Abamectin affects the bioenergetics of liver mitochondria: A potential mechanism of hepatotoxicity

Smartphone-assimilated colorimetric sensor for sub-nanomolar emamectin detection via KA30 capped silver nanoparticles in food, bio-fluids and water samples

In this report, we firstly synthesized nitro calix [4] resorcinarene compound (referred as KA30) and characterized it though proton (1H) nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and Fourier Transform Infra-red (FTIR) spectroscopy. KA30 was applied as functionalizing agent for the formation of silver nanoparticles (KA30-AgNPs). These NPs were confirmed as highly selective and extremely sensitive colorimetric sensor for ultra-low level detection of emamectin (EMA) as a novel report. Significant aspect of the sensor is its unique detection range between 0.0005 and 29.5 μM via color change from yellow to colorless with hypochromic-bathochromic shift exhibiting limit of detection (LOD) and limit of quantification (LOQ) as 0.12 nM and 0.4 nM respectively. The sensor was applied to colorimetrically and optically detect EMA in real samples of serum, urine and food. The sensor was further allied with smartphone for real-time, and on-site detection of EMA and results were validated through UPLC.

Sex comparison of oxidative stress, mitochondrial dysfunction, and apoptosis triggers induced by single-dose Abamectin in albino rats

Abamectin (AB) is widely used in agriculture and has been employed as an insecticide, nematicide, and livestock pest control agent. However, it may also pose a serious threat to mammals. The primary purpose of this research was to compare the sex variations between male and female rats during exposure and to assess the risk of toxicity of abamectin, which are still largely unknown. The twenty albino rats were divided randomly into four groups (n = 5): 1) the male control group; 2) the male treatment group treated with AB (1 mg/kg B.W.); 3) the female control group; and 4) the female treatment group treated with AB (1 mg/kg B.W.). AB administration caused a drop in body weight in females more than males with showing oxidative stress in both sexes of animals, as characterized by an increase in MDA content and a decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. Reported sex-specific effects suggested that females are more susceptible from males in brain tissues for alteration of antioxidant markers while females' liver and kidney tissues showed more level of lipid peroxidation than males. In addition, mitochondrial dysfunction was associated with a significant decrease in NADH dehydrogenase (Complex I) and a significant decrease in mitochondrial ATPase, which led to apoptosis and histopathological alterations in the targeted tissues, indicating that females are higher sensitive than males to these biological events. In brief, the results of this study led to female rats are generally more sensitive than male rats to neurobehavioral and hepatic complications associated with abamectin treatment. Further evaluation should be performed to determine the adverse outcome pathways involved and to determine the effects of sex on improving the risk assessment of abamectin in both sexes.

Hepatotoxicity of the Pesticide Avermectin Exposure to Freshwater-Farmed Carp: Evidence from In Vivo and In Vitro Research

Avermectin (AVM) is presently one of the most extensively employed insecticides across the globe. A number of toxicity research studies of AVM have been carried out in freshwater-farmed carp; however, there are currently no toxicity studies on the liver. This investigation aims to replicate an acute liver injury model induced by AVM in carp, subsequently analyzing the adverse effects imposed on the nontarget species while delving into potential mechanisms underlying its toxicity. In this study, we found that AVM-exposed carp liver tissue showed cellular hydration degeneration and necrosis and reduced the viability of hepatocyte L8824. Second, AVM induced oxidative stress in carp, and AVM stimulation led to reactive oxygen species (ROS) accumulation and Ca2+ overload in hepatocyte L8824, suggesting that AVM exposure induces mitochondrial dysfunction in hepatocytes. AVM induced inflammation in carp liver tissue by inducing mitochondrial kinetic disruption, which triggered hepatic tissue injury. AVM induced autophagy and apoptosis in carp liver tissue and ROS mediated AVM-induced autophagy and apoptosis. The formation of autophagy attenuated the AVM-induced liver injury. In conclusion, the present study elucidated the hepatotoxicity and potential mechanisms of freshwater aquaculture carp exposed to the pesticide AVM, emphasized the importance of monitoring pesticide AVM contamination in freshwater aquaculture aquatic environments, and provided theoretical references for the targeted prevention of AVM-induced toxicity in carp.

Eucalyptol alleviates avermectin exposure-induced apoptosis and necroptosis of grass carp hepatocytes by regulating ROS/NLRP3 axis

The wide application of Avermectin (AVM) has caused pollution of surface water and damage to non-target organisms. A growing body of evidence supports the most prominent role of Eucalyptol (EUC) is antioxidation. To the purpose of explore the injury mechanism of Avermectin on grass carp hepatocytes and the antagonistic effect of Eucalyptol, 5.7 μM AVM and/or 20 μM EUC were used to treat grass carp hepatocytes for 24 h to establish hepatocyte exposure model. The results showed that Avermectin exposure significantly increased the contents of reactive oxygen species (ROS) and malondialdehyde (MDA) in cells, reduced the activities of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC). Also, the expressions of NLRP3 inflammasome-related genes including NLRP3, ASC, and Caspase-1, the necroptosis-related genes including RIPK1, RIPK3, and MLKL and apoptotic genes including Bax, Caspase-3, and Caspase-9 were all up-regulated. Meanwhile, the expressions of Caspase-8 and Bcl-2 were significantly decreased upon exposure to Avermectin. However, the toxicity was significantly alleviated with the treatment of EUC or N-acetyl-l-cysteine (NAC). The above results indicated that eucalyptol alleviated AVM exposure-induced apoptosis and necroptosis of grass carp hepatocytes by regulating the ROS/NLRP3 signaling pathway.

Avermectin reduces bone mineralization via the TGF-β signaling pathway in zebrafish

Avermectin, a widely used insecticide, is primarily effective against animal parasites and insects. Given its extensive application in agriculture, a large amount of avermectin accumulates in natural water bodies. Studies have shown that avermectin has significant toxic effects on various organisms and on the nervous system, spine, and several other organs in humans. However, the effects of avermectin on bone development have not been reported yet. In this study, zebrafish embryos were treated with different concentrations of avermectin to explore the effects of avermectin on early bone development. The results showed that avermectin disturbed early bone development in zebrafish, caused abnormal craniofacial chondrogenesis, and reduced bone mineralization. Avermectin treatment significantly reduced mineralization in zebrafish scales and increased osteoclast activity. Real-time quantitative PCR results showed that avermectin decreased the expression of genes related to osteogenesis and transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling pathways. The TGF-β inhibitor SB431542 rescued avermectin-induced bone mineralization and osteogenesis related gene expression in zebrafish during early development. Thus, this study provides insight into the mechanism of damage caused by avermectin on bone development, thus helping demonstrate its toxicity.

The potential effect of Moringa oleifera ethanolic leaf extract against oxidative stress, immune response disruption induced by abamectin exposure in Oreochromis niloticus

Abamectin (ABM), a naturally fermented product of Streptomyces avermitilis, is applied to pest control in livestock and agriculture fields. The aim of the current study is to evaluate the protective effects of Moringa oleifera leaf ethanolic extract (MOE) on biochemical changes including oxidative stress indices, immune response marker, lipid profiles as well as mRNA expression of immune related genes, and abamectin (ABM, 5% EC) residue levels in Nile tilapia (Oreochromis niloticus) exposed to a sub-lethal concentration (0.5 µg/l) for 28 days. Disturbance in liver and kidney biomarkers was markedly increased in ABM-exposed fish compared to the control group. Malondialdehyde levels in the liver and brain tissues, as well as the activities of glutathione-s-transferase, superoxide dismutase, and glutathione peroxides, all increased significantly in ABM group. Additionally, ABM exposure increased the levels of interleukin 10 beta and growth factor gene expression. On the other hand, fish exposed to ABM had significantly lower serum alkaline phosphatase, creatinine, high-density lipoprotein, glutathione peroxides in brain, glutathione in liver and brain tissues, lysozyme activity, nitric oxide, immunoglobulin M, tumor necrosis factor, and interleukin 1 beta as compared to the control group. The recorded detrimental effects of ABM on tilapia have been overcome by the addition of MOE to the diet (1%) and ameliorating hepato-renal damage and enhancing antioxidant activity, innate immune responses, and upregulating the anti-inflammatory gene expression. Therefore, it could be concluded that MOE dietary supplementation at 1% could be used to counteract the oxidative stress, immune response disruption induced by abamectin exposure in Oreochromis niloticus, and reduce its accumulation in fish tissues.

Abamectin promotes behavior changes and liver injury in zebrafish

The indiscriminate use of pesticides is a worldwide concern due to the environment contamination since it can cause deleterious effects to non-target organisms including the fishes. The effects of abamectin, a pesticide from the avermectin family, were evaluated in adult zebrafish (Danio rerio) after exposure to a commercial formula commonly used in Brazil. The animals were submitted to acute (96 h) and to a short-term chronic exposure (15 days) of distinct concentrations of abamectin. LC50 was determined and a histological study followed by an immunohistochemistry analysis for P-gp and HSP70 identification were performed on livers of the animals submitted to the acute and chronic treatment, respectively. Moreover, behavior patterns were observed daily in both trials. A LC50 value of 105.68 μg/L was determined. The histological analysis revealed a morphological alteration of the hepatocytes, glycogen accumulation, degeneration, and disorganization of the cytoplasm, and a pyknotic, irregular, and laterally located nuclei. The immunohistochemistry for HSP70 and P-gp showed strong staining in the hepatocytes of the control groups and progressive decrease as the concentration of abamectin increased. Changes were observed in body posture, movement around the aquarium, opercular activity, body color and search for food in the groups treated with abamectin. The results presented suggest that abamectin can affect the behavioral pattern of the animals, promote morphological changes, and decrease the expression of HSP70 and P-gp in zebrafish liver.

Subcellular-Level Mitochondrial Energy Metabolism Response in the Fat Body of the German Cockroach Fed Abamectin

Mitochondria are the leading organelle for energy metabolism. The toxic effects of environmental toxicants on mitochondrial morphology, energy metabolism, and their determination of cell fate have already been broadly studied. However, minimal research exists on effects of environmental toxicants such as pesticides on mitochondrial energy metabolism at in vitro subcellular level, particularly from an omics perspectives (e.g., metabolomics). Here, German cockroach (Blattella germanica) was fed diets with (0.01 and 0.001 mg/mL) and without abamectin, and highly purified fat body mitochondria were isolated. Swelling measurement confirmed abnormal mitochondrial swelling caused by abamectin stress. The activity of two key mitochondrial energy metabolism-related enzymes, namely succinic dehydrogenase and isocitrate dehydrogenase, was significantly affected. The metabolomic responses of the isolated mitochondria to abamectin were analyzed via untargeted liquid chromatography/mass spectrometry metabolomics technology. Fifty-two differential metabolites (DMs) were identified in the mitochondria between the 0.001 mg/mL abamectin-fed and the control groups. Many of these DMs were significantly enriched in pathways involved in ATP production and energy consumption (e.g., oxidative phosphorylation, TCA cycle, and pentose phosphate pathway). Nineteen of the DMs were typically related to energy metabolism. This study is valuable for further understanding mitochondrial toxicology under environmental toxicants, particularly its subcellular level.

Involvement of Multidrug Resistance Modulators in the Regulation of the Mitochondrial Permeability Transition Pore

The permeability transition pore in mitochondria (MPTP) and the ATP-binding cassette transporters (АВС transporters) in cell membranes provide the efflux of low-molecular compounds across mitochondrial and cell membranes, respectively. The inhibition of ABC transporters, especially of those related to multi drug resistance (MDR) proteins, is an actively explored approach to enhance intracellular drug accumulation and increase thereby the efficiency of anticancer therapy. Although there is evidence showing the simultaneous effect of some inhibitors on both MDR-related proteins and mitochondrial functions, their influence on MPTP has not been previously studied. We examined the participation of verapamil and quinidine, classified now as the first generation of MDR modulators, and avermectin, which has recently been actively studied as an MDR inhibitor, in the regulation of the MPTP opening. In experiments on rat liver mitochondria, we found that quinidine lowered and verapamil increased the threshold concentrations of calcium ions required for MPTP opening, and that they both decreased the rate of calcium-induced swelling of mitochondria. These effects may be associated with the positive charge of the drugs and their aliphatic properties. Avermectin not only decreased the threshold concentration of calcium ions, but also by itself induced the opening of MPTP and the mitochondrial swelling inhibited by ADP and activated by carboxyatractyloside, the substrate and inhibitor of adenine nucleotide translocase (ANT), which suggests the involvement of ANT in the process. Thus, these data indicate an additional opportunity to evaluate the effectiveness of MDR modulators in the context of their influence on the mitochondrial-dependent apoptosis.

Assessment of Avermectins-Induced Toxicity in Animals

Macrocyclic lactones, particularly the avermectins, have completely revolutionized the approaches aimed at control of parasites. These avermectins are the most widely used anti-parasitic drugs in veterinary field with sales exceeding one billion US dollars annually. However, before clinical usage, their safety evaluation in the animals is a major critical factor that must be considered. Many studies have reported the negative effects of avermectins like ivermectin, abamectin, doramectin, and eprinomectin on the host animals. These harmful effects arise from avermectins targeting GABA and glutamate-gated chloride channels present both in the parasites and the host animals. In this review, various modes of avermectins action along with the negative effects on the host like nephrotoxicity, hepatotoxicity, neurotoxicity, reproductive toxicity, and endocrine disruption were discussed in detail. Furthermore, other important issues like ecotoxicity, drug resistance, and drug residues in milk associated with avermectins usage were also discussed, which need special attention.

Investigation of the effects of hesperidin administration on abamectin-induced testicular toxicity in rats through oxidative stress, endoplasmic reticulum stress, inflammation, apoptosis, autophagy, and JAK2/STAT3 pathways

In this study, the potential effects of hesperidin (HES) on chronic toxicity caused by abamectin (ABM) in the testicular tissue were investigated through oxidative stress, inflammation, endoplasmic reticulum stress (ERS), apoptosis, and autophagy pathways. Male Sprague Dawley rats were used in the study. Animals in the ABM group were orally administered 1 mg/kg ABM every other day for 28 days, while HES used against ABM was given at 100 or 200 mg/kg 30 min after ABM administration for 28 days. Markers of oxidative stress, inflammation, ERS, apoptosis, and autophagy in the testicular tissues removed after the animals are sacrificed were analyzed using biochemical, real-time polymerase chain reaction (RT-PCR), or western blot techniques. The results obtained showed that ABM caused oxidative stress, and triggered ERS, inflammation, apoptosis, and autophagy. On the other hand, HES showed antioxidant effect by increasing superoxide dismutase, catalase, glutathione peroxidase enzyme activities, and glutathione levels in testis tissue and attenuated lipid peroxidation. Accordingly, MAPK14 reduced the NF-κB, IL-1β, TNF-α, and IL-6 expression levels, presenting an anti-inflammatory effect. In addition, Bax protected against apoptosis and autophagy by reducing the caspase-3, beclin-1, LC3A, and LC3B expressions, and increasing Bcl-2 expression. It was observed that HES also interrupted the JAK2/STAT3 signaling pathway by suppressing IL-6 expression. Taken into consideration together, HES provided significant protection against the destruction caused by ABM in testicular tissue with antioxidant, anti-inflammatory, antiapoptotic, and anti-autophagic effects. Thus, it was revealed that HES has the potential to serve as an alternative treatment option in ABM toxicity.

Oxidative Stress in NAFLD: Role of Nutrients and Food Contaminants

Non-alcoholic fatty liver disease (NAFLD) is often the hepatic expression of metabolic syndrome and its comorbidities that comprise, among others, obesity and insulin-resistance. NAFLD involves a large spectrum of clinical conditions. These range from steatosis, a benign liver disorder characterized by the accumulation of fat in hepatocytes, to non-alcoholic steatohepatitis (NASH), which is characterized by inflammation, hepatocyte damage, and liver fibrosis. NASH can further progress to cirrhosis and hepatocellular carcinoma. The etiology of NAFLD involves both genetic and environmental factors, including an unhealthy lifestyle. Of note, unhealthy eating is clearly associated with NAFLD development and progression to NASH. Both macronutrients (sugars, lipids, proteins) and micronutrients (vitamins, phytoingredients, antioxidants) affect NAFLD pathogenesis. Furthermore, some evidence indicates disruption of metabolic homeostasis by food contaminants, some of which are risk factor candidates in NAFLD. At the molecular level, several models have been proposed for the pathogenesis of NAFLD. Most importantly, oxidative stress and mitochondrial damage have been reported to be causative in NAFLD initiation and progression. The aim of this review is to provide an overview of the contribution of nutrients and food contaminants, especially pesticides, to oxidative stress and how they may influence NAFLD pathogenesis.

Diazinon impairs bioenergetics and induces membrane permeability transition on mitochondria isolated from rat liver

Diazinon (DZN) is a broad-spectrum insecticide extensively used to control pests in crops and animals. Several investigators demonstrated that DZN produced tissue toxicity especially to the liver. In addition, the mitochondrion was implicated in DZN-induced toxicity, but the precise role of this organelle remains to be determined. The aim of this study was thus to examine the effects of DZN (50 to 150 μM) on the bioenergetics and mitochondrial permeability transition (MPT) associated processes in isolated rat liver mitochondria. DZN inhibited state-3 respiration in mitochondria energized with glutamate plus malate, substrates of complex I, and succinate, substrate of complex II of the respiratory chain and decreased the mitochondrial membrane potential resulting in inhibition of ATP synthesis. MPT was estimated by the extent of mitochondrial swelling, in the presence of 10 µM Ca²⁺. DZN elicited MPT in a concentration-dependent manner, via a mechanism sensitive to cyclosporine A, EGTA, ruthenium red and N-ethylmaleimide, which was associated with mitochondrial Ca²⁺ efflux and cytochrome c release. DZN did not result in hydrogen peroxide accumulation or glutathione oxidation, but this insecticide oxidized endogenous NAD(P)H and protein thiol groups. Data suggest the involvement of mitochondria, via apoptosis, in the hepatic cytotoxicity attributed to DZN.

Mitochondrial Respiratory Inhibition Promoted by Pyraclostrobin in Fungi is Also Observed in Honey Bees

There is no use restriction associated with bees for many fungicides used in agriculture; however, this does not always mean that these pesticides are harmless for these nontarget organisms. We investigated whether the fungicide pyraclostrobin, which acts on fungal mitochondria, also negatively affects honey bee mitochondrial bioenergetics. Honey bees were collected from 5 hives and anesthetized at 4 °C. The thoraces were separated, and mitochondria were isolated by grinding, filtering, and differential centrifugation. An aliquot of 0.5 mg of mitochondrial proteins was added to 0.5 mL of a standard reaction medium with 4 mM succinate (complex II substrate) plus 50 nM rotenone (complex I inhibitor), and mitochondrial respiration was measured at 30 °C using a Clark-type oxygen electrode. Mitochondrial membrane potential was determined spectrofluorimetrically using safranin O as a probe, and adenosine triphosphate (ATP) synthesis was determined by chemiluminescence. Pyraclostrobin at 0 to 50 μM was tested on the mitochondrial preparations, with 3 repetitions. Pyraclostrobin inhibited mitochondrial respiration in a dose-dependent manner at concentrations of 10 μM and above, demonstrating typical inhibition of oxidative phosphorylation. Pyraclostrobin also promoted a decline in the mitochondrial membrane potential at doses of 5 μM and above and in ATP synthesis at 15 μM and above. We conclude that pyraclostrobin interferes with honey bee mitochondrial function, which is especially critical for the energy-demanding flight activity of foraging bees. Environ Toxicol Chem 2020;39:1267-1272. © 2020 SETAC.

Implications of gut microbiota dysbiosis and metabolic changes in prion disease

Evidence of the gut microbiota influencing neurodegenerative diseases has been reported for several neural diseases. However, there is little insight regarding the relationship between the gut microbiota and prion disease. Here, using fecal samples of 12 prion-infected mice and 25 healthy controls, we analyzed the structure of the gut microbiota and metabolic changes by 16S rRNA sequencing and LC-MS-based metabolomics respectively as multi-omic analyses. Additionally, SCFAs and common amino acids were detected by GC-MS and UPLC respectively. Enteric changes induced by prion disease affected both structure and abundances of the gut microbiota. The gut microbiota of infected mice displayed greater numbers of Proteobacteria and less Saccharibacteria at the phylum level and more Lactobacillaceae and Helicobacteraceae and less Prevotellaceae and Ruminococcaceae at the family level. A total of 145 fecal metabolites were found to be significantly different in prion infection, and most (114) of these were lipid metabolites. Using KEGG pathway enrichment analysis, we found that 3 phosphatidylcholine (PC) compounds significantly decreased and 4 hydrophobic bile acids significantly increased. Decreases of 8 types of short-chain acids (SCFAs) and increases of Cys and Tyr and decreases of His, Trp, and Arg were observed in prion infection. Correlation analysis indicated that the gut microbiota changes observed in our study may have been the shared outcome of prion disease. These findings suggest that prion disease can cause significant shifts in the gut microbiota. Certain bacterial taxa can then respond to the resulting change to the enteric environment by causing dramatic shifts in metabolite levels. Our data highlight the health impact of the gut microbiota and related metabolites in prion disease.

Abamectin induces apoptosis and autophagy by inhibiting reactive oxygen species-mediated PI3K/AKT signaling in MGC803 cells

Abamectin (ABA) is one of the most widely used compounds in agriculture and veterinary medicine. However, the cytotoxicity of ABA in human gastric cells is utterly unknown. In this study, ABA suppressed the proliferation of MGC803 cells by arresting the cell cycle at the G0/G1-phase. Moreover, ABA induced mitochondrial-mediated apoptosis by inducing the loss of mitochondrial membrane potential, upregulation of Bax/Bcl-2, and activation of caspase-3. ABA significantly improved the LC3-II/LC3-I ratio and reduced P62 protein expression in a dose-dependent manner. Through detection of the reactive oxygen species (ROS) levels, we found ABA induced the accumulation of intracellular ROS and then reduced PI3K/AKT signaling activation related to MGC803 cell apoptosis and autophagy. Our results indicate that ABA exerts cytotoxic effects on human MGC803 cells through apoptosis and autophagy by inhibiting ROS-mediated PI3K/AKT signaling. Furthermore, ABA may be a potential risk to human gastric health.

The chronic exposure to abamectin causes spatial memory deficit and depressive behavior in mice

It is known that abamectin (ABA), which is a component belonging to the group of avermectins, has been broadly used as biopesticide. Although its effect on non-target aquatic organisms is known, knowledge about its impacts on terrestrial animals such as mammals remains incipient. Thus, we aim at investigating the effects (phycical and neural-behavioral) from the chronic exposure (90 days) to ABA (1/10 of LD₅₀) on Swiss and C57Bl/6J mice from both sexes. Accordingly, at the end of the experimental period the animals were subjected to the following tests: Novel Object Recognition Test (NORT), Morris Water Maze (MWM), Tail Suspension Test (TST), and Forced Swimming Test (FST). We showed that the new-object recognition indexes in the NORT test sessions did not differ between experimental groups; however, animals exposed to ABA, regardless of sex or strain, recorded longer latency time to find the quadrant holding the platform in the MWM training sessions, as well as stayed shorter in this quadrant. Such results highlight the negative effect of the pesticide on the animals' spatial memory evocation, without evident influence from their genetic status and sex. With regard to TST, we also did not observe differences in immobility time between groups; however, Swiss mice (males and females) presented depressive behavior in the FST, and apparent influence from their genetic status in their responses during the test. Therefore, our study confirms the neurotoxic potential of ABA and is pioneer in reporting memory deficit and depressive behavior in mammal experimental models.

Autophagy response in the liver of pigeon exposed to avermectin

Pesticide residues are an important aspect of environmental pollution. Environmental avermectin residues have produced adverse effects in organisms. Many pesticides exert their toxic effects via the mechanism of autophagy. The purpose of this study was to examine the changes in autophagy levels and in autophagy-related genes, including LC3, Beclin 1, Dynein, ATG5, TORC1, and TORC2, resulting from exposure to subchronic levels of AVM in liver tissue in the king pigeon model. We observed abundant autophagic vacuoles with extensively degraded organelles, autophagosomal vacuoles, secondary lysosomes, and double-membrane structures in the liver. The expression levels of the autophagy-related genes LC3-I, LC3-II, Beclin 1, ATG5, and Dynein were up-regulated; however, TORC1 and TORC2 expression levels were down-regulated. These changes occurred in a concentration-dependent manner after AVM exposure for 30, 60, and 90 days in pigeons. Taken together, these results suggested that AVM increased the autophagic flux and that upregulation of autophagy might be closely related to the hepatotoxicity of AVM in birds.

Lactational exposure to abamectin induced mortality and adverse biochemical and histopathological effects in suckling pups

Information about the adverse effects of lactation transfer of abamectin (ABA) is important for human health, especially in the third-world countries where breastfeeding is the only source of nutrition for infants. So, the present study was undertaken to evaluate the adverse effects of breastfeeding exposure to ABA on oxidative damage and liver and kidney dysfunction in suckling rats. Dams were orally administered ABA at a doses 22.10, 11.05, and 2.21 mg a.i./kg b.wt from postnatal day 1 (PND1) until day 20 (PND20). The signs of toxicity and high mortality were recorded in suckling male (67.5%) and female (55.0%) pups whose mother exposed to the ABA at dose 22.1 mg a.i./kg b.wt. ABA induced significantly decrease in body weights of mothers and their male and female pups and significant increase in relative liver weights. It caused oxidative stress in the liver and kidney of mothers and their pups by increasing the level of malondialdehyde (MDA) and decreased activities of superoxide dismutase (SOD) and glutathione-transferase (GST). ABA altered the level of serum liver and kidney dysfunction biomarkers either in the mothers or their male and female pups in a dose-dependent manner. It caused histopathological alterations in the liver and kidney tissues. It can be decided that ABA was accumulated in mother's milk, transferred through breast feeding, and induced mortality in their suckling pups. It caused oxidative stress, lipid peroxidation, and biochemical and histopathological alterations in the liver and kidney of mothers and their suckling pups. The results in the present study add some information about the adverse effect of lactation transfer of ABA, which is important for human health in the third-world countries where breastfeeding may be the only source of nutrition for infants in the first and most critical weeks of life.

Spectroscopic, Polarographic, and Microcalorimetric Studies on Mitochondrial Dysfunction Induced by Ethanol

Liver mitochondria are involved in several important life processes; mitochondrial dysfunction and disorders are implicated in several human diseases. Alcohol permeates all tissues of the body and exerts some intrinsic hepatotoxicity. In this work, our results demonstrated that ethanol caused a series of mitochondria permeability transition pore (MPTP) opening factors such as mitochondrial swelling, increased permeability of H⁺ and K⁺, collapsed membrane potential, and increased membrane fluidity. Furthermore, mitochondrial ultrastructure alternation observed clearly by transmission electron microscopy and the release of Cytochrome c could explain the MPTP opening from another aspect. Moreover, ethanol damaged the mitochondrial respiration system and induced disturbance of mitochondrial energy metabolism which was monitored by polarographic and microcalorimetric methods, respectively. Considered together, these damages may promote both apoptotic and necrotic cell death and contribute to the onset or progression alcohol-induced liver diseases.

Cytotoxic effects of Avermectin on human HepG2 cells in vitro bioassays

Avermectin (AVM) has been widely used in agriculture and animal husbandry based on its broad spectrum of effective anthelmintic activity and specificity targets. However, AVM induction of cytotoxicity in human liver is largely unknown. In this study, we investigate the cytotoxic effects of AVM on HepG2 cells in vitro. The results revealed that AVM inhibited the viability of HepG2 cells and enhanced apoptosis. Established assays of cytotoxicity were performed to characterize the mechanism of AVM toxicity on HepG2 cells. Typical apoptosis morphological changes were shown in AVM-treatment cells including chromatin condensation and DNA fragmentation. We demonstrated that AVM-induced apoptosis of HepG2 cells were mediated by generated ROS. Moreover, a decrease in mitochondrial membrane potential (MMP) and up-regulating the Bax/Bcl-2 ratio, resulted in a release of cytochrome-c as well as activation of caspase-9/-3. In conclusion, our experimental results show that AVM has a potential threat to human health which may be induce apoptosis of human hepatocyte cells via caspase-dependent mitochondrial pathways.

Evaluation of the toxicity of fungicides to flight muscle mitochondria of bumblebee (Bombus terrestris L.)

Insects pollinate 75% of crops used for human consumption. Over the last decade, a substantial reduction in the abundance of pollinating insects has been recorded and recognized as a severe matter for food supply security. Many of the important food crops destined for human consumption are grown in greenhouses. A unique feature of greenhouse agriculture is the extensive use of fungicides to curb multiple fungal infections. The most widely used pollinating insects in greenhouses are commercially reared bumblebees. However, there is no data regarding the toxicity of fungicides to bumblebee mitochondria. To fill this gap in knowledge, we examined the effects of 16 widely used fungicides on the energetics of the flight muscles mitochondria of Bombus terrestris. We found that diniconazole and fludioxonil uncoupled the respiration of mitochondria; dithianon and difenoconazole inhibited it. By analyzing the action of these inhibitors on mitochondrial respiration and generation of reactive oxygen species, we concluded that difenoconazole inhibited electron transport at the level of Complex I and glycerol-3-phosphate dehydrogenase. Dithianon strongly inhibited succinate dehydrogenase and glycerol-3-phosphate dehydrogenase. It also strongly inhibited mitochondrial oxidation of NAD-linked substrates or glycerol 3-phosphate, but it had no effect on the enzymatic activity of Complex I. It may be suggested that dithianon inhibits electron transport downstream of Complex I, likely at multiply sites.

The Effects of Ivermectin on Brugia malayi Females In Vitro: A Transcriptomic Approach

BACKGROUND

Lymphatic filariasis and onchocerciasis are disabling and disfiguring neglected tropical diseases of major importance in developing countries. Ivermectin is the drug of choice for mass drug administration programs for the control of onchocerciasis and lymphatic filariasis in areas where the diseases are co-endemic. Although ivermectin paralyzes somatic and pharyngeal muscles in many nematodes, these actions are poorly characterized in adult filariae. We hypothesize that paralysis of pharyngeal pumping by ivermectin in filariae could result in deprivation of essential nutrients, especially iron, inducing a wide range of responses evidenced by altered gene expression, changes in metabolic pathways, and altered developmental states in embryos. Previous studies have shown that ivermectin treatment significantly reduces microfilariae release from females within four days of exposure in vivo, while not markedly affecting adult worms. However, the mechanisms responsible for reduced production of microfilariae are poorly understood.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed transcriptomic profiles from Brugia malayi adult females, an important model for other filariae, using RNAseq technology after exposure in culture to ivermectin at various concentrations (100 nM, 300 nM and 1 μM) and time points (24, 48, 72 h, and 5 days). Our analysis revealed drug-related changes in expression of genes involved in meiosis, as well as oxidative phosphorylation, which were significantly down-regulated as early as 24 h post-exposure. RNA interference phenotypes of the orthologs of these down-regulated genes in C. elegans include "maternal sterile", "embryonic lethal", "larval arrest", "larval lethal" and "sick".

CONCLUSION/SIGNIFICANCE

These changes provide insight into the mechanisms involved in ivermectin-induced reduction in microfilaria output and impaired fertility, embryogenesis, and larval development.

Comparative effects of fipronil and its metabolites sulfone and desulfinyl on the isolated rat liver mitochondria

Fipronil is an insecticide extensively used to control pests in crops and animals. There are relates of poisoning due to exposure of fipronil in mammals and the liver has been suggested as potential target. In this study, we evaluated the effects of fipronil and its metabolites sulfone and desulfinyl on the bioenergetics, reactive oxygen species (ROS) production and calcium efflux from mitochondria isolated from rat liver. Fipronil (5-25 μM) inhibited state-3 respiration in mitochondria energized with glutamate plus malate, substrates of complex I of the respiratory chain and decreased the mitochondrial membrane potential resulting in inhibition of ATP synthesis. Fipronil also caused uncoupling in succinate-energized mitochondria and calcium efflux. The metabolites sulfone and desulfinyl also acted as mitochondrial inhibitors and uncouplers and caused calcium efflux, but with different potencies, being the sulfone the more potent one. These effects of fipronil and its metabolites on mitochondrial bioenergetics and calcium homeostasis may be related to toxic effects of the insecticide in the liver.

Rat Liver Mitochondrial Dysfunction Induced by an Organic Arsenical Compound 4-(2-Nitrobenzaliminyl) Phenyl Arsenoxide

Arsenic is successfully used in cancer chemotherapy and several cancer treatments on account of its apoptogenic effects. However, it is environmentally hazardous with potential for toxicity when distributed in the soil, water, and food, and long exposure to water contaminated with Arsenic may induce cancers. Some research studies have reported that liver is the storage site and an important target organ for Arsenic toxicity. In the present work, a new kind of organic arsenic compound, 4-(2-nitrobenzaliminyl) phenyl arsenoxide (NPA), was synthesized, and its potential involvement of mitochondria was explored. The results presented that the toxicology of NPA, at least in part, mediated mitochondrial function and may thoroughly destroy mitochondrial membrane physiological functions. NPA induced mitochondrial permeability transition pore (mtPTP) opening that induces mitochondrial biochemical abnormalities as evidenced by mitochondrial swelling, mitochondrial membrane potential breakdown, membrane fluidity alterations, and the strikingly remarkable protection of CsA. Meanwhile, both the decreased respiration rate of state 4 and the increased inner membrane H(+) permeabilization revealed that the inner membrane function regarding important energy production chain was destroyed. The toxicity of NPA is due to its interaction with mitochondrial membrane thiol protein. This conclusion is based on the protective effects of RR, DTT, and MBM(+).

Autophagy is upregulated in brain tissues of pigeons exposed to avermectin

Avermectin (AVM) is used in agriculture and veterinary medicine for the prevention of parasitic diseases; AVM is the active component of some insecticidal and nematicidal products. Residues of AVM drugs or their metabolites in livestock feces have toxic effects on non-target aquatic and terrestrial organisms. In this study, changes in the levels of autophagy related genes and ultrastructure in pigeon brain tissues after subchronic exposure to AVM for 30, 60 and 90 d were investigated. The decrease in the mRNA levels of TORC1 and TORC2 and increase in the mRNA levels of LC3, Beclin 1, Dynein, ATG5 and ATG4B and the increase in the protein levels of LC3, Beclin 1 and Dynein in a dose- and time-dependent manner in the pigeon brain were observed. The number of autophagic vacuoles in the cerebrum, cerebellum and optic lobe increased significantly with the concentration of AVM and the exposure time. We found that the changes in the levels of autophagy related genes and the ultrastructure in the cerebrum were more obvious than in the cerebellum and the optic lobe. The results suggest that AVM could induce autophagy in pigeon brain tissues. The information presented in this study is helpful for understanding the mechanism of AVM-induced autophagy in birds.

Insight into biological system responses in goldfish (Carassius auratus) to multiple doses of avermectin exposure by integrated1H NMR-based metabolomics

AVM disturbed the metabolomic profiles of goldfish dose-dependently, affecting the metabolic pathways related with its toxicity.

Fipronil and imidacloprid reduce honeybee mitochondrial activity

Bees have a crucial role in pollination; therefore, it is important to determine the causes of their recent decline. Fipronil and imidacloprid are insecticides used worldwide to eliminate or control insect pests. Because they are broad-spectrum insecticides, they can also affect honeybees. Many researchers have studied the lethal and sublethal effects of these and other insecticides on honeybees, and some of these studies have demonstrated a correlation between the insecticides and colony collapse disorder in bees. The authors investigated the effects of fipronil and imidacloprid on the bioenergetic functioning of mitochondria isolated from the heads and thoraces of Africanized honeybees. Fipronil caused dose-dependent inhibition of adenosine 5'-diphosphate-stimulated (state 3) respiration in mitochondria energized by either pyruvate or succinate, albeit with different potentials, in thoracic mitochondria; inhibition was strongest when respiring with complex I substrate. Fipronil affected adenosine 5'-triphosphate (ATP) production in a dose-dependent manner in both tissues and substrates, though with different sensitivities. Imidacloprid also affected state-3 respiration in both the thorax and head, being more potent in head pyruvate-energized mitochondria; it also inhibited ATP production. Fipronil and imidacloprid had no effect on mitochondrial state-4 respiration. The authors concluded that fipronil and imidacloprid are inhibitors of mitochondrial bioenergetics, resulting in depleted ATP. This action can explain the toxicity of these compounds to honeybees.

Avermectin induced liver injury in pigeon: mechanisms of apoptosis and oxidative stress

Extensive use of avermectin (AVM) can result in environment pollution, and it is important to evaluate the potential impact this antibiotic has on ecological systems. Few published literatures have discussed the liver injury mechanisms induced by AVM on birds. In this study, pigeons were exposed to feed containing AVM (0, 20, 40 and 60 mg/kg diet) for 30, 60, 90 days respectively. The results showed that AVM increased the number of apoptosis and the expression level of caspase-3, 8, fas mRNA in the liver of pigeons. Ultrastructural alterations, including mitochondrial damage and chromatin aggregation, become severe with increase exposure dose. Exposure to AVM induced significant changes in antioxidant enzyme {superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)} activities and malondialdehyde (MDA) content, augmented protein carbonyl (PCO) content and DNA-protein crosslink (DPC) coefficient, in a concentration-dependent manner in the liver of pigeons. Our results show that AVM has toxic effect in pigeon liver, and the mechanism of injury caused by AVM is closely related to apoptosis and oxidative stress.

The role of mitochondria and biotransformation in abamectin-induced cytotoxicity in isolated rat hepatocytes

Abamectin (ABA), which belongs to the family of avermectins, is used as a parasiticide; however, ABA poisoning can impair liver function. In a previous study using isolated rat liver mitochondria, we observed that ABA inhibited the activity of adenine nucleotide translocator and FoF1-ATPase. The aim of this study was to characterize the mechanism of ABA toxicity in isolated rat hepatocytes and to evaluate whether this effect is dependent on its metabolism. The toxicity of ABA was assessed by monitoring oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, cell viability, intracellular Ca(2+) homeostasis, release of cytochrome c, caspase 3 activity and necrotic cell death. ABA reduces cellular respiration in cells energized with glutamate and malate or succinate. The hepatocytes that were previously incubated with proadifen, a cytochrome P450 inhibitor, are more sensitive to the compound as observed by a rapid decrease in the mitochondrial membrane potential accompanied by reductions in ATP concentration and cell viability and a disruption of intracellular Ca(2+) homeostasis followed by necrosis. Our results indicate that ABA biotransformation reduces its toxicity, and its toxic action is related to the inhibition of mitochondrial activity, which leads to decreased synthesis of ATP followed by cell death.