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

The aryl hydrocarbon receptor (AhR) activation mediates benzo(a)pyrene-induced overexpression of AQP3 and Notch1 in HaCaT cells

The aim of this study was twofold: (1) evaluate the effect of benzo[a]pyrene (BaP) on expression levels of AQP3 and Notch1 genes in HaCaT cells exposed "in vitro" and (2) investigate the possible biological role of assessed genes by bioinformatics methods. Cells were exposed to increasing concentrations of BaP (0.0-4.0 μM) for 1-4 days. After treatments, cell viability and expression levels of AhR, CYP1A1, AQP3, and Notch1 genes were evaluated. The possible biological role of assessed genes was evaluated using bioinformatics tools. Low cytotoxicity in HaCaT cells dosed with BaP was detected. A significant overexpression (p < .05) of CYP1A1, AQP3, and Notch1 was found in exposed HaCaT cells. The gene expression upregulation was dependent on AhR activation. The bioinformatics analysis showed that these genes were enriched in related cancer signaling pathways. The findings suggest that AQP3 and Notch1 are upregulated by AhR activation in HaCaT cells exposed to BaP.

Targeted metabolomics analysis identified the role of FOXA1 in the change in glutamate-glutamine metabolic pattern of BaP malignantly transformed 16HBE cells

The carcinogenic mechanism of benzo[a]pyrene (BaP) is far from being elucidated. FOXA1 has been confirmed to play an oncogenic role in BaP-transformed cell THBEc1. To explore the changes in amino acid metabolic patterns, especially glutamate-glutamine (Glu-Gln) metabolic pattern caused by BaP-induced transformation and the possible role FOXA1 might play in it, we compared amino acid metabolic characteristics between THBEc1 cells and control 16HBE cells using a targeted metabolomics method and determined the effects of FOXA1 knockout on the amino acid metabolic pattern using FOXA1 knockout cell THBEc1-ΔFOXA1-c34. The amino acid metabolic patterns of THBEc1 and 16HBE cells were different, which was manifested by the differential consumption of 18 amino acids and the difference in the intracellular content of 21 amino acids. The consumption and intracellular content of Glu and Gln are different between the two types of cells, accompanied by upregulation of FOXA1, GLUL, SLC1A3, SLC1A4, SLC1A5 and SLC6A14, and downregulation of FOXA2 and GPT2 in THBEc1 cells. FOXA1 knockout changed the consumption of 19 amino acids and the intracellular content of 21 amino acids and reversed the metabolic pattern of Glu and the changes in FOXA2, GLUL, SLC1A3 and SLC6A14 in THBEc1 cells. Additionally, FOXA1 knockout inhibited cell proliferation and further increased the dependence of THBEc1 cells on Glu. In conclusion, FOXA1 knockout partially reversed the change in Glu-Gln metabolism caused by BaP-induced transformation by upregulating the expression of GLUL and SLC1A3. Our findings provide a clue for the possible role of FOXA1 in amino acid metabolism regulation.

Prenatal benzo[a]pyrene exposure impairs hippocampal synaptic plasticity and cognitive function in SD rat offspring during adolescence and adulthood via HDAC2-mediated histone deacetylation

Benzo[a]pyrene (B[a]P) is a widespread carcinogenic pollutant in the environment. Although previous studies have demonstrated the neurodevelopmental toxicity of B[a]P, the precise mechanisms underlying the neurotoxic effects induced by prenatal B[a]P exposure remain largely unknown. In the present study, pregnant Sprague-Dawley (SD) rats were injected intraperitoneally with 0, 10, 20, or 40 mg/kg-bw of B[a]P for three consecutive days on embryonic days 17-19. The learning and memory abilities of offspring were determined by Morris Water Maze (MWM) test, while the number of dendritic branches and the density of dendritic spines in hippocampal CA1 and DG regions were evaluated by Golgi-Cox staining at PND 45 and PND 75. The mRNA expression of BDNF, PSD-95, and SYP in offspring hippocampus were detected by qRT-PCR, and the protein expression of BDNF, PSD-95, SYP, HDAC2, acH3K9, and acH3K14 were measured by Western blotting or immunohistochemistry. CHIP-PCR was performed to further detect the levels of acH3K9 and acH3K14 in the promoter regions of BDNF and PSD-95 genes. Our results showed that rats prenatally exposed to B[a]P exhibited impaired spatial learning and memory abilities and the number of dendritic branches and the density of dendritic spines in the hippocampal CA1 and DG regions were significantly reduced during adolescence and adulthood. The expression of HDAC2 protein was significantly upregulated, while acH3K9, acH3K14, BDNF, PSD-95, and SYP protein levels were significantly downregulated in the hippocampus of B[a]P- exposed rats. In addition, CHIP results showed that prenatal B[a]P exposure markedly decreased the level of acH3K9 and acH3K14 in the promoter region of BDNF and PSD-95 gene in the hippocampus of PND 45 and PND 75 offspring. All of the results suggest that prenatal B[a]P exposure impairs cognitive function and hippocampal synaptic plasticity of offspring in adolescence and adulthood, and HDAC2-mediated histone deacetylation plays a crucial role in these deficits.

Exploring the Muscle Metabolomics in the Mouse Model of Sepsis-Induced Acquired Weakness

Background/Aim

We aimed to identify the differentially expressing metabolites (DEMs) in the muscles of the mouse model of sepsis-induced acquired weakness (sepsis-AW) using liquid chromatography-mass spectrometry (LC-MS).

Materials and Methods

Sepsis by cecal ligation puncture (CLP) with lower limb immobilization was used to produce a sepsis-AW model. After this, the grip strength of the C57BL/6 male mice was investigated. The transmission electron microscopy was utilized to determine the pathological model. LC-MS was used to detect the metabolic profiles within the mouse muscles. Additionally, a statistically diversified analysis was carried out.

Results

Compared to the sepsis group, 30 DEMs, including 17 upregulated and 13 down-regulated metabolites, were found in the sepsis-AW group. The enriched metabolic pathways including purine metabolism, valine/leucine/isoleucine biosynthesis, cGMP-PKG pathway, mTOR pathway, FoxO pathway, and PI3K-Akt pathway were found to differ between the two groups. The targeted metabolomics analysis explored significant differences between four amino acid metabolites (leucine, cysteine, tyrosine, and serine) and two energy metabolites (AMP and cAMP) in the muscles of the sepsis-AW experimental model group, which was comparable to the sepsis group.

Conclusion

The present work identified DEMs and metabolism-related pathways within the muscles of the sepsis-AW mice, which offered valuable experimental data for diagnosis and identification of the pathogenic mechanism underlying sepsis-AW.

Associations between household incense burning and delayed motor development among preterm infants modified by gestational age and maternal educational status

BACKGROUND

Household incense burning is a common ritual behavior in the Asia-Pacific region but has been associated with inferior developmental outcomes in term infants. We aimed to examine these associations among preterm infants.

METHODS

Information from 1190 mother-infant pairs during 6- and 18-month follow-up to the Taiwan Birth Cohort Study was examined for associations between household incense burning exposure and infant neurodevelopmental milestone achievement using multivariable Cox proportional hazard model with propensity score weighting, along with stratified, sensitivity, and decomposition analysis.

RESULTS

Household incense burning exposure was associated with delayed gross motor milestone achievement among all preterm infants according to the Cox model and after propensity score weighting. Meanwhile, associations for delayed development were found in gross motor domain milestones among late preterm infants, while fine motor domain delay was found among other preterm infants. Furthermore, the associations between household incense burning status and gross motor milestone delays were attenuated by the interaction between higher education level and household incense burning exposure status.

CONCLUSIONS

Household incense burning exposure was associated with delays, and the motor domains affected differed according to degree of prematurity. These associations were modified by the attenuation upon higher maternal educational status and exposure status interaction.

Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades. Metabolomics, a functional readout of cellular activity, can capture organismal responses to various contaminant-related stressors, acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better. This review entails the application of metabolomics to profile metabolic responses of environmental organisms, e.g. animals (rodents, fish, crustacean and earthworms) and microorganisms (bacteria, yeast and microalgae) to different anthropogenic contaminants, including heavy metals, nanomaterials, pesticides, pharmaceutical and personal products, persistent organic pollutants, and assesses their ecotoxicological impacts with regard to literature published in the recent five years. Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms. The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms. Thus with a novel ecotechnique of environmental metabolomics, risk assessments of anthropogenic contaminants are profoundly demonstrated.

Benzo[a]pyrene injures BMP2-induced osteogenic differentiation of mesenchymal stem cells through AhR reducing BMPRII

Benzo[a]pyrene(BaP), a polycyclic aromatic hydrocarbons (PAH) of environmental pollutants, is one of the main ingredients in cigarettes and an agonist of the aryl hydrocarbon receptor (AhR). Mesenchymal stem cells (MSCs) including C3H10T1/2 and MEF cells, adult multipotent stem cells, can be differentiated toward osteoblasts during the induction of osteogenic induction factor-bone morphogenetic protein 2(BMP2). Accumulating evidence suggests that BaP decreases bone development in mammals, but the further mechanisms of BaP on BMP2-induced bone formation involved are unknown. Here, we researched the role of BaP on BMP2-induced osteoblast differentiation and bone formation. We showed that BaP significantly suppressed early and late osteogenic differentiation, and downregulated the runt-related transcription factor 2(Runx2), osteocalcin(OCN) and osteopontin (OPN) during the induction of BMP2 in MSCs. Consistent with in vitro results, administration of BaP inhibited BMP2-induced subcutaneous ectopic osteogenesis in vivo. Interestingly, blocking AhR reversed the inhibition of BaP on BMP2-induced osteogenic differentiation, which suggested that AhR played an important role in this process. Moreover, BaP significantly decreased BMP2-induced Smad1/5/8 phosphorylation. Furthermore, BaP significantly reduced bone morphogenetic protein receptor 2(BMPRII) expression and excessively activated Hey1. Thus, our data demonstrate the role of BaP in BMP2-induced bone formation and suggest that impaired BMP/Smad pathways through AhR regulating BMPRII and Hey1 may be an underlying mechanism for BaP inhibiting BMP2-induced osteogenic differentiation.

Sub-chronic administration of benzo[a]pyrene disrupts hippocampal long-term potentiation via inhibiting CaMK II/PKC/PKA-ERK-CREB signaling in rats

Benzo[a]pyrene (B[a]P) is recognized as a neurotoxic pollutant to mammals, which could impair learning and memory function. Although there is some evidence to suggest that N-methyl-d-aspartate receptor (NMDAR), a glutamate receptor and ion channel protein in nerve cells, is involved into the B[a]P induced neurotoxicity, the exact molecular mechanisms remain to be elucidated, particularly the effects of B[a]P on the NMDAR downstream signaling transduction pathways. In the present study, we examined the neurotoxicity of sub-chronic administrated B[a]P on male Sprague-Dawley rats. Our data suggested that B[a]P exposure caused significant deficits in learning and memory function and the impairment of hippocampal LTP in rats. Further mechanistic studies indicate that B[a]P-induced learning and memory deficits are associated with the inhibition of NMDAR NR1 subunit transcription and protein phosphorylation. More importantly, the inactivation of CaMK II/PKC/PKA-ERK-CREB signaling pathways in hippocampus was detected at both the 2.5 and 6.25 mg/kg B[a]P-treated groups, indicating that multiple targets in NMDAR and downstream signaling pathways are involved in the B[a]P-induced neurotoxicity.

Resveratrol ameliorates disorders of mitochondrial biogenesis and mitophagy in rats continuously exposed to benzo(a)pyrene from embryonic development through adolescence

Exposure to benzo(a)pyrene (BaP) is associated with poor neurodevelopment in children and memory impairment in adults. Previous research has demonstrated that mitochondrial damage plays an important role in BaP-induced neurotoxicity. Of interest, increasing evidence has suggested that resveratrol (RSV) can alleviate nerve cell damage, however the exact mechanisms of biological activity in mitochondria are not fully understood. In the current study, Wistar rats were exposed to BaP (1, 2, 4 mg/kg) and/or RSV (15, 30 mg/kg) during embryonic development and adolescence, and learning and memory ability, mitochondrial damage, and the expression of proteins associated with mitochondrial biogenesis and mitophagy were evaluated. These studies indicated that 2 and 4 mg/kg BaP could induce disorders of mitochondrial biogenesis and mitophagy, which leads to abnormal nerve cell development. However, pretreatment with 30 mg/kg RSV alleviated cell damage and the disorder of mitochondrial biogenesis by activating the AMPK/PGC-1α signaling pathway and promoting mitophagy. These findings suggested that RSV had utility in promoting mitochondrial homeostasis against BaP-induced nerve cell damage in the hippocampus of rats.

Bacopa monnieri inhibits apoptosis and senescence through mitophagy in human astrocytes

Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon, is a potent neurotoxic agent that is responsible for impaired neuronal development and is associated with aging. Here, it was demonstrated that extracts of Bacopa monnieri (BM), a traditional Ayurvedic medicine, diminished the B[a]P-induced apoptosis and senescence in human astrocytes. BM was demonstrated to protect the immortalized primary fetal astrocytes (IMPHFA) from B[a]P-induced apoptosis and senescence by reducing the damaged mitochondria that produced reactive oxygen species (ROS). Furthermore, it was shown that B[a]P-triggered G2 arrest could be altered by BM, thus indicating that BM could reverse the cell cycle arrest and mediate a normal cell cycle in IMPHFA cells. In addition, the lifespan of Caenorhabditis elegans was assessed, which confirmed these effects in the presence of BM, compared to the B[a]P-treated group. Furthermore, the anti-senescence and anti-apoptotic activities of BM were observed to be mediated through the protective effect of mitophagy, and inhibition of mitophagy could not protect the astrocytes from mitochondrial ROS-induced apoptosis and senescence in BM-treated cells. Moreover, it was revealed that BM induced Parkin-dependent mitophagy to exert its cytoprotective activity in IMPHFA cells. In conclusion, the anti-senescence and anti-apoptotic effects of BM in astrocytes could combat pollution and aging-related neurological disorders.

Lactational exposure to environmentally relevant benzo(a)pyrene causes astrocytic activation and anxiety-like behavior in male mice

Previous studies have shown the adversely neurodevelopmental effects of exposure to benzo(a)pyrene (BaP) at early life stage. However, it is unclear the effects of lactational exposure to environmentally relevant BaP on anxiety-like behavior and the molecular mechanisms related. In this study, lactational exposure to 1 and 10 μg/kg bw BaP from postnatal day 3-21 caused anxiety-like behavior and alterations of the expressions of the neurodevelopment and anxiety-related genes in adolescence male mice using O cycle maze. Moreover, BaP exposure increased the expression level of glial fibrillary acidic protein, a typical marker of astrocytes, in hippocampus of male offspring. The release of pro-inflammatory cytokines interleukin 6 and tumor necrosis factor α was also elevated in BaP-treated offspring. Further, lactational exposure to BaP decreased the level of glutathione and the expressions of antioxidant genes (Thioredoxin 1 and Glutaredoxin 2) in male offspring. Our study demonstrated that environmentally relevant BaP lactational exposure caused anxiety-like behavior in male offspring involved in astrocytic activation, neuroinflammation, and antioxidant capability dysfunction.

Benzo(a)pyrene degradation by cytochrome P450 hydroxylase and the functional metabolism network of Bacillus thuringiensis

The relationship between benzo(a)pyrene biodegradation and certain target biomolecules has been investigated. To regulate the degradation process, the associated metabolism network must be clarified. To this end, benzo(a)pyrene degradation, carbon substrate metabolism and exometabolomic mechanism of Bacillus thuringiensis were analyzed. Benzo(a)pyrene was degraded through hydroxylation catalyzed by cytochrome P450 hydroxylase. After the treatment of 0.5 mg L^-1 of benzo(a)pyrene by 0.2 g L^-1 of cells for 9 d, biosorption and degradation efficiencies were measured at approximately 90% and 80%, respectively. During this process, phospholipid synthesis, glycogen, asparagine, arginine, itaconate and xylose metabolism were significantly downregulated, while glycolysis, pentose phosphate pathway, citrate cycle, amino sugar and nucleotide sugar metabolism were significantly upregulated. These findings offer insight into the biotransformation regulation of polycyclic aromatic hydrocarbons.