A versatile toxicity evaluation of ethyl carbamate (urethane) on zebrafish embryos: Morphological, physiological, histopathological, immunohistochemical, transcriptional and behavioral approaches

Protective effects of curcumin against valproic acid induced brain kidney and liver damage in rats

Valproic acid (VPA) is a broad-spectrum drug that is now widely used as an antiepileptic. Although VPA has positive therapeutic effects, it also causes various toxic effects in tissues. Curcumin, a natural antioxidant found in ginger, has antibacterial and antiinflammatory activity. In this study, the toxic effects of VPA on brain, kidney, and liver tissues and the protective activity of curcumin against these effects were investigated. In this study, male Wistar-Albino rats were used. Rats were divided into 4 groups control, VPA, CUR, and CUR + VPA. Rats were administered intraperitoneal VPA and CUR intragastrically. In the study, MDA, SOD, IL-6, and IL-18 levels were measured by the ELISA method in rats. It was observed that VPA triggered oxidative stress and inflammation in tissues, while CUR administration positively regulated these parameters. Studies also showed that VPA increased the expressions of TNF-α and NF-kB in tissues, but CUR administration downregulated these expressions The findings revealed that CUR protects by preventing the oxidative stress and inflammation caused by VPA in the tissues and may be an important agent in reducing the side effects of this drug used as an antiepileptic.

Nephroprotective potential of robinin to counteract aldicarb induced renal dysfunction via modulating TLR4/MyD88, HMGB1/RAGE, NF-κB pathway: A biochemical and pharmacodynamic approach

The current investigation was conducted to evaluate the nephroprotective potential of robinin (RBN) to avert aldicarb (ALD) induced renal impairments. Thirty-two adult albino rats (Sprague Dawley) were divided into four groups including control, ALD (15 mgkg-1), ALD (15 mgkg-1) + RBN (6 mgkg-1) and RBN (6 mgkg-1) alone treated group. The results of the current study demonstrated that ALD intoxication increased the gene expression of receptor for advanced glycation end products (RAGE), tumor necrosis factor- α (TNF-α), toll-like receptor 4 (TLR4), high mobility group box1 (HMGB1), nuclear factor-kappa B (NF-κB), myeloid differentiation primary response protein 88 (MyD88), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), and interleukin-1β (IL-1β). Moreover, activities of HO-1, GSH, GPx, SOD, GSR, and CAT were suppressed while the levels of ROS and MDA were escalated following the ALD exposure. ALD intoxication upregulated the levels of cystatin C, KIM-1, creatinine, NAG, uric acid, urea, NGAL and BUN while reducing the levels of creatinine clearance in renal tissues. The levels of Bax, Caspase-9 and Caspase-3 were elevated while the levels of Bcl-2 were reduced after ALD administration. Histopathological analysis showed ALD disrupted the normal architecture of renal tissues. However, RBN therapy substantially protected the renal tissues owing to its antioxidative, anti-inflammatory and anti-apoptotic potential.

Okadaic acid enhances NfKB, TLR-4, caspase 3, ERK ½, c-FOS, and 8-OHdG signaling pathways activation in brain tissues of zebrafish larvae

This study was designed to investigate the potential neuronal damage mechanism of the okadaic acid (OA) in the brain tissues of zebrafish embryos by evaluating in terms of immunofluorescence of Nf KB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG signaling pathways. We also evaluated body malformations. For this purpose, zebrafish embryos were exposed to 0.5 μg/ml, 1 μg/ml and 2.5 μg/ml of OA for 5 days. After application, FITC/GFP labeled protein-specific antibodies were used in immunofluorescence assay for NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG respectively. The results indicated that OA caused immunofluorescence positivity of NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG in a dose-dependent manner in the brain tissues of zebrafish embryos. Pericardial edema (PE), nutrient sac edema (YSE) and body malformations, tail malformation, short tail and head malformation (BM) were detected in zebrafish embryos. These results suggest that OA induces neuronal damage by affecting the modulation of DNA damage, apoptotic, and inflammatory activities in the brain tissues of zebrafish embryos. The increase in signaling pathways shows that OA can cause damage in the structure and function of brain nerve cells. Our results provide a new basis for the comprehensive assessment of the neural damage of OA and will offer enable us to better understand molecular the mechanisms underlying the pathophysiology of OA toxicity.

Formation and hazard of ethyl carbamate and construction of genetically engineered Saccharomyces cerevisiae strains in Huangjiu (Chinese grain wine)

Huangjiu, a well-known conventional fermented Chinese grain wine, is widely consumed in Asia for its distinct flavor. Trace amounts of ethyl carbamate (EC) may be generated during the fermentation or storage process. The International Agency for Research on Cancer elevated EC to a Class 2A carcinogen, so it is necessary to regulate EC content in Huangjiu. The risk of intake of dietary EC is mainly assessed through the margin of exposure (MOE) recommended by the European Food Safety Authority, with a smaller MOE indicating a higher risk. Interventions are necessary to reduce EC formation. As urea, one of the main precursors of EC formation in Huangjiu, is primarily produced by Saccharomyces cerevisiae through the catabolism of arginine, the construction of dominant engineered fermentation strains is a favorable trend for the future production and application of Huangjiu. This review summarized the formation and carcinogenic mechanism of EC from the perspectives of precursor substances, metabolic pathways after ingestion, and risk assessment. The methods of constructing dominant S. cerevisiae strains in Huangjiu by genetic engineering technology were reviewed, which provided an important theoretical basis for reducing EC content and strengthening practical control of Huangjiu safety, and the future research direction was prospected.

Whole-Mount Immunohistochemical and Immunofluorescence Assays in Zebrafish Embryos

Zebrafish embryos are an important organism used as an in vivo model in a wide variety of disciplines from the past to the present. Immunohistochemistry analyses are an important method used to determine the localization of specific antigens in tissue sections with labeled antibodies depending on antigen-antibody interactions in zebrafish embryos. Immunofluorescence assays are an immunohistochemistry method that uses fluorophores to determine diverse cellular antigens. Zebrafish embryos and larvae, with their small size, are the most ideal model organisms for whole-mount immunohistochemical and immunofluorescent methods today. The small size of these organisms allows simultaneous evaluation of different tissues and organs, and results are obtained in a shorter time. In this section, whole-mount immunohistochemical and immunofluorescent analysis methods in zebrafish embryos, and larvae are summarized in detail, taking into account different studies and recent advances.

Ethyl Lithospermate Reduces Lipopolysaccharide-Induced Inflammation through Inhibiting NF-κB and STAT3 Pathways in RAW 264.7 Cells and Zebrafish

OBJECTIVE

To explore the anti-inflammatory effects of ethyl lithospermate in lipopolysaccharide (LPS)-stimulated RAW 264.7 murine-derived macrophages and zebrafish, and its underlying mechanisms.

METHODS

3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) assays were performed to investigate the toxicity of ethyl lithospermate at different concentrations (12.5-100 µ mol/L) in RAW 264.7 cells. The cells were stimulated with LPS (100 ng/mL) for 12 h to establish an inflammation model in vitro, the production of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor α (TNF-α) were assessed by enzyme linked immunosorbent assay (ELISA). Western blot was used to ascertain the protein expressions of signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa B (NF-κB) p65, phospho-STAT3 (p-STAT3, Tyr705), inhibitor of NF-κB (IκB) α, and phospho-I κB α (p-IκB α, Ser32), and confocal imaging was used to identify the nuclear translocation of NF-κB p65 and p-STAT3 (Tyr705). Additionally, the yolk sacs of zebrafish (3 days post fertilization) were injected with 2 nL LPS (0.5 mg/mL) to induce an inflammation model in vivo. Survival analysis, hematoxylin-eosin (HE) staining, observation of neutrophil migration, and quantitative real-time polymerase chain reaction (qRT-PCR) were used to further study the anti-inflammatory effects of ethyl lithospermate and its probable mechanisms in vivo.

RESULTS

The non-toxic concentrations of ethyl lithospermate have been found to range from 12.5 to 100 µ mol/L. Ethyl lithospermate inhibited the release of IL-6 and TNF-α(P<0.05 or P<0.01), decreased IκBα degradation and phosphorylation (P<0.05) as well as the nuclear translocation of NF-κB p65 and p-STAT3 (Tyr705) in LPS-induced RAW 264.7 cells (P<0.01). Ethyl lithospermate also decreased inflammatory cells infiltration and neutrophil migration while increasing the survival rate of LPS-stimulated zebrafish (P<0.05 or P<0.01). In addition, ethyl lithospermate also inhibited the mRNA expression levels of of IL-6, TNF-α, IκBα, STAT3, and NF-κB in LPS-stimulated zebrafish (P<0.01).

CONCLUSION

Ethyl lithospermate exerts anti-Inflammatory effected by inhibiting the NF-κB and STAT3 signal pathways in RAW 264.7 macrophages and zebrafish.

A Nationwide Survey and Risk Assessment of Ethyl Carbamate Exposure Due to Daily Intake of Alcoholic Beverages in the Chinese General Population

Ethyl carbamate (EC) is carcinogenic, and, in China, oral intake of EC mainly occurs as a result of the consumption of alcoholic beverages. To obtain the latest EC intake and risk analysis results for the general population in China, the China National Center for Food Safety Risk Assessment (CFSA) conducted the sixth total diet study (TDS) as a platform to analyze EC contents and exposure due to the intake of alcoholic beverages. A total of 100 sites in 24 provinces were involved in the collection and preparation of alcohol mixture samples for the sixth TDS. There were 261 different types of alcohol collected across the country, based on local dietary menus and consumption survey results. Ultimately, each province prepared a mixed sample by mixing their respective samples according to the percentage of local consumption. The EC levels of these twenty-four mixed samples were determined using our well-validated gas chromatography-mass spectrometry (GC-MS) method. The values ranged from 1.0 μg/kg to 33.8 μg/kg, with 10.1 μg/kg being the mean. China's EC daily intake ranged from 0.001 ng/kg bw/d to 24.56 ng/kg bw/d, with a mean of 3.23 ng/kg bw/d. According to the margin of exposure (MOE), virtually safe dose (VSD), and T25 risk assessments of the carcinogenicity of EC, the mean lifetime cancer risk for the Chinese population was 9.8 × 104, 1.5 × 10-7, and 8.6 × 10-8, respectively. These data show that the carcinogenicity of EC in the general Chinese population due to alcoholic intake is essentially minimal.

Avocado peel extract loaded on chitosan nanoparticles alleviates urethane toxicity that causes lung cancer in a mouse model

Lung cancer progresses without obvious symptoms and is detected in most patients at late stages, causing a high rate of mortality. Avocado peels (AVP) were thought to be biowaste, but they have antioxidant and anticancer properties in vitro. Chitosan nanoparticles (Cs-NPs) were loaded with various plant extracts, increasing their in vitro and in vivo anticancer activities. Our goal was to load AVP onto Cs-NPs and determine the role of AVP-extract or AVP-loaded Cs-NPs in controlling the progression of lung cancer caused by urethane toxicity. The AVP-loaded chitosan nano-combination (Cs@AVP NC) was synthesized and characterized. Our in vitro results show that Cs@AVP NC has higher anticancer activity than AVP against three human cancer cell lines. The in vivo study proved the activation of apoptosis in lung cancer cells with the Cs@AVP NC oral treatment more than the AVP treatment. Additionally, Cs@AVP NC-treated animals showed significantly higher p53 and Bax-expression levels and lower NF-κB p65 levels in their lung tissues than in positive control animals. In conclusion, our study demonstrated the superior anticancer potency of Cs@AVP NC over AVP extract and its ability to inhibit lung cancer proliferation. Therefore, oral consumption of Cs@AVP NC might be a promising treatment for lung cancer.

Fluoride exposure causes behavioral, molecular and physiological changes in adult zebrafish (Danio rerio) and their offspring

Fluoride exposure through drinking water, foods, cosmetics, and drugs causes genotoxic effects, oxidative damage, and impaired cognitive abilities. In our study, the effects of fluoride on anxiety caused by the circadian clock and circadian clock changes in a zebrafish model were investigated at the molecular level on parents and the next generations. For this purpose, adult zebrafish were exposed to 1.5 ppm, 5 ppm, and 100 ppm fluoride for 6 weeks. At the end of exposure, anxiety-like behaviors and sleep/wake behaviors of the parent fish were evaluated with the circadian rhythm test and the novel tank test. In addition, antioxidant enzyme activities and melatonin levels in brain tissues were measured. In addition, morphological, physiological, molecular and behavioral analyzes of offspring taken from zebrafish exposed to fluoride were performed. In addition, histopathological analyzes were made in the brain tissues of both adult zebrafish and offspring, and the damage caused by fluoride was determined. The levels of BMAL1, CLOCK, PER2, GNAT2, BDNF and CRH proteins were measured by immunohistochemical analysis and significant changes in their levels were determined in the F- treated groups. The data obtained as a result of behavioral and molecular analyzes showed that parental fluoride exposure disrupts the circadian rhythm, causes anxiety-like behaviors, and decreases the levels of brain antioxidant enzymes and melatonin in parents. In addition, delay in hatching, increase in death and body malformations, and decrease in blood flow velocity, and locomotor activity was observed in parallel with dose increase in offspring. On the other hand, an increase in offspring apoptosis rate, ROS level, and lipid accumulation was detected. As a result, negative effects of fluoride exposure on both parents and next generations have been identified.

Nano-sized polystyrene plastic particles affect many cancer-related biological processes even in the next generations; zebrafish modeling

With the ever-increasing plastic pollution, the nano-sized plastic particles that are constantly released from the main materials have a greater potential threat. Studies continue on how to eliminate plastic waste, which has become a global problem, from nature. We are aware that complete elimination is not easy at all, but it is not known clearly that even if it is successful, its effects on organisms will also disappear completely. In this study, zebrafish injected with 20 nm-sized polystyrene particles (PS) only during the embryonic period were grown in an environment without plastic exposure. The effects of PS on their offspring embryo/larvae were examined at morphological, molecular and metabolomic levels. Results showed that parental PNP exposure caused significant malformations, decreased survival rate, increased heart rate and blood flow rate, as well as decreased eye size, height and locomotor activity, which were attributed to growth retardation in the offspring. According to the results of whole-mount immunofluorescence larval staining, cell death and reactive oxygen species were significantly increased, while lipid accumulation was decreased in new generation larvae from zebrafish injected with PNP. In order to elucidate the mechanisms underlying these morphological, physiological and molecular damages, the metabolome analyses were performed by evaluating the Q-TOF MS/MS spectra with chemometric analyses in the offspring larvae. According to the metabolomics results, 28 annotated metabolomes suggested by the OPLS-DA analysis that may vary significantly through a variable in projection scores were detected. In addition, it was detected that the significantly increased histopathological findings and immunopositivity of JNK, H2A.X, PI3 and NOP10 in new generation larvae. In conclusion, it has been shown that exposure to PS, even only during the embryonic period, may affect many cancer-related biological processes in the next generation.

Molecular characterization of ethyl carbamate toxicity in Caenorhabditis elegans

Ethyl carbamate is a common contaminant prevalent in fermented food with probable carcinogenic effects in animals. To date, other toxicological properties of ethyl carbamate are not well characterized. Using the genetic model Caenorhabditis elegans, we found that chronic exposure to ethyl carbamate during larval development impedes growth while exposure during adulthood inhibits reproduction, shortens lifespan, and promotes degeneration to dopaminergic neurons. Through whole-transcriptome RNA-sequencing, we found that ethyl carbamate invokes a widespread transcriptomic response inducing the differential expression of > 4,000 genes by at least 2-fold. Functional analysis of RNA-sequencing data revealed that up-regulated genes enrich to various neuron regulatory processes and xenobiotic defense. Gene expression analysis confirms that various genes encoding antioxidant enzymes and those functioning within phase I and II detoxification responses along with ABC transporters are highly up-regulated after ethyl carbamate exposure, suggesting the onset of oxidative stress. Overall, these findings report new toxicological properties of chronic ethyl carbamate exposure and provide new insights on its effects on transcriptome regulation in the C. elegans model.

Effects of the food colorant carmoisine on zebrafish embryos at a wide range of concentrations

Since the middle of the twentieth century, the use of dyes has become more common in every food group as well as in the pharmaceutical, textile and cosmetic industries. Azo dyes, including carmoisine, are the most important of the dye classes with the widest color range. In this study, the effects of carmoisine exposure on the embryonic development of zebrafish at a wide dose scale, including recommended and overexposure doses (from 4 to 2000 ppm), were investigated in detail. For this purpose, many morphological and physiological parameters were examined in zebrafish exposed to carmoisine at determined doses for 96 h, and the mechanisms of action of the changes in these parameters were tried to be clarified with the metabolite levels determined. The no observed effect concentration (NOEC) and median lethal concentration (LC₅₀) were recorded at 5 ppm and 1230.53 ppm dose at 96 hpf, respectively. As a result, it was determined that the applied carmoisine caused serious malformations, reduction in height and eye diameter, increase in the number of free oxygen radicals, in apoptotic cells and in lipid accumulation, decrease in locomotor activity depending on the dose and at the highest dose, decrease in blood flow rate. In the metabolome analysis performed to elucidate the metabolism underlying all these changes, 45 annotated metabolites were detected.