This study investigates the effects of environmentally-relevant concentrations of fluoxetine (FLX, commercial name: Prozac) on wound healing. Pollution of water systems with pharmaceutical and personal care products, including antidepressants such as FLX and other selective serotonin reuptake inhibitors, is a growing environmental concern. Environmentally-relevant FLX concentrations are known to impact physiological functions and behaviour of aquatic animals, however, the effects of exposure on humans are currently unknown. Using a combination of human skin biopsies and a human keratinocyte cell line, we show that exposure to environmental FLX promotes wound closure. We show dose-dependent increases in wound closure with FLX concentrations from 125 ng/l. Using several –omics and pharmaceutical approaches, we demonstrate that the mechanisms underlying enhanced wound closure are increased cell proliferation and serotonin signalling. Transcriptomic analysis revealed 350 differentially expressed genes after exposure. Downregulated genes were enriched in pathways related to mitochondrial function and metabolism, while upregulated genes were associated with cell proliferation and tissue morphogenesis. Kinase profiling showed altered phosphorylation of kinases linked to the MAPK pathway. Consistent with this, phosphoproteomic analyses identified 235 differentially phosphorylated proteins after exposure, with enriched GO terms related to cell cycle, division, and protein biosynthesis. Treatment of skin biopsies and keratinocytes with ketanserin, a serotonin receptor antagonist, reversed the increase in wound closure observed upon exposure. These findings collectively show that exposure to environmental FLX promotes wound healing through modulating serotonin signalling, gene expression and protein phosphorylation, leading to enhanced cell proliferation. Our results justify a transition from the study of behavioural effects of environmental FLX in aquatic animals to the investigation of effects of exposure on wound healing in aquatic and terrestrial animals, including direct impacts on human health. | QRB acknowledges a ‘Happy Chemical’ PhD studentship funded by the University of Hull. BGM would also like to express her gratitude to the Spanish Ministry of Science, Innovation and Universities for the FPI predoctoral contract PRE2019–089339 and to the University of Cantabria for the predoctoral mobility grant Erasmus+ nº 2021-1-ES01-KA131-HED-000005117. The York Centre of Excellence in Mass Spectrometry was created thanks to a major capital investment through Science City York, supported by Yorkshire Forward with funds from the Northern Way Initiative, and subsequent support from EPSRC (EP/K039660/1; EP/M028127/1).

The beta-blocker atenolol (ATE), and the selective serotonin and norepinephrine reuptake inhibitor, venlafaxine (VEN) are frequently detected in municipal wastewater effluents, but little is known about their ecotoxicological effect on aquatic animals. Herein, ATE and VEN were selected to explore their accumulation and global DNA methylation (GDM) in zebrafish tissues after a 30-day exposure. Molecular dynamics (MD) stimulation was used to investigate the toxic mechanism of ATE and VEN exposure. The results demonstrated that ATE and VEN could reduce the condition factor of zebrafish. The bioaccumulation capacity for ATE and VEN was in the order of liver > gut > gill > brain and liver > gut > brain > gill, respectively. After a 30-day recovery, ATE and VEN could still be detected in zebrafish tissues when exposure concentrations were ≥10 μg/L. Moreover, ATE and VEN induced global DNA hypomethylation in different tissues with a dose-dependent manner and their main target tissues were liver and brain. When the exposure concentrations of ATE and VEN were increased to 100 μg/L, the global DNA hypomethylation of liver and brain were reduced to 27% and 18%, respectively. In the same tissue exposed to the same concentration, DNA hypomethylation induced by VEN was more serious than that of ATE. After a 30-day recovery, the global DNA hypomethylations caused by the two drugs were still persistent, and the recovery of VEN was slower than that of ATE. The MD simulation results showed that both ATE and VEN could reduce the catalytic activity of DNA Methyltransferase 1 (DNMT1), while the effect of VEN on the 3D conformational changes of the DNMT1 domain was more significant, resulting in a lower DNA methylation rate. The current study shed new light on the toxic mechanism and potential adverse impacts of ATE and VEN on zebrafish, providing essential information to the further ecotoxicological risk assessment of these drugs in the aquatic environment.

Despite publication of numerous of papers, the effects of fluoxetine on fish behaviour remains mired in controversy and contradiction. One reason for this controversy is that fluoxetine displays distinct and opposing acute and chronic effects. A second reason is that most studies have been limited to two or at the most three concentrations. To address these deficiencies we exposed adult zebrafish, both single females and shoals consisting of one male and two females, to seven fluoxetine concentrations, ranging from 5 ng/L to 5 μg/L and measured their swimming behaviour, and response to a conspecific alarm substance (CAS) at seven, 14 and 28 days. We also measured the light startle response of unexposed F1 larvae at days seven and 28 post-hatch and the response to CAS at day 28. On day 7 fluoxetine decreased swimming speed at concentrations ≥500 ng/L. After addition of CAS fish exposed to 5, 500 and 1000 ng/L decreased swimming, while fish exposed to 10, 500 and 1000 ng/L significantly increased time motionless. On day 14 only fish exposed to 50 ng/L were significantly slower than controls before addition of CAS, but afterwards fish exposed to 5, 50, 1000 and 5000 ng/L showed significant differences from controls. On day 28 fish exposed to 50 and 5000 ng/L had slower average swimming speeds than controls before addition of CAS. After addition all fish except controls and those exposed to 500 ng/L showed decreased average speed. At seven days post-hatch, F1 larvae whose parents were exposed to 100 ng/L showed significantly higher activity than controls and those exposed to 500 ng/L fluoxetine showed lower activity in the light startle response. This study shows that the effects of fluoxetine vary with time and also in a non-monotonic manner. We suggest that the complex nature of the serotonergic system with multilateral effects at the genomic, biochemical and physiological levels interacting with environmental stimuli result in non-linear dose-response behavioural patterns.

Known as a cause of food poisoning, Bacillus cereus (B. cereus) is widespread in nature. Cereulide, the heat-stable and acid-resistant emetic toxin which is produced by some B. cereus strains, is often associated with foodborne outbreaks, and causes acute emetic toxicity at high dosage exposure. However, the toxicological effect and underlying mechanism caused by chronic low-dose cereulide exposure require to be further addressed. In the study, based on mouse model, cereulide exposure (50 μg/kg body weight) for 28 days induced intestinal inflammation, gut microbiota dysbiosis and food intake reduction. According to the cell models, low dose cereulide exposure disrupted the intestinal barrier function and caused intestinal inflammation, which were resulted from endoplasmic reticulum (ER) stress IRE1/XBP1/CHOP pathway activation to induce cell apoptosis and inflammatory cytokines production. For gut microbiota, cereulide decreased the abundances of Lactobacillus and Oscillospira. Furthermore, cereulide disordered the metabolisms of gut microbiota, which exhibited the inhibitions of butyrate and tryptophan. Interestingly, cereulide exposure also inhibited the tryptophan hydroxylase to produce the serotonin in the gut and brain, which might lead to depression-like food intake reduction. Butyrate supplementation (100 mg/kg body weight) significantly reduced intestinal inflammation and serotonin biosynthesis suppression caused by cereulide in mice. In conclusion, chronic cereulide exposure induced ER stress to cause intestinal inflammation, gut microbiota dysbiosis and serotonin biosynthesis suppression. IRE1 could be the therapeutic target and butyrate supplementation is the potential prevention strategy.

Hydrogen peroxide (H₂O₂), as a common disinfectant, has been extensively used in aquaculture. The toxicity of high ambient H₂O₂ for gills and liver of fish has received attention from many researchers. However, whether H₂O₂ exposure induced brain injury and neurotoxicity has not been reported in fish. Therefore, this study aimed to explore the potential mechanism of H₂O₂ toxicity in brain of common carp via transcriptome analysis and biochemical parameter detection. The fish were exposed to 0 (control) and 1 mM of H₂O₂ for 1 h per day lasting 14 days. The results showed that H₂O₂ exposure caused oxidative damage in brain evidenced by decreased glutathione (GSH), total antioxidant capacity (T-AOC) and nicotinamide adenine dinucleotide (NAD⁺) levels, and increased formation of malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Meanwhile, H₂O₂ exposure reduced 5-hydroxytryptamine (5-HT) level, and down-regulated tryptophan hydroxylase 1 (tph1a), tph2, 5-hydroxytryptamine receptor 1A-beta (htr1ab) and htr2b expression in brain. Transcriptome analysis showed that H₂O₂ exposure up-regulated 604 genes and down-regulated 1209 genes in brain. Go enrichment displayed that the differently expressed genes (DEGs) were enriched mainly in cellular process, single-organism process, metabolic process, and biological regulation in the biological process category. Further, KEGG enrichment indicated that H₂O₂ exposure led to dysregulation of neurotransmitter signals including depression of glutamatergic synapse, GABAergic synapse and endocannabinoid signaling. Also, we found the alteration of three key pathways including calcium, cAMP and HIF-1 in brain after H₂O₂ exposure. In conclusion, our data indicated that H₂O₂ exposure induced oxidative damage and neurotoxicity, possibly related to dysregulation of neurotransmitters and calcium, cAMP and HIF-1 signaling pathways, which may adversely affect learning, memory and social responses of common carp. This study provided novel insight into biological effects and underlying mechanism of H₂O₂ toxicity in aquatic animal, and contributed to proper application of H₂O₂ in aquaculture.

Heat stress (HS) during gestation has been associated with negative outcomes, such as preterm birth or postnatal metabolic syndromes. The intestinal microbiota is a unique ecosystem playing an essential role in mediating the metabolism and health of mammals. Here we hypothesize late gestational HS alters maternal microbial transmission and structures offspring’s intestinal microbiota and serum metabolic profiles. Our results show maternal HS alters bacterial β-diversity and composition in sows and their piglets. In the maternal intestine, genera Ruminococcaceae UCG-005, [Eubacterium] coprostanoligenes group and Halomonas are higher by HS (q < 0.05), whereas the populations of Streptococcus, Bacteroidales RF16 group_norank and Roseburia are decreased (q < 0.05). In the maternal vagina, HS mainly elevates the proportions of phylum Bacteroidetes and Fusobacteria (q < 0.05), whereas reduces the population of Clostridiales Family XI (q < 0.05). In the neonatal intestine, maternal HS promotes the population of Proteobacteria but reduces the relative abundance of Firmicutes (q < 0.05). Moreover, the core Operational taxonomic units (OTU) analysis indicates the proportions of Clostridium sensu stricto 1, Romboutsia and Turicibacter are decreased by maternal HS in the intestinal and vaginal co-transmission, whereas that of phylum Proteobacteria and Epsilonbacteraeota, such as Escherichia-Shigella, Klebsiella, Acinetobacter, and Comamonas are increased in both the intestinal and vaginal co-transmission and the vagina. Additionally, Aeromonas is the only genus that is transmitted from environmental sources. Lastly, we evaluate the importance of neonatal differential OTU for the differential serum metabolites. The results indicate Acinetobacter significantly contributes to the differences in the adrenocorticotropic hormone (ACTH) and glucose levels due to HS (P < 0.05). Further, Stenotrophomonas is the most important variable for Cholesterol, low-density lipoprotein (LDL), diamine oxidase (DAO), blood urea nitrogen (BUN) and 5-hydroxytryptamine (5-HT) (P < 0.10). Overall, our data provides evidence for the maternal HS in establishing the neonatal microbiota via affecting maternal transmission, which in turn affects the maintenance of metabolic health.

The present study was performed to evaluate the neurobehavioural deficit induced by nonylphenol (NP), a well-known xenobiotic chemical. The neurotoxic mechanism from oxidative stress and serotonin-related progress was also investigated. Caenorhabditis elegans was exposed at different levels of NP ranging from 0 to 200 μg L⁻¹ for 10 days. The results revealed that from a relatively low concentration (i.e., 10 μg L⁻¹), significant effects including decreased head thrashes, body bends and forging behaviour could be observed, along with impaired learning and memory behaviour plasticity. The level of reactive oxygen species (ROS) in head was significantly elevated with the increase of NP concentrations from 10 to 200 μg L⁻¹. Through antioxidant experiment, the oxidative damage caused by NP restored to some extent. At a NP concentration of 200 μg L⁻¹, the significant increased expression of stress-related genes, including sod-1, sod-3, ctl-2, ctl-3 and cyp-35A2 gene, was observed from integrated gene expression profiles. In addition, in comparison with wild-type N2 worms, the ROS accumulation was increased significantly with the mutation of sod-3. Tryptophan hydroxylase (TPH) in ADF and NSM neurons sharply decreased at the concentrations of 10–200 μg L⁻¹. The transcription of TPH synthesis-related genes and serotonin-related genes were both suppressed, including tph-1, cat-1, cat-4, ser-1, and mod-5. Overall, these results indicated that NP could induce neurotoxicity on Caenorhabditis elegans through excessive induction of ROS and disturbance synthesis of serotonin. The conducted research opened up new avenues for more effective exploration of neurotoxicity caused by NP.

Sleep disorders may pose a risk to workers in the workplace. We aimed to investigate the associations between metal fume fine particulate matter (PM2.5) and sleep quality in workers. We assessed the effects of personal exposure to metal fume PM2.5 on lung functions, urinary biomarkers, and sleep quality in shipyard welding workers. In total, 96 welding workers and 54 office workers were recruited in the present study; office workers were exposed to 82.1 ± 94.1 μg/m³ PM2.5 and welding workers were exposed to 2166.5 ± 3149.1 μg/m³. Welding workers had significantly lower levels of FEV25-75 than office workers (p < 0.05). An increase in 1 μg/m³ PM2.5 was associated with a decrease of 0.003 ng/mL in urinary serotonin (95% CI = −0.007–0.000, p < 0.05) in all workers and with a decrease of 0.001 ng/mL in serotonin (95% CI = −0.004–0.002, p < 0.05) in welding workers, but these were not observed in office workers. There was no significant association of PM2.5 with urinary cortisol observed in any workers. Urinary serotonin was associated with urinary Cu, Mn, Co, Ni, Cd, and Pb. Urinary cortisol was associated with Cu, Mn, Co, Ni, Cd, and Pb. Sixteen subjects were randomly selected from each of the office and welding workers for personal monitoring of sleep quality using a wearable device. We observed that welding workers had greater awake times than did office workers (p < 0.05). Our study observed that exposure to heavy metals in metal fume PM2.5 may disrupt sleep quality in welding workers.

Microcystin-LR (MCLR) has been reported to cause developmental neurotoxicity in zebrafish, but there are few studies on the mechanisms of MCLR-induced transgenerational effects of developmental neurotoxicity. In this study, zebrafish were exposed to 0, 1, 5, and 25 μg/L MCLR for 60 days. The F1 zebrafish embryos from the above-mentioned parents were collected and incubated in clean water for 120 h for hatching. After examining the parental zebrafish and F1 embryos, MCLR was detected in the gonad of adults and F1 embryos, indicating MCLR could potentially be transferred from parents to offspring. The larvae also showed a serious hypoactivity. The contents of dopamine, dihydroxyphenylacetic acid (DOPAC), serotonin, gamma-aminobutyric acid (GABA) and acetylcholine (ACh) were further detected, but only the first three neurotransmitters showed significant reduction in the 5 and 25 μg/L MCLR parental exposure groups. In addition, the acetylcholinesterase (AChE) activity was remarkably decreased in MCLR parental exposure groups, while the expression levels of manf, bdnf, ache, htr1ab, htr1b, htr2a, htr1aa, htr5a, DAT, TH1 and TH2 genes coincided with the decreased content of neurotransmitters (dopamine, DOPAC and serotonin) and the activity of AChE. Neuronal development related genes, α1-tubulin, syn2a, mbp, gfap, elavl3, shha and gap43 were also measured, but gap43 was the gene only up-regulated. Our results demonstrated MCLR could be transferred to offspring, and subsequently induce developmental neurotoxicity in F1 zebrafish larvae by disturbing the neurotransmitter systems and neuronal development.

Due to worldwide production, sales and application, neonicotinoids dominate the global use of insecticides. While, neonicotinoids are considered as pinpoint neurotoxicants that impair cholinergic neurotransmission in pest insects, the sublethal effects on nontarget organisms and other neurotransmitters remain poorly understood. Thus, we investigated long-term neurological outcomes in the decomposer nematode Caenorhabditis elegans. In the adult roundworm the neonicotinoid thiacloprid impaired serotonergic and dopaminergic neuromuscular behaviors, while respective exposures to thiamethoxam showed no effects. Thiacloprid caused a concentration-dependent delay of the transition between swimming and crawling locomotion that is controlled by dopaminergic and serotonergic neurotransmission. Age-resolved analyses revealed that impairment of locomotion occurred in young as well as middle-aged worms. Treatment with exogenous serotonin rescued thiacloprid-induced swimming deficits in young worms, whereas additional exposure with silica nanoparticles enhanced the reduction of swimming behavior. Delay of forward locomotion was partly caused by a new paralysis pattern that identified thiacloprid as an agent promoting a specific rigidity of posterior body wall muscle cells and peripheral neuropathy in the nematode (lowest-observed-effect-level 10 ng/ml). On the molecular level exposure with thiacloprid accelerated protein aggregation in body wall muscle cells of polyglutamine disease reporter worms indicating proteotoxic stress. The results from the soil nematode Caenorhabditis elegans show that assessment of neurotoxicity by neonicotinoids requires acknowledgment and deeper research into dopaminergic and serotonergic neurochemistry of nontarget organisms. Likewise, it has to be considered more that different neonicotinoids may promote diverse neural end points.