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

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.

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.

Long-term low-dose exposure of permethrin induces liver and kidney damage in rats

BACKGROUND

Permethrin is one of the pyrethroid insecticides, which is widely used in agriculture and public health. Although acute toxicity of the insecticide has been studied, the chronic toxicity upon the long-term exposure has not been clear yet. The purpose of the current study is to investigate the organ toxicities of permethrin following its long-term low-dose exposure.

METHODS

Male Wistar rats were daily administrated orally with permethrin (75 mg/kg body weight/day, gavage) for 90 days, and then the samples of biofluids (blood and urine) and organs including liver and kidney were collected. The serum and urine samples were measured by biochemical assay and the tissues of kidney and liver were examined and analyzed by histopathological method.

RESULTS

The results showed that no change was found in serum and urine biochemical parameters for the toxicity; however, significant changes including hyperchromatic nuclei swollen in the hepatic parenchymal cells and the swelling proximal tubules in the kidneys were observed in the tissue structures of liver and kidneys in the histopathological sections.

CONCLUSION

These results indicate that low-dose long-term exposure of permethrin can cause chronic toxicity with slight liver and kidney damage.

Use of permethrin and other pyrethroids and mortality in the Agricultural Health Study

OBJECTIVES

Pyrethroid insecticides have been linked with multiple health outcomes. One study reported an association with increased all-cause and cardiovascular mortality. Given the widespread use of pyrethroids, these findings warrant confirmation. We explored associations of permethrin/pyrethroid use with overall and cause-specific mortality among 50 665 licensed pesticide applicators in the Agricultural Health Study.

METHODS

At enrolment (1993-1997), participants self-reported information on permethrin/pyrethroid use. Information on causes of death came from linkage with death registries through 2016. We used Cox proportional hazards models to estimate HRs and 95% CIs with adjustment for potential confounders.

RESULTS

Over an average 21 years of follow-up, 19.6% (9,955) of the cohort died. We found no clear evidence that ever-use of permethrin/pyrethroid was associated with elevated overall mortality or with mortality from most causes examined. There was suggestive evidence, based on a small number of deaths among those exposed, for elevated pyrethroid-associated mortality from some neurological, respiratory and genitourinary diseases in the overall sample and from lung cancer among never-smokers.

CONCLUSION

Although based on mortality, which is also affected by survival, rather than incidence, these findings are biologically plausible, and future investigations in other populations may be warranted.

Use of metabolomics in refining the effect of an organic food intervention on biomarkers of exposure to pesticides and biomarkers of oxidative damage in primary school children in Cyprus: A cluster-randomized cross-over trial

BACKGROUND

Exposure to pesticides has been associated with oxidative stress in animals and humans. Previously, we showed that an organic food intervention reduced pesticide exposure and oxidative damage (OD) biomarkers over time; however associated metabolic changes are not fully understood yet.

OBJECTIVES

We assessed perturbations of the urine metabolome in response to an organic food intervention for children and its association with pesticides biomarkers [3-phenoxybenzoic acid (3-PBA) and 6-chloronicotinic acid (6-CN)]. We also evaluated the molecular signatures of metabolites associated with biomarkers of OD (8-iso-PGF2a and 8-OHdG) and related biological pathways.

METHODS

We used data from the ORGANIKO LIFE + trial (NCT02998203), a cluster-randomized cross-over trial conducted among primary school children in Cyprus. Participants (n = 149) were asked to follow an organic food intervention for 40 days and their usual food habits for another 40 days, providing up to six first morning urine samples (>850 samples in total). Untargeted GC-MS metabolomics analysis was performed. Metabolites with RSD ≤ 20% and D-ratio ≤ 50% were retained for analysis. Associations were examined using mixed-effect regression models and corrected for false-discovery rate of 0.05. Pathway analysis followed.

RESULTS

Following strict quality checks, 156 features remained out of a total of 610. D-glucose was associated with the organic food intervention (β = -0.23, 95% CI: -0.37,-0.10), aminomalonic acid showed a time-dependent increase during the intervention period (β_int = 0.012; 95% CI:0.002, 0.022) and was associated with the two OD biomarkers (β = -0.27, 95% CI:-0.34,-0.20 for 8-iso-PGF2a and β = 0.19, 95% CI:0.11,0.28 for 8-OHdG) and uric acid with 8-OHdG (β = 0.19, 95% CI:0.11,0.26). Metabolites were involved in pathways such as the starch and sucrose metabolism and pentose and glucuronate interconversions.

DISCUSSION

This is the first metabolomics study providing evidence of differential expression of metabolites by an organic food intervention, corroborating the reduction in biomarkers of OD. Further mechanistic evidence is warranted to better understand the biological plausibility of an organic food treatment on children's health outcomes.

Effect of oral administration of a mixture of pyrethroids at doses relevant to human exposure on the general and male reproductive physiology in the rat

Studies on the effects of unintentional intake of pyrethroid pesticides that are akin to actual human exposure settings are very rare. Such an exposure is primarily by consuming the food products as routine diet that contain residual levels of pyrethroids. In this study, rats were orally administered for 15 months with a mixture of pyrethroids at a dose that is one-fifth (high dose; HD) or one-twenty fifth (low dose; LD) of the residual levels commonly present in the average amount of rice and vegetables consumed by Indian population. Lipid profile, kidney and liver function were assessed. Lipid peroxidation, nitric oxide, antioxidant enzyme activities and histopathological changes were analyzed in the liver, lung, kidney, pancreas, testes, caput, cauda and prostate. The effect on the male reproductive system as a function of sperm count, enzyme activity of 3β-HSD and 17β-HSD and the expression profile of genes involved in spermatogenesis, steroidogenesis, genetic reprogramming and apoptosis of male gametes were evaluated. Significant increase in the relative organ weight, perturbations in the activities of antioxidant enzymes, lipid profile and liver function were observed in both LD and HD groups. Damage to the anatomical architecture was evident in all the tissues due to pyrethroid toxicity. Exposure to LD and HD of pyrethroid mixture resulted in decreased sperm count, activities of 3β-HSD and 17β-HSD, impaired capacitation and acrosome reaction and perturbations in the expression of genes that govern male gamete production. Results of our study indicate that exposure to pyrethroids for longer durations even at doses that are far below the residual levels present in the food consumed will result in severe damage to general physiological processes as well as reproductive function.

Multi- and transgenerational effects following early-life exposure of zebrafish to permethrin and coumarin 47: Impact on growth, fertility, behavior and lipid metabolism

Transgenerational effects induced by environmental stressors are a threat to ecosystems and human health. However, there is still limited observation and understanding of the potential of chemicals to influence life outcomes over several generations. In the present study, we investigated the effects of two environmental contaminants, coumarin 47 and permethrin, on exposed zebrafish (F0) and their progeny (F1-F3). Coumarin 47 is commonly found in personal care products and dyes, whereas permethrin is used as a domestic and agricultural pyrethroid insecticide/insect repellent. Zebrafish (F0) were exposed during early development until 28 days post-fertilization and their progeny (F1-F3) were bred unexposed. On one hand, the effects induced by coumarin 47 suggest no multigenerational toxicity. On the other hand, we found that behavior of zebrafish larvae was significantly affected by exposure to permethrin in F1 to F3 generations with some differences depending on the concentration. This suggests persistent alteration of the neural or neuromuscular function. In addition, lipidomic analyses showed that permethrin treatment was partially correlated with lysophosphatidylcholine levels in zebrafish, an important lipid for neurodevelopment. Overall, these results stress out one of the most widely used pyrethroids can trigger long-term, multi- and possibly transgenerational changes in the nervous system of zebrafish. These neurobehavioral changes echo the effects observed under direct exposure to high concentrations of permethrin and therefore call for more research on mechanisms underlying effect inheritance.

Urinary Metabonomic Profiling Discriminates Between Children with Autism and Their Healthy Siblings

Background

Autism spectrum disorder (ASD) is a complicated neuropsychiatric disease that displays significant heterogeneity. The diagnosis of ASD is currently primarily dependent upon descriptions of clinical symptoms, and it remains urgent to find biological markers for the detection and diagnosis of autism. The current study applied the urinary metabolic profiling approach to characterize metabolic phenotypes in ASD.

Material/Methods

Urine was obtained from children with ASD and their matched healthy siblings. Samples were analyzed using ¹H NMR-based methods designed to measure a broad range of metabolites. Partial least-square-discriminant analysis (PLS-DA) was used to develop models to identify metabonomic variations that can be used to distinguish between individuals with ASD and their unaffected siblings.

Results

A significant difference was observed between the metabolomic profiles of children with ASD and that of their healthy siblings. An increase in the levels of tryptophan, hippurate, glycine, and creatine, and a decrease in trigonelline, melatonin, pantothenate, serotonin, and taurine were observed compared to the control group. We conclude that several metabolic pathways are affected by autism, which suggests that a gut-brain link may be important in the pathophysiology of ASD.

Conclusions

¹H NMR-based metabonomic analysis of the urine can determine perturbations of specific metabolic pathways related to ASD and help identify a characteristic metabolic fingerprint to better understand the disease and its causes.