Bisphenol A inhibits compound action potentials in the frog sciatic nerve in a manner independent of estrogen receptors

Bisphenol A contamination in aquatic environments: a review of sources, environmental concerns, and microbial remediation

The production of polycarbonate, a high-performance transparent plastic, employs bisphenol A, which is a prominent endocrine-disrupting compound. Polycarbonates are frequently used in the manufacturing of food, bottles, storage containers for newborns, and beverage packaging materials. Global production of BPA in 2022 was estimated to be in the region of 10 million tonnes. About 65-70% of all bisphenol A is used to make polycarbonate plastics. Bisphenol A leaches from improperly disposed plastic items and enters the environment through wastewater from plastic-producing industries, contaminating, sediments, surface water, and ground water. The concentration BPA in industrial and domestic wastewater ranges from 16 to 1465 ng/L while in surface water it has been detected 170-3113 ng/L. Wastewater treatment can be highly effective at removing BPA, giving reductions of 91-98%. Regardless, the remaining 2-9% of BPA will continue through to the environment, with low levels of BPA commonly observed in surface water and sediment in the USA and Europe. The health effects of BPA have been the subject of prolonged public and scientific debate, with PubMed listing more than 17,000 scientific papers as of 2023. Bisphenol A poses environmental and health hazards in aquatic systems, affecting ecosystems and human health. While several studies have revealed its presence in aqueous streams, environmentally sound technologies should be explored for its removal from the contaminated environment. Concern is mostly related to its estrogen-like activity, although it can interact with other receptor systems as an endocrine-disrupting chemical. Present review article encompasses the updated information on sources, environmental concerns, and sustainable remediation techniques for bisphenol A removal from aquatic ecosystems, discussing gaps, constraints, and future research requirements.

Bisphenol A and its effects on the systemic organs of children

For the past two decades, growing research has been pointing to multiple repercussions of bisphenol A (BPA) exposure to human health. BPA is a synthetic oestrogen which primarily targets the endocrine system; however, the compound also disturbs other systemic organ functions, in which the magnitude of impacts in those other systems is as comparable to those in the endocrine system. To date, the discoveries on the association between BPA and health outcomes mainly came from animal and in vitro studies, with limited human studies which emphasised on children's health. In this comprehensive review, we summarised studies on human, in vivo and in vitro models to understand the consequences of pre-, post- and perinatal BPA exposure on the perinatal, children and adult health, encompassing cardiovascular, neurodevelopmental, endocrine and reproductive effects.Conclusion: Evidence from in vitro and animal studies may provide further support and better understanding on the correlation between environmental BPA exposure and its detrimental effects in humans and child development, despite the difficulties to draw direct causal relations of BPA effects on the pathophysiology of the diseases/syndromes in children, due to differences in body system complexity between children and adults, as well as between animal and in vitro models and humans. What is known: • Very limited reviews are available on how BPA adversely affects children's health. • Previous papers mainly covered two systems in children. What is new: • Comprehensive review on the detrimental effects of BPA on children health outcomes, including expectations on adult health outcomes following perinatal BPA exposure, as well as covering a small part of BPA alternatives. • Essentially, BPA exposure during pregnancy has huge impacts on the foetus in which it may cause changes in foetal epigenetic programming, resulting in disease onsets during childhood as well as adulthood.

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation

Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na⁺ and K⁺ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, ₂-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na⁺ and K⁺ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.

Bisphenol F-Induced Neurotoxicity toward Zebrafish Embryos

In this study, the influence of bisphenol F (BPF) toward central nervous system (CNS) was assessed using zebrafish embryos. We found that BPF could induce significant neurotoxicity toward zebrafish embryos, including inhibited locomotion, reduced moving distance, and CNS cell apoptosis at an effective concentration of 0.0005 mg/L. Immunofluorescence assay showed that both microglia and astrocyte in zebrafish brain were significantly activated by BPF, indicating the existence of neuroinflammatory response. Peripheral motor neuron development was significantly inhibited by BPF at 72 hpf. RNA-seq data indicated that neuronal developmental processes and cell apoptosis pathways were significantly affected by BPF exposure, which was consistent with the phenotypic results. Chip-seq assay implied that the transcriptional changes were not mediated by ERα. Additionally, no significant change was found in neurotransmitter levels (5-hydroxytryptamine, dopamine, and acetylcholine) or acetylcholinesterase (Ache) enzyme activity after BPF exposure, indicating that BPF may not affect neurotransmission. In conclusion, BPF could lead to abnormal neural outcomes during zebrafish early life stage through inducing neuroinflammation and CNS cell apoptosis even at environmentally relevant concentration.

Inhibition by general anesthetic propofol of compound action potentials in the frog sciatic nerve and its chemical structure

Although the intravenous general anesthetic propofol (2,6-diisopropylphenol) has an ability to inhibit nerve conduction, this has not been fully examined. Various agents inhibit compound action potentials (CAPs) in a manner dependent on their chemical structures. To determine propofol's chemical structure that is important in nerve conduction inhibition, we examined the effects of propofol and its related compounds on fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Propofol concentration-dependently reduced the peak amplitude of the CAP with a half-maximal inhibitory concentration (IC₅₀) value of 0.14 mM. A similar inhibition was produced by other phenols, 4-sec-butylphenol and 4-amylphenol (IC₅₀ values: 0.33 and 0.20 mM, respectively). IC₅₀ values for these and more phenols (4-isopropylphenol, 4-tert-butylphenol, and 4-ter-amylphenol; data published previously) were correlated with the logarithm of their octanol-water partition coefficients. A phenol having ketone group (raspberry ketone) and alcohols (3-phenyl-1-propanol and 2-phenylethylalcohol) inhibited CAPs less effectively than the above-mentioned phenols. The local anesthetic (LA) benzocaine reduced CAP peak amplitudes with an IC₅₀ of 0.80 mM, a value larger than that of propofol. When compared with other LAs, propofol activity was close to those of ropivacaine, levobupivacaine, and pramoxine, while benzocaine activity was similar to those of cocaine and lidocaine. It is concluded that propofol inhibits nerve conduction, possibly owing to isopropyl and hydroxyl groups bound to the benzene ring of propofol and to its lipophilicity; propofol's efficacy is comparable to those of some LAs. These results could serve to develop propofol-related agents exhibiting analgesia when applied topically.