Hepatic damage in newborns from female rats exposed to the pesticide derivative ethylenethiourea

Low concentrations of ethylene bisdithiocarbamate pesticides maneb and mancozeb impair manganese and zinc homeostasis to induce oxidative stress and caspase-dependent apoptosis in human hepatocytes

The worldwide and intensive use of phytosanitary compounds results in environmental and food contamination by chemical residues. Human exposure to multiple pesticide residues is a major health issue. Considering that the liver is not only the main organ for metabolizing pesticides but also a major target of toxicities induced by xenobiotics, we studied the effects of a mixture of 7 pesticides (chlorpyrifos-ethyl, dimethoate, diazinon, iprodione, imazalil, maneb, mancozeb) often detected in food samples. Effects of the mixture was investigated using metabolically competent HepaRG cells and human hepatocytes in primary culture. We report the strong cytotoxicity of the pesticide mixture towards hepatocytes-like HepaRG cells and human hepatocytes upon acute and chronic exposures at low concentrations extrapolated from the Acceptable Daily Intake (ADI) of each compound. Unexpectedly, we demonstrated that the manganese (Mn)-containing dithiocarbamates (DTCs) maneb and mancozeb were solely responsible for the cytotoxicity induced by the mixture. The mechanism of cell death involved the induction of oxidative stress, which led to cell death by intrinsic apoptosis involving caspases 3 and 9. Importantly, this cytotoxic effect was found only in cells metabolizing these pesticides. Herein, we unveil a novel mechanism of toxicity of the Mn-containing DTCs maneb and mancozeb through their metabolization in hepatocytes generating the main metabolite ethylene thiourea (ETU) and the release of Mn leading to intracellular Mn overload and depletion in zinc (Zn). Alteration of the Mn and Zn homeostasis provokes the oxidative stress and the induction of apoptosis, which can be prevented by Zn supplementation. Our data demonstrate the hepatotoxicity of Mn-containing fungicides at very low doses and unveil their adverse effect in disrupting Mn and Zn homeostasis and triggering oxidative stress in human hepatocytes.

Assessment of changes in the liver of pregnant female rats and their fetuses following monosodium glutamate administration

Monosodium glutamate (MSG) is a common flavor enhancer and stabilizer for ready-made or packaged foods. This research investigated the impact of MSG on the maternal and fetal liver. The present study was carried out on sixteen mature female Albino rats and eight male rats of reproductive age. The control group was dissected on day 20 of gestation. MSG group was administrated MSG daily at a dosage of 1 g/5 mL/kg body weight from day 0 to day 20 of gestation. The liver function and lipid profile of the control and treated mothers were investigated in the blood sera. The levels of nitric oxide (NO), tumor necrosis factor (TNF-α), superoxide dismutase (SOD), and reduced glutathione (GSH) activities in the liver homogenate of maternal and fetal tissue were assayed, in addition to histopathological, histochemical and immunohistochemical studies were done to the liver tissue. The activities of liver functions and lipid profile significantly altered in the treated mothers with MSG. MSG significantly reduced the SOD and reduced GSH activities in addition to the elevated TNF-α and NO in liver tissue of pregnant mothers and their fetuses. Severe histopathological alterations were observed in both maternal and fetal liver tissues of MSG-treated groups. Moreover, histochemical observations showed a reduction of total polysaccharides in the liver of pregnant rats and fetuses. A significant increase in the percentage area of positive immunoreaction for caspase 3 was observed in the liver of treated rats with MSG compared to the liver of the control. The liver of fetuses treated with MSG revealed an alteration like their mother. This study showed that during the gestational period MSG exposure resulted in several biochemical, histological, and histochemical changes in the maternal and fetal liver tissues which emphasize the toxic effect of MSG.

Disruption of fertility, placenta, pregnancy outcome, and multigenerational inheritance of hepatic steatosis by organotin exposure from contaminated seafood in rats

Early life exposure to endocrine-disrupting chemicals (EDCs) is an emerging risk factor for development of complications later in life and in subsequent generations. We previously demonstrated that exposure to the EDC organotin (OT), which is present in contaminated seafood, resulted in reproductive abnormalities in female rats. However, few studies have explored the effect of OT accumulation in seafood on pregnancy outcomes. This led us to consider the potential effects of the OT present in seafood on fertility, pregnancy, the placenta, and the offspring. In this investigation, we assessed whether exposure to the OT in contaminated seafood resulted in abnormal fertility and pregnancy features and offspring complications. OT in contaminated seafood (LNI) was administered to female rats, and their fertility, pregnancy outcomes, and fetal liver morphology were assessed. LNI caused abnormal fertility, a reduction in the total number of pups, and an increase in serum testosterone levels compared to controls. Furthermore, LNI exposure caused irregular uterine morphology with inflammation and fibrosis and led to a reduction in embryonic implantation. In pregnant rats, LNI caused abnormal lipid profiles and livers with steatosis features. LNI exposure also causes placental morpho-physiology disruption, a high presence of glycogen and inflammatory cells, and irregular lipid profiles. In addition, LNI exposure caused an increase in large amounts of carbohydrate and lipid delivery to the fetus via an increase in placental nutrient sensor protein expressions (GLUT1, IRβ/mTOR and Akt). In both genders of offspring, LNI exposure led to an increase in body weights, liver megakaryocytes, lipid accumulation, and oxidative stress (OS) levels. Collectively, these data suggest that OT exposure from contaminated seafood in female rats leads to reduced fertility, uterine implantation failure, pregnancy and placental metabolic outcome irregularities, offspring adiposity, liver steatosis, and an increase in OS. Furthermore, some of the effects of OT may be the result of obesogenic and multigenerational effects of OT in adult female rats.

Development and validation of a novel enzyme-linked immunosorbent assay for monitoring ethylene thiourea in soil and vegetable samples

A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of ethylene thiourea (ETU); a metabolite of ethylenebisdithiocarbamates (EBDCs) fungicides such as mancozeb. The ELISA performed well under optimal conditions based one limit of detection (0.201 ng mL-1), sensitivity (IC50 3.71 µg mL-1), recovery (81.6-102.7%) and relative standard deviation (<12.5%). This method was used to determine ETU residues in soil and vegetables after 0, 1, 3, 5, 7 and 10 days following mancozeb application. Concentrations of ETU gradually increased in the soil up to the tenth day of application. While in tomato and potato samples, the maximum concentrations of ETU residues were reached on the third and fifth days, respectively, and then dissipated with half-lives of 1.33 and 4.33 days, respectively. The method was simple, rapid, cost-effective, environmentally friendly, and has the potential for high sample throughput.

High-throughput method for the analysis of ethylenethiourea with direct injection of hydrolysed urine using online on-column extraction liquid chromatography and triple quadrupole mass spectrometry

Ethylenethiourea (ETU) is of major toxicological concern, since in experimental animal studies, ETU has shown a large spectrum of adverse effects. High occupational exposure can be found among agricultural workers or during manufacturing of ethylenbisdithiocarbamates (EBDC). For the general public, sources of environmental exposure may be residues of ETU in commercial products, food and beverages. For the determination of ETU in human urine we present a high-throughput online on-column extraction liquid chromatography triple quadrupole mass spectrometry method using direct injection of hydrolysed urine samples. This method is simple, user- and environmentally friendly and all sample preparation is performed in 96-well plates. A labelled ETU internal standard was used for quantification. The method showed a good sensitivity with a limit of quantification (LOQ) of 0.5ng ETU/mL urine and the calibration curve was linear in the range 0.25-200ng ETU/mL urine. The within-run, between-run and between-batch precision was between 6% and 13%. Alkaline hydrolysis considerably increased the levels of ETU indicating a potential conjugate. The method was applied in an experimental dermal exposure study in humans, with sample concentrations ranging from 0.4 to 5.0ng ETU/mL urine. The excretion in urine was 10% of the applied dose. The elimination profile seemed to differ between the two individuals. The results show an estimated half-life of ETU between 34 and 72h. Although the experiment is limited to two individuals, the data provide valuable and new information regarding the toxicokinetics of ETU after dermal exposure.