Imidacloprid Promotes High Fat Diet-Induced Adiposity and Insulin Resistance in Male C57BL/6J Mice

Imbalance of gut microbiota and fecal metabolites in offspring female mice induced by nitenpyram exposure during pregnancy

Ubiquitous exposure to the neonicotinoid insecticide nitenpyram has raised concerns about its potential toxicity. In this study, we explored its health effects on the female offspring of mice that had been exposed during pregnancy. We found that exposure of pregnant mice to nitenpyram resulted in decreased levels of serum triglycerides, total cholesterol, and glucose in female offspring, and additional research uncovered gut microbiota disturbances, accompanied by abnormal fecal metabolic profiles. Based on Pearson correlation analysis, we found that decreased abundance of Lactobacillus may play the most critical role, and changes in gut bacterial purine metabolism, BCAAs metabolism, and the TCA cycle are all closely related to the abundance of Lactobacillus. In summary, these results help explain the observed serum biochemical abnormalities and provide new insights into the intergenerational toxicity of nitenpyram.

Imidacloprid disturbed the gut barrier function and interfered with bile acids metabolism in mice

The toxicity of neonicotinoid insecticide imidacloprid (IMI) to mammals has recently received increasing attention. However, the effects of IMI on the gut barrier and liver function of male C57BL/6J mice are still unknown. The study showed that exposure to IMI could reduce relative liver weights, change hepatic tissue morphology and induce hepatic oxidative stress. The gut barrier function was greatly impaired by IMI exposure, which might increase the body's susceptibility to harmful substances in the gut. Meanwhile, the synthesis and metabolism of hepatic bile acids (BAs) was also affected by IMI exposure. The levels of serum and hepatic total bile acids (TBAs) decreased; in contrast, the fecal TBA levels increased after exposure to 30 mg/L IMI for 10 weeks. Sequencing of colonic contents revealed that the operational taxonomic units (OTUs) and α-diversity index increased and that the gram-negative bacteria overgrew, indicating that the balance of the gut microbiota was disrupted. The present study indicated that subchronic exposure to IMI interfered with the gut barrier function, interfering with BAs metabolism and causing gut microbiota imbalance in male C57BL/6J mice. Taken together, IMI residues appear to be potentially toxic to mammals and even humans.

Toxicities of Neonicotinoid-Containing Pesticide Mixtures on Nontarget Organisms

Neonicotinoids are a widely used class of pesticides. Co-exposure to neonicotinoids and other classes of pesticides can exert potentiating or synergistic effects, and these mixtures have been detected in human bodily fluids. The present review summarizes studies into the effects of neonicotinoid-containing pesticide mixtures on humans and other nontarget organisms. Exposure to these mixtures has been reported to result in reproductive and hormonal toxicity, genotoxicity, neurotoxicity, hepatotoxicity, and immunotoxicity in vertebrates. Mortality of pollinators and toxicity in other organisms has also been reported. The underlying mechanism of pesticide mixture toxicity may be associated with impairment of cytochrome 450 enzymes, which are involved in metabolizing pesticides. However, a comprehensive explanation of the adverse effects of neonicotinoid-containing pesticide mixtures is still required so that effective prevention and control measures can be formulated. Environ Toxicol Chem 2020;39:1884-1893. © 2020 SETAC.

Gut Microbiota: A Key Factor in the Host Health Effects Induced by Pesticide Exposure?

In the past few decades, a large number of pesticides have been widely used for plant protection. Pesticides may enter non-target organisms through multiple ways and bring potential health risks. There is a dense and diverse microbial community in the intestines of mammals, which is called the gut microbiota. The gut microbiota and its metabolites play vital roles in maintaining the health of the host. Interestingly, many studies have shown that exposure to multiple pesticides could affect the gut microbiota of the host. However, the roles of gut microbiota and its related metabolites in the host health effects induced by pesticide exposure of non-target organisms need further study. We reviewed the relationships between pesticide exposure and host health effects as well as between the gut microbiota and host health effects. Importantly, we reviewed the latest research on the gut microbiota and its metabolites in the host health effects induced by pesticide exposure.

Agrochemicals and obesity

Obesity has become a very large concern worldwide, reaching pandemic proportions over the past several decades. Lifestyle factors, such as excess caloric intake and decreased physical activity, together with genetic predispositions, are well-known factors related to obesity. There is accumulating evidence suggesting that exposure to some environmental chemicals during critical windows of development may contribute to the rapid increase in the incidence of obesity. Agrochemicals are a class of chemicals extensively used in agriculture, which have been widely detected in human. There is now considerable evidence linking human exposure to agrochemicals with obesity. This review summarizes human epidemiological evidence and experimental animal studies supporting the association between agrochemical exposure and obesity and outlines possible mechanistic underpinnings for this link.

Pesticides-induced energy metabolic disorders

Metabolic disorders have become a heavy burden on society. Recently, through excessive use, pesticides have been found to be present in environmental matrixes and sometimes even accumulate in humans or other mammals through the food chain, which then causes health concerns. Evidence has indicated that pesticides have the potential to induce energy metabolic disorders by disturbing the physical process of energy absorption in the intestine and energy storage in the liver, adipose tissue and skeletal muscle in humans or other mammals. In addition, the homeostasis of energy regulation by the pancreas and immune cells is also affected by pesticides. These pesticide-induced disruptions ultimately cause abnormal levels of blood glucose and lipids, which in turn induce the development of related metabolic diseases, including overweight, underweight, insulin resistance and even diabetes. In this review, the results of previous studies focused on the induction of metabolic disorders by pesticides are summarized. We hope that this work will facilitate the discovery of a potential strategy for the treatment of diseases caused by pesticides.

Impact of pesticide exposure on adipose tissue development and function

Obesity is a leading cause of morbidity, mortality and health care expenditure whose incidence is rapidly rising across the globe. Although the cause of the obesity epidemic is typically viewed as a product of an increased availability of high calorie foods and/or a reduction in physical activity, there is mounting evidence that exposure to synthetic chemicals in our environment may play an important role. Pesticides, are a class of chemicals whose widespread use has coincided with the global rise of obesity over the past two decades. Importantly, given their lipophilic nature many pesticides have been shown to accumulate with adipose tissue depots, suggesting they may be disrupting the function of white adipose tissue (WAT), brown adipose tissue (BAT) and beige adipose tissue to promote obesity and metabolic diseases such as type 2 diabetes. In this review, we discuss epidemiological evidence linking pesticide exposure with body mass index (BMI) and the incidence of diabetes. We then review preclinical studies in rodent models which have directly evaluated the effects of different classes of insecticides and herbicides on obesity and metabolic dysfunction. Lastly, we review studies conducted in adipose tissue cells lines and the purported mechanisms by which pesticides may induce alterations in adipose tissue function. The review of the literature reveals major gaps in our knowledge regarding human exposure to pesticides and our understanding of whether physiologically relevant concentrations promote obesity and elicit alterations in key signaling pathways vital for maintaining adipose tissue metabolism.

Longitudinal Study of Metabolic Biomarkers among Conventional and Organic Farmers in Thailand

The aim of this longitudinal study is to assess how pesticide use may impact metabolic biomarkers by collecting and comparing data from conventional (n = 13) and organic farmers (n = 225) every eight months for four rounds. Farmers were interviewed about family health history, food consumption behaviors, self-reported health problems, agricultural activities, and history of pesticide use. Systolic and diastolic blood pressure and body mass index (BMI) were measured. Blood samples were collected for total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), blood glucose, and triglycerides. A linear mixed model with random intercepts for subjects was used to compare the metabolic biomarkers between conventional and organic farmers and to examine the impact of the number of pesticide spray days for all four rounds after controlling for covariates. The conventional farmers reported using insecticides, herbicides, and fungicides. The marginal means for chemical farmers were significantly higher than organic farmers for total cholesterol, LDL, HDL, glucose, systolic and diastolic blood pressure, BMI, and waist circumference. Increasing the number of days of spraying either insecticides or fungicides was associated with an increase in HDL, LDL, and cholesterol levels. Increasing the number of herbicide spray days was associated with an increase in systolic and diastolic blood pressure and a decrease in BMI. These findings suggest that pesticide-using conventional farmers may be at higher risk of metabolic disease in the future.

Neonicotinoid insecticides exposure cause amino acid metabolism disorders, lipid accumulation and oxidative stress in ICR mice

Neonicotinoids are increasingly being used for pest control, and their potential health risks are now receiving attention. In this study, the toxic effects of three neonicotinoids (dinotefuran, nitenpyram and acetamiprid) were evaluated in ICR mice. After 30 days of exposure to neonicotinoids (1/200 LD50), oxidative stress levels, biochemical parameters, free fatty acids contents, and ¹H NMR-based hepatic metabolomics were tested. All treatment groups showed signs of amino acid metabolism disorders especially elevated branched chain amino acids and phenylalanine. Furthermore, animals exposed to neonicotinoids had elevated lipid levels, which induced oxidative stress. Overall, we found that oxidative stress is a common toxic effect of exposure to neonicotinoids. In addition, lipid accumulation induced by amino acid metabolism disorder may be the cause of oxidative stress. Our results further our understanding of the toxicological effects of neonicotinoids on mammals.

Imidacloprid disrupts the endocrine system by interacting with androgen receptor in male mice

In the current study, six-week-old male ICR mice were administered imidacloprid (IMI) at concentrations of 3, 10 and 30 mg/L for a duration of 10 weeks to investigate the toxicity of IMI on the endocrine system. We observed that testicular morphology was severely impaired and damaged, and the levels of serum testosterone (T) and the expression of androgen receptor (AR) decreased significantly. Molecular docking analysis suggested that IMI docks into the active site of AR successfully and that three key hydrogen bonds were formed with the active site residues Glu11, Gln41 and Lys138. The binding free energy value of the AR-IMI complex suggested a stable binding between IMI and AR. All these results indicated that IMI could interact with AR. In addition, major genes in the testis involved in the synthesis of cholesterol and T were generally inhibited, and the serum cholesterol sources were also reduced. Moreover, the aromatase in male mice was lacking after subchronic IMI exposure. The data acquired from the present study indicated that IMI could lead to endocrine disruption by interacting with AR and influence the expression of genes involved in the production of T in male mice.

Environmental Obesogens and Their Impact on Susceptibility to Obesity: New Mechanisms and Chemicals

The incidence of obesity has reached an all-time high, and this increase is observed worldwide. There is a growing need to understand all the factors that contribute to obesity to effectively treat and prevent it and associated comorbidities. The obesogen hypothesis proposes that there are chemicals in our environment termed obesogens that can affect individual susceptibility to obesity and thus help explain the recent large increases in obesity. This review discusses current advances in our understanding of how obesogens act to affect health and obesity susceptibility. Newly discovered obesogens and potential obesogens are discussed, together with future directions for research that may help to reduce the impact of these pervasive chemicals.

Perfluorobutanesulfonic Acid (PFBS) Induces Fat Accumulation in HepG2 Human Hepatoma

Per- and poly-fluoroalkyl substances, especially perfluorooctanesulfonic acid, have been extensively used for over 50 years. A growing body of evidence has emerged demonstrating the potential adverse effects of these substances, including its effect on the development of non-alcoholic fatty liver disease, as one of the most prevalent chronic liver diseases. Nonetheless, there is no report of effects of perfluorobutanesulfonic acid, the major replacement for perfluorooctanesulfonic acid, on non-alcoholic fatty liver disease. Therefore, the effects of perfluorobutanesulfonic acid exposure on fat accumulation in a human hepatoma cell line were examined. Cells were exposed to perfluorobutanesulfonic acid with or without 300 μmol/L fatty acid mixture (oleic acid:palmitic acid = 2:1) conjugated by bovine serum albumin as an inducer of steatosis for 48 hours. Perfluorobutanesulfonic acid at 200 μmol/L significantly increased the triglyceride level in the presence of fatty acid compared to the control, but not without fatty acid, which was abolished by a specific peroxisome proliferator-activated receptor gamma antagonist. Perfluorobutanesulfonic acid upregulated key genes controlling lipogenesis and fatty acid uptake. Perfluorobutanesulfonic acid treatment also promoted the production of reactive oxygen species, an endoplasmic reticulum stress marker and cytosolic calcium. In conclusion, perfluorobutanesulfonic acid increased fat accumulation, in part, via peroxisome proliferator-activated receptor gamma-mediated pathway in hepatoma cells.

A cluster-randomized crossover trial of organic diet impact on biomarkers of exposure to pesticides and biomarkers of oxidative stress/inflammation in primary school children

Despite suggestive observational epidemiology and laboratory studies, there is limited experimental evidence regarding the effect of organic diet on human health. A cluster-randomized 40-day-organic (vs. 40-day-conventional) crossover trial was conducted among children (11–12 years old) from six schools in Cyprus. One restaurant provided all organic meals, and adherence to the organic diet intervention was measured by parent-provided diet questionnaire/diary data. Biomarkers of pyrethroid and neonicotinoid pesticide exposures were measured using tandem mass spectrometry, and oxidative stress/inflammation (OSI) biomarkers using immunoassays or spectrophotometry. Associations were assessed using mixed-effect regression models including interactions of treatment with time. Seventy-two percent of neonicotinoid biomarkers were non-detectable and modeled as binary (whether detectable). In post-hoc analysis, we considered the outcome of age-and-sex-standardized BMI. Multiple comparisons were handled using Benjamini-Hochberg correction for 58 regression parameters. Outcome data were available for 149 children. Children had lower pesticide exposures during the organic period (pyrethroid geometric mean ratio, GMR = 0.297; [95% confidence interval (95% CI): 0.237, 0.373], Q-value<0.05); odds for detection of neonicotinoids (OR = 0.651; [95% CI: 0.463, 0.917), Q-value<0.05); and decreased OSI biomarker 8-OHdG (GMR = 0.888; [95% CI: 0.808, 0.976], Q-value<0.05). An initial increase was followed by a countervailing decrease over time in the organic period for OSI biomarkers 8-iso-PGF2a and MDA. BMI z-scores were lower at the end of the organic period (β = -0.131; [95% CI: 0.179, -0.920], Q-value<0.05). Energy intake during the conventional period was reported to be higher than the recommended reference levels. The organic diet intervention reduced children’s exposure to pyrethroid and neonicotinoid pesticides and, over time lowered biomarkers of oxidative stress/inflammation (8-iso-PGF2a, 8-OHdG and MDA). The several-week organic diet intervention also reduced children’s age-and-sex-standardized BMI z-scores, but causal inferences regarding organic diet’s physiological benefits are limited by the confounding of the organic diet intervention with caloric intake reduction and possible lifestyle changes during the trial.

Trial registration: This trial is registered with ClinicalTrials.gov, number: NCT02998203.

Neonicotinoid insecticides in surface water from the central Yangtze River, China

Neonicotinoid insecticides (NNIs) are extensively used insecticides worldwide, yet the data on NNIs residues in the Yangtze River, China is scarce. Occurrence and distribution of six NNIs and a metabolite (desmethyl-acetamiprid) in surface water were investigated in the central Yangtze River, China at 20 sites from March to July and September 2015. Acetamiprid (ACE), imidacloprid (IMI) and thiamethoxam (THM) were the most frequently detected NNIs and IMI had a highest median concentration of 4.37 ng/L, followed by ACE (2.50 ng/L), THM (1.10 ng/L), nitenpyram (NTP; 0.34 ng/L), clothianidin (CLO; 0.10 ng/L), and thiacloprid (THCP; 0.02 ng/L). Significantly higher concentrations and detection frequencies of NNIs were observed in the summer than in the spring, which may be explained by the heavier precipitation in summer. Spatial variation with higher levels among the lower sites than the upper sites may be related with the agriculture land use. NNI contamination presented a low risk to aquatic life according to the risk quotient method, while IMI had potential risk to aquatic life according to the threshold of IMI (8.3 ng/L) in freshwater recommended in Netherland. Using the relative potency factors method for chronic cumulative risk assessment for NNIs, potential exposure to NNIs through water ingestion are three orders of magnitude lower than the recommended relative chronic reference dose. Ongoing environmental monitoring of NNIs is needed due to the increase use of NNIs in China.

Dietary risk of neonicotinoid insecticides through fruit and vegetable consumption in school-age children

Although the systemic property of neonicotinoid (neonics) has become the most widely used insecticide worldwide since late 1990s, the current literature offers limited information about the human dietary intake and the potential risks of neonics. In this study, we aimed to assess the cumulative risk of total neonics intakes through fruit and vegetable consumption in 58 children ages 8-12 participated in the Hangzhou China (HZC) study over 5 consecutive weekends. Individual neonic residues in each food item were aggregated using the relative potency factor approach into a single metric (IMI_RPF), representing dietary intakes of imidacloprid-equivalent total neonics. We then estimated the average daily intake (ADI) of total neonics through fruit and vegetable consumption and evaluated the cumulative dietary risk of neonics. All of the 123 samples were detected with at least one neonic. Commonly consumed foods, such as carrots, green vegetables, baby cabbage, and apple were found with more than 6 neonics. The estimated ADIs of total neonics vegetable and fruit consumption using the mean IMI_RPF for apples and green vegetables, two most consumed food items, were 237.1*10^-6 and 106.8*10^-6 mg/kg/day, respectively. Although the estimated ADIs were below the current chronic reference dose (cRfD) of imidacloprid, we have stipulated the possible future downward revision of cRfD. The potential health risk of neonics to children via dietary exposure should raise more public concern considering the increase use of neonics and the ubiquitous presence in fruits and vegetables.

Permethrin and ivermectin modulate lipid metabolism in steatosis-induced HepG2 hepatocyte

Recent studies have reported the positive association between exposure to insecticides and increased risk of obesity and type 2 diabetes, which are closely associated with non-alcoholic fatty liver disease (NAFLD). However, it is not known if insecticide exposure can contribute to NAFLD. Thus, the goal of the current study was to determine if insecticide exposures can exacerbate the physiological conditions of NAFLD by modulating hepatic lipid metabolism. The effects of 12 insecticides on triglycerides (TG) accumulation were tested using palmitic acid (PA)-induced HepG2 hepatoma steatosis model. Results showed that among tested insecticides, permethrin and ivermectin significant interacted with palmitic acid to potentiate (permethrin) or decrease (ivermectin) TG accumulation. Further study showed that permethrin significantly promoted fatty acid synthesis, while suppressed lipid oxidation-related genes only under steatosis conditions. In comparison, ivermectin inhibited lipogenesis-related genes and promoted farnesoid X receptor, which upregulates fatty acid oxidation. Results in this study suggested that hepatic lipid metabolism may be more susceptible to insecticide exposure in the presence of excessive fatty acids, which can be associated with the development of NAFLD.

Vitexin ameliorates high fat diet-induced obesity in male C57BL/6J mice via the AMPKα-mediated pathway

Vitexin, a bioactive compound isolated from hawthorn leaf extracts, can prevent HFD-induced obesity/adipogenesis via the AMPKα mediated pathway.

Exposures of children to neonicotinoids in pine wilt disease control areas

Neonicotinoid insecticides that have been on the market since 1992 have been used globally including in Japan. Because they are sprayed over forests and agricultural areas, inadvertent toxicity in nontarget insects (especially honey bees) and humans is a matter of public concern. However, information on exposure levels and potential health impacts of neonicotinoids in children living around sprayed areas is scarce. Thus, we determined neonicotinoid exposure levels in children living in communities where thiacloprid was used to control pine wilt disease. A total of 46 children (23 males and 23 females) were recruited for the present study, and informed written consent was obtained from their guardians. Urine specimens were collected before, during, and after insecticide spraying events; and atmospheric particulate matter was also collected. Concentrations of thiacloprid and 6 other neonicotinoid compounds were determined in urine samples and in atmospheric particulate matter specimens using liquid chromatography-electrospray ionization-tandem mass spectrometry. In urine specimens, thiacloprid concentrations were <0.13 μg/L and were detectable in approximately 30% of all samples. Concentrations of the other neonicotinoids, N-dm-acetamiprid, thiamethoxam, dinotefuran, and clothianidin, were 18.7, 1.92, 72.3, and 6.02 µg/L, respectively. Estimated daily intakes of these neonicotinoids were then calculated from urinary levels; although the estimated daily intakes of the neonicotinoids were lower than current acceptable daily intake values, the children were found to be exposed to multiple neonicotinoids on a daily basis. Environ Toxicol Chem 2019;38:71-79. © 2018 SETAC.

Imidacloprid Impacts on Neurobehavioral Performance, Oxidative Stress, and Apoptotic Events in the Brain of Adolescent and Adult Rats

Currently, imidacloprid (IMI) is the first insecticide and the second agrochemical highly applied all over the world. Here, we report on the impacts of IMI on neurobehavioral performance, oxidative stress, and apoptotic changes in the brain in either adult or adolescent rats. Forty male rats (adult and adolescent) were allocated to four groups. IMI groups were orally given 1 mg IMI/kg b.wt. dissolved in corn oil, whereas the controls were orally administered corn oil daily for 60 days. The obtained results demonstrated that IMI exposure resulted in less exploratory activity, deficit sensorimotor functions, and high depression. Levels of neurotransmitter including serotonin, gamma-aminobutyric acid, and dopamine were significantly reduced. Oxidative damage of brain tissues was evident following IMI exposure represented by the high levels of protein carbonyl, 8-hydroxyguanosine, and malondialdehyde, but total antioxidant capacity was reduced. Histopathological investigations of the brain tissues of IMI treated group revealed varying degrees of degeneration of the neuron. The immunohistochemical evaluation revealed a strong presence of glial fibrillary acidic protein (GFAP) and Bax positive cells, but a low expression of Bcl-2. These injurious impacts of IMI were very prominent in the adult rats than in the adolescent rats. Conclusively, exposure to IMI even at very low concentration could induce multiple neurobehavioral aberrations and neurotoxic impacts, especially in adults.

Non-target toxicity of novel insecticides

Humans have used insecticides since ancient times. The spectrum and potency of available insecticidal substances has greatly expanded since the industrial revolution, resulting in widespread use and unforeseen levels of synthetic chemicals in the environment. Concerns about the toxic effects of these new chemicals on non-target species became public soon after their appearance, which eventually led to the restrictions of use. At the same time, new, more environmentally-friendly insecticides have been developed, based on naturally occurring chemicals, such as pyrethroids (derivatives of pyrethrin), neonicotinoids (derivatives of nicotine), and insecticides based on the neem tree vegetable oil (Azadirachta indica), predominantly azadirachtin. Although these new substances are more selective toward pest insects, they can still target other organisms. Neonicotinoids, for example, have been implicated in the decline of the bee population worldwide. This review summarises recent literature published on non-target toxicity of neonicotinoids, pyrethroids, and neem-based insecticidal substances, with a special emphasis on neonicotinoid toxicity in honeybees. We also touch upon the effects of pesticide combinations and documented human exposure to these substances.

Insecticide Exposure and Development of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the prevalent liver disease resulting from metabolic disorder, which is highly associated with obesity and type 2 diabetes. Emerging evidence has shown that insecticide exposure disrupts lipid and glucose metabolism and results in obesity and type 2 diabetes. However, the potential impact of insecticide exposure on the liver functions related to NAFLD development is largely unknown. Thus, this perspective focused on the current knowledge of the effect of insecticides on the liver functions, particularly lipid and glucose metabolism, as well as other liver functions to correlate insecticide exposure and the development of NAFLD.

Perfluorobutanesulfonic acid (PFBS) potentiates adipogenesis of 3T3-L1 adipocytes

Perfluorobutanesulfonic acid (PFBS) is used as the replacement of perfluorooctanesulfonic acid (PFOS) since 2000 because of the concern on PFOS' persistence in the environment and the bioaccumulation in animals. Accumulating evidence has shown the correlation between the exposure to perfluorinated compounds and enhanced adipogenesis. There is no report, however, of the effect of PFBS on adipogenesis. Therefore, the present work aimed to investigate the role of PFBS in adipogenesis using 3T3-L1 adipocytes. PFBS treatment for 6 days extensively promoted the differentiation of 3T3-L1 preadipocytes to adipocytes, resulting in significantly increased triglyceride levels. In particular, the treatments of PFBS at the early adipogenic differentiation period (day 0-2) were positively correlated with increased the triglyceride accumulation on day 6. PFBS treatments significantly increased the protein and mRNA levels of the master transcription factors in adipocyte differentiation; CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ), along with acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), the key proteins in lipogenesis. PFBS significantly activated the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) after 4-h treatment, and PFBS' effect on triglyceride was abolished by U0126, a specific MAPK/ERK kinase (MEK) inhibitor. In conclusion, PFBS increased the adipogenesis of 3T3-L1 adipocytes, in part, via MEK/ERK-dependent pathway.

Imidacloprid as reproductive toxicant and endocrine disruptor: investigations in laboratory animals

Imidacloprid, a neonicotinoid insecticide, has been used worldwide due to its selective toxicity for insects. Its residues may enter the food chain, which is why it is important to investigate the potential adverse effects of imidacloprid exposure. This review summarises current knowledge of the reproductive toxicity and disruptive endocrine effects of imidacloprid in laboratory animals. Investigations, conducted mostly on laboratory rats, have shown adverse effects of imidacloprid on the reproductive ability in both parental and offspring generation as well as on the development of the offspring. Like many pesticides, imidacloprid may also act as endocrine disrupting chemical (EDC). It may disrupt the metabolic homeostasis, contribute to obesity, and disrupt steroidogenesis by inhibiting cytochrome P450 (CYP) enzyme activities. All these adverse effects of imidacloprid may pose a serious risk for reproduction and development with long-term consequences in adulthood.

Metabolome disruption of pregnant rats and their offspring resulting from repeated exposure to a pesticide mixture representative of environmental contamination in Brittany

The use of pesticides exposes humans to numerous harmful molecules. Exposure in early-life may be responsible for adverse effects in later life. This study aimed to assess the metabolic modifications induced in pregnant rats and their offspring by a pesticide mixture representative of human exposure. Ten pregnant rats were exposed to a mixture of eight pesticides: acetochlor (246 μg/kg bw/d) + bromoxynil (12 μg/kg bw/d) + carbofuran (22.5 μg/kg bw/d) + chlormequat (35 μg/kg bw/d) + ethephon (22.5 μg/kg bw/d) + fenpropimorph (15.5 μg/kg bw/d) + glyphosate (12 μg/kg bw/d) + imidacloprid (12.5 μg/kg bw/d) representing the main environmental pesticide exposure in Brittany (France) in 2004. Another group of 10 pregnant rats served as controls. Females were fed ad libitum from early pregnancy, which is from gestational day (GD) 4 to GD 21. Urine samples were collected at GD 15. At the end of the exposure, mothers and pups were euthanized and blood, liver, and brain samples collected. 1H NMR-based metabolomics and GC-FID analyses were performed and PCA and PLS-DA used to discriminate between control and exposed groups. Metabolites for which the levels were significantly modified were then identified using the Kruskal-Wallis test, and p-values were adjusted for multiple testing correction using the False Discovery Rate. The metabolomics analysis revealed many differences between dams of the two groups, especially in the plasma, liver and brain. The modified metabolites are involved in TCA cycle, energy production and storage, lipid and carbohydrate metabolism, and amino-acid metabolism. These modifications suggest that the pesticide mixture may induce oxidative stress associated with mitochondrial dysfunction and the impairment of glucose and lipid metabolism. These observations may reflect liver dysfunction with increased relative liver weight and total lipid content. Similar findings were observed for glucose and energy metabolism in the liver of the offspring, and oxidative stress was also suggested in the brains of male offspring.

Exposure to permethrin promotes high fat diet-induced weight gain and insulin resistance in male C57BL/6J mice

Permethrin is a pyrethroid pesticide that was previously reported to promote fat accumulation and insulin resistance in vitro. A recent study in female mice also found that permethrin could promote high fat-induced insulin resistance. The effects of permethrin on glucose and lipid metabolisms in male mice, however, remain unknown. The purpose of this study was to investigate the effects and interactions of permethrin exposure (50, 500, and 5000 μg/kg body weight/day) and dietary fat (low fat, 4% w/w; high fat, 20% w/w) on development of obesity and insulin resistance in male C57BL/6J mice. Our results showed that permethrin treatment significantly increased body weight, fat mass, and insulin resistance with high fat diet, but not with low fat diet, without influencing energy intake. Permethrin treatment also significantly increased serum levels of insulin, glucose, leptin, triglycerides and cholesterol. Further results showed that permethrin inhibited AMP-activated protein kinase in white adipose tissue. These results suggest that permethrin interacts with dietary fat to alter lipid and glucose metabolisms in male C57BL/6J mice.

Imidacloprid insecticide exposure induces stress and disrupts glucose homeostasis in male rats

In the present study, we evaluated the stress response in adult rats who were administered imidacloprid (IMI) orally in two doses (0.5 and 1.0mg/kg bw for 60days). It led to an alteration in the levels of cortisone and catecholamines and induced behavioral deficits, particularly in the animals exposed to the dose of 1.0mg/kg. IMI was further analyzed for the effect on glucose homeostasis in developing and adult rats at a dose of 1.0mg/kg bw where it elicited a hyperglycemic effect. Moreover, we observed an alteration in the mRNA levels of glucose transporters. Histopathological and immunohistochemical data displayed structural perturbations in pancreatic tissue with a decline in the expression of insulin and GLUT4, particularly in the developing rats. Collectively, IMI treatment resulted in stress represented by behavioral and biochemical changes, particularly at a dose of 1.0mg/kg bw. Moreover, IMI perturbed the glucose regulation through hyperglycemic activity in both developing and adult rats, an observation clearly evident in the developing rats.

Imidacloprid Promotes High Fat Diet-Induced Adiposity in Female C57BL/6J Mice and Enhances Adipogenesis in 3T3-L1 Adipocytes via the AMPKα-Mediated Pathway

Imidacloprid, a neonicotinoid insecticide, was previously reported to enhance adipogenesis and resulted in insulin resistance in cell culture models. It was also reported to promote high fat diet-induced obesity and insulin resistance in male C57BL/6J mice. Thus, the goal of the present study was to determine the effects of imidacloprid and dietary fat interaction on the development of adiposity and insulin resistance in female C57BL/6J mice. Mice were fed with a low (4% w/w) or high fat (20% w/w) diet containing imidacloprid (0.06, 0.6, or 6 mg/kg bw/day) for 12 weeks. Mice fed with imidacloprid (0.6 mg/kg bw/day) significantly enhanced high fat diet-induced weight gain and adiposity. Treatment with imidacloprid significantly increased serum insulin levels with high fat diet without effects on other markers of glucose homeostasis. AMPKα activation was significantly inhibited by 0.6 and 6 mg imidacloprid/kg bw/day in white adipose tissue. Moreover, AMPKα activation with 5-aminoimidazole-4-carboxamide ribonucleotide abolished the effects of imidacloprid (10 μM) on enhanced adipogenesis in 3T3-L1 adipocytes. N-Acetyl cysteine also partially reversed the effects of imidacloprid on reduced phosphorylation of protein kinase B (AKT) in C2C12 myotubes. These results indicate that imidacloprid may potentiate high fat diet-induced adiposity in female C57BL/6J mice and enhance adipogenesis in 3T3-L1 adipocytes via the AMPKα-mediated pathway. Imidacloprid might also influence glucose homeostasis partially by inducing cellular oxidative stress in C2C12 myotubes.

Permethrin alters glucose metabolism in conjunction with high fat diet by potentiating insulin resistance and decreases voluntary activities in female C57BL/6J mice

Permethrin, a type 1 pyrethroid insecticide, was previously reported to promote adipogenesis in 3T3-L1 adipocytes and insulin resistance in C2C12 muscle cells; however, the effects of permethrin exposure on glucose and lipid metabolisms in vivo remain unknown. The purpose of this study was to investigate the effects of permethrin exposure on glucose and lipid homeostasis as well as voluntary movement in female mice in response to dietary fat. We tested three doses of permethrin (50, 500, & 5000 μg/kg body weight/day) in low fat diet-fed (4% w/w of diet) and high fat diet-fed (20% w/w of diet) female C57BL/6 J mice for twelve weeks. Our results demonstrated that permethrin treatment potentiated high fat diet-induced insulin resistance as indicated by insulin tolerance tests, glucose tolerance tests, and homeostasis model assessment - insulin resistance (HOMA-IR) without altering weight or fat mass. Permethrin treatment significantly decreased voluntary movement and elevated blood glucose and insulin levels. Western blot results further showed that permethrin impaired insulin signaling via the Akt signaling pathway in the gastrocnemius muscle. Taken together, these results suggest that oral administration of permethrin potentiated high fat diet-induced insulin resistance, possibly increasing the risk of type 2 diabetes without altering weight gain in female C57BL/6 J mice.

Potential contribution of insecticide exposure and development of obesity and type 2 diabetes

The introduction of insecticides has greatly improved agricultural productivity and human nutrition; however, the wide use of insecticides has also sparked growing concern over their health impacts. Increased rate of cancers, neurodegenerative disorders, reproductive dysfunction, birth defects, respiratory diseases, cardiovascular diseases and aging have been linked with insecticide exposure. Meanwhile, a growing body of evidence is suggesting that exposure to insecticides can also potentiate the risk of obesity and type 2 diabetes. This review summarizes the relationship between insecticide exposure and development of obesity and type 2 diabetes using epidemiological and rodent animal studies, including potential mechanisms. The evidence as a whole suggests that exposure to insecticides is linked to increased risk of obesity and type 2 diabetes.