Exposure to carbon black nanoparticles during pregnancy aggravates lipopolysaccharide-induced lung injury in offspring: an intergenerational effect.

Carbon black nanoparticles (CBNPs) are one of the most frequently used nanoparticles. Exposure to CBNPs during pregnancy (PrE to CBNPs) can directly induce inflammation, lung injury, and genotoxicity in dams and results in abnormalities in offspring. However, whether exposure to CBNPs during pregnancy enhances the susceptibility of offspring to environmental stimuli remains unknown. To address this issue, in this study, we intranasally treated pregnant mice with mock or CBNPs from gestational day (GD) 9 to GD18, and F1 and F2 offspring were normally obtained. By intratracheal instillation of mice with lipopolysaccharide (LPS) to trigger a classic animal model for acute lung injury, we intriguingly found that after LPS treatment, F1 and F2 offspring after exposure during pregnancy to CBNPs both exhibited more pronounced lung injury symptoms, including more degenerative histopathological changes, vascular leakage, elevated MPO activity, and activation of inflammation-related signaling transduction, compared with F1 and F2 offspring in the mock group, suggesting PrE to CBNPs would aggravate LPS-induced lung injury in offspring, and this effect was intergenerational. We also observed that PrE to CBNPs upregulated the mRNA expression of DNA methyltransferases (Dnmt) 1/3a/3b and DNA hypermethylation in both F1 and F2 offspring, which might partially account for the intergenerational effect. Together, our study demonstrates for the first time that PrE to CBNPs can enhance sensitivity to LPS in both F1 and F2 offspring, and this intergenerational effect may be related to DNA hypermethylation caused by CBNPs.

Autophagy deficiency exacerbates acute lung injury induced by copper oxide nanoparticles.

Copper oxide nanoparticles (CuONPs) are one of the widely used metal nanoparticles in the industrial and commercial fields. Autophagy is an intracellular degradation system that delivers cytoplasmic constituents to the lysosome and has been linked to nanoparticles-induced toxicity. In particular, the roles of autophagy in response to CuONPs have been explored in vitro, although the conclusions are controversial. To clarify the role of autophagy in CuONPs-induced acute lung injury, microtubule-associated protein 1 light chain 3 beta (Map1lc3b or lc3b) knockout mice and their corresponding wild type mice are applied. Our results showed that single-dose intratracheal instillation of CuONPs with dosages of 1.25, 2.5 or 5 mg/kg caused acute lung injury 3 days after treatment in a dose-dependent manner, as evidenced by deteriorative lung histopathology, more infiltration of macrophage cells, increased oxidative stress and copper ions. Loss of lc3b resulted in aggravated lung injury induced by CuONPs, which was probably due to the blockade of mitophagy and consequently the accumulation of aberrant mitochondria with overloaded copper ions. Our study provides the first in vivo evidence that autophagy deficiency exacerbates CuONPs-induced acute lung injury, and highlights that targeting autophagy is a meaningful strategy against CuONPs-associated respiratory toxicity.

Gas chromatography-mass spectrometry based metabolomics profile of hippocampus and cerebellum in mice after chronic arsenic exposure.

Intake of arsenic (As) via drinking water has been a serious threat to global public health. Though there are numerous reports of As neurotoxicity, its pathogenesis mechanisms remain vague especially its chronic effects on metabolic network. Hippocampus is a renowned area in relation to learning and memory, whilst recently, cerebellum is argued to be involved with process of cognition. Therefore, the study aimed to explore metabolomics alternations in these two areas after chronic As exposure, with the purpose of further illustrating details of As neurotoxicity. Twelve 3-week-old male C57BL/6J mice were divided into two groups, receiving deionized drinking water (control group) or 50 mg/L of sodium arsenite (via drinking water) for 24 weeks. Learning and memory abilities were tested by Morris water maze (MWM) test. Pathological and morphological changes of hippocampus and cerebellum were captured via transmission electron microscopy (TEM). Metabolic alterations were analyzed by gas chromatography-mass spectrometry (GC-MS). MWM test confirmed impairments of learning and memory abilities of mice after chronic As exposure. Metabolomics identifications indicated that tyrosine increased and aspartic acid (Asp) decreased simultaneously in both hippocampus and cerebellum. Intermediates (succinic acid) and indirect involved components of tricarboxylic acid cycle (proline, cysteine, and alanine) were found declined in cerebellum, indicating disordered energy metabolism. Our findings suggest that these metabolite alterations are related to As-induced disorders of amino acids and energy metabolism, which might therefore, play an important part in mechanisms of As neurotoxicity.

[Effect of Benzo [α]pryene and Butylated Hydroxylanisole on Learning and Memory in Rats].

OBJECTIVE: To investigate the neurotoxic effect of benzo[α]pryene (B[α]P) and protective effect of butylated hydroxyl anisole (BHA) on learning and memory in hippocampus of rats. METHODS: Ninety male, SD rats were randomly divided into blank control group, solvent control group, B[α]P exposed group [(2 mg/(kg x d)], BRA group [50 mg/(kg x d)] and B[α]P + BHA combined group. Rats were given the appropriate dose oral treatment according to body mass and group (the same volume of saline and peanut oil were given to blank and solvent control group, respectively) for 90 d. After 90 d exposer, Morris water maze (MWM) was conducted to estimate rats' learning and memory ability. The level of malonaldehyde (MDA), superoxide dismutase (SOD) activity, Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activity and Ca2+ concentration were measured after rats were sacrificed and brain tissue were removed. RESULTS: Behavioral test results showed that the escape latency of B[α]P exposed group were significantly increased than other groups (P < 0.05); however, the number of crossing platform (4.13 ± 0.78) were decreased significant. The level of MDA [( 2.46 ± 0.39) nmol/mg prot.] and Ca2+ concentration [(146.3 ± 16.68) nmol/L] in the B[α]P exposed group increased significant, while the activity of Na(+)-K(+)-ATPase and SOD [(76.1 ± 11.42) nmol/mg prot.] were significantly decreased. Compared with B[α]P group, each index in B[α]P+ BHA combined group improved significantly (P < 0.05), besides, there were no statistically difference when compared with solvent control group. CONCLUSION: The neurotoxic effect of B[α]P may be related to the decrease of ATPase activity and the increase of Ca2+ concentration in hippocampus, while BHA can prevent these damages.

[Vitamin E prevents the toxic effect of benzo(a)pryene on reproductive system in male SD rats].

OBJECTIVE: To investigate the protective effects and the potential mechanisms of vitamin E (VE) on benzo(a)pryene (B[a]P)-induced toxicity in the reproductive system of male rats. 
 METHODS: A total of 60 male Sprague Dawley (SD) rats, weighted 70-90 g, were randomly assigned to 6 groups: a control group, a vehicle group, a B[a]P group (5 mg/kg), a VE (10 mg/kg)+ B[a]P (5 mg/kg) group, a VE (50 mg/kg) + B[a]P (5 mg/kg) group and a VE (100 mg/kg)+B[a]P (5 mg/kg) group (n=10 per group). The rats were treated with B[a]P and/or VE once a day for 30 days via intragastric administration. The sperm quality and the levels of SOD, GSH-Px, 8-OHdG and MDA were detected, respectively. The testicular tissue morphology and DNA damage were observed by HE staining and comet assay.
 RESULTS: The sperm count, the rate of sperm deformation, the content of MDA and 8-OHdG were all significantly increased in single B[a]P-treated group in comparison to the control groups. The activities of SOD and GSH-Px were markedly decreased by B[a]P as compared with the control groups (P<0.05). The injury of testicular tissue in B[a]P-treated rats was remarkably improved after VE treatment. The levels of oxidative stress and DNA damage indicators in the B[a]P-treated group were all attenuated by VE. These protective effects of VE were in a dose-dependent manner (P<0.05).
 CONCLUSION: Vitamin E can protect the male SD rats against the B[a]P-induced reproductive toxicity.

[Effects of benzo(a)pyrene exposure on the ATPase activity and content of Ca²âº in the hippocampus of neonatal SD rats].

OBJECTIVE: To investigate the effect of benzo(α)pyrene on the ATPase activity and content of Ca²âº in the hippocampus of neonatal SD rats. METHODS: Sixty male and 60 female 4-days-old neonatal SD rats were randomly divided into 5 groups (n=24): a blank control group, a vehicle control group (peanut oil), 3 benzo(α)pyrene groups (0.02, 0.2 and 2 mg/kg, respectively). SD rats were given benzo(α)pyrene (dissolved in peanut oil) by gavage daily from postnatal day 4 (PND4) to PND20. The nerve reflex, the condition of neuro-muscle development and motion function were examined in the period of treatment. The colorimetric technique was used to detect the activity of Ca²âº-ATPase and Ca²âº-Mg²âº-ATPase in hippocampus after the treatment. The concentration of Ca²âº of synapse in the hippocampus of rats was detected by fluorescent labeling. RESULTS: The results from the behavior tests showed that duration of surface reflex latency in rats with medium dose of benzo(α)pyrene was longer compared with that in the control group in PND12. The duration of surface reflex latency in rats with high dose of benzo(α) pyrene is longer in PND 14 and PND 16 compared with that in the control group (P<0.05). Compared with the rats in the control group, the activities of Ca²âº-Mg²âº-ATPase and Ca²âº-ATPase in hippocampus in rats with high dose benzo(α) pyrene were significantly decreased, and the degree in the decrease of Ca²âº-ATPase activity was dose-dependent (P<0.05). The contents of Ca²âº in the hippocampus in rats with medium or high dose of benzo(α) pyrene were significantly increased compared with that in the control group (P<0.05), which showed a dose-dependent manner (P<0.05). CONCLUSION: Benzo(α)pyrene exposure led to the decrease in ATPase activity as well as Ca²âº overload of the synapse in the hippocampal tissue, which in turn results in the nerve damage of newborn SD rats.

The effect of occupational exposure to benzo[a]pyrene on neurobehavioral function in coke oven workers.

BACKGROUND: Coke oven workers are regularly exposed to polycyclic aromatic hydrocarbons (PAHs). Benzo[a]pyrene (B[a]P), known as an indicator species for PAH contamination, is a neurobehavioral toxicant. The purpose of the study was to evaluate the relationship between B[a]P exposure, a B[a]P-related urinary metabolite and neurobehavioral function among coke oven workers. METHODS: Coke oven workers and oxygen factory workers participated in this study. B[a]P exposure was monitored by air sampling pump, and urinary 1-hydroxypyrene (1-OHP) level was detected with high performance liquid chromatography (HPLC). A questionnaire and the neurobehavioral core test battery (NCTB) were administered to all subjects. RESULTS: B[a]P-exposed workers were found to have higher urinary 1-OHP levels and worse NCTB performances on eight items than control workers. B[a]P concentrations were higher in the coke oven plant than that in the controls' workplace. The performances on simple reaction time, correct pursuit aiming, and error pursuit aiming decreased with increasing airborne B[a]P in coke oven workers. There were significant correlations between urinary 1-OHP level and six items of the NCTB. CONCLUSIONS: Occupational exposure to B[a]P is associated with neurobehavioral function impairment in coke oven workers.

[Effects of benzo(a)pyrene exposure on oxidative stress and ATPase in the hippocampus of rats].

OBJECTIVE: To investigate the effects of benzo[a]pyrene (B[a]P) exposure on the behaviors and hippocampal oxidative stress and ATPase in rats and the molecular mechanism of neurobehavioral toxicity of B[a]P. METHODS: A total of 120 male SD rats (21 days old) were randomly and equally assigned to five groups: blank control group, vegetable oil (solvent control) group, and 2.5, 5, and 10 mg/kg B[a]P exposure groups. The rats in B[a]P exposure groups were injected intraperitoneally with B[a]P once a day for 4 consecutive weeks. Then, Morris water maze and shuttle box were used to evaluate the learning and memory abilities of rats; colorimetric assay was used to measure the activities of superoxide dismutase (SOD), Na(+)/K(+)-ATPase, and Ca(2+)/Mg(2+)-ATPase and the content of malonaldehyde (MDA) in the hippocampus; the concentration of Ca(2+) in the hippocampus was measured by fluorescent labeling. RESULTS: Compared with the blank control group and solvent control group, the B[a]P exposure groups exhibited significant increases in escape latency, active avoidance response latency, and passive avoidance response latency and significant decreases in number of platform crossings and active avoidance response frequency in the last test (P < 0.05 for all comparisons), with a dose-effect relationship. In addition, the B[a]P exposure groups had significantly lower activities of SOD, Na(+)/K(+)-AT-Pase, and Ca(2+)/Mg(2+)-ATPase and significantly higher MDA level and Ca(2+) concentration than the blank control group and solvent control group (P < 0.05 for all comparisons), with a dose-effect relationship. CONCLUSION: The neurobehavioral toxicity of B[a]P may be related to increased oxidative stress and decreased activities of Na(+)/K(+)-ATPase and Ca(2+)/Mg(2+)-ATPase in the hippocampus of rats.

Results of a 30-day safety assessment in young mice orally exposed to polystyrene nanoparticles.

Polystyrene nanoparticles (PSNPs) are a newly emerging pollutant in the natural environment. However, due to the lack of sufficient toxicological studies in mammals, the potential effects of PSNPs on human health remain largely undefined. Therefore, in this study, young mice aged four weeks old were subjected to oral administration of 0, 0.2, 1, or 10 mg/kg PSNPs for 30 days. Our results demonstrated for the first time that oral exposure to PSNPs affected the expressions of mucus secretion-related genes and altered the community composition of intestinal microbiota, although this treatment did not cause behavioral impairments in young mice. No significant alterations in inflammatory or oxidative stress-related indicators were observed in the liver, lung, intestine, cortex or serum of PSNPs-treated animals. Moreover, exposure to PSNPs did not cause pathological changes in the liver, lung, or cortex tissues. Notably, although oral administration of PSNPs did not produce obvious toxic effects in the major organs of young mice, the possible toxicity of PSNPs remains unresolved and it may depend on the dose, exposure route and species. The potential hazardous effects of PSNPs still need to be systematically assessed, especially for children who are susceptible to exposure to nanoparticles.

Modulation of behavior and glutamate receptor mRNA expression in rats after sub-chronic administration of benzo(a)pyrene.

OBJECTIVE: The present study aimed to test whether exposure to benzo(a)pyrene [B(a)P] affects spatial learning and short-term memory by modulating the expression of the Gria1 and Grin2a glutamate receptor subunit genes in the hippocampus. METHODS: Thirty-six 21-24-day-old, male rats were randomly assigned into high-, medium-, and low-dose toxin exposure groups (6.25, 2.5, and 1 mg/kg, respectively) and a control group, each containing nine rats. The behavioral performance of adult rats exposed to sub-chronic administration of B(a)P was monitored by learning and memory tests (Morris water maze). Real-time PCR assays were used to quantify Gria1 and Grin2a gene expression in the hippocampus. RESULTS: At medium and high doses, B(a)P impaired spatial learning performance. The crossing-platform-location frequency and the time spent swimming in the platform area, which both relate to short-term memory, were significantly decreased in B(a)P-treated rats compared with controls. The level of Gria1 mRNA increased 2.6-5.9-fold, and the level of Grin2a mRNA increased 10-14.5-fold, with a greater fold increase associated with higher doses of B(a)P. CONCLUSION: We demonstrated that sub-chronic administration of B(a)P inhibits spatial learning and short-term memory, and increases Gria1 and Grin2a expression in the hippocampus. This suggests a relationship of B(a)P exposure levels with Gria1 and Grin2a expression and impairment of short-term and spatial memory.

Pulmonary Exposure to Copper Oxide Nanoparticles Leads to Neurotoxicity via Oxidative Damage and Mitochondrial Dysfunction.

Copper oxide nanoparticles (CuONPs) are widely used in pharmaceutical, food, and textile industries. They have been shown to cause lung, liver, and kidney damage. However, whether an intratracheal instillation of CuONPs would affect the brain and its underlying mechanisms remain poorly studied. In this study, healthy C57BL/6J male mice were equally subdivided into control group, low-dose (30 µg/animal), medium-dose (50 µg/animal), and high-dose (100 µg/animal) CuONPs-treated groups. Mice were subjected to acute exposure of CuONPs via intratracheal instillation. Brain histopathology, inflammatory factors, oxidative stress markers, and mitochondrial function-related protein expression were determined. Our results demonstrated that CuONPs caused a dose-dependent brain damage in mice. Histopathological changes in the brain, elevation of inflammatory factors (Tnf, Il-6), and significant alterations in oxidative stress markers were also observed after treatment with CuONPs. Intriguingly, we did not observe infiltration of macrophage cell. Moreover, Tim23, TFAM, and MFN2 protein expression levels showed the decreasing trend after treatment with CuONPs. Taken together, these results indicate that pulmonary exposure to CuONPs induces pathological damage, inflammation, oxidative stress, and mitochondrial dysfunction in the cerebral cortex, suggesting that neurotoxicity caused by pulmonary exposure of CuONPs needs more attention from the public and relevant departments.

Arsenite induces ferroptosis in the neuronal cells via activation of ferritinophagy.

Ferroptosis is a novel form of cell death that involves in the pathophysiological process of diverse brain diseases. However, how arsenite induces ferroptosis in the neuronal cells remains unsolved. In this study, by using in vitro and in vivo models, we demonstrated that arsenite was able to trigger ferroptosis in the neuronal cells. Exposure of arsenite for 6 months at 0.5, 5 and 50 mg/L arsenite via drinking water significantly reduced the number of neurons and caused the pathological changes in the mitochondria of hippocampus. Treatment of arsenite elevated the contents of lipid peroxidation products, disrupted the iron homeostasis, altered the expressions of ferroptosis-related proteins in the hippocampus and PC-12 cells. The results also showed that arsenite significantly decreased the expressions of ferritin and NCOA4, but sharply enhanced the level of autophagy marker LC3B, suggesting the activation of ferritinophagy by arsenite. Co-treatment of arsenite with ferroptosis inhibitor ferrostatin-1, or autophagy inhibitors 3-MA and BafA1, all remarkably attenuated the cytotoxic effects of arsenite. These findings not only present a novel mechanism that arsenite triggers ferroptosis in the neuronal cells via activation of ferritinophagy, but also indicate that regulating ferritinophagy to control iron level may provide a clue for prevention against arsenite neurotoxicity.

Lysosomal dysfunction is associated with persistent lung injury in dams caused by pregnancy exposure to carbon black nanoparticles.

AIMS: Carbon black nanoparticles (CBNPs) are widely used in industrial field. Sensitive stages such as pregnancy are assumed to be more susceptible to stimulus, however whether pregnancy exposure to CBNPs (PrE-to-CBNPs) would cause long-term toxic effects in dams and the underlying mechanisms remain poorly addressed. The present study is aimed to determine the long-term toxic effects of PrE-to-CBNPs in dams. MATERIALS AND METHODS: The pregnant mice were randomly divided into control group, low (21 µg/animal), medium (103 µg/animal) and high (515 µg/animal) CBNPs-treated groups. From gestational day (GD) 9 to GD18, the pregnant mice were intranasal exposed. At 49 days after parturition, lung tissues and bronchoalveolar lavage fluid (BALF) were obtained. Weight change, lung histopathology, lung ultrastructural pathology, cell count in BALF, oxidative stress/inflammatory maker and autophagy/lysosome-related protein expression were determined. KEY FINDINGS: PrE-to-CBNPs caused a dose-dependent persistent lung injury in mice even 49 days after parturition, including the deteriorative lung histopathological changes, elevation of oxidative stress marker Nrf-2, HO-1 and CHOP, infiltration of macrophage and increased mRNA expression of inflammatory cytokines in the lung tissues and elevation of cells in BALF. However, PrE-to-CBNPs did not induce significant neutrophil infiltration and fibrosis. Moreover, we found that CBNPs could deposit in the lysosomes and decrease cathepsin D (an important hydrolase in lysosome), which might be associated with the dysfunction of lysosome and autophagy. SIGNIFICANCE: Our study demonstrated that PrE-to-CBNPs could result in long-term lung injury in dams, and lysosomal dysfunction was probably linked to this process.

Synaptic dopamine release is positively regulated by SNAP-25 that involves in benzo[a]pyrene-induced neurotoxicity.

Benzo[a]pyrene (B[a]P) is a ubiquitous neurotoxic pollutant that widely distributes in the natural environment. However, the exact mechanism of B[a]P-induced neurotoxicity has not been well established. As one key synaptic protein, SNAP-25 plays an important role in the regulation of neurotransmitter release, including synaptic dopamine release. In this study, we demonstrated that, after intragastric administration of B[a]P in rats aged postnatal day 5 for 7 weeks, B[a]P significantly increased the level of dopamine and the expression of SNAP-25, dopamine receptor 1 (DRD1) and DRD 3. Moreover, treatment of B[a]P also caused the ultra-structural pathological changes in the cerebral cortex of rats. To further reveal the potential role of SNAP-25 in the regulation of DRDs, we treated the dopaminergic PC-12 cells with 20 µM B[a]P for 24 h. A significant cytotoxicity and apoptosis were observed, and more importantly, we found that SNAP-25, DRD 1 and DRD 3 co-localized in the cells, and down-regulation of SNAP-25 by CRISPR-Cas9 plasmid remarkably reduced the expression of DRD1 and DRD3. Together, our findings suggest that, synaptic dopamine release may be positively regulated by SNAP-25 via its receptors, and thus affecting the neurotoxicity induced by B[a]P.

Exposure to carbon black nanoparticles during pregnancy persistently damages the cerebrovascular function in female mice.

Maternal exposure to carbon black nanoparticles (CBNPs) during pregnancy have been well documented to induce harmful outcomes of offspring on brain function. However, it remains largely unknown whether females exposed to CBNPs during sensitive period of pregnancy can cause the neurotoxic effects on their own body after parturition. In this study, our results showed that pregnancy CBNPs exposure induced the persistent pathological changes in the cerebral cortex tissues and impaired cerebrovascular function of mice manifested by significant alterations of endothelin-1, endothelial nitric oxide synthase, vascular endothelial growth factor-A and ATP-binding cassette transporter G1. Intriguingly, we observed that these deleterious effects on brain and cerebrovascular functions in mice could persist for 49 days after delivery of pups. By using in vitro human umbilical vein endothelial cells, we further verified the potential vascular dysfunction after CBNPs exposure. In summary, our results provide the first evidence that pregnancy CBNPs exposure-induced brain pathological changes and cerebrovascular dysfunction can persist for a relative long time. These finding suggest exposure to CBNPs during sensitive stages of pregnancy may not only show the harmful effects on offspring neurodevelopment, but also result in the irreversible brain damage on mother body.

[Changes of cerebral cortical metabolomics in rats following benzo[a]pyrene exposure].

OBJECTIVE: To analyze the changes in endogenous small molecule metabolites after benzo[a]pyrene (B[a]P) exposure in rat cerebral cortex and explore the mechanism of B[a]P neurotoxicity. METHODS: Five-day-old SD rats were subjected to gavage administration of 2 mg/kg B[a]P for 7 consecutive weeks. After the exposure, the rats were assessed for spatial learning ability using Morris water maze test, ultrastructural changes of the cortical neurons under electron microscope, and metabolite profiles of the cortex using GC/MS. The differential metabolites between the exposed and control rats were identified with partial least squares discriminant analysis (PLS-DA) and the metabolic pathways related with the differential metabolites were analyzed using Cytoscape software. RESULTS: Compared with the control group, the rats exposed to B[a]P showed significantly increased escape latency (P<0.05) and decreased time spent in the target area (P<0.05). The exposed rats exhibited widened synaptic cleft, thickened endplate membrane and swollen cytoplasm compared with the control rats. Eighteen differential metabolites (VIP>1, P<0.05) in the cortex were identified between the two groups, and 9 pathways associated with B[a]P neurotoxicity were identified involving amino acid metabolism, tricarboxylic acid cycle and Vitamin B3 (niacin and nicotinamide) metabolism. CONCLUSION: B[a]P can cause disturbance in normal metabolisms and its neurotoxicity is possibly related with disorders in amino acid metabolism, tricarboxylic acid cycle and vitamin metabolism.

Postnatal Subacute Benzo(a)Pyrene Exposure Caused Neurobehavioral Impairment and Metabolomic Changes of Cerebellum in the Early Adulthood Period of Sprague-Dawley Rats.

Benzo(a)pyrene (BaP) is a widespread environmental contaminant that has been associated with neurotoxicity in mammals. It has strong toxic effects on the developing central nervous system. Cerebellum is associated with locomotor activity and anxiety behavior, but there is very little research about the toxic effects of BaP in cerebellum. The present study aims to investigate the global influence of BaP subacute exposure on the metabolome of rat cerebellum. Male neonatal rats (postnatal day 5) were divided into two groups: control group and BaP-treated group (2 mg/kg/day for 7 weeks). Open field test and transmission electron microscopy were performed to analyze neurobehavior and ultramicrostructure alteration. Gas chromatography-mass spectrometry (GC-MS) was used to analyze metabolites of the cerebellum in both groups. The results revealed that postnatal exposure to BaP promoted pathological changes in the cerebellum and increased locomotor and anxiety activities in early adulthood. Twenty differential significant metabolites were identified by multivariate statistical analysis. Further metabolic pathway impact analysis and network analysis suggested that the primary metabolic pathways affected included pathway involved in energy metabolism, methionine and cysteine metabolism, and glutathione metabolism. These findings suggest that BaP-induced cerebellum injury may be correlated with metabolic changes and provide an area to target to reduce the negative effects of BaP.

Integrated Epigenetics, Transcriptomics, and Metabolomics to Analyze the Mechanisms of Benzo[a]pyrene Neurotoxicity in the Hippocampus.

Benzo[a]pyrene (B[a]P) is a common environmental pollutant that is neurotoxic to mammals, which can cause changes to hippocampal function and result in cognitive disorders. The mechanisms of B[a]P-induced impairments are complex .To date there have been no studies on the association of epigenetic, transcriptomic, and metabolomic changes with neurotoxicity after B[a]P exposure. In the present study, we investigated the global effect of B[a]P on DNA methylation patterns, noncoding RNAs (ncRNAs) expression, coding RNAs expression, and metabolites in the rat hippocampus. Male Sprague Dawley rats (SD rats) received daily gavage of B[a]P (2.0 mg/kg body weight [BW]) or corn oil for 7 weeks. Learning and memory ability was analyzed using the Morris water maze (MWM) test and change to cellular ultrastructure in the hippocampus was analyzed using electron microscope observation. Integrated analysis of epigenetics, transcriptomics, and metabolomics was conducted to investigate the effect of B[a]P exposure on the signaling and metabolic pathways. Our results suggest that B[a]P could lead to learning and memory deficits, likely as a result of epigenetic and transcriptomic changes that further affected the expression of CACNA1C, Tpo, etc. The changes in expression ultimately affecting LTP, tyrosine metabolism, and other important metabolic pathways.

m6A Demethylase FTO Regulates Dopaminergic Neurotransmission Deficits Caused by Arsenite.

Arsenite exposure is known to increase the risk of neurological disorders via alteration of dopamine content, but the detailed molecular mechanisms remain largely unknown. In this study, using both dopaminergic neurons of the PC-12 cell line and C57BL/6J mice as in vitro and in vivo models, our results demonstrated that 6 months of arsenite exposure via drinking water caused significant learning and memory impairment, anxiety-like behavior and alterations in conditioned avoidance and escape responses in male adult mice. We also were the first to reveal that the reduction in dopamine content induced by arsenite mainly resulted from deficits in dopaminergic neurotransmission in the synaptic cleft. The reversible N6- methyladenosine (m6A) modification is a novel epigenetic marker with broad roles in fundamental biological processes. We further evaluated the effect of arsenite on the m6A modification and tested if regulation of the m6A modification by demethylase fat mass and obesity-associated (FTO) could affect dopaminergic neurotransmission. Our data demonstrated for the first time that arsenite remarkably increased m6A modification, and FTO possessed the ability to alleviate the deficits in dopaminergic neurotransmission in response to arsenite exposure. Our findings not only provide valuable insight into the molecular neurotoxic pathogenesis of arsenite exposure, but are also the first evidence that regulation of FTO may be considered as a novel strategy for the prevention of arsenite-associated neurological disorders.

Effects of benzo(a)pyrene exposure on the ATPase activity and calcium concentration in the hippocampus of neonatal rats.

OBJECTIVES: To investigate whether postnatal benzo(a)pyrene (B(a)P) exposure caused the impairments on the process of neurodevelopment and the alteration in the calcium medium in the neonatal rats. MATERIAL AND METHODS: Eighty neonatal Sprague Dawley (SD) rats were randomly divided into 5 groups (untreated control group, vehicle group, 0.02 mg/kg, 0.2 mg/kg and 2 mg/kg B(a)P-exposed group). Rats were treated with B(a)P by the intragastric administration from postnatal day (PND) 4 to 25. Morris water maze (MWM) was employed to observe the spatial memory of rats. The activity of calcium adenosine triphosphatase (Ca2+-ATPase), sodium-potassium adenosine triphosphatase (Na+-K+-ATPase) and calcium-magnesium adenosine triphosphatase (Ca2+-Mg2+-ATPase) in the hippocampus were detected by commercial kits. Fura-2 pentakis(acetoxymethyl) (Fura-2/AM) probe and reactive oxygen species (ROS) reagent kit were used for measuring the concentration of Ca2+ and ROS in the hippocampus synapse, respectively. RESULTS: Rats exposed to B(a)P resulted in the deficits in the spatial memory manifested by the increased escape latency and decreased number of crossing platform and time spent in target quadrant in comparison with the control groups. Benzo(a)pyrene exposure caused the significant decrease in the ATPase activity in the hippocampus and caused Ca2+ overload in the synaptic, besides, the ROS concentration increased significantly which may further induce neurobehavioral impairment of the neonatal rats. CONCLUSIONS: Our findings suggest that postnatal B(a)P exposure may cause the neurobehavioral impairments in the neonatal rats, which were mediated by the decreased ATPase activity and elevated Ca2+ concentration. Int J Occup Med Environ Health 2017;30(2):203-211.