Metabolic Profiles of Serum from Rats after Subchronic Exposure to Chlorpyrifos and Carbaryl

Exploring microbiota-gut-brain axis biomarkers linked to autism spectrum disorder in prenatally chlorpyrifos-exposed Fmr1 knock-out and wild-type male rats

Fmr1 (fragile X messenger ribonucleoprotein 1)-knockout (KO) rats, modeling the human Fragile X Syndrome (FXS), are of particular interest for exploring the ASD-like phenotype in preclinical studies. Gestational exposure to chlorpyrifos (CPF) has been associated with ASD diagnosis in humans and ASD-like behaviors in rodents and linked to the microbiota-gut-brain axis. In this study, we have used both Fmr1-KO and wild-type male rats (F2 generation) at postnatal days (PND) 7 and 40 obtained after F1 pregnant females were randomly exposed to 1 mg/kg/mL/day of CPF or vehicle. A nuclear magnetic resonance (NMR) metabolomics approach together with gene expression profiles of these F2 generation rats were employed to analyze different brain regions (such as prefrontal cortex, hippocampus, and cerebellum), whole large intestine (at PND7) and gut content (PND40). The statistical comparison of each matrix spectral profile unveiled tissue-specific metabolic fingerprints. Significant variations in some biomarker levels were detected among brain tissues of different genotypes, including taurine, myo-inositol, and 3-hydroxybutyric acid, and exposure to CPF induced distinct metabolic alterations, particularly in serine and myo-inositol. Additionally, this study provides a set of metabolites associated with gastrointestinal dysfunction in ASD, encompassing several amino acids, choline-derived compounds, bile acids, and sterol molecules. In terms of gene expression, genotype and gestational exposure to CPF had only minimal effects on decarboxylase 2 (gad2) and cholinergic receptor muscarinic 2 (chrm2) genes.

Effects of commonly used carbamates (carbaryl and thiram) on the regulatory, secretory and motor functions of bovine cervixes in vitro

Previously studied classes of pesticides, including organochlorines, organophosphates and pyrethroids disturb the mechanism that causes bovine myometrial contractions. Hence, the aim of this study was to investigate the effects of carbaryl and thiram, which are representative carbamate pesticides commonly used in global agriculture, on the motor and secretory functions of bovine cervixes. Additionally, the impacts of these pesticides on intra- and intercellular signaling in vitro were estimated. In this study, cervical cells or strips were obtained from cows at days 18-20 of the estrous cycle and were treated with carbaryl or thiram. Neither carbamate (10 or 100 ng/ml) exerted cytotoxic effects. Carbaryl increased the level of mRNA (at a dose of 0.1 ng/ml) and protein (at both doses, 1 and 10 ng/ml) expression for the oxytocin receptor (OXTR), while thiram (at 0.1 and 10 ng/ml or 0.1-10 ng/ml, respectively) caused the opposite effects. Moreover, the level of the second messenger inositol-trisphosphate (IP3) was decreased by carbaryl (10 ng/ml) but increased by thiram (10 ng/ml). Only thiram decreased prostaglandin-endoperoxide synthase 2 (PTGS2; 0.1 ng/ml) and aldo-keto reductase family 1, member B1 (AKR1B1; 0.1 ng/ml), and prostaglandin E synthase 2 (PTGES2; 0.1-10 ng/ml) mRNA expression, while thiram (0.1-10 ng/ml) and carbaryl (0.1 and 10 ng/ml) both decreased the release of PGF2α. Carbaryl (10 ng/ml) and thiram (10 ng/ml) also decreased the level of a gap junction protein (GAP). Moreover, carbaryl (10 ng/ml) decreased the level of myosin light chain kinase (MLCK). However, the strength of cervical contractions was increased by thiram (1 and 10 ng/ml) but decreased by carbaryl (1 and 10 ng/ml). Carbaryl increased the receptivity of cervical cells to oxytocin (OXT), but inhibited further transduction (IP3) of this signal. Hence, direct inhibition of cervical strip contraction may occur. In contrast, thiram mostly decreased the receptivity of cervical cells to OXT, while it stimulated the contraction of cervical strips. Moreover, compared to carbaryl, thiram more greatly affected the synthesis and release of prostaglandins. These results suggest that carbaryl and thiram disturb OXT signaling, PG secretion and cervical contraction in vitro.

Metabolomic analysis of the serum and urine of rats exposed to diazinon, dimethoate, and cypermethrin alone or in combination

BACKGROUND

Multiple pesticides are often used in combination for plant protection and public health. Therefore, it is important to analyze the physiological changes induced by multiple pesticides exposure. The objective of this study was to investigate the combined toxicity of the widely-used organophosphorus and pyrethroid pesticides diazinon, dimethoate, and cypermethrin.

METHODS

Male Wistar rats were administrated by gavage once daily with the three pesticides individual or in combination for consecutive 28 days. The metabolic components of serum and urine samples were detected by using 1H nuclear magnetic resonance (NMR)-based metabolomics method. Histopathological examination of liver and kidneys and serum biochemical determination were also carried out.

RESULTS

The results showed that after the 28-day subacute exposure, serum glutamic transaminase and albumin were significantly increased and blood urea nitrogen was significantly decreased in the rats exposed to the mixture of the pesticides compared with the control rats, suggesting that the co-exposure impaired liver and kidney function. Metabolomics analysis indicated that the indicators 14 metabolites were statistically significant altered in the rats after the exposure of the pesticides. The increase in 3-hydroxybutyric acid in urine or decrease of lactate and N-acetyl-L-cysteine in serum could be a potentially sensitive biomarker of the subchronic combined effects of the three insecticides. The reduction level of 2-oxoglutarate and creatinine in urine may be indicative of dysfunction of liver and kidneys.

CONCLUSION

In summary, the exposure of rats to pesticides diazinon, dimethoate, and cypermethrin could cause disorder of lipid and amino acid metabolism, induction of oxidative stress, and dysfunction of liver and kidneys, which contributes to the understanding of combined toxic effects of the pesticides revealed by using the metabolomics analysis of the urine and serum profiles.

Bioenergetic function is decreased in peripheral blood mononuclear cells of veterans with Gulf War Illness

Gulf War Illness (GWI) is a major health problem for approximately 250,000 Gulf War (GW) veterans, but the etiology of GWI is unclear. We hypothesized that mitochondrial dysfunction is an important contributor to GWI, based on the similarity of some GWI symptoms to those occurring in some mitochondrial diseases; the plausibility that certain pollutants to which GW veterans were exposed affect mitochondria; mitochondrial effects observed in studies in laboratory models of GWI; and previous evidence of mitochondrial outcomes in studies in GW veterans. A primary role of mitochondria is generation of energy via oxidative phosphorylation. However, direct assessment of mitochondrial respiration, reflecting oxidative phosphorylation, has not been carried out in veterans with GWI. In this case-control observational study, we tested multiple measures of mitochondrial function and integrity in a cohort of 114 GW veterans, 80 with and 34 without GWI as assessed by the Kansas definition. In circulating white blood cells, we analyzed multiple measures of mitochondrial respiration and extracellular acidification, a proxy for non-aerobic energy generation; mitochondrial DNA (mtDNA) copy number; mtDNA damage; and nuclear DNA damage. We also collected detailed survey data on demographics; deployment; self-reported exposure to pesticides, pyridostigmine bromide, and chemical and biological warfare agents; and current biometrics, health and activity levels. We observed a 9% increase in mtDNA content in blood in veterans with GWI, but did not detect differences in DNA damage. Basal and ATP-linked oxygen consumption were respectively 42% and 47% higher in veterans without GWI, after adjustment for mtDNA amount. We did not find evidence for a compensatory increase in anaerobic energy generation: extracellular acidification was also lower in GWI (12% lower at baseline). A subset of 27 and 26 veterans returned for second and third visits, allowing us to measure stability of mitochondrial parameters over time. mtDNA CN, mtDNA damage, ATP-linked OCR, and spare respiratory capacity were moderately replicable over time, with intraclass correlation coefficients of 0.43, 0.44, 0.50, and 0.57, respectively. Other measures showed higher visit-to-visit variability. Many measurements showed lower replicability over time among veterans with GWI compared to veterans without GWI. Finally, we found a strong association between recalled exposure to pesticides, pyridostigmine bromide, and chemical and biological warfare agents and GWI (p < 0.01, p < 0.01, and p < 0.0001, respectively). Our results demonstrate decreased mitochondrial respiratory function as well as decreased glycolytic activity, both of which are consistent with decreased energy availability, in peripheral blood mononuclear cells in veterans with GWI.

Investigating the relationship between non-occupational pesticide exposure and metabolomic biomarkers

The relationship between pesticide exposures and metabolomics biomarkers is not well understood. We examined the changes in the serum metabolome (early biomarkers) and the metabolic pathways associated with various pesticide exposure scenarios (OPE: overall exposure, PEM: exposure in months, PEY: exposure in years, and PEU: reported specific pesticides use) using data from the Northern Finland Birth Cohort 1966 31-year cross-sectional examination. We utilized questionnaire data on pesticide exposures and serum samples for nuclear magnetic resonance (NMR)-based metabolomics analyses. For exposures and metabolites associations, participants size varied between 2,361 and 5,035. To investigate associations between metabolomics biomarkers and exposure to pesticide scenarios compared to those who reported no exposures multivariable regression analyses stratified by sex and adjustment with covariates (season of pesticide use, socioeconomic position (SEP), alcohol consumption, BMI, and latitude of residence) were performed. Multiple testing by Benjamini-Hochberg false discovery rate (FDR) correction applied. Pesticide exposures differed by sex, season of pesticide use, alcohol, SEP, latitude of residence. Our results showed that all pesticide exposure scenarios were negatively associated with decreased HDL concentrations across all lipoprotein subclasses in women. OPE, PEY, and PEU were associated with decreased branched-chain amino acid concentrations in men and decreased albumin concentrations in women. OPE, PEY and PEU were also associated with changes in glycolysis metabolites and ketone bodies in both sexes. Specific pesticides exposure was negatively associated with sphingolipids and inflammatory biomarkers in men. In women, OPE, PEM, and PEU were associated with decreased apolipoprotein A1 and increased apolipoprotein B/apolipoprotein A1 ratio. Our findings suggest that identification of early biomarkers of disease risk related to pesticide exposures can inform strategies to reduce exposure and investigate causal pathways. Women may be more susceptible to non-occupational pesticide exposures when compared to men, and future sex-specific studies are warranted.

High-Fat Diet Aggravates the Disorder of Glucose Metabolism Caused by Chlorpyrifos Exposure in Experimental Rats

Epidemiological research has demonstrated that the increase in high fat consumption has promoted the morbidity of diabetes. Exposure to organophosphorus pesticides (such as chlorpyrifos) may also increase the risk of diabetes. Although chlorpyrifos is a frequently detected organophosphorus pesticide, the interaction effect between chlorpyrifos exposure and a high-fat diet on glucose metabolism is still unclear. Thus, the effects of chlorpyrifos exposure on glucose metabolism in rats eating a normal-fat diet or a high-fat diet were investigated. The results demonstrated that the glycogen content in the liver decreased and that the glucose content increased in chlorpyrifos-treated groups. Remarkably, the ATP consumption in the chlorpyrifos-treatment group was promoted in the rats eating a high-fat diet. However, chlorpyrifos treatment did not change the serum levels of insulin and glucagon. Notably, the contents of liver ALT and AST changed more significantly in the high-fat chlorpyrifos-exposed group than in the normal-fat chlorpyrifos-exposed group. Chlorpyrifos exposure caused an increase in the liver MDA level and a decrease in the enzyme activities of GSH-Px, CAT, and SOD, and the changes were more significant in the high-fat chlorpyrifos-treatment group. The results indicated that chlorpyrifos exposure led to disordered glucose metabolism in all dietary patterns as a result of antioxidant damage in the liver, in which a high-fat diet may have aggravated its toxicity.

A systematic review on the metabolic effects of chlorpyrifos

Organophosphate (OP) pesticides, including chlorpyrifos (CPF), can alter metabolic hemostasis. The current systematic study investigated blood glucose, lipid profiles, and body weight alterations in rodents and fish exposed to CPF. The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Guidelines, querying online databases, including Web of Science, PubMed, and Scopus and also search engine including Google Scholar, through January 2021. Studies on rodent and fish exposed to CPF assessing metabolic functions were selected. All studies were in the English language, with other languages being excluded from the review. Two investigators independently assessed each of the articles. The first author's name, publication date, animal model, age, sample size, gender, dose, duration, and route of exposure and outcomes were extracted from each publication. The present review summarizes findings from 61 publications on glycemic, lipid profile, insulin, and body weight changes in rodents and fish exposed to CPF exposure. Most of the studies reported hyperglycemia, hyperlipidemia, and decreased insulin levels and body weight following exposure to CPF. Additionally, we confirmed that the CPF-induced metabolic alterations were both dose- and time-dependent. Our findings support an association between CPF exposure and metabolic diseases. However, more studies are needed to identify the metabolic-disrupting effects of CPF and their underlying mechanisms.

Chronic Perigestational Exposure to Chlorpyrifos Induces Perturbations in Gut Bacteria and Glucose and Lipid Markers in Female Rats and Their Offspring

An increasing burden of evidence is pointing toward pesticides as risk factors for chronic disorders such as obesity and type 2 diabetes, leading to metabolic syndrome. Our objective was to assess the impact of chlorpyrifos (CPF) on metabolic and bacteriologic markers. Female rats were exposed before and during gestation and during lactation to CPF (1 mg/kg/day). Outcomes such as weight, glucose and lipid profiles, as well as disturbances in selected gut bacterial levels, were measured in both the dams (at the end of the lactation period) and in their female offspring at early adulthood (60 days of age). The results show that the weight of CPF dams were lower compared to the other groups, accompanied by an imbalance in blood glucose and lipid markers, and selected gut bacteria. Intra-uterine growth retardation, as well as metabolic disturbances and perturbation of selected gut bacteria, were also observed in their offspring, indicating both a direct effect on the dams and an indirect effect of CPF on the female offspring. Co-treatment with inulin (a prebiotic) prevented some of the outcomes of the pesticide. Further investigations could help better understand if those perturbations mimic or potentiate nutritional risk factors for metabolic syndrome through high fat diet.

Chlorpyrifos and Δ9 Tetrahydrocannabinol exposure and effects on parameters associated with the endocannabinoid system and risk factors for obesity

Marilyn Silva. Retired from a career in toxicology and risk assessment. Increased childhood and adult obesity are associated with chlorpyrifos (CPF), an organophosphate pesticide. Cannabis (Δ9Tetrahydrocannabinol: Δ9THC) use has increased globally with legalization. CPF applications on cannabis crops lacks federally regulated tolerances and may pose health risks through exposure during development and in adulthood. Both CPF and Δ9THC affect the endocannabinoid system (eCBS), a regulator of appetite, energy balance, and gut microbiota, which, if disrupted, increases risk for obesity and related diseases. CPF inhibits eCB metabolism and Δ9THC is a partial agonist/antagonist at the cannabinoid receptor (CB1R). Effects of each on obesogenic parameters were examined via literature search. Male rodents with CPF exposure showed increased body weights, dysbiosis, inflammation and oxidative stress, potentially associated with increased eCBs acting through the gut-microbiota-adipose-brain regulatory loop. Δ9THC generally decreased body weights via partial agonism at the CB1R, lowering levels of eCBs. Dysbiosis and/or oxidative stress associated inflammation occurred with CPF, but these parameters were not tested with Δ9THC. Database deficiencies included limited endpoints to compare between chemicals/age-groups, inter-study variables (dose ranges, dosing vehicle, rodent strain, treatment duration, etc.). CPF and Δ9THC were not tested together, but human co-chemical effects would depend on exposure ratio, subject age, exposure duration, and health status, among others. An overriding concern is that both chemicals are well-documented developmental neurotoxins in addition to their low dose effects on energy balance. A co-exposure risk assessment is warranted with increased use and lack of federal CPF regulation on cannabis.

Discovery of treatment for nerve agents targeting a new metabolic pathway

The inhibition of acetylcholinesterase is regarded as the primary toxic mechanism of action for chemical warfare agents. Recently, there have been numerous reports suggesting that metabolic processes could significantly contribute to toxicity. As such, we applied a multi-omics pipeline to generate a detailed cascade of molecular events temporally occurring in guinea pigs exposed to VX. Proteomic and metabolomic profiling resulted in the identification of several enzymes and metabolic precursors involved in glycolysis and the TCA cycle. All lines of experimental evidence indicated that there was a blockade of the TCA cycle at isocitrate dehydrogenase 2, which converts isocitrate to α-ketoglutarate. Using a primary beating cardiomyocyte cell model, we were able to determine that the supplementation of α-ketoglutarate subsequently rescued cells from the acute effects of VX poisoning. This study highlights the broad impacts that VX has and how understanding these mechanisms could result in new therapeutics such as α-ketoglutarate.

TCP structure intensified the chlorpyrifos-induced decrease in testosterone synthesis via LH-LHR-PKA-CREB-Star pathway

Similar to diethylphosphate (DEP), 3,5,6-trichloro-2-pyridinol (TCP) is also a characteristic chemical substance and ultimate transformation product of chlorpyrifos (CPF) because the structure of TCP is equivalent to the trichloro pyridine structure of CPF. TCP is often used as a biomarker of CPF exposure. TCP and DEP are often detected in human blood and urine due to the widespread use of CPF. No studies have sufficiently clarified which structure contributes to the negative effect of CPF on testosterone synthesis. This study aims to explain which structure promotes the inhibitory effect of CPF on testosterone synthesis and the related influence mechanisms. After 20 weeks of exposure, the testosterone level in testes was significantly reduced by different doses of CPF (0.3 mg/kg body weight CPF and 3.0 mg/kg body weight CPF). Meanwhile, the level of testosterone synthesized by isolated primary Leydig cells was also reduced by CPF. In addition, TCP but not DEP aggravated the decrease in testosterone synthesis in isolated primary Leydig cells. On the other hand, CPF and TCP significantly decreased the levels of the Star protein, CREB phosphorylation and PKA phosphorylation, which are important in regulating testosterone synthesis. Based on these results, TCP is a key structure that mediates the CPF-induced decrease in testosterone synthesis by terminating the signal transmission of the LH-LHR-PKA-CREB-Star pathway. Thus, chemicals with the TCP structure may be potential endocrine disruptors that decrease fertility. Chemicals that can be converted to TCP or achieve a trichloro pyridine structure must be considered during reproductive toxicity risk assessment.

The impact of age-related sub-chronic exposure to chlorpyrifos on metabolic indexes in male rats

Chlorpyrifos (CPF), an organophosphorus pesticide (OP), has been implicated in metabolic diseases; however, the data are controversial. Rising age has been found as a main risk factor for metabolic diseases, and it has been proposed that advanced age increases susceptibility to the toxic effects of OPs. Therefore, this investigation aimed to evaluate the impact of CPF on hyperglycemia, hypercholesterolemia, and inflammation in animals with different ages. CPF (5 mg/kg) for 45 consecutive days was administered orally to male Wistar rats with different ages including 2-, 10-, and 20-month-old. The results indicated an increase in glucose and inflammatory indices, and also lipid profile was changed in the serum of aged animals in comparison with the 2-month-old animals. CPF administration amplified these parameters in the 20-month-old rats in comparison with that of aged-matched controls. The histopathological examination also indicated that CPF caused slight to moderate changes in the liver of 2-, 10-, and 20-month-old animals. Cholestasis was also observed in the CPF-administrated 20-month-old rats. In conclusion, aging may increase the susceptibility to CPF-induced metabolic disturbances in the animal models. It is proposed that advancing in age elevates the susceptibility to the metabolic effects of CPF.

Medium and long-term effects of low doses of Chlorpyrifos during the postnatal, preweaning developmental stage on sociability, dominance, gut microbiota and plasma metabolites

Autism spectrum disorder (ASD) is a complex neurodevelopmental pathology characterized by altered verbalizations, reduced social interaction behavior, and stereotypies. Environmental factors have been associated with its development. Some researchers have focused on pesticide exposure. Chlorpyrifos (CPF) is the most used Organophosphate. Previous developmental studies with CPF showed decreased, enhanced or no effect on social outcomes eminently in mice. The study of CPF exposure during preweaning stages on social behavior is sparse in mice and non-existent in rats. d stressors could be at the basis of ASD development, and around postnatal day 10 in the rat is equivalent to the human birthday in neurodevelopmental terms. We explored the effects of exposure to low doses (1mg/kg/mL/day) of CPF during this stage regarding: sociability, dominance gut microbiome and plasma metabolomic profile, since alterations in these systems have also been linked to ASD. There was a modest influence of CPF on social behavior in adulthood, with null effects during adolescence. Dominance and hierarchical status were not affected by exposure. Dominance status explained the significant reduction in reaction to social novelty observed on the sociability test. CPF induced a significant gut microbiome dysbiosis and triggered a hyperlipidemic, hypoglycemic/hypogluconeogenesis and a general altered cell energy production in females. These behavioral results in rats extend and complement previous studies with mice and show novel influences on gut metagenomics and plasma lipid profile and metabolomics, but do not stablish a relation between the exposure to CPF and the ASD phenotype. The effects of dominance status on reaction to social novelty have an important methodological meaning for future research on sociability.

Impact of chlorpyrifos on blood glucose concentration in an animal model: a systematic review and meta-analysis

Chlorpyrifos, an organophosphate insecticide, disturbs blood glucose hemostasis in experimental models and causes metabolic disorders. However, there are controversial findings of its impact on the BS level. The present meta-analysis aimed to investigate blood gluocse levels in rats exposed to chlorpyrifos. Present systematic review and meta-analysis study was done by searching in the online databases, including Google Scholar, Web of Science, PubMed, and Scopus. Data were analyzed by performing "random effects meta-regression." Findings were expressed as standardized mean value and 95% confidence interval (CI). Heterogeneity between studies was assessed using I-square and Q test. Meta-analysis of 7 animal studies indicated the dose-dependence manner of chlorpyrifos exposure on the blood glucose levels. The subgroup analysis indicated that exposure to low doses of chlorpyrifos significantly increased the blood glucose levels in exposed animals versus the nonexposed (0.11; 95% CI: - 1.14, 1.36, z = 2.25, p = 0.03, I2 = 90.1%, p < 0.001) and high doses markedly decreased blood glucose levels in exposed rats versus the nonexposed (7.34; 95%CI: - 9.35, - 5.32, z = 6.41, p < 0.001, I2 = 96.9%, p < 0.001). The random effects and pooled analysis indicated that the blood glucose levels were 4.22-fold lower in exposed animals versus the nonexposed ones (95% CI: - 5.59,- 2.85; Z = 3.97; p < 0.001); therefore, heterogeneity was significant (I2 = 96.5%, p < 0.001). The present finding indicated the association between chlorpyrifos exposure and a decrease in blood glucose levels. However, more studies should be designed to clarify this effect of chlorpyrifos exposure on blood glucose levels and involved mechanisms.

The progressive alteration of urine metabolomic profiles of rats following long-term and low-dose exposure to permethrin

Background: Permethrin is a type of widely used pyrethroid pesticide. Although acute toxicity of permethrin has been well-characterised, the non-acute toxicity of permethrin upon long-term exposure at low dose has been seldom studied yet. The current study investigates the time-course change of the metabolomic profiles of urine following the low level long-term exposure of permethrin and identified biomarkers of the chronic toxicity of permethrin.Methods: Male Wistar rats were administrated orally with permethrin (75 mg/kg body weight/day, 1/20 LD₅₀) daily for consecutive 90 days. The urine samples from day 30, day 60, and day 90 after the first dosing were collected and analysed by ¹H NMR spectrometry. Serum biochemical analysis was also carried out.Results: Permethrin caused significant changes in the urine metabolites such as taurine, creatinine, acetate, lactate, dimethylamine, dimethylglycine, and trimethylamine-N-oxide. These biological markers indicated prominent kidney and liver toxicity induced by permethrin. However, there was no change in serum biochemical parameters for the toxicity, indicating that metabolomic approach was much more sensitive in detecting the chronic toxicity.Conclusion: The time-course alteration of metabolomic profiles of the urine based on ¹H NMR reflects the progressive development of the chronic toxicity with the long-term low-level exposure of permethrin.

Time-Course Changes in Urine Metabolic Profiles of Rats Following 90-Day Exposure to Propoxur

As a major kind of carbamate insecticide, propoxur plays an important role in agriculture, veterinary medicine, and public health. The acute toxicity of propoxur is mainly neurotoxicity due to the inhibition of cholinesterase. However, little is known regarding the toxicity of propoxur upon long-term exposure at low dose. In this study, Wistar rats were orally administrated with low dose (4.25 mg/kg body weight/day) for consecutive 90 days. And the urine samples in rats treated with propoxur for 30, 60, and 90 days were collected and analyzed by employing ¹H NMR-based metabolomics approach. We found that propoxur caused significant changes in the urine metabolites, including taurine, creatinine, citrate, succinate, dimethylamine, and trimethylamine-N-oxide. And the alteration of the metabolites was getting more difference compared with that of the control as the exposure time extending. The present study not only indicated that the changed metabolites could be used as biomarkers of propoxur-induced toxicity but also suggested that the time-course alteration of the urine metabolomic profiles could reflect the progressive development of the toxicity following propoxur exposure.

Organophosphorus pesticides can influence the development of obesity and type 2 diabetes with concomitant metabolic changes

Widespread use and the bioaccumulation of pesticides in the environment lead to the contamination of air, water, soil and agricultural resources. A huge body of evidence points to the association between the pesticide exposure and increase in the incidence of chronic diseases, e.g. cancer, birth defects, reproductive disorders, neurodegenerative, cardiovascular and respiratory diseases, developmental disorders, metabolic disorders, chronic renal disorders or autoimmune diseases. Organophosphorus compounds are among the most widely used pesticides. A growing body of evidence is suggesting the potential interdependence between the organophosphorus pesticides (OPs) exposure and risk of obesity and type 2 diabetes mellitus (T2DM). This article reviews the current literature to highlight the latest in vitro and in vivo evidences on the possible influence of OPs on obesity and T2DM development, as well as epidemiological evidence for the metabolic toxicity of OPs in humans. The article also draws attention to the influence of maternal OPs exposure on offspring. Summarized studies suggest that OPs exposure is associated with metabolic changes linked with obesity and T2DM indicated that such exposures may increase risk or vulnerability to other contributory components.

Age- and diet-specific effects of chronic exposure to chlorpyrifos on hormones, inflammation and gut microbiota in rats

Chlorpyrifos is a pesticide frequently detected in food and has been reported to disturb endocrine and gut health, which was regulated by gut microbiota and enteroendocrine cells. In this study, newly weaned (3 week) and adult (8 week) male rats fed a normal- or high- fat diet were chronically exposed to 0.3 mg chlorpyrifos/kg bodyweight/day. The effects of chlorpyrifos exposure on serum hormone levels, proinflammatory cytokines and gut microbiota were evaluated. Chronic exposure to chlorpyrifos significantly decreased the concentrations of luteinizing hormone, follicule stimulating hormone and testosterone, which was found only in the normal-fat diet. The counteracted effect of high-fat diet was also found in gut hormones and proinflammatory cytokines. Significantly higher concentrations of glucagon-like peptide-1, pancreatic polypeptide, peptide tyrosine tyrosine (PYY), ghrelin, gastric inhibitory poly-peptide, IL-6, monocyte chemoattractant protein-1, and TNF-α were found in rats exposed to chlorpyrifos beginning at newly weaned, whereas only the PYY, ghrelin and IL-6 concentrations increased significantly in rats exposed in adulthood. Furthermore, a decrease in epinephrine induced by chlorpyrifos exposure was found in rats exposed to chlorpyrifos beginning at newly weaned, regardless of their diet. Chlorpyrifos-induced disturbances in the microbiome community structure were more apparent in rats fed a high-fat diet and exposed beginning at newly weaned. The affected bacteria included short-chain fatty acid-producing bacteria (Romboutsia, Turicibacter, Clostridium sensu stricto 1, norank_f_Coriobacteriaceae, Faecalibaculum, Parasutterella and norank_f__Erysipelotrichaceae), testosterone-related genus (Turicibacter, Brevibacterium), pathogenic bacteria (Streptococcus), and inflammation-related bacteria (unclassified_f__Ruminococcaceae, Ruminococcaceae_UCG-009, Parasutterella, Oscillibacter), which regulated the endocrine system via the hypothalamic-pituitary-adrenal axis, as well as the immune response and gut barrier. Early exposure accelerated the endocrine-disturbing effect and immune responses of chlorpyrifos, although these effects can be eased or recovered by a high-fat diet. This study helped clarify the relationship between disrupted endocrine function and gut microbiota dysbiosis induced by food contaminants such as pesticides.

Chlorpyrifos-induced reproductive toxicity in rats could be partly relieved under high-fat diet

The widely used pesticide, chlorpyrifos, was found to inhibit the secretion of sex hormones and decrease the count and quality of sperm. A high-fat diet damaged the reproductive system by inducing oxidative damage and interfering with hormone synthesis, indicating the possibility of diet-specific effects of chlorpyrifos on reproductive toxicity. Several studies have demonstrated diet-specific toxicity of pesticides in the central nervous system, metabolism and gut microbiome, but the effect of a high-fat diet on the reproductive toxicity of chlorpyrifos has not been studied. In this study, rats were fed a normal-fat or high-fat diet and exposed to 3.0 mg chlorpyrifos/kg body weight by gavage for 20 weeks. Chlorpyrifos changed the sperm, serum hormones, oxidative stress in the testis, and enzyme activity related to spermatogenesis in rat testes when comparing the different diets. Chlorpyrifos significantly decreased total sperm count, serum testosterone and gonadotropin levels and the activity of enzymes involved in spermatogenesis, as well as lead to oxidative damage in the testis. It was interesting that a high-fat diet relieved all these effects, and chlorpyrifos only exhibited obvious reproductive toxicity in the normal-fat condition. It was necessary to consider the effect of dietary fats when evaluating pesticide toxicity.

The effects of hexaconazole and epoxiconazole enantiomers on metabolic profile following exposure to zebrafish (Danio rerio) as well as the histopathological changes

Hexaconazole and epoxiconazole are the worldwidely used fungicides. However, limited information is known about the toxicological effects of their enantiomers on aquatic organisms. In this study, zebrafish were separately exposed to 100 and 1000 μgL^-1 hexaconazole and epoxiconazole enantiomers for 21 d ¹H NMR-based metabolomics analysis showed that the exposure of low and high dose of hexaconazole enantiomers altered energy metabolism, lipid metabolism and amino acid metabolism of zebrafish, with the different metabolic profiles resulted from the same dose of (+)-hexaconazole and (-)-hexaconazole. Similar to hexaconazole enantiomers, the metabolic profiles, including the changes related to energy metabolism, lipid metabolism and amino acid metabolism, were demonstrated in low and high dose epoxiconazole enantiomers treatment groups. There are differences in the metabolic profiles of zebrafish between exposed to (+)-epoxiconazole and (-)-epoxiconazole of the same dose. The results of histological examination revealed that the exposure of both enantiomers for hexaconazole and epoxiconazole resulted in the similar histopathological changes. The exposure of hexaconazole and epoxiconazole enantiomers at low and high dose resulted the vacuolization and swell in the liver of the female and male zebrafish. Compared to female zebrafish, more liver damage was found in male zebrafish in the hexaconazole enantiomers exposure groups. The reduction of spermatids was observed in hexaconazole and epoxiconazole enantiomers treatment groups of both doses. Hexaconazole enantiomers exposure of low and high dose resulted the increase in the number of mature eggs, while such effect was not observed in epoxiconazole enantiomers exposure groups. Hexaconazole and epoxiconazole enantiomers exposure resulted in no changes in brains of female and male zebrafish. As a result, both triazole-based chiral bactericides, hexaconazole and epoxiconazole, have similar toxicological effects but their mechanisms of action are not exactly the same. The above results will play an important part in making the differences in toxic effects of hexaconazole and epoxiconazole enantiomers clear. What's more, it is an indispensable part for an integrated environmental risk assessment.

Effects of Diethyl Phosphate, a Non-Specific Metabolite of Organophosphorus Pesticides, on Serum Lipid, Hormones, Inflammation, and Gut Microbiota

Organophosphorus pesticides (OPs) can be metabolized to diethyl phosphate (DEP) in the gut environment, which may affect the immune and endocrine systems and the microbiota. Correlations between OPs and diseases have been established by epidemiological studies, mainly based on the contents of their metabolites, including DEP, in the serum or urine. However, the effects of DEP require further study. Therefore, in this study, adult male rats were exposed to 0.08 or 0.13 mg/kg DEP for 20 weeks. Serum levels of hormones, lipids, and inflammatory cytokines as well as gut microbiota were measured. DEP significantly enriched opportunistic pathogens, including Paraprevotella, Parabacteroides, Alloprevotella, and Helicobacter, leading to a decrease in interleukin-6 (IL-6). Exposure to the high dose of DEP enriched the butyrate-producing genera, Alloprevotella and Intestinimonas, leading to an increase in estradiol and a resulting decrease in total triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C); meanwhile, DEP-induced increases in peptide tyrosine‒tyrosine (PYY) and ghrelin were attributed to the enrichment of short-chain fatty acid-producing Clostridium sensu stricto 1 and Lactobacillus. These findings indicate that measuring the effects of DEP is not a proxy for measuring the effects of its parent compounds.

Metabonomics analysis of kidneys in rats administered with chronic low-dose cadmium by ultra-performance liquid chromatography-mass spectrometry

This study aimed to investigate the nephrotoxicity in rats administered with chronic low-dose cadmium (Cd) by ultra-performance liquid chromatography-mass spectrometry. A total of 40 male Sprague-Dawley rats were randomly assigned to four groups, namely: control; low-dose (0.13 mg/kg·body weight [bw]); middle-dose (0.80 mg/kg·bw); and high-dose (4.89 mg/kg·bw). The rats received CdCl₂ daily via drinking water for 24 weeks. Rat kidneys were collected for metabonomics analysis. Principal components analysis and partial least-squares discriminant analysis were used to investigate the metabonomics profile changes in the kidney samples and to screen the potential biomarkers. Ten metabolites were identified in the positive and negative ion modes. Compared with the control group, the intensities of tetranor 12-HETE, uric acid, hypoxanthine, phenylacetylglycine, guanidinosuccinic acid and xanthosine significantly increased (P < 0.01), and those of imidazolelactic acid, lactose 6-phosphate, l-urobilinogen and arachidonic acid significantly decreased (P < 0.01) in the high-dose group. Results showed that exposure to Cd in rats induced oxidative stress to the kidneys and disrupted amino acid metabolism, fatty acid metabolism and energy metabolism.

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.

Subacute oral toxicity assessment of benalaxyl in mice based on metabolomics methods

In this study, the metabolic responses of mice after 30 days of exposure to benalaxyl were assessed using NMR-based untargeted metabolomics and LC-MS-based targeted profiling of 20 amino acids. Urinary ¹H NMR analyses revealed alterations in energy metabolism, lipid metabolism, vitamin B metabolism, the urea cycle and amino acid metabolism, and targeted analyses indicated that the serum levels of asparagine, histidine, lysine and aspartic acid were significantly altered. Additionally, significant oxidative stress was observed in the liver and kidney, although no apparent histopathological injury was observed. The tissue distribution indicated a significant stereoselectivity in the brain, where (-)-R-benalaxyl was enriched. These data provide a comprehensive picture of the subacute toxic effects of benalaxyl in mice. The results of this study suggested that, for a toxicity evaluation, metabolomics analysis is much more sensitive than traditional toxicological methods. The results also highlight the combined use of untargeted and targeted metabolomics approaches in evaluating the health risks of xenobiotics.

1H NMR-based metabolomics analysis of adult zebrafish (Danio rerio) after exposure to diniconazole as well as its bioaccumulation behavior

As a systemic triazole fungicide, limited information is known about diniconazole. In this study, toxicological effects and bioaccumulation behavior of diniconazole in zebrafish were both evaluated to perform an overall assessment of its environmental risk towards aquatic organisms. The ¹H NMR-based metabolomics analysis revealed that 70 μg L^-1 diniconazole exposure increased valine, leucine, isoleucine, alanine, lactate and choline, accompanied by decreased glucose, creatine and taurine, in comparison to the control. In the exposure group of 300 μg L^-1 diniconazole, only down-regulated glucose and creatine were observed. The above results indicated that diniconazole disturbed energy metabolism, amino acid metabolism and lipid metabolism. Histological examination showed that the swell and vacuolization in the liver, as well as the reduction of spermatids in the diniconazole exposure groups. No enantioselectivity was observed in the bioaccumulation process of both 70 and 300 μg L^-1 diniconazole exposure groups. The above results play a vital role for a comprehensive environmental assessment of diniconazole.

Single-walled carbon nanotubes disturbed the immune and metabolic regulation function 13-weeks after a single intratracheal instillation

Due to their unique physicochemical properties, the potential health effects of single-walled carbon nanotubes (SWCNTs) have attracted continuous attention together with their extensive application. In this study, we aimed to identify local and systemic health effects following pulmonary persistence of SWCNTs. As expected, SWCNTs remained in the lung for 13 weeks after a single intratracheal instillation (50, 100, and 200μg/kg). In the lung, the total number of cells and the percentages of lymphocytes and neutrophils significantly increased at 200μg/kg compared to the control, and the Th1-polarized immune response was induced accompanying enhanced expression of tissue damage-related genes and increased release of chemokines. Additionally, SWCNTs enhanced the expression of antigen presentation-related proteins on the surface of antigen-presenting cells, however, maturation of dendritic cells was inhibited by their persistence. As compared to the control, a significant increase in the percentage of neutrophils and a remarkable decrease of BUN and potassium level were observed in the blood of mice treated with the highest dose. This was accompanied by the down-regulation of the expression of antigen presentation-related proteins on splenocytes. Moreover, protein and glucose metabolism were disturbed with an up-regulation of fatty acid β-oxidation. Taken together, we conclude that SWCNTs may induce adverse health effects by disturbing immune and metabolic regulation functions in the body. Therefore, careful application of SWCNTs is necessary for the enforcement of safety in nano-industries.

Effects of chlorpyrifos on the gut microbiome and urine metabolome in mouse (Mus musculus)

In this study, the toxic effects of clorpyrifos (CPF) on the gut microbiome and related urine metabolome in mouse (Mus musculus) were investigated. Mice were exposed to a daily dose of 1 mg kg(-1) bodyweight of CPF for 30 d. As a result, CPF significantly altered the gut microbiota composition in terms of the relative abundance of key microbes. Meanwhile, CPF exposure induced the alterations of urine metabolites related to the metabolism of amino acids, energy, short-chain fatty acids (SCFAs), phenyl derivatives and bile acids. High correlations were observed between perturbed gut microbiome and altered metabolic profiles. These perturbations finally resulted in intestinal inflammation and abnormal intestinal permeability, which were also confirm by the histologic changes in colon and remarkable increase of lipopolysaccharide (LPS) and diamine oxidase (DAO) in the serum of CPF-treated mice. Our findings will provide a new perspective to reveal the mechanism of CPF toxicity.

Metabonomic analysis of quercetin against the toxicity of chronic exposure to a mixture of four organophosphate pesticides in rat plasma

1. A metabonomics approach was performed to investigate the effect of quercetin on the toxicity of chronic exposure to a mixture of four organophosphate pesticides (OPs) at their corresponding no-observed-adverse-effect level (NOAEL). The rats were divided into six groups (n = 10/group): control, two different doses of quercetin, OPs mixture and different doses of quercetin plus OPs mixture-treated groups. 2. Nine metabolites, including two quercetin metabolites and seven endogenous metabolites were identified in plasma. The intensities of metabolites significantly changed in the OP mixture-treated group compared with the control group (p < 0.01), such as lysoPE (16:0/0:0), lysoPC (17:0/0:0), lysoPC (15:0/0:0) and 4-pyridoxic acid, significantly increased; by contrast, the intensities of arachidonic acid and citric acid significantly decreased. Anomalous intensity changes in aforementioned metabolites were alleviated in the OP mixture plus 50 mg/kgċbw/d quercetin-treated group compared with the OP mixture-treated group (p < 0.05). 3. The results indicated that quercetin elicited partial protective effects against the toxicity induced by a mixture of OPs, which include regulation of lipid metabolism, improvement of tricarboxylic acid (TCA) cycle disorders, enhancement of antioxidant defence system to protect the liver.

Subchronic neurotoxicity of chlorpyrifos, carbaryl, and their combination in rats

Anticholinesterase pesticides have been widely used in agricultural and domestic settings and can be detected in the environment after long-term use. Although the acute toxic effects of chlorpyrifos and carbaryl have been well described, little is known about the chronic toxicity of the pesticides mixture. To investigate their chronic neurotoxicity, Wistar rats were exposed to chlorpyrifos, carbaryl, and their mixture (MIX) for 90 consecutive days. The activities of serum cholinesterase (ChE) as well as acetylcholinesterase (AChE) and neuropathy target esterase (NTE) in nerve tissues were determined. Furthermore, the histopathological examination was carried out. The results showed that ChE activity significantly decreased in all treated rats except the rats treated with low dose carbaryl. Treatment with middle- and high-dose chlorpyrifos and MIX in rats significantly inhibited AChE activity in the central nervous tissues, whereas treatment with carbaryl alone did not. In sciatic nerve, AChE activity was significantly inhibited by high-dose carbaryl and MIX, but not by chlorpyrifos alone. No significant NTE inhibition was observed in all treatment groups. Histopathological examination revealed that both chlorpyrifos and MIX treatment induced hippocampal damage. However, no obvious hippocampal damage was found in carbaryl-treated rats. Carbaryl and MIX, but not chlorpyrifos alone, induced pathological damage of sciatic nerve. Taken together, all of the results indicated that chlorpyrifos and carbaryl have different toxicological target tissues in nervous system and showed corresponding effects in the nervous tissues, which may reflect the different sensitivity of central and peripheral nervous tissues to different pesticides individually and in combination.

Potential input from metabolomics for exploring and understanding the links between environment and health

Humans may be exposed via their environment to multiple chemicals as a consequence of human activities and use of synthetic products. Little knowledge is routinely generated on the hazards of these chemical mixtures. The metabolomic approach is widely used to identify metabolic pathways modified by diseases, drugs, or exposures to toxicants. This review, based on the state of the art of the current applications of metabolomics in environmental health, attempts to determine whether metabolomics might constitute an original approach to the study of associations between multiple, low-dose environmental exposures in humans. Studying the biochemical consequences of complex environmental exposures is a challenge demanding the development of careful experimental and epidemiological designs, in order to take into account possible confounders associated with the high level of interindividual variability induced by different lifestyles. The choices of populations studied, sampling and storage procedures, statistical tools used, and system biology need to be considered. Suggestions for improved experimental and epidemiological designs are described. Evidence indicates that metabolomics may be a powerful tool in environmental health in the identification of both complex exposure biomarkers directly in human populations and modified metabolic pathways, in an attempt to improve understanding the underlying environmental causes of diseases. Nevertheless, the validity of biomarkers and relevancy of animal-to-human extrapolation remain key challenges that need to be properly explored.

A metabonomic investigation of the effects of 60 days exposure of rats to two types of pyrethroid insecticides

Type I and II pyrethroid insecticides display different neurotoxicity. To investigate the long-term (60 days exposure) metabolic effect of the two types of pyrethroid insecticides deltamethrin and permethrin, (1)H nuclear magnetic resonance (NMR) spectroscopy-based metabonomics was used to analyze the biochemical composition of urine and serum samples from rats administrated daily with deltamethrin or permethrin for 60 consecutive days, and principal component analysis used to visualize similarities and differences in the resultant biochemical profiles. Rats treated with either deltamethrin or permethrin displayed increased levels of urinary acetate, dimethylamine, dimethylglycine, trimethylamine and serum free amino acids, and decreased urinary 2-oxoglutarate, all of which are indicative of kidney lesions and nephrotoxicity. The reduced excretion of tricarboxylic acid cycle intermediates, together with increased 3-D-hydroxybutyrate, acetate, and lactate in treated rats could suggest disturbance of the energy metabolism, including an increased rate of anaerobic glycolysis, enhanced fatty acid β-oxidation and ketogenesis. These results show that these two types of insecticides have similarities in the urine and serum spectra, indicating that similar metabolic pathways are perturbed by the insecticides, which induced hepatotoxicity and nephrotoxicity. This approach may lead to the discovery of novel biomarkers of pyrethroids toxicity and thereby provide new insights into the toxicological mechanisms of pesticides pyrethroids.

Applying biofluid metabonomic techniques to analyze the combined subchronic toxicity of propoxur and permethrin in rats

BACKGROUND

NMR combined with pattern recognition was recently introduced as a new technique for rapid xenobiotic toxicity evaluation. In this article, metabolic changes in the biofluid of rats after 90-day oral treatment with propoxur, permethrin and a combination of these two pesticides were investigated.

RESULTS

Propoxur dosing induced increased urinary taurine, creatinine and glucose, whereas urinary lactate and acetate were increased in the highest permethrin dose group. Urinary acetate, alanine, lactate and trimethylamine levels were increased in the mixture group, accompanied by decreased urinary tricarboxylic acid cycle intermediates. In addition, the highest dose of the mixture displayed raised 3-D-hydroxybutyrate, acetate and lactate levels in the serum sample.

CONCLUSION

Chronic exposure to a combination of propoxur and permethrin may induce hepatotoxicity and nephrotoxicity. An increase in acetate, alanine and formate in the urine could be a potentially sensitive biomarker of the chronic, combined effects of permethrin and propoxur.

Specific metabolic fingerprint of a dietary exposure to a very low dose of endosulfan

Like other persistent organochlorine pesticides, endosulfan residues have been detected in foods including fruit, vegetables, and fish. The aim of our study was to assess the impact of a dietary exposure to low doses of endosulfan from foetal development until adult age on metabolic homeostasis in mice and to identify biomarkers of exposure using an ¹H-NMR-based metabonomic approach in various tissues and biofluids. We report in both genders an increase in plasma glucose as well as changes in levels of factors involved in the regulation of liver oxidative stress, confirming the prooxidant activities of this compound. Some metabolic changes were distinct in males and females. For example in plasma, a decrease in lipid LDL and choline content was only observed in female. Lactate levels in males were significantly increased. In conclusion, our results show that metabolic changes in liver could be linked to the onset of pathologies like diabetes and insulin resistance. Moreover from our results it appears that the NMR-based metabonomic approach could be useful for the characterization in plasma of a dietary exposure to low dose of pesticide in human.

Sub-chronic exposure to paraoxon neither induces nor exacerbates diabetes mellitus in Wistar rat

There is an increasing belief that organophosphorus compounds (OPCs) impair glucose homeostasis and cause hyperglycemia and diabetes mellitus. The present study was undertaken to investigate the putative diabetogenic effect of sub-lethal and sub-chronic exposure to paraoxon (POX), an extremely hazardous OPC used in pesticides. The effect of paraoxon on streptozotocin-induced diabetic rats was also examined. Each rat was injected with 100 nmol of POX 5 days per week for 6 weeks. Blood glucose levels and red blood cell acetylcholinesterase activity were measured weekly. Biochemical analysis and morphological studies were performed at the end of the experiment. The results revealed that POX neither induces nor exacerbates diabetes mellitus in experimental rats. Liver and kidney/body weight ratios revealed statistically insignificant differences when compared with controls. Biochemical analysis of urine samples showed a small but not significant increase in protein level in all groups. Urine bilirubin was significantly higher in the diabetes + POX group when compared with the control group. The number of blood cells in urine was significantly higher in the POX-treated group compared with the control group. Hyperglycemia was noted in the diabetes and diabetes + POX groups, but neither in the saline control nor in POX-treated normal rats. Electron microscopy of POX-treated pancreas did not show any morphological changes in beta cells. These results suggest that POX does not cause diabetes mellitus at sub-lethal sub-chronic exposure.

Alteration of leaf metabolism in Bt-transgenic rice (Oryza sativa L.) and its wild type under insecticide stress

Insecticide is always used to control the damage from pests, while the potential influence on plants is rarely known. Time-course metabolic changes of wild and Bacillus thuringiensis (Bt) transgenic rice (Oryza sativa L.) plants after insecticide treatment were investigated by using gas chromatography-mass spectrometry (GC-MS). A combined statistical strategy of 2-way ANOVA and multivariate analyses (principal component analysis and hierarchal cluster analysis) was performed to find the stress-associated effects. The results reveal that a wide range of metabolites were dynamically varied in both varieties as a response to insecticide, in multiple metabolic pathways, such as biosynthesis and metabolism of amino acids, carbohydrates, fatty acids, TCA cycle, and the shikimate/phenylpropanoid pathway, and most of the changes were correlated with the exposure time and dependent on the variety. A set of stress defenses were activated, including phytohormone signaling pathway, antioxidant defense system, shikimate-mediated secondary metabolism, and so on. In particular, insecticide led to much stronger regulations of signaling molecules (salicylate and the precursor of jasmonate) and antioxidants (α-tocopherol and dehydroascorbate/ascorbate) in Bt-transgenic variety at the early stage. Our results demonstrated that the Bt-transgenic rice had a more acute and drastic response to insecticide stress than its non-transgenic counterpart in antioxidant system and signaling regulation.

(1)H NMR-based metabonomic profiling of rat serum and urine to characterize the subacute effects of carbamate insecticide propoxur

Carbamate insecticide propoxur is widely used in agriculture and public health programs. To prevent adverse health effects arising from exposure to this insecticide, sensitive methods for detection of early stage organismal changes are necessary. We present here an integrative metabonomic approach to investigate toxic effects of pesticide in experimental animals. Results showed that propoxur even at low dose levels can induce oxidative stress, impair liver function, enhance ketogenesis and fatty acid β-oxidation, and increase glycolysis, which contribute to the hepatotoxocity. These findings highlight the applicability of (1)H NMR spectroscopy and multivariate statistics in elucidating the toxic effects of propoxur.

Metabonomic Responses in Rat Urine Following Subacute Exposure to Propoxur

Metabolic profiling of urine from pesticide-treated rats was investigated by the nuclear magnetic resonance (NMR)-based metabonomic strategy. Twenty-four-hour urine samples of rats were collected after administration with propoxur at doses of 0.85, 1.70, and 8.51 mg/kg, respectively, for 28 consecutive days. Liver tissue was fixed and the histopathological alterations were examined. The results showed that propoxur at high dose induced liver histopathological injury. Metabonomic analysis demonstrated that the levels of creatine and taurine markedly increased together with slight elevation of hippurate, glucose, and amino acids in low- and medium-dose groups. However, concentrations of urinary lactate, acetate, acetone, succinate, citrate, and 2-oxoglutarate increased in high-dose group. All these results suggested that propoxur could inhibit liver function through altering the energy and lipid metabolism. These data also supported the contention that the NMR-based metabonomic approach represents a promising new technology for the development of pesticide toxicity screening and mechanism exploration.

Nephrotoxicity induced by long-term oral administration of different doses of chlorpyrifos

Wistar rats (male) were divided into 3 groups — group A (GA) served as control, group B (GB) were daily administered chlorpyrifos (Anu Products Ltd., India) orally at a dose of 5 mg/kg b wt. and animals in group C (GC) received daily an oral administration of chlorpyrifos at a dose of 10 mg/kg b wt. Rats were sacrificed on 1st, 2nd, 4th, 6th and 8th week after initiation of the experiment. Kidneys were extirpated and fixed in aqueous Bouin’s solution. The tissues thus fixed were routinely processed for histological studies. The present study showed that the histopathological changes were caused in kidney of rats by chlorpyrifos administration. The changes noticed were mainly the shrinkage of glomerulus at initial stage of treatment, the tubular dilation, the glomerular hypercellularity, hypertrophy of tubular epithelium, degeneration of glomerulus and renal tubules, deposition of eosin-positive substances in the glomerulus and renal tubules and infiltration of leucocytes. A decrease in the body weight gain was observed in chlorpyrifos-treated rats. However, variable intensities of these changes were noticed depending upon the doses and duration of the treatment.

Biocompatibility and safety of a hybrid core-shell nanoparticulate OP-1 delivery system intramuscularly administered in rats

A hybrid, localized and release-controlled delivery system for bone growth factors consisting of a liposomal core incorporated into a shell of alternating layer-by-layer self-assembled natural polyelectrolytes has been formulated. Hydrophilic, monodisperse, spherical and stable cationic nanoparticles (< or =350 nm) with an extended shelf-life resulted. Cytocompatibility was previously assayed with MC3T3-E1.4 mouse preosteoblasts showing no adverse effects on cell viability. In this study, the in vivo biocompatibility of unloaded and loaded nanoparticles with osteogenic protein-1 or OP-1 was investigated. Young male Wistar rats were injected intramuscularly and monitored over a period of 10 weeks for signs of inflammation and/or adverse reactions. Blood samples (600 microL/collection) were withdrawn followed by hematological and biochemical analysis. Body weight changes over the treatment period were noted. Major organs were harvested, weighed and examined histologically for any pathological changes. Finally, the injection site was identified and examined immunohistochemically. Overall, all animals showed no obvious toxic health effects, immune responses and/or change in organ functions. This hybrid core-shell nanoparticulate delivery system localizes the effect of the released bioactive load within the site of injection in muscle with no significant tissue distress. Hence, a safe and promising carrier for therapeutic growth factors and possibly other biomolecules is presented.