Inihibition of mullet (M. liza) brain acetylcholinesterase activity by in vitro polycyclic aromatic hydrocarbon exposure

Integrating pollutant levels and biochemical biomarkers in oysters (Crassostrea rhizophorae and Crassostrea gasar) indicates anthropic impacts on marine environments along the coast of Santa Catarina state, Brazil

This study aimed to carry out a general diagnosis of the contamination of the coastal marine environment of the Santa Catarina state (SC, Brazil) by different classes of environmental pollutants, as well as to evaluate possible adverse effects of the contaminants on biochemical biomarkers of oysters, Crassostrea gasar and Crassostrea rhizophorae. 107 chemicals were evaluated in water, sediment and oyster samples from nine sites along the coastline of SC. We also examined various biochemical biomarkers in the oysters' gills and digestive glands to assess potential effects of contaminants. In general, the northern and central regions of the littoral of SC presented higher occurrences and magnitudes of contaminants than the southern region, which is probably related to higher urbanization of center and northern areas of the littoral. The biomarker analysis in the oysters reflected these contamination patterns, with more significant alterations observed in regions with higher levels of pollutants. Our results may serve as a first baseline for future and more extensive monitoring actions and follow-up of the degree of contamination in the state, allowing for inspection actions and management of areas most affected by marine pollutants.

The association between polycyclic aromatic hydrocarbons exposure and neuropsychiatric manifestations in perimenopausal women: A cross-sectional study

BACKGROUND

Increasing evidence shows that polycyclic aromatic hydrocarbons (PAHs) exposure may adversely affect human health. However, the links between combined exposure to PAHs and neuropsychiatric manifestations in perimenopausal women remain unclear.

METHODS

To explore these relationships further, we used the data from the National Health and Nutrition Examination Surveys (NHANES) of the 2005-2012 cycles. After filtering, five hundred forty-seven perimenopausal women aged 45-55 years were included in our analysis. Eight PAHs metabolites were measured to represent PAHs exposure in the body. In our study, depression, sleep disorders, and frequent mental distress (FMD) were used to describe the neuropsychiatric manifestations. Because of the bivariate correlations among PAHs compounds, principal component analysis (PCA) was conducted to achieve the dimension reduction process of PAHs compounds. To figure out if there is a relationship between urinary PAH metabolites and outcomes, multiple logistic regression, restricted cubic splines (RCS), and the Bayesian kernel machine regression (BKMR) were used.

RESULTS

The findings showed that urinary PAHs concentrations in a certain range were related to neuropsychiatric manifestations. In detail, the results of logistic regressions, RCS, and BKMR all indicated that urinary PAHs were positively correlated with depression. In addition, the results of principal components regression and RCS showed associations between urinary PAHs and the risk of FMD or sleep disorders, respectively.

CONCLUSIONS

Exposure to PAHs was linked to neuropsychiatric manifestations in perimenopausal women, but more pertinent researches are required to understand the connections fully.

Polycyclic aromatic hydrocarbons exposure was associated with microRNA differential expression and neurotransmitter changes: a cross-sectional study in coal miners

Exposure to polycyclic aromatic hydrocarbons (PAHs) may cause neurobehavioral changes. This study aimed to explore the underlying mechanism of PAH neurotoxicity in coal miners. Urinary PAH metabolites, neurotransmitters, and oxidative stress biomarkers of 652 coal miners were examined. Subjects were divided into high and low-exposure groups based on the median of total urinary PAH metabolites. Differentially expressed miRNAs were screened from 5 samples in the low-exposure group (≤ 4.88 μmol/mol Cr) and 5 samples in the high-exposure group (> 4.88 μmol/mol Cr) using microarray technology, followed by bioinformatics analysis of the potential molecular functions of miRNA target genes. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to validate differentially expressed miRNAs. Restricted cubic splines (RCS) were applied to assess the possible dose-response relationships. Compared to the low PAH exposure group, the high-exposure group had higher levels of 5-hydroxytryptamine (5-HT), epinephrine (E), and acetylcholine (ACh), and lower levels of acetylcholinesterase (AChE). 1-OHP had a dose-response relationship with malondialdehyde (MDA), dopamine (DA), 5-HT, and AChE (P for overall associations < 0.05). There were 19 differentially expressed microRNAs in microarray analysis, significantly enriched in the cell membrane, molecular binding to regulate transcription, and several signaling pathways such as PI3K-Akt. And in the validation stage, miR-885-5p, miR-20a-5p, and let-7i-3p showed differences in the low and high-exposure groups (P < 0.05). Changes in neurotransmitters and microRNA expression levels among the coal miners were associated with PAH exposure. Their biological functions are mainly related to the transcriptional regulation of nervous system diseases or signaling pathways of disorders. These findings provide new insights for future research of PAH neurotoxicity.

Neurotoxicity of Polycyclic Aromatic Hydrocarbons: A Systematic Mapping and Review of Neuropathological Mechanisms

Several studies present the neurotoxic effects of polycyclic aromatic hydrocarbons (PAHs), a class of environmental pollutants capable of causing neurological deficits. However, a collective review approach to this research topic is scarce. This study presents the effect of PAHs on the central nervous system using a bibliometric approach. The neuropathological mechanisms of PAHs are also highlighted. Published articles were searched for in the Scopus and Web of Science databases from January 1979 to December 2020 using the keywords ‘polycyclic aromatic hydrocarbons’ and ‘neurotoxicity’. The total number of documents retrieved from both databases was 338. Duplicated documents (80) were excluded and 258 articles were used for the final analysis. Our findings revealed that there has been a significant increase in research outputs on this topic in the last ten years. The countries with the highest scientific productivity in this area are USA, China, France and Italy. The result also showed that, in the past few years, global scientific output in research relating to PAH neurotoxicity focused on neurodegeneration, cholinergic function, neurodevelopmental toxicity, behavioural studies, oxidative stress, neuroprotection and therapeutic intervention using different experimental models, including zebrafish, neuronal cell lines, Caenorhabditis elegans and rats. Recent studies also revealed the neuroprotective roles of some natural products against PAH-induced neurotoxicity. However, more investigation involving clinical trials is required to emphasize the observed neurotoxic effects.

Acetylcholinesterase activity in fish species exposed to crude oil hydrocarbons: A review and new perspectives

Crude oil and its derivatives are primary energy resources for humans, and processes involving these materials could affect aquatic environments. Acetyl cholinesterase (AChE) activity is a suitable biomarker for exposure to organophosphate pesticides. Under controlled conditions, fish exposed to polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene, pyrene and anthracene, showed inhibition of this biomarker; however, PAHs with a low molecular weight did not induce changes or cause stimulation of AChE activity. Diverse responses of fish exposed to soluble fractions of crude oil, fuels or gasoline were documented. Most studies in which AChE activity was considered for environmental monitoring have been performed to evaluate the presence of pesticides, and the effects of petroleum hydrocarbons are unclear. The objective of this review was to provide the recent status of research on this topic and suggest proposals for future investigations. To establish the suitability of this biomarker in fish species exposed to these pollutants and to determine their neurotoxic effects, researchers must determinate the mechanism involved in the AChE inhibition by petroleum hydrocarbons, unify criteria concerning the experimental in vitro and in vivo designs and apply multivariate statistical and correlation analyses between these pollutants with AChE activity in field studies.

Effectiveness of melatonin to restore fish brain activity in face of permethrin induced toxicity

Present study demonstrates permethrin induced oxidative damage in fish brain and explores effectiveness of melatonin to ameliorate brain function. Adult female Notopterus notopterus were exposed to nominal permethrin concentrations at 1/20th (0.34 μg/l) and 1/10th (0.68 μg/l) of LC₅₀ for 15 days. The measured permethrin concentrations using gas chromatography (GC-ECD) were 0.28 μg/l and 0.57 μg/l, respectively. Some fish were sacrificed to collect brain tissue after 15 days of exposure. Remaining fish from both groups were administered exogenous melatonin (50 μg/kg, 100 μg/kg body weight) for 7 days and brain tissues were collected. Brain enzymes, ntioxidant factors, HSP70, HSP90, nuclear factor-kappa binding (NFkB), melatonin receptor (MT1R) proteins were measured. Permethrin treatment significantly (P < 0.05) decreased the levels of glutathione and brain enzymes. Malondialdehyde (MDA), xanthine oxidase (XO), HSPs increased at each concentration of permethrin. However, superoxide dismutase, glutathione s-transferase levels increased at low permethrin concentration followed by sharp decrease at higher concentration. Expression of NFkB and MT1R increased significantly (P < 0.05). Melatonin administration reinstated activity of brain enzymes, reduced MDA, XO levels and modulated HSPs. Melatonin also increased expression of NFkB and MT1R. Exogenous melatonin improves oxidative status in permethrin stressed fish brain. Melatonin modulates expression of HSPs that enables brain to become stress tolerant and survive by initiating NFkB translocation. Melatonin could act through melatonin receptor protein to induce synthesis of antioxidant proteins. Therefore the study successfully evaluates the potential of melatonin application for better culture and management of fish against pesticide toxicity.

Clofibrate, a PPAR-α agonist, abrogates sodium fluoride-induced neuroinflammation, oxidative stress, and motor incoordination via modulation of GFAP/Iba-1/anti-calbindin signaling pathways

Fluoride is an environmental contaminant that is ubiquitously present in air, water, and soil. It is commonly added in minute quantity to drinking water, toothpaste, and mouth rinses to prevent tooth decay. Epidemiological findings have demonstrated that exposure to fluoride induced neurodevelopmental toxicity, developmental neurotoxicity, and motor disorders. The neuroprotective effect of clofibrate, a peroxisome proliferator-activated receptor alpha agonist, was investigated in the present study. Forty male Wistar rats were used for this study and randomly grouped into 10 rats per group as control, sodium fluoride (NaF) alone (300 ppm), NaF plus clofibrate (250 mg/kg), and NaF plus lisinopril (10 mg/kg), respectively, for 7 days. NaF was administered in drinking water while clofibrate and lisinopril were administered by oral gavage. Markers of neuronal inflammation and oxidative stress, acetylcholinesterase activity, and neurobehavioral (hanging wire and open field) tests were performed. Immunohistochemistry was performed on brain tissues, and they were probed with glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, and cerebellar Ca²⁺ -binding protein calbindin-D28k. The results showed that NaF significantly increased of oxidative stress and neuroinflammation and inhibited AChE activity. Immunostaining showed reactive astrocytes, microgliosis, loss of dendritic spines, and arborization in Purkinje cells in rats administered only NaF. Neurobehavioral results showed that cotreatment of NaF with clofibrate improved muscular strength and locomotion, reduced anxiety, and significantly reduced astrocytic count. Overall, cotreatment of NaF with either clofibrate or lisinopril showed neuroprotective effects by mitigating neuronal inflammation and oxidative and motor incoordination. Hence, clofibrate could be seen as a novel drug candidate against neurodegeneration and motor disorders.

Histological, biochemical and transcriptomic analyses reveal liver damage in zebrafish (Danio rerio) exposed to phenanthrene

Phenanthrene (PHE) is a common polycyclic aromatic hydrocarbon (PAH) in aquatic environments, and this contaminant can cause adverse effects on teleostean performance. In this study, we exposed the model freshwater fish (zebrafish; Danio rerio) to 300 μg/L PHE for 15 days. Histological analysis demonstrated that liver morphology deteriorated in PHE-exposed zebrafish, and cellular damage in the liver increased. Biological analysis revealed that exposure to PHE elicited significant changes in glutathione S-transferases (GST) and superoxide dismutase (SOD) activities. 476 differentially expressed genes (DEGs) were identified in liver between control and PHE treated groups through the transcriptomic analysis. Gene Ontology enrichment analysis (GO) suggested that PHE exposure induced changes in the expression of genes associated with "lipid transporter activity", "catalytic activity", "metal ion binding", "lipid transport" and "transmembrane transport". Furthermore, the "vitamin digestion and absorption" and "fat digestion and absorption" pathways enriched in Kyoto Encyclopedia of Genes and Genomes analysis (KEGG). Additionally, five candidate biomarkers associated with the PHE response in zebrafish were identified. In conclusion, our results elucidate the physiological and molecular responses to PHE exposure in the liver of zebrafish, and provide a framework for further studies of the mechanisms underlying the toxic effects of polycyclic aromatic hydrocarbons (PAHs) on aquatic organisms.