacts of BPS, a long-term (154 days) exposure experiment was conducted on mice, during which the physiological indicators of the liver, intestine, and blood were observed. The findings revealed that exposure to BPS resulted in dysbiosis of the gut microbiota, obesity, hepatic lipid accumulation, intestinal lesions, and dyslipidemia. Furthermore, there exists a significant correlation between gut microbiota and indicators of host health. Consequently, the identification of specific gut microbiota can be considered as potential biomarkers for the evaluation of risk associated with BPS. This study will effectively address the deficiency in toxicological data pertaining to BPS. The novel BPS data obtained from this research can serve as a valuable reference for professionals in the field.

Bisphenol analogues induce thyroid dysfunction via the disruption of the thyroid hormone synthesis pathway

Bisphenol analogues are widely used in industrial and daily-use consumer products having imperfect thyroid hormones (THs) structures. Widespread exposure interferes with thyroid-related health outcomes in human. The mechanisms of disruption on TH synthesis and subsequent thyroid dysfunction by different bisphenol analogues remain unclear. Here, we evaluated bisphenol-induced thyroid endocrine disruption in C57BL/6 mice at doses of 0.002, 0.02, 2, and 20 mg/kg body weight/day (BW/d) for five consecutive weeks. Administration of 20 mg/kg BW/d bisphenol S (BPS) and 2 mg/kg BW/d tetrabromobisphenol S (TBBPS) significantly increased serum thyrotropin (TSH) levels to 1.21-fold and 1.20-fold of control group, respectively, indicating that bisphenols induced thyroid dysfunction in mice. Height of the thyroid follicle epithelium significantly increased to 1.27-, 1.24-, 1.26-, and 1.36-fold compared to control group with BPA, BPS, TBBPA, and TBBPS at 20 mg/kg BW/d, respectively, indicating impairment of the thyroid gland structure, and TBBPS showed potent effect. Exposure to bisphenol analogues of 0.02 mg/kg BW/d downregulated the protein expression levels of thyrotropin receptor, the sodium/iodide symporter, thyroperoxidase. The TH-dependent effects were further determined using the T-Screen assay at 10-11 M to 10-5 M concentrations. Bisphenol analogues significantly decreased TH-dependent GH3 cell proliferation, indicating the antagonistic activity of bisphenol analogues. The gene responsible for THs synthesis of thyrotropin releasing hormone receptor and TSH were upregulated, but downregulation of thyroid receptor β was observed. Our results suggest that bisphenol analogues distinctly induce thyroid dysfunction via TH synthesis, implying adverse effect of bisphenol analogues on TH homeostasis and subsequent physiological processes.

Effects of prenatal bisphenol S and bisphenol F exposure on behavior of offspring mice

Bisphenol A (BPA) is a representative endocrine-disrupting chemical that exhibits hormonal disturbance reactions. Various alternatives, such as Bisphenol S (BPS) and Bisphenol F (BPF), are being developed. BPS and BPF (which are representative alternatives to BPA) are used in consumer products such as polycarbonate plastics and epoxy resins. They have structures similar to those of BPA and have also been proven to be exogenous endocrine disruptors. However, although there are many studies on BPA, there are few studies on the neurodevelopmental effects of BPS and BPF. Therefore, in this study, we analyzed neurobehavioral changes in offspring mice exposed to BPS and BPF during brain development by administering BPS and BPF to pregnant mice. We found that prenatal exposure to BPS and BPF did not affect anxiety-and depression-like behaviors, locomotion, sociability, memory, or cognition functions in offspring mice. However, exposure to BPS and BPF decreased the preference for social novelty in the offspring mice. Taken together, these findings suggest that perinatal exposure to BPS and BPF affects changes in social behaviors, but not other behavioral changes such as emotion, memory, or cognition in the offspring mice.

In vivo hypoglycemic effects of bisphenol F exposure in high-fat diet mice

Bisphenol F (BPF) is a widely used bisphenol A (BPA) substitute plastic additive that has attracted increasing public concerns due to its potential toxic effects on animal and human health. Although previous studies have indicated that BPF might have harmful effects on metabolic homeostasis, the systematic effects of BPF on glucose disorders remain controversial. In this study, mice fed a normal chow diet (ND) and high-fat diet (HFD) were administered BPF at a dose of 100 μg/kg of body weight, and glucose metabolism was monitored after both short- and long-term treatment. Little change in glucose metabolism was observed in BPF-treated ND mice, but improved glucose metabolism was observed in BPF-treated HFD mice. Consistently, BPF treatment led to increased insulin signalling in the skeletal muscle of HFD mice. Additionally, liver metabolite levels also revealed increased carbohydrate digestion and improved TCA cycle progression in BPF-treated HFD mice. Our results demonstrate that sustained BPF exposure at an environmentally relevant dosage may substantially improve glucose metabolism and enhance insulin sensitivity in mice fed a high-fat diet.

Exposure to Bisphenol A Substitutes, Bisphenol S and Bisphenol F, and Its Association with Developing Obesity and Diabetes Mellitus: A Narrative Review

Bisphenol A, a well-known endocrine-disrupting chemical, has been replaced with its analogs bisphenol S (BPS) and bisphenol F (BPF) over the last decade due to health concerns. BPS and BPF are present in relatively high concentrations in different products, such as food products, personal care products, and sales receipts. Both BPS and BPF have similar structural and chemical properties to BPA; therefore, considerable scientific efforts have investigated the safety of their exposure. In this review, we summarize the findings of relevant epidemiological studies investigating the association between urinary concentrations of BPS and/or BPF with the incidence of obesity or diabetes. The results showed that BPS and BPF were detected in many urinary samples at median concentrations ranging from 0.03 to 0.4 µg·L-1. At this exposure level, BPS median urinary concentrations (0.4 µg·L-1) were associated with the development of obesity. At a lower exposure level (0.1-0.03 µg·L-1), two studies showed an association with developing diabetes. For BPF exposure, only one study showed an association with obesity. However, most of the reported studies only assessed BPS exposure levels. Furthermore, we also summarize the findings of experimental studies in vivo and in vitro regarding our aim; results support the possible obesogenic effects/metabolic disorders mediated by BPS and/or BPF exposure. Unexpectedly, BPS may promote worse obesogenic effects than BPA. In addition, the possible mode of action underlying the obesogenic effects of BPS might be attributed to various pathophysiological mechanisms, including estrogenic or androgenic activities, alterations in the gene expression of critical adipogenesis-related markers, and induction of oxidative stress and an inflammatory state. Furthermore, susceptibility to the adverse effects of BPS may be altered by sex differences according to the results of both epidemiological and experimental studies. However, the possible mode of action underlying these sex differences is still unclear. In conclusion, exposure to BPS or BPF may promote the development of obesity and diabetes. Future approaches are highly needed to assess the safety of BPS and BPF regarding their potential effects in promoting metabolic disturbances. Other studies in different populations and settings are highly suggested.

Bisphenol analogues induced metabolic effects through eliciting intestinal cell heterogeneous response

The metabolic effects of endocrine-disrupting chemicals, such as bisphenol analogues, have drawn increasing attention. Bisphenol A (BPA) usage is associated with the occurrence of many metabolic diseases. With the restricted use of BPA, alternatives like bisphenol F (BPF) and bisphenol AF (BPAF) have been greatly introduced for industrial manufacture, and brings new hazard to public health. To understand how bisphenol analogues induced metabolic effects, zebrafish are continuous exposed to environmental level (0.5 μg/L) of BPA, BPF and BPAF since embryonic stage, and identified hepatic steatosis and insulin resistance at 60-day post fertilization. Hepatic transcriptional profile indicated that pancreatic disease pathways were activated by BPA, but were inhibited by BPF. At the same time, increased lipid secretion and gluconeogenesis pathways in zebrafish liver was found post BPAF exposure. Significant inflammatory response, histological injury and increased mucus secretion was detected in zebrafish intestine post exposure of three bisphenol analogues. Single-cell RNA sequencing of zebrafish intestinal cells revealed activation of lipid uptake and absorption pathways in enterocyte lineages, which well explained the hepatic steatosis induced by BPA and BPF. Besides, genes related to carbohydrate metabolism, diabetes and insulin resistance were activated in intestinal immune cell types by three bisphenol analogues. These findings indicated that BPA and its alternatives could lead to abnormal lipid and carbohydrate metabolism of zebrafish through inducing cell heterogeneous changes in gut, and revealed both molecular and cellular mechanism in mediating this effect.

Hyperactivity of basolateral amygdala mediates behavioral deficits in mice following exposure to bisphenol A and its analogue alternative

Bisphenol A (BPA) is a known endocrine disruptor and has been gradually replaced in industrial applications by other bisphenols, such as bisphenol S (BPS). However, whether these analogues are any safer for the central nervous system remains elusive. Here, we investigated behavioral impairments in mice after BPA and BPS exposure from postnatal days 21-49 (P21~P49). Results showed that BPA (0.1 and 1 mg/kg/d) and BPS (1 mg/kg/d) impaired emotion and social interaction of mice, while low dose exposure (0.1 mg/kg/d) induced no observable changes on emotion in mice. The behavioral deficits were accompanied by hyperactivation of the basolateral amygdala (BLA), i.e., dose-dependent increase in neuronal firing rates and local field potential power. In addition, glutamate receptors were up-regulated in the BLA, showing the same activation trend after exposure to different doses of BPA and BPS. Taken together, these findings imply that BPA and BPS cause behavioral impairments in juvenile mice by disrupting local neuronal activation in the BLA. Although BPS exerted less adverse effects on mice than BPA at the low dose, it does not appear to be a safe alternative to BPA in regard to brain function after prolonged high-volume exposure.

Short-term exposure to acrylamide exacerbated metabolic disorders and increased metabolic toxicity susceptibility on adult male mice with diabetes

Diabetes mellitus is a common endocrine metabolic disorder, and previous studies have shown that diabetics are more sensitive to the toxic environmental contaminants. Acrylamide (ACR) is both an industrially multipurpose compound and a common endogenous food contaminant to which people are frequently exposed and at high risk. However, the toxicity of ACR on diabetes hasn't attracted much attention. In this study, both healthy mice and diabetic mice received ACR administration orally to investigate the ACR-induced metabolic toxicity, mechanism and susceptibility to ACR toxicity in adult diabetic male mice. The results showed that ACR significantly increased FBG level and decreased bodyweight, serum lipid and liver lipid biomarkers (TC, TG, LDL-C, HDL-C) levels as well as expression of lipid and glucose metabolism-related genes in diabetic mice, indicating that ACR can exacerbate metabolic disorders of glucose and lipid in diabetic male mice. Moreover, ACR exposure significantly increased levels of MDA and COX-2), decreased GSH level and antioxidant enzyme activity (SOD, GSH-PX and CAT) by downregulating expression of Nrf2 and Keap1 in diabetic mice. Factorial analysis showed ACR had a more significant disturbance in diabetic mice compared with healthy mice. Our results indicated that ACR exposure can cause oxidative stress and inflammatory damage, which can exacerbate abnormal glucose and lipid metabolism. This work helps to elucidate the effects and underlying mechanisms of ACR-induced metabolic toxicity in adults with diabetes.