Short-term exposure to bisphenol A affects water and salt intakes differently in male and ovariectomised female rats

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Environmental level bisphenol A accelerates alterations of the reno-cardiac axis by the MAPK cascades in male diabetic rats: An analysis based on transcriptomic profiling and bioinformatics

In humans and animal models, the kidneys and cardiovascular systems are negatively affected by BPA from the environment. It is considered that BPA have some potential estrogen-like and non-hormone-like properties. In this study, RNA-sequencing and its-related bioinformatics was used as the basic strategy to clarify the characteristic mechanisms of kidney-heart axis remodeling and dysfunction in diabetic male rats under BPA exposure. We found that continuous BPA exposure in diabetic rats aggravated renal impairment, and caused hemodynamic disorders and dysfunctions. There were 655 and 125 differentially expressed genes in the kidney and heart, respectively. For the kidneys, functional annotation and enrichment, and gene set enrichment analyses identified bile acid secretion related to lipid synthesis and transport, and MAPK cascade pathways. For the heart, these bioinformatics analyses clearly pointed to MAPKs pathways. A total of 12 genes and another total of 6 genes were identified from the kidney tissue and heart tissue, respectively. Western blotting showed that exposure to BPA activated MAPK cascades in both organs. In this study, the exacerbated remodeling of diabetic kidney-heart axis under BPA exposure and diabetes might occur through hemodynamics, metabolism disorders, and the immune-inflammatory response, as well as continuous estrogen-like stimulation, with focus on the MAPK cascades.

Chronic exposure to low doses of bisphenol A alters hydromineral responses in rats

Bisphenol A (BPA) is a chemical commonly used in the industrial sectors, hence humans are exposed to the compound repetitively. BPA is an endocrine disruptor and has been anticipated to interfere on chemical estrogen receptor functions and other nuclear hormone receptors. Estrogens are steroid hormones that, in addition to their neuroendocrine roles, affect water and salt intakes in numerous species, including humans and rodents. Changes in the hydrosaline balance produce compensatory behavioral and physiological responses, which serve to preserve or restore osmolarity and blood volume to optimal levels, thus preventing cardiovascular disease. The aim of the present work was to determine for first time the effect of long-term and low-dose BPA treatment on thirst and sodium appetite. Wistar rats were exposed to BPA via drinking water to mimic the most likely route of human exposure, and different dipsogenic and natriorexigenic stimuli were assessed. The BPA-treated rats tend to drink less water that control rats following 24-h fluid restriction, but there was no statistically significant decrease. Perhaps the BPA dose does not have enough estrogenic potency to affect water intake. In the extracellular fluid depletion test, the control rats significantly increased 2.7% NaCl solution intake on repeated testing, showing sodium appetite sensitization, i.e. the capacity to enhance sodium intake produced by stimulus repetition; whereas BPA-treated rats did not. In this study, fluid and electrolyte balance in BPA-treated rats is generally adequate but impaired in osmotic challenges, for example by sodium depletion. Thus, neuroendocrine systems involved in maintaining body fluid and electrolyte homeostasis were altered in BPA-treated rats.