BACKGROUND: Indoor air quality (IAQ) is an important determinant of human health. In Japan, IAQ guidelines have been established for 13 chemicals since 1997. Regarding ethylbenzene (EB), a previous guideline value of 3800 µg/m³ was established in 2000. However, the Ministry of Health, Labour, and Welfare decided to revise the value because of the publication of new hazard information after the establishment of the previous guideline value and the establishment of their respective IAQ guidelines by foreign organizations based on the new hazard information. This study conducted a detailed hazard assessment on EB and derived hazard assessment values to provide a toxicologically valid basis for revising the IAQ guideline value. METHODS: As it was defined that the IAQ guidelines would not exert adverse health effects on humans even if they inhaled the chemicals from indoor air over a lifetime, we investigated the general toxicity, developmental and reproductive toxicity, genotoxicity, and carcinogenicity of EB based on reliable hazard information cited in published assessment documents by domestic, foreign, or international risk assessment organizations. All the collected hazard information was examined, and we originally judged the no-observed adverse effect level and the lowest observed adverse effect level of each toxicity study. We then selected the most appropriate key study, an endpoint, and a point of departure and derived the hazard assessment values for each toxicity category. Finally, we selected a representative hazard assessment value for EB from the minimum hazard assessment value among general toxicity, developmental and reproductive toxicity, and carcinogenicity. RESULTS: Among the three toxicity categories, the minimum hazard assessment value was obtained from general toxicity, which was 0.0858 ppm (370 µg/m³) based on the loss of the outer hair cells in the organ of Corti in the cochlea observed in a 13-week repeated-dose inhalation toxicity study using rats. CONCLUSIONS It would be appropriate to adopt 0.0858 ppm (370 µg/m³) as a representative hazard assessment value to provide a basis for revising the IAQ guideline value for EB.
Japan ; Air Pollution, Indoor/adverse effects* ; Risk Assessment ; Humans ; Benzene Derivatives/toxicity* ; Guidelines as Topic ; Animals ; Air Pollutants/toxicity*

Per- and polyfluoroalkyl substances (PFAS) have recently been shown to affect human health at low levels in the blood, according to epidemiological evidence. Consequently, human exposure to these chemicals should be strictly controlled to prevent health risks. This review reports on the potential sources of PFAS using Japan as an example. Tap water has attracted attention as a source of exposure to PFAS. PFAS have also been detected in the air, in household dust, and in consumer products. Furthermore, in the general population, diet is the most common source of exposure, and there is particular concern about human exposure to PFAS accumulated in seafood. Continuous monitoring is important for appropriate management of exposure for both humans and the environment.
Seafood/toxicity* ; Fluorocarbons/toxicity* ; Japan ; Drinking Water/standards* ; Air Pollutants/toxicity* ; Humans ; Dust/analysis* ; Environmental Exposure/standards* ; Food Contamination/analysis* ; Environmental Pollutants/toxicity* ; Water Pollutants, Chemical/toxicity*

BACKGROUND: Methylmercury (MeHg) causes damage specifically in cerebrocortical neurons, but not in hippocampal neurons. In our previous studies using cultured neurons, we found that brain-derived neurotrophic factor (BDNF), which is prominently present in hippocampal neurons, plays a key role in resistance to MeHg neurotoxicity. Our findings, combined with recent findings that moderate exercise increases BDNF in the brain, led us to hypothesize that moderate exercise protects against MeHg-induced neurotoxicity by inducing BDNF expression. METHODS: C57 black 6NJcl (C57BL/6NJcl) male mice were used to evaluate the effects of treadmill exercise (a moderate exercise) on the neurotoxicity of MeHg exposure at 1.5 mg/kg/day. The effects of treadmill exercise on MeHg neurotoxicity were evaluated through neurobehavioral, neuropathological, and biochemical analyses using brain tissue, blood, and muscle tissue. RESULTS: Treadmill exercise had a significant inhibitory effect on the neurological symptoms associated with apoptotic neuronal death and subsequent cerebrocortical neuron loss induced by MeHg exposure. In the cerebral cortex, treadmill exercise significantly increased BDNF levels and activated the neuroprotective-related BDNF-tropomyosin receptor kinase (Trk) B and p44/42 mitogen-activated protein kinase (MAPK) pathways along with significantly suppressing the neuronal cell death-associated p38 MAPK pathway. Furthermore, treadmill exercise significantly increased fibronectin type III domain containing 5 (FNDC5) expression in the muscle tissue and elevated ed the concentration of its metabolite, irisin, in the blood. CONCLUSIONS These results suggest that treadmill exercise increases BDNF in the brain and suppresses neurotoxic pathways, ultimately protecting against MeHg neurotoxicity. Moreover, the increase of BDNF in the brain may be attributed to the exercise-induced increased expression of FNDC5 in muscle tissue from where it is released into the blood as irisin and finally transferred into the brain and promoted BDNF production.
Animals ; Brain-Derived Neurotrophic Factor/genetics* ; Methylmercury Compounds/toxicity* ; Male ; Mice ; Mice, Inbred C57BL ; Physical Conditioning, Animal ; Brain/drug effects* ; Neurotoxicity Syndromes/prevention & control*

OBJECTIVE: To investigate the hepatotoxicity of alkaloids from Euodiae Fructus combined with berberine (BBR) in Zuojin Pill, and to preliminarily explore the possible detoxification mechanism of the combination components. METHODS: The combination ratio of components was determined by the maximum concentration (Cmax) of the chemical components in Zuojin Pill. HepG2 cell model was used to investigate the combined toxicity of the hepatotoxic components from Euodiae Fructus, such as evodiamine (EVO) or dehydroevodiamine (DHED), with BBR for 48 h. The experimental groups were set as follows: the vehicle control group, the EVO group, the DHED group, the BBR group, and the combination group of EVO or DHED with BBR. The cell counting kit-8 (CCK-8) method was used to determine the cell viability, and the combination index (CI) was used to determine the combined toxicity of the components. The alanine transaminase (ALT), aspartate aminotransferase (AST), lactate dehydroge-nase (LDH), and alkaline phosphatase (ALP) activities as well as total bilirubin (TBIL) content in the cell culture supernatant were detected. The protein expression levels of bile acid transporters, such as bile salt export pump (BSEP) and multidrug resistance-associated protein 2 (MRP2), were detected by Western blot. The intracellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in HepG2 cells were detected. RESULTS: Compared with EVO or DHED group, the combination of EVO 1 μmol/L with BBR 10 μmol/L or DHED 50 μmol/L with BBR 35 μmol/L significantly increased cell viability of HepG2 cells (P < 0.01), with CI values of 77.89 or 4.49, respectively, much greater than 1. Significant decreases in the activities of ALT, AST, LDH, ALP, and TBIL content in the cell culture supernatant were found in both combination groups (P < 0.05, P < 0.01). Compared with the EVO group, the combination of EVO with BBR upregulated the protein expression levels of BSEP and MRP2. Compared with the DHED group, the combination of DHED with BBR significantly downregulated the protein expression levels of BSEP and MRP2 (P < 0.01). Compared with EVO or DHED group, the combination of EVO or DHED with BBR significantly reduced the MDA content in HepG2 cells (P < 0.05, P < 0.01). CONCLUSION A certain ratio of BBR combined with EVO or DHED had an antagonistic effect on HepG2 cytotoxicity, which might be related to regulating the expression of bile acid transpor-ters, and reducing lipid peroxidation damage.
Humans ; Hep G2 Cells ; Berberine/pharmacology* ; Drugs, Chinese Herbal/toxicity* ; Evodia/chemistry* ; Alkaloids/pharmacology* ; Cell Survival/drug effects* ; Multidrug Resistance-Associated Proteins/metabolism* ; Multidrug Resistance-Associated Protein 2 ; Quinazolines

OBJECTIVE: To investigate the protective effects of stir-fried Semen Armeniacae Amarum (SAA) against aristolochic acid I (AAI)-induced nephrotoxicity and DNA adducts and elucidate the underlying mechanism involved for ensuring the safe use of Asari Radix et Rhizoma. METHODS: In vitro, HEK293T cells overexpressing Flag-tagged multidrug resistance-associated protein 3 (MRP3) were constructed by Lentiviral transduction, and inhibitory effect of top 10 common pairs of medicinal herbs with Asari Radix et Rhizoma in clinic on MRP3 activity was verified using a self-constructed fluorescence screening system. The mRNA, protein expressions, and enzyme activity levels of NAD(P)H quinone dehydrogenase 1 (NQO1) and cytochrome P450 1A2 (CYP1A2) were measured in differentiated HepaRG cells. Hepatocyte toxicity after inhibition of AAI metabolite transport was detected using cell counting kit-8 assay. In vivo, C57BL/6 mice were randomly divided into 5 groups according to a random number table, including: control (1% sodium bicarbonate), AAI (10 mg/kg), stir-fried SAA (1.75 g/kg) and AAI + stir-fried SAA (1.75 and 8.75 g/kg) groups, 6 mice in each group. After 7 days of continuous gavage administration, liver and kidney damages were assessed, and the protein expressions and enzyme activity of liver metabolic enzymes NQO1 and CYP1A2 were determined simultaneously. RESULTS: In vivo, combination of 1.75 g/kg SAA and 10 mg/kg AAI suppressed AAI-induced nephrotoxicity and reduced dA-ALI formation by 26.7%, and these detoxification effects in a dose-dependent manner (P<0.01). Mechanistically, SAA inhibited MRP3 transport in vitro, downregulated NQO1 expression in vivo, increased CYP1A2 expression and enzymatic activity in vitro and in vivo, respectively (P<0.05 or P<0.01). Notably, SAA also reduced AAI-induced hepatotoxicity throughout the detoxification process, as indicated by a 41.3% reduction in the number of liver adducts (P<0.01). CONCLUSIONS Stir-fried SAA is a novel drug candidate for the suppression of AAI-induced liver and kidney damages. The protective mechanism may be closely related to the regulation of transporters and metabolic enzymes.
Aristolochic Acids/toxicity* ; Animals ; Humans ; NAD(P)H Dehydrogenase (Quinone)/genetics* ; HEK293 Cells ; Kidney/pathology* ; Cytochrome P-450 CYP1A2/genetics* ; Mice, Inbred C57BL ; DNA Adducts/drug effects* ; Male ; Kidney Diseases/drug therapy* ; Drugs, Chinese Herbal/therapeutic use* ; Mice ; Prunus armeniaca ; Plant Extracts

OBJECTIVE: To investigate the effects of Bushen Huoxue Granule on the ubiquitin-proteasome system (UPS) in an in vitro model of Parkinson's disease. METHODS: After treated with 1-methyl-4-phenylpyridinium (MPP⁺, 1 mmol/L) for 24 h, the cells were incubated with drug-free serum, Madopar-containing serum or Bushen Huoxue Granule-containing serum (BCS, 5%, 10%, and 20%) for another 24 h. The levels of α-synuclein (α-syn), tyrosine hydroxylase (TH) and UPS-related proteins were detected by Western blot. The expression levels of α-syn in PC12 cells were also analyzed by Western blot after treated with proteasome inhibitor MG132 and WT-α-syn plasmid transfection, respectively, as well as the alterations induced by subsequent BCS intervention. Immunocytochemistry was performed to determine the changes in α-syn phosphorylation at serine 129 (pSer129-α-syn) expression. The 20S proteasome levels were measured by enzyme-linked immunosorbnent assay. RESULTS: BCS (volume fraction ⩽20%) intervention could alleviate the MMP⁺-induced cell viability decrease (P<0.05). In the MPP⁺ treated cells, α-syn was up-regulated, while TH and proteins of UPS such as ubiquitin (Ub), Ub binding with Ub-activating enzyme (UBE1), Parkin and Ub C-terminal hydrolase-1 (UCHL-1) were down-regulated (P<0.05). BCS intervention could attenuate the above changes (P<0.05). The activity of BCS on blocking α-syn accumulation was weakened by MG132 (P<0.05). While α-syn level was significantly increased in cells transfected with plasmid, and reduced by BCS intervention (P<0.05). pSer129-α-syn was increased in MPP⁺-induced PC12 cells, whereas decreased by later BCS intervention (P<0.05). The 20S proteasome activity of MPP⁺-induced PC12 cells was decreased, but increased after BCS intervention (P<0.05). CONCLUSION BCS intervention protected UPS function, increased 20S proteasome activity, promoted pathological α-syn clearance, restored cell viability, and reversed the damage caused by MPP⁺ in the in vitro model of Parkinson's disease.
PC12 Cells ; alpha-Synuclein/metabolism* ; Rats ; Animals ; 1-Methyl-4-phenylpyridinium/toxicity* ; Proteasome Endopeptidase Complex/metabolism* ; Drugs, Chinese Herbal/pharmacology* ; Ubiquitin/metabolism* ; Cell Survival/drug effects* ; Phosphorylation/drug effects* ; Tyrosine 3-Monooxygenase/metabolism*

OBJECTIVES: Exposure to rare earth elements (REEs) has been linked to various systemic diseases, but their impact on the offspring blood-brain barrier (BBB) via the gut-brain axis remains unclear. This study aims to investigate the effects of maternal exposure to neodymium oxide (Nd₂O₃) on the BBB integrity of offspring rats, and to evaluate the potential protective role of bifidobacterium tetrad viable tablets (BTVT) against Nd₂O₃-induced intestinal and BBB damage. METHODS: Healthy adult SD rats were mated at a 1:1 male-to-female ratio, with the day of vaginal plug detection marked as gestational day 0. A total of 60 pregnant rats were randomly assigned to the following groups: Control, 50 mg/(kg·d) Nd₂O₃, 100 mg/(kg·d) Nd₂O₃, 200 mg/(kg·d) Nd₂O₃, and 200 mg/(kg·d) Nd₂O₃ + BTVT group. Treatments were administered by daily oral gavage throughout pregnancy and lactation. On postnatal day 21 (weaning), offspring feces, brain, and colon tissues were collected. Hematoxylin and eosin (HE) staining was used to assess structural changes in brain and intestinal tissues. Short-chain fatty acids (SCFAs) in feces were quantified by gas chromatography-mass spectrometry (GC-MS). Evans Blue (EB) dye extravasation assessed BBB permeability. Gene and protein expression levels of tight junction proteins occludin and zonula occludens-1 (ZO-1) were measured by reverse transcription PCR (RT-PCR) and Western blotting (WB), respectively. Neodymium levels in brain tissue were determined via inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: HE staining revealed that maternal Nd₂O₃ exposure caused mucosal edema, increased submucosal spacing, and lymphocyte infiltration in offspring colon, as well as neuronal degeneration and vacuolization in brain tissue. BTVT intervention alleviated these changes. GC-MS analysis showed that levels of acetic acid, propionic acid, butyric acid, and isobutyric acid significantly decreased, while valeric acid and isovaleric acid increased in offspring of Nd₂O₃-exposed mothers (P<0.05). BTVT significantly restored levels of acetic, propionic, and isobutyric acids and reduced valeric acid content (P<0.05). EB permeability was significantly elevated in Nd₂O₃-exposed offspring brains (P<0.05), but reduced with BTVT treatment (P<0.05). RT-PCR and WB showed downregulation of occludin and ZO-1 expression following Nd₂O₃ exposure (P<0.05), which was reversed by BTVT (P<0.05). ICP-MS results indicated significantly increased brain neodymium levels in offspring from all Nd₂O₃-exposed groups (P<0.05), while BTVT significantly reduced neodymium accumulation compared to the 200 mg/(kg·d) Nd₂O₃ group (P<0.05). CONCLUSIONS Maternal exposure to Nd₂O₃ during pregnancy and lactation disrupts intestinal health and BBB integrity in offspring, elevates brain neodymium accumulation, and induces neuronal degeneration. BTVT effectively mitigates Nd₂O₃-induced intestinal and BBB damage in offspring, potentially through modulation of the gut-brain axis.
Animals ; Female ; Blood-Brain Barrier/pathology* ; Pregnancy ; Rats, Sprague-Dawley ; Rats ; Male ; Neodymium/toxicity* ; Prenatal Exposure Delayed Effects/prevention & control* ; Lactation ; Maternal Exposure/adverse effects* ; Brain

The zebrafish has emerged as a powerful model organism in life science owing to its remarkable biological characteristics and wide-ranging applications. This review provides a comprehensive overview of the recent advancements in research on zebrafish within the field of environmental toxicology, highlighting specific studies where this species was used to investigate various pollutants to elucidate their impacts and underlying mechanisms. The findings of these studies underscore the significant potential of zebrafish as a model to gain crucial insights into the ecological consequences of environmental contamination and toxicity pathways. By incorporating cutting-edge technologies such as artificial intelligence (AI), high-throughput screening, and omics approaches, the use of zebrafish as a model organism is poised to significantly accelerate toxicological investigations, promote environmental conservation efforts, contribute to safeguarding human health, and advance sustainable development objectives.
Animals ; Zebrafish ; Ecotoxicology/methods* ; Artificial Intelligence ; Humans ; Models, Animal ; Environmental Pollutants/toxicity*

OBJECTIVES: To investigate the protective effect of catalpol against triptolide-induced liver injury and explore its mechanism to test the Fuzheng Zhidu theory for detoxification. METHODS: C57BL/6J mice were randomized into blank control group, catalpol group, triptolide group and triptolide+catalpol group. After 13 days of treatment with the agents by gavage, the mice were examined for liver tissue pathology, liver function, hepatocyte subcellular structure, lipid peroxidation, ferrous ion deposition and expressions of ferroptosis-related proteins in the liver. In a liver cell line HL7702, the effect of catalpol or the ferroptosis inhibitor Fer-1 on triptolide-induced cytotoxicity was tested by examining cell functions, Fe²⁺ concentration, lipid peroxidation, ROS level and the ferroptosis-related proteins. RESULTS: In C57BL/6J mice, catalpol significantly alleviated triptolide-induced hepatic injury, lowered the levels of ALT, AST and LDH, and reversed the elevation of Fe²⁺ concentration and MDA level and the reduction of GP_X level. In HL7702 cells, inhibition of ferroptosis by Fer-1 significantly reversed triptolide-induced elevation of ALT, AST and LDH levels. Western blotting and qRT-PCR demonstrated that catalpol reversed abnormalities in expressions of SLC7A11, FTH1 and GPX4 at both the mRNA and protein levels in triptolide-treated HL7702 cells. CONCLUSIONS The combined use of catalpol can reduce the hepatotoxicity of triptolide in mice by inhibiting excessive hepatocyte ferroptosis through the SLC7A11/GPX4 pathway.
Animals ; Phenanthrenes/toxicity* ; Ferroptosis/drug effects* ; Diterpenes/toxicity* ; Epoxy Compounds/toxicity* ; Mice, Inbred C57BL ; Hepatocytes/metabolism* ; Mice ; Phospholipid Hydroperoxide Glutathione Peroxidase ; Iridoid Glucosides/pharmacology* ; Liver/metabolism* ; Chemical and Drug Induced Liver Injury/prevention & control* ; Male ; Amino Acid Transport System y+/metabolism*

OBJECTIVES: To explore whether the antioxidant axis Nrf2/HO-1 is involved in the regulation of hippocampus injury induced by cypermethrin and its underlying mechanism. METHODS: Ten-week-old C57BL/6 mice were randomly divided into control group and cypermethrin exposure groups with low, medium, and high exposure levels. After 21 days of oral gavage of corn oil (control) or cypermethrin, the levels of MDA, T-SOD, GSH-Px and CAT in the hippocampus of the mice were examined to evaluate the oxidative stress levels. HE staining was used to observe morphological changes of the hippocampal neurons. Western blotting, immunofluorescence staining and RT-qPCR were employed to detect the protein expressions and mRNA expression of Nrf2 and HO-1 and HO-1. RESULTS: Subacute oral exposure to cypermethrin significantly increased MDA level, decreased the activities of antioxidant enzymes T-SOD, GSH-Px and CAT, and induced neuronal damage in the CA1 and CA3 regions in the hippocampus of C57BL/6 mice. Cypermethrin exposure also caused Nrf2 protein translocation from the cytoplasm to the nucleus, accompanied by upregulated expression levels of the key antioxidant factor Nrf2 and its downstream target kinase HO-1. CONCLUSIONS Cypermethrin exposure dose-dependently causes oxidative damage in the hippocampus of C57BL/6 mice, which is regulated by the Nrf2/HO-1 antioxidant pathway.
Animals ; Pyrethrins/toxicity* ; NF-E2-Related Factor 2/metabolism* ; Hippocampus/cytology* ; Mice, Inbred C57BL ; Mice ; Oxidative Stress/drug effects* ; Neurons/pathology* ; Heme Oxygenase-1/metabolism* ; Signal Transduction ; Membrane Proteins