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Background: Chlorpyrifos belongs to a broad-spectrum organophosphate insecticide that has high toxicity, is metabolized in the liver by the oxidation reaction, and can inhibit acetylcholinesterase activity. Acetylcholinesterase inhibition generates the reactive oxygen species and induces oxidative stress, which ultimately results in cellular damage like in the kidney. Examining blood urea nitrogen (BUN) levels, creatinine, and kidney histopathology is an appropriate indicator to assess the toxicity of chlorpyrifos to the degree of damage to cells and kidney tissue., Materials and Methods: This research used to determine the effect of duration of exposure to chlorpyrifos and dose-response relationships is important for early detection of the effects of chlorpyrifos toxicity on health. The research study was a true experimental (completely randomized design) consisting of 30 subjects divided into 5 groups. Controlled Group (K1) given 1 mg/kg BW Tween 20 and NaCl 0, 9% until the 56th day. The chlorpyrifos exposed group (P1, P2, P3, and P4) was given chlorpyrifos 5 mg/kg BW for 7, 14, 28, and 56 days. After the treatment, BUN and creatinine levels were measured, and microscopic changes in the kidney were analyzed. The results of BUN, creatinine, and kidney histopathologic were analyzed using the analysis of variance statistical test., Results: The data result showed that compared to the control group, there were significant increases of BUN and creatinine (P = 0.013 and P = 0.003). Histopathological examinations of kidney glomerulus diameter were also smaller compared to the control group (P = 0.00). All the data measurement indicates significant differences compared to the control group., Conclusions: We concluded that sub-chronic oral exposure to chlorpyrifos at low doses can damage the kidneys and cause kidney failure., (Copyright © 2024 Copyright: © 2024 Indian Journal of Pharmacology.)

This study probed the neuroprotective influence of indole-3-propionic acid (IPA) in rats exposed to chlorpyrifos (CPF) alone at 5 mg/kg body weight or co-administered with IPA at 12.5 and 25 mg/kg for 14 days. Behavioral data indicated that IPA significantly (p < 0.05) abated CPF-mediated anxiogenic-like behaviors with concomitant improvement in the locomotor and exploratory behaviors as substantiated by track plots and heat maps data. Also, IPA mitigated CPF-mediated diminution in cholinergic and antioxidant defense systems whereas it markedly improved thioredoxin level and thioredoxin reductase activity in cerebral and cerebellar tissues of the animals. Co-administration of IPA significantly enhanced anti-inflammatory cytokine, interleukin-10 but suppressed oxidative and inflammatory stress, caspase-9 and caspase-3 activation with concomitant reduction in 8-hydroxy-2'-deoxyguanosine (8-OHdG) level and histological damage. Collectively, IPA-mediated neuroprotection involves modulation of cholinergic and redox-regulatory systems, inflammatory stress, apoptotic responses and DNA damage in cerebrum and cerebellum of rats., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Chlorpyrifos (CPF), the most used insecticide in Argentina, can act as an endocrine disruptor at low doses. We previously demonstrated that chronic exposure to CPF induces hormonal imbalance in vivo. The aim of this work was to study the effects of low concentrations of CPF (0.01 and 1 mg/kg/day) on the reproductive system of virgin adult rats. In the ovary, we studied the effects of CPF on steroidogenesis by determining steroid hormone content by RIA and CYP11 and CYP19 enzyme expression by qRT-PCR. The estrous cycle was evaluated by microscopic observation of vaginal smear, as well as by changes in uterine histology. In endometrium, we determined the fractal dimension and expression of PCNA, ERα and PR by IHC. Our results showed that chronic exposure to CPF affects ovarian steroid synthesis, causing alterations in the normal cyclicity of animals. In addition, CPF induced proliferative changes in the uterus, suggesting that it could affect reproduction or act as a risk factor in the development of uterine proliferative pathologies., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Common carp (Cyprinus carpio) is an important aquaculture species. However, their production and health is sometimes threatened by pesticides. In common carp, extensive studies have been done for exposures of single pesticides, but effects of mixtures such as those of the commonly used chlorpyrifos and dichlorvos, are still unknown for this species. In the first phase of this work, an acute lethal exposure experiment was conducted to estimate 24 h to 96 h lethal concentrations (LC 10 - 90 ) of chlorpyrifos, dichlorvos and their mixture. Compared to dichlorvos, chlorpyrifos was found to be highly toxic to the tested species. Joint toxicity assessment of these pesticides in binary mixtures was dominated by synergism. In the second experimental phase, common carp were exposed to sub-lethal concentrations (LD-10% and HD-50% 96 h-LC 50 ) of individual pesticides and their mixture. General fish behaviors, buccal movements and feeding attempts by fish were recorded after 1 h, 24 h, 48 h, 72 h and 96 h whereas aerobic metabolism of fish was recorded for 0-24 h, 24-48 h 48-72 h and 72-96 h of exposure. All pesticide treatments elevated buccal movements and oxygen uptake in a dose dependent manner. Feeding depression was also observed by pesticide exposure. The augmented deleterious effect of these pesticides in a mixture suggests that joint toxicity assessment is critical to develop more realistic water quality standards and monitoring guidelines., (Copyright © 2021 Elsevier Inc. All rights reserved.)

3,5,6-Trichloro-2-pyridinol (TCP) is an important biomarker and one of the final metabolites of chlorpyrifos (CPF). TCP inhibits secretion of sex hormones. Similar to CPF, TCP can bind to sex steroid hormone receptors and decrease the secretion of sex hormones. However, little attention has been paid to the ability of TCP and CPF to interfere with androgen receptor (AR) in Sertoli cells. This study aimed to explain how TCP promotes the inhibitory effect of CPF on the paracrine function of Sertoli cells. Western blotting indicated that after 20 weeks of exposure, expression of AR in testes was significantly reduced by CPF. An in vitro assay measured the cytotoxicity of CPF, TCP and diethylphosphate (DEP) on viability of Sertoli cells by Cell Counting Kit-8. CPF cytotoxicity was greater than that of TCP, and TCP cytotoxicity was greater than that of DEP at concentrations of 1000 μmol/L. Western blotting indicated that TCP and CPF both decreased expression of AR and cAMP-response element binding protein phosphorylation, while DEP had no effect in Sertoli cells, which are important in regulating paracrine function of Sertoli cells. The fluorescence measurements and docking studies revealed that testosterone, CPF and TCP showed four types of intermolecular interactions with AR, highlighting alkyl bonds with some of the same amino acids. Compared with testosterone, CPF and TCP also showed significant synergistic interaction with AR. CPF interacted with more amino acids and interaction energy than TCP did. This research elucidates TCP in the antiandrogenic effect of CPF on the paracrine function and suggests that TCP or chemicals with a trichloropyridine structure must be considered during reproductive toxicity assessment of potential environmental pollutants., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Organophosphate (OP) pesticides are commonly known for their neurotoxicity. In the current experiments, two OPs used agriculturally, chlorpyrifos and dimethoate, were separately adminis- tered with centrally acting caffeine that is known to affect the pharmacological action of other substances. The aim of this study was to determine whether the combination of OP and caffeine may influence their neurotoxic potential. For this purpose, some neurobehavioral effects of this concomitant exposure were assessed in adult Swiss mice. All substances were given intra- peritoneally (i.p.) as single injections. In the passive avoidance task, chlorpyrifos (100 mg/kg) administered together with caffeine (40 mg/kg) significantly impaired acquisition. In the rota-rod test, the addition of caffeine at doses of 20 and 40 mg/kg, induced motor coordination impairment in chlorpyrifos (100 mg/kg)-treated mice. Neurobehavioral impairments were not observed for caffeine, chlorpyrifos and dimethoate (50 mg/kg) given separately as well as for the combina- tion of dimethoate and caffeine. Chlorpyrifos (100 mg/kg) alone and in combination with caffeine (40 mg/kg) significantly reduced acetylcholinesterase (AChE) activity. The current study shows that concomitant exposure to caffeine and chlorpyrifos can cause neurotoxic effects in mice despite the absence of these effects when caffeine and chlorpyrifos are administered alone. How- ever, the possible mechanisms involved need further investigations., (Copyright© by the Polish Academy of Sciences.)

Exposure to chlorpyrifos-cypermethrin combination during early development resulted in defective looping and ventricular noncompaction of heart in domestic chicken. The study was extended to elucidate the molecular basis of this novel observation. The primary culture of chicken embryonic heart cells showed a concentration-dependent loss of viability when challenged with this combination of technical-grade insecticides. Comet assay, DNA ladder assay, and analyses of appropriate markers at transcript and protein levels, revealed that chlorpyrifos-cypermethrin combination induced cell death by activating apoptosis. Parallelly, the tissues derived from control and experimental group hearts were checked for apoptotic markers, and the result was much similar to that of the in-vitro study. Further analysis showed that chlorpyrifos-cypermethrin combination deranged the expression pattern of the transcriptional regulators of cardiogenesis, namely TBX20, GATA5, HAND2, and MYOCD. This, together with heightened apoptosis, could well be the reason behind the observed structural anomalies in the heart of chlorpyrifos-cypermethrin poisoned embryos., (© 2020 Wiley Periodicals LLC.)

Hyperglycemia induces low-grade systemic inflammation and immune dysregulation, leading to overstated reactions to immune stimuli and diabetes-related organ damage. Tissue inflammation is characterized by leukocyte infiltration, and T cells play crucial roles in directing leukocyte-mediated inflammatory responses. The aim of the study was to investigate the effects of dietary exposure to chlorpyrifos (CPF) on systemic and hepatic immune-cell phenotypes in C57BL/6 mice with streptozotocin (STZ)-induced diabetes. Mice received an intraperitoneal injection of STZ for 5 consecutive days to induce diabetes, and diabetic mice were given either an AIN-93-based control diet or a CPF-containing diet at doses of 0.5, 1, or 2 mg/kg body weight/day for 28 days. Results showed that dietary exposure to CPF had no influence on the body weight or the erythrocyte hemoglobin A1c level in diabetic mice. Both blood and hepatic neutrophil populations were enhanced by CPF exposure. CPF-exposed groups had lower percentages of blood T cells without altering the proportions of CD4 + and CD8 + T-cell subsets, and lower expression levels of the Bcl-2 antiapoptotic gene in the spleen. CPF exposure reduced the percentage of blood regulatory T cells (Tregs); however, the Treg population was upregulated in the liver even when hepatic T cells were not affected by CPF in diabetic mice. Hepatic expressions of Treg-related genes were suppressed in all CPF-exposed groups. Higher plasma levels of aspartate aminotransferase and expression levels of the hepatic interleukin-1β gene were observed in diabetic mice exposed to medium and high doses of CPF. These findings suggest that dietary exposure to CPF affects the distribution of both myeloid and lymphoid immune cells in the blood and liver under hyperglycemic conditions, which may lead to hyperinflammation when encountering immune stimuli., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Organophosphates are among the most used pesticides. Particularly, chlorpyrifos (CPF) is responsible for a number of deleterious effects on brain development, which may program behavioral changes later in life. Here, we investigated whether a regimen of early low level CPF exposure that did not result in a significant inhibition of acetylcholinesterase (AChE) had deleterious effects on mood-related behaviors, as well as on cholinergic and serotonergic biomarkers in the mice brain. From the 3rd to 9th postnatal day (PN), male and female Swiss mice were subcutaneously injected with CPF. Mice were submitted to a battery of behavioral tests from PN60 to PN63: open field, elevated plus maze and forced swimming tests. The cholinergic and serotonergic biomarkers were assessed at PN10 and PN63. Our data indicated that early CPF exposure increased anxiety-like behavior in females and altered decision-making behavior in both sexes. Most biochemical alterations were sex-dependent and restricted to females. At PN10, CPF female mice showed increased serotonin and choline transporter binding in cerebral cortex. Distinctively, in adult females, the effects indicated a hypoactive state: CPF exposure reduced 5-HT1a receptor binding in cerebral cortex, as well as serotonin transporter binding and choline acetyltransferase activity in brainstem. Our results indicate that CPF exposure during the brain growth spurt deregulates serotonergic and cholinergic biomarkers. The effects are consistent with impaired synaptic function, may be related to long-term mood disorders and point out to higher female susceptibility., Competing Interests: The authors have declared that no competing interests exist.

The intra-tissue levels of thyroid hormones (THs) regulate organ functions. Environmental factors can impair these levels by damaging the thyroid gland and/or peripheral TH metabolism. We investigated the effects of embryonic and/or long-life exposure to low-dose pesticides, ethylene thiourea (ETU), chlorpyrifos (CPF) and both combined on intra-tissue T4/T3 metabolism/signaling in zebrafish at different life stages. Hypothyroidism was evident in exposed larvae that showed reduced number of follicles and induced tshb mRNAs. Despite that, we found an increase in free T4 (fT4) and free T3 (fT3) levels/signaling that was confirmed by transcriptional regulation of TH metabolic enzymes (deiodinases) and T3-regulated mRNAs (cpt1, igfbp1a). Second-generation larvae showed that thyroid and TH signaling was affected even when not directly exposed, suggesting the role of parental exposure. In adult zebrafish, we found that sex-dependent damage of hepatic T3 level/signaling was associated with liver steatosis, which was more pronounced in females, with sex-dependent alteration of transcripts codifying the key enzymes involved in 'de novo lipogenesis' and β-oxidation. We found impaired activation of liver T3 and PPARα/Foxo3a pathways whose deregulation was already involved in mammalian liver steatosis. The data emphasizes that the intra-tissue imbalance of the T3 level is due to thyroid endocrine disruptors (THDC) and suggests that the effect of a slight modification in T3 signaling might be amplified by its direct regulation or crosstalk with PPARα/Foxo3a pathways. Because T3 levels define the hypothyroid/hyperthyroid status of each organ, our findings might explain the pleiotropic and site-dependent effects of pesticides.

Chlorpyrifos (CPF) and cadmium (Cd) are widespread environmental pollutants, which are often present in drinking water and foods. However, the combined effects of CPF and Cd were not entirely clear at present. There was also no biomarker available to diagnose the poisoning of the two chemicals at low dose for long-term exposures. In this study, we investigated the change of serum metabolites of rats with subchronic exposure to CPF, Cd, and CPF plus Cd using gas chromatography-mass spectrometer-based metabolomics approach. We performed a stepwise optimization algorithm based on receiver operating characteristic to identify serum metabolite biomarkers for toxic diagnosis of the chemicals at different doses after 90-day exposure. We found that aminomalonic acid was the biomarker for the toxicity of Cd alone administration, and serine and propanoic acid were unique biomarkers for the toxicities of CPF plus Cd administrations. Our results suggest that subchronic exposure to CPF and Cd alone, or in combination at their low doses, could cause disturbance of energy and amino acid metabolism. Overall, we have shown that analysis of serum metabolomics can make exceptional contributions to the understanding of the toxic effects following long-term low-dose exposure of the organophosphorus pesticide and heavy metal.

The gut microbiota comprises a large number of microorganisms, whose composition can be modified by genetic and environmental factors. The host's genetic background, including the different isoforms of the apolipoprotein E (APOE) gene, can exert an influence over microbiota composition. Exposure to the widely-used pesticide chlorpyrifos (CPF), can lead to dysbiosis and alter the levels of metabolites produced by the microbiota, such as short-chain fatty acids (SCFAs). This study was aimed at assessing the contribution of the APOE genotype and early exposure to CPF on gut microbiota and SCFA in brain. For it, C57BL/6, apoE3-and apoE4-TR mice were orally exposed to CPF from postnatal day (PND) 10 to PND 15. Microbiota in the gut and SCFA in the brain were assessed at PND 15 after CPF exposure. Differences between genotypes at different taxonomic levels were found, A. muciniphila presented greater abundance in APOE4 genotype, but was reduced by CPF exposure. APOE and CPF influenced cerebral SCFAs, with APOE3 genotype showing the highest levels of acetic, propionic and butyric acids and CPF exposure inducing the highest levels of isovaleric and 4-methylvaleric acids. These results provide further knowledge about gut microbiota and cerebral SCFAs composition at early ages and their modulation by APOE and postnatal CPF exposure., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The combination of the organophosphate (OP) chlorpyrifos (CPF) and the pyrethroid cypermethrin (CPM) is commonly marketed as pour-on formulations for the control of sheep lice, ked, and blowflies. CPF irreversibly inhibits acetylcholinesterases (AChE), while pyrethroids are not AChE inhibitors. However, combinations of pyrethroids with OPs showed a highly synergistic effect on AChE inhibition. Thus, the aim of the current work was to evaluate in vitro and in vivo the inhibitory potency of both pesticides, alone and in combination with AChE and butyrylcholinesterase (BChE) activities in sheep blood. In vitro, IC50 values were similar after CPF or CPF plus CPM incubations. The pour-on coadministration of recommended doses of CPF and CPM did not cause a significant inhibition of AChE and BChE in sheep blood. Only slight percentages of inhibition of their catalytic activities were observed when both drugs were given at 4-fold higher dose rates. The lower systemic availability of topical administration of OPs in sheep may help to explain the lower degree of inhibition of blood AChE and BChE in vivo. The results emerged from this research are a further contribution to the knowledge of the risks of implementing higher dosage regimens of OPs-containing antiparasitic formulations., (© 2019 John Wiley & Sons Ltd.)

Background: Experimental pharmacology deals with effects of various test substances studied on different animal species which is aimed at finding out safe therapeutic agent suitable for public health as well as mechanism and site of action of a test substance. It is the basic step in the discovery of new drugs or studying the pharmacological actions of already developed one using both preclinical and clinical study designs in a stepwise phase of investigations. However, the investigations in the first phase of experimental pharmacology are usually concluded with assumption hypothesis without any adequate validation of the scientific evidence. Single dose acute toxicology had been conducted on Balb c mice with three different level of doses prepared from each of three different test chemicals (Dichlorvos, Chlorpyrifos and Cypermethrin) with known median lethal dose (LD 50 ) to define the fundamental principles, cause of toxicity and investigation timeframe in the first phase of experimental pharmacology., Methods: The methods used for data collection were: procurement of test chemicals, investigation of single dose acute toxicity on Balb c mice and quantitative immunoglobulins test. Data was thematically compiled for validation of the findings from each of the sources., Results: The result showed that the dose had never limited the toxic property of tested chemicals but the magnitude of adverse effect and length of time at which adverse effect was manifested on treated Balb c mice. The toxicity of tested chemicals was however limited by the toxic reaction rate of a dose in the biological process of exposed Balb c mice. The toxic effect of tested chemicals became magnified within a short period of time when large amount administered orally. It also remained after a long period of time when small amount administered in the same route., Conclusion: Adequate investigation time for acute toxicity study was therefore essential for comprehensive analysis of pharmacological property of tested chemicals at different level of doses.

Cadmium (Cd) and chlorpyrifos (CPF) often coexist in the environment and induce combined toxicity to organisms. Here we studied the combined nephrotoxicity of environmentally relevant low doses of Cd and CPF. We treated the mice for 90 days with different doses of Cd and CPF and their mixtures via oral gavage. Then histopathological evaluation and biochemical analysis for kidney tissues were carried out. The change of metabolites in kidney was detected by using a metabolomics approach using GC-MS. We found that Cd, CPF, and their mixtures caused oxidative damage as well as disturbance of renal amino acid metabolism. We identified potential metabolite biomarkers in kidney, which included acetic acid for CPF treatment, glycerol and carboxylic acid for Cd treatment, and l-ornithine for the mixture of CPF and Cd treatment, respectively. In addition, we found that Cd promoted the metabolism of CPF in kidney. This may contribute to the result that the toxicity of the mixtures was lower than the sum of the toxicities of Cd and CPF alone. In conclusion, our results indicated that CPF and Cd could disrupt the kidney metabolism in rats even when they were exposed to a very low dose of CPF and Cd.

Three phosphate solubilizing bacteria were isolated and identified by 16S rRNA sequencing as Pseudomonas putida, Pseudomonas sp and Pseudomonas fulva . The strains were subjected to plant biochemical testing and all the PGPR attributes were checked in the presence of pesticides (chlorpyrifos and pyriproxyfen). The phosphate solubilizing index of strain Ros2 was highest in NBRIP medium i.e 2.23 mm. All the strains showed acidic pH (ranges from 2.5-5) on both medium i.e PVK and NBRIP. Strain Ros2 was highly positive for ammonia production as well as siderophore production while strain Rad2 was positive for HCN production. The results obtained by the strains Rad1, Rad2 and Ros2 for auxin production were 33.1, 30.67 and 15.38 µg ml-1, respectively. Strain Rad1 showed 16% increase in percentage germination in comparison to control in the presence of pesticide stress. Most promising results for chlorophyll content estimation were obtained in the presence of carotenoids upto 6 mgg-1 without stress by both strains Rad1 and Rad2. Study suggests that especially strain Ros2 can enhance plant growth parameters in the pesticide stress.

Polyurethane modified with polylactic acid microcapsules were fabricated for controlled release of chlorpyrifos (one of the high usage solid phosphorous insecticides) via interfacial polymerisation with diphenylmethane diisocyanate, polyether triol, 1,4-butanediol and polylactic acid as modifier. The structure, morphology and release properties of synthesised microcapsules were characterised by Fourier transform infra-red spectroscopy, thermogravimetric analyser, scanning electron microscope, particle size analyser and high-performance liquid chromatography. More benign solvents, namely ethyl acetate and n-butyl acetate were used as replacement for toxic solvents commonly used in the preparation of polyurethane microcapsules, namely xylene. The spherical microcapsules prepared in this study were 1-20 μm in diameter. Fourier transform infra-red spectroscopy indicated that polylactic acid had successfully participated in the interfacial polymerisation of polyurethane. Encapsulation efficiency of microcapsules can amount up to 71.0% w/w with a loading efficiency of 26.2% w/w. The microcapsules exhibited a sustained release period above 60 days. Combining polylactic acid into the soft segment of polyurethane proves to effectively accelerate the release rate.

This study evaluated the in vitro effect of three concentrations of atrazine, chlorpyrifos and endosulfan on the growth parameters of four non-toxigenic Aspergillus section Flavi strains. The ability of the strains to remove these pesticides in a synthetic medium was also determined. Growth parameters were measured on soil extract solid medium supplied with 5, 10 and 20mg/l of each pesticide, and conditioned to -0.70, -2.78, -7.06 and -10.0 water potential (MPa). Removal assays were performed in Czapek Doc medium (CZD) supplied with 20mg/l of each pesticide under optimal environmental conditions (-2.78 of MPa and 25°C). The residual levels of each pesticide were detected by the reversed-phase HPLC/fluorescence detection system. The lag phases of the strains significantly decreased in the presence of the pesticides with respect to the control media. This result indicates a fast adaptation to the conditions assayed. Similarly, the mycelial growth rates in the different treatments increased depending on pesticide concentrations. Aspergillus oryzae AM 1 and AM 2 strains showed high percentages of atrazine degradation (above 90%), followed by endosulfan (56 and 76%) and chlorpyrifos (50 and 73%) after 30 days of incubation. A significant (p<0.001) correlation (r=0.974) between removal percentages and growth rate was found. This study shows that non-toxigenic Aspergillus section Flavi strains from agricultural soils are able to effectively grow in the presence of high concentrations of atrazine, chlorpyrifos and endosulfan under a wide range of MPa conditions. Moreover, these strains have the ability to remove high levels of these pesticides in vitro in a short time., (Copyright © 2018 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)

The annual bluegrass weevil, Listronotus maculicollis (Kirby) (Coleoptera: Curculionidae), is the most difficult to control insect pest on golf courses in eastern North America. Insecticide resistance, particularly to pyrethroids, is a serious and expanding issue in its management. Optimal diagnostic tools for resistance detection are crucial for efficient resistance monitoring and mitigation. Developed vial and Petri dish assays clearly separated different resistance levels among weevil populations. With the pyrethroid bifenthrin, susceptible, moderately resistant (resistance ratios, RR50s 12.2-95.7), and highly resistant (RR50s 258.2-1760.9) populations were distinguished. With the organophosphate chlorpyrifos, susceptible, tolerant (RR50s 2.4-6.7), and resistant (RR50s 8.8-120.7) populations were distinguished. In validation assays, several bifenthrin and chlorpyrifos concentrations were needed to separate resistance levels in Petri dish (bifenthrin: 112.2 and 336.3 or 3,362.5 mg AI/m2; chlorpyrifos: 3.4 and 33.6 mg AI/m2) and vial (bifenthrin: 112.1 or 1,120.8 mg AI/m2; chlorpyrifos: 2.2 and 11.2 mg AI/m2) assays. The Petri dish assay with formulated bifenthrin and chlorpyrifos was the best option for L. maculicollis resistance detection and monitoring. It demonstrated sufficient discriminating power, accurately reflected resistance levels, and was easier to conduct. A single diagnostic concentration sufficed to separate susceptible and resistant populations. To determine different resistance or tolerance levels, two to three concentrations were necessary.

Earthworms are important and useful soil organisms, but in agricultural soils, they are potentially exposed to a wide variety of pesticides. Insecticides represent the highest threat to earthworms and many are neurotoxic. There is a need for a reliable, relevant, simple biomarker to assess the sub-lethal effects of neurotoxic insecticides on earthworms under laboratory or field conditions. The Aporrectodea caliginosa earthworms were exposed to 0 (control), 0.5×, 1× (normal field application rate), and 5× concentrations of a carbamate (Pirimor®) and an organophosphate (Lorsban®) insecticides. The nerve conduction velocity (NCV) of the medial giant fibers of A. caliginosa earthworm was recorded on days 0, 1, 2, 3, 4, and 7 to quantify sub-lethal neurotoxic effects. Acetylcholinesterase (AChE) enzyme activity of A. caliginosa homogenates was measured at the conclusion of the experiment. Pirimor® but not Lorsban® induced a significant decrease in NCV on days 3, 4, and 7 at 1× and 5× doses. A significant dose-dependent decrease was observed on AChE activity to Pirimor® at the doses used but not Lorsban®. A clear relationship is observed between AChE activity and NCV in the case of Pirimor®. This study showed that NCV is a sensitive biomarker that correlates well with classical biomarker measurements such as AChE enzyme activity. This technique could be used to study the impact of insecticides on earthworms and also their recovery.

This study examined the effect of chlorpyrifos and/or enrofloxacin on the activity of acetylcholinesterase (AChE) in the blood and brain, and the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum. The experiment was conducted on Wistar strain rats. Chlorpyrifos was administered with a stomach tube at a dose of 0.04 LD50 for 28 days and enrofloxacin at a dose of 5 mg/kg bw for 5 consecutive days. The experiment found that enrofloxacin changed the activity of the enzymes under study only to a small extent. At the dose applied in the experiment, chlorpyrifos decreased the activity of AChE significantly, both in blood and in the brain, and increased the activity of ALT and AST in rat serum. The administration of chlorpyrifos in combination with enrofloxacin changed the activity of the enzymes under study only slightly. A weaker, but longer, inhibition of AChE activity in both blood and the brain was observed in this group compared to the animals exposed only to chlorpyrifos. However, although enrofloxacin, like chlorpyrifos, increases the activity of ALT and AST in serum, their combined administration did not increase the hepatotoxic effect., (Copyright© by the Polish Academy of Sciences.)

In this study, we aimed to study the possible preventive effect of docosahexaenoic acid (DHA), a dietary omega-3 fatty acid, on toxicity caused by chlorpyrifos (CPF). Six groups of Sprague Dawley rats (200-250 g) consisting of equal numbers of males and females (n = 8) were assigned to study. The rats were orally given for 5 days. The control group was administered pure olive oil, which was the vehicle for CPF. The CPF challenge groups were administered oral physiological saline, pure olive oil, or DHA (50, 100 and 400 mg/kg dosages) for 5 days. The animals were weighed on the sixth day and then administered CPF (279 mg/kg, subcutaneously). The rats were weighed again 24 h following CPF administration. The body temperatures and locomotor activities of the rats were also measured. Blood samples, brain and liver tissues were collected for biochemical, histopathological and immunohistochemical examinations. A comparison with the control group demonstrated that CPF administration increased malondialdehyde (MDA) levels in blood, brain and liver, while it reduced catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) concentrations ( p < 0.05-0.001). Advanced oxidation protein products (AOPPs) increased only in the brain ( p < 0.001). DHA reduced these changes in MDA and AOPP values ( p < 0.05-0.001), while it increased CAT, SOD and GPx concentrations ( p < 0.05-0.001). Similarly, DHA prevented the decreases in body weight, body temperature and locomotor activities caused by CPF at 100 mg/kg and 400 mg/kg dosages ( p < 0.05-0.001). Similar to the physiological and biochemical changes, the histopathological damage scores, which increased with CPF ( p < 0.05-0.01), decreased at all three dosages of DHA ( p < 0.05-0.01). Our findings suggest that DHA, by supporting the antioxidant mechanism, reduces toxicity caused by CPF.

The widely used organophosphorus pesticide chlorpyrifos (CPF) is often detected in food. CPF inhibits acetylcholinesterase and can modify muscle contractility and respiratory patterns. We studied the effects of chronic exposure to CPF on respiratory parameters and diaphragm contractility in 21- and 60-days old rats. Pregnant rats were exposed to oral CPF (1 or 5 mg/ kg /day: CPF-1 or CPF-5 groups vs vehicle: controls) from gestation onset up to weaning of the pups that were individually gavaged (CPF or vehicle) thereafter. Two developmental time points were studied: weaning (day 21) and adulthood (day 60). Whole-body plethysmography was used to score breathing patterns and apnea index during sleep. Then, diaphragm strips were dissected for the assessment of contractility and acetylcholinesterase activity. Results showed that the sleep apnea index was higher in CPF-exposed rats than in controls. In adult rats, the expiratory time and tidal volume were higher in CPF-exposed animals than in controls. At both ages, the diaphragm's amplitude of contraction and fatigability index were higher in the CPF-5 group, due to lower acetylcholinesterase activity. We conclude that chronic exposure to CPF is associated with higher sleep apnea index and diaphragm contractility, and modifies respiratory patterns in sleeping juvenile and adult rats.

In this 28 day-study, we evaluated the effects of the insecticide chlorpyrifos orally administered to Wistar rats at doses 0.160, 0.015, and 0.010 mg/kg b. w./day. Following treatment, total cholinesterase activity and activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were measured. Oxidative stress responses were evaluated using a battery of endpoints to establish lipid peroxidation, changes in total antioxidant capacity, level of reactive oxygen species (ROS), glutathione (GSH) level and activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase. Using HPLC-UV DAD analysis, levels of the parent compound and its main metabolite 3,5,6-trichloro-2-pyridinol in plasma and brain tissue were measured. The genotoxic effect was estimated using alkaline comet assay in leukocytes and brain tissue. The exposure did not result in significant effects on total cholinesterase, AChE and BChE activity in plasma and brain tissue. Lipid peroxidation slightly increased both in plasma and brain tissue. Total antioxidant capacity, ROS and GSH levels were marginally influenced by the exposure. Treatment led to significant increases of GSH-Px activity in blood, SOD activity in erythrocytes and a slight increase of catalase activity in plasma. HPLC-UV DAD analysis revealed the presence of both the parent compound and its main metabolite in the plasma of all of the experimental animals and brain tissue of the animals treated at the two higher doses. All of the tested doses of chlorpyrifos were slightly genotoxic, both to leukocytes and brain tissue. Our results call for further research using other sensitive biomarkers of effect, along with different exposure scenarios., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Pest-induced changes in plant reflectance are crucial for the development of pest management programs using remote sensing. However, it is unknown if plant reflectance data is also affected by foliar insecticides applied for pest management. Our study assessed the effects of foliar insecticides on leaf reflectance of soybean. A 2-yr field trial and a greenhouse trial were conducted using randomized complete block and completely randomized designs, respectively. Treatments consisted of an untreated check, a new systemic insecticide (sulfoxaflor), and two representatives of the most common insecticide classes used for soybean pest management in the north-central United States (i.e., λ-cyhalothrin and chlorpyrifos). Insecticides were applied at labeled rates recommended for controlling soybean aphid; the primary insect pest in the north-central United States. Leaf-level reflectance was measured using ground-based spectroradiometers. Sulfoxaflor affected leaf reflectance at some red and blue wavelengths but had no effect at near-infrared or green wavelengths. Chlorpyrifos affected leaf reflectance at some green, red, and near-infrared wavelengths but had no effect at blue wavelengths. λ-cyhalothrin had the least effect on spectral reflectance among the insecticides, with changes to only a few near-infrared wavelengths. Our results showing immediate and delayed effects of foliar insecticides on soybean reflectance indicate that application of some insecticides may confound the use of remote sensing for detection of not only insects but also plant diseases, nutritional and water deficiencies, and other crop stressors., (© The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

To predict a risk to gardeners not wearing protective gloves, the dermal absorption of three active insecticides was assessed in vitro using porcine ear-skin simulating 1-h handling of diluted plant protection products. Acetamiprid and Pirimicarb were found in the receptor fluid immediately after 1-h skin exposure, whereas Chlorpyrifos-methyl absorbed in the skin was not released into the receptor fluid even after 23 hours. The Estimated Gardener Exposure Level (EGEL) at 23 hours after 1-h exposure for two worst-case scenarios (i) non-gloved hands; (ii) non-gloved hands/uncovered forearms, was (i) 0.002, 0.042, and 0.057; (ii) 0.006, 0.101, and 0.135 mg/kg bw/day for Acetamiprid, Pirimicarb, and Chlorpyrifos-methyl, respectively, although the systemically available Chlorpyrifos-methyl amount, due to retention in the skin, is probably lower than determined. The Gardener Exposure Risk (GER), as a ratio of Acceptable Operator Exposure Level (databased values) to EGEL, for Acetamiprid was (i) 35 and 12-fold higher than the limit 1, so the risk via the skin is assumed to be low. Based on the GER values of (i) 0.83 and 0.18; (ii) 0.34 and 0.07 (i.e.<1) for Pirimicarb and Chlorpyrifos-methyl, respectively there is a level of concern regarding the health risk to gardeners handling pesticide products without skin protection., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Acute organophosphorus (OP) intoxication is a worldwide clinical and public health problem. In addition to cholinergic crisis, neurodegeneration and brain damage are hallmarks of the severe form of this toxidrome. Recently, we generated a chemical model of severe acute OP intoxication in zebrafish that is characterized by altered head morphology and brain degeneration. The pathophysiological pathways resulting in brain toxicity in this model are similar to those described in humans. The aim of this study was to assess the predictive power of this zebrafish model by testing the effect of a panel of drugs that provide protection in mammalian models. The selected drugs included "standard therapy" drugs (atropine and pralidoxime), reversible acetylcholinesterase inhibitors (huperzine A, galantamine, physostigmine and pyridostigmine), N-methyl-D-aspartate (NMDA) receptor antagonists (MK-801 and memantine), dual-function NMDA receptor and acetylcholine receptor antagonists (caramiphen and benactyzine) and anti-inflammatory drugs (dexamethasone and ibuprofen). The effects of these drugs on zebrafish survival and the prevalence of abnormal head morphology in the larvae exposed to 4 µM chlorpyrifos oxon [1 × median lethal concentration (LC 50 )] were determined. Moreover, the neuroprotective effects of pralidoxime, memantine, caramiphen and dexamethasone at the gross morphological level were confirmed by histopathological and transcriptional analyses. Our results demonstrated that the zebrafish model for severe acute OP intoxication has a high predictive value and can be used to identify new compounds that provide neuroprotection against severe acute OP intoxication.

The study was aimed at evaluating the protective role of α-lipoic acid (ALA) on long-term exposure of rats to the combination of chlorpyrifos (CPF) and deltamethrin (DLT). Forty-two (42) male Wistar rats were divided into 6 exposure groups with 7 animals in each group: (I) soya oil (2 ml kg -1 ), (II) ALA (60 mg kg -1 ), (III) DLT (6.25 mg kg -1 ), (IV) CPF (4.75 mg kg -1 ), (V) (CPF + DLT) DLT (6.25 mg kg -1 ) and CPF (4.75 mg kg -1 ; 1/20th of the previously determined median lethal dose) and (VI) (ALA + CPF + DLT) pretreated with ALA (60 mg kg -1 ) and then co-exposed to CPF and DLT, 45 min later. The regimens were administered by gavage once daily for a period of 16 weeks. Sera obtained from blood collected at the end of the experimental period were used for the evaluation of serum glucose, total protein, albumin, urea, creatinine and the activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase and acetylcholinesterase. The liver homogenate was used to assay for the activities of superoxide dismutase and glutathione peroxidase and the concentrations of malondialdehyde, cytokine and tumour necrotic factor α. The result showed that the combination of CPF and DLT resulted in marked alterations of these biochemical parameters in most cases compared to either of the pesticides singly, supplementation with ALA ameliorated these alterations.

This study elucidated the acute toxicity of chlorpyrifos on the early life stages of banded gourami (Trichogaster fasciata). To determine the acute effects of chlorpyrifos on their survival and development, we exposedthe embryos and two-day-old larvae to six concentrations (0, 0.01, 0.10, 1.0, 10 and 100 µg L -1 ) of chlorpyrifos in plastic bowls. Log-logistic regression was used to calculate LC10 and LC50 values. Results showed that embryo mortality significantly increased with increasing chlorpyrifos concentrations. The 24-h LC10 and LC50 values (with 95% confidence limits) of chlorpyrifos for embryos were 0.89 (0.50-1.58) and 11.8 (9.12-15.4) µg L -1 , respectively. Hatching success decreased and mortality of larvae significantly increased with increasing concentrations of chlorpyrifos. The 24-h LC10 and LC50 values (with 95% confidence limits) of chlorpyrifos for larvae were 0.53 (0.27-1.06) and 21.7 (15.9-29.4) µg L -1 , respectively; the 48-h LC10 and LC50 for larvae were 0.04 (0.02-0.09) and 5.47 (3.77-7.94) µg L -1 , respectively. The results of this study suggest that 1 µg L -1 of chlorpyrifos in the aquatic environment may adversely affect the development and the reproduction of banded gourami. Our study also suggests that banded gourami fish can serve as an ideal model species for evaluating developmental toxicity of environmental contaminants.

The extensive use of insecticides in public health and agriculture sectors is the main reason for development of resistance in fleas associated in domestic rodents. The present work was planned to investigate the insecticidal efficacy of Lambda-cyhalothrin, Chlorpyrifos and Fenitrothion against rat flea (Xenopsylla cheopis) infesting rodent species in Giza Governorate, Egypt. The lethal concentration Lc₅₀ and Lc₉₀ of population percent were obtained from the established regression log concentrate-response lines. Data indicated that the values of lethal concentration (Lc₅₀) were 0.293, 1.725 & 2.328% for Lambda-cyhalothrin, chlorpyrifos and Fenitrothion, respectively. The values of lethal concentration (Lc₉₀) were 0.467, 2.839 & 5.197% for Lambda-cyhalothrin, chlorpyrifos and Fenitrothion, respectively.

The aim of the study was to determine the level of antioxidant vitamins A and E in the liver of rats exposed to chlorpyrifos and/or enrofloxacin. Chlorpyrifos (Group I) was administered at a dose of 0.04 LD50 (6 mg/kg b.w.) for 28 days, and enrofloxacin (Group II) at a dose of 5 mg/kg b.w. for 5 consecutive days. The animals of group III were given both of the mentioned above compounds at the same manner as groups I and II, but enrofloxacin was applied to rats for the last 5 days of chlorpyrifos exposure (i.e. on day 24, 25, 26, 27 and 28). Chlorpyrifos and enrofloxacin were administered to rats intragastrically via a gastric tube. The quantitative determination of vitamins was made by the HPLC method. The results of this study indicated a reduction in the hepatic concentrations of vitamins A and E, compared to the control, which sustained for the entire period of the experiment. The four-week administration of chlorpyrifos to rats resulted in a significant decrease of vitamins in the initial period of the experiment, i.e. up to 24 hours after exposure. For vitamin A the maximum drop was observed after 24 hours (19.24%) and for vitamin E after 6 hours (23.19%). Enrofloxacin caused a slight (3-9%) reduction in the level of the analysed vitamins. In the chlorpyrifos-enrofloxacin co-exposure group reduced vitamins A and E levels were also noted, but changes in this group were less pronounced in comparison to the animals intoxicated with chlorpyrifos only. The decrease in the antioxidant vitamin levels, particularly noticeable in the chlorpyrifos- and the chlorpyrifos combined with enrofloxacin-treated groups, may result not only from the increase in the concentration of free radicals, but also from the intensification of the secondary stages of lipid peroxidation.

Following their return from deployment, Gulf War (GW) veterans reported widespread joint and muscle pain at rates that far exceeded those of soldiers returning from other conflicts. It is widely believed that exposure to insecticides, repellants and nerve gas prophylactics contributed to the symptoms of Gulf War Illness (GWI), but an animal model of GW pain has been elusive. In our previous work, we observed that 4-8 weeks exposure to pyridostigmine bromide (PB), permethrin and chlorpyrifos could produce persistent alterations in the physiology of Nav1.9 and Kv7 expressed in deep tissue nociceptors of the dorsal root ganglion. However, behavioral assessments from these same rats were not consistent with a delayed pain syndrome similar to that of GWI pain. In the present studies, we intensified the exposure to anticholinesterases PB and chlorpyrifos while retaining the same dosages. Animals receiving the intensified protocol for 30 days exhibited significant increases in resting for about 8 weeks after exposure. Thereafter, all measures were comparable to controls. Animals treated with intensified anticholinesterases for 60 days exhibited increased resting and reduced movement 12 weeks post-exposure. In whole cell patch studies, muscle and vascular nociceptor KDR and Kv7 ion channels exhibited increased amplitude relative to controls (e.g., normalized current and/or peak conductance) at 8 weeks post-exposures; however, at 12 weeks post-exposure, the amplitude of these currents was significantly decreased in muscle nociceptors. In current clamp studies, muscle nociceptors also manifested increased action potential duration, afterhyperpolarization and increased discharge to muscarinic agonists 12 weeks post-exposure. The decline in activity of muscle nociceptor KDR and Kv7 channel proteins was consistent with increased nociceptor excitability and a delayed myalgia in rats exposed to GW chemicals., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Cadmium (Cd) and chlorpyrifos (CPF) are widespread harmful environmental pollutants with neurotoxicity to mammals. Although the exposure to Cd and CPF at the same time may pose a significant risk to human health, the subchronic combined neurotoxicity of these two chemicals at low levels in the brain is poorly understood. In this study, we treated rats with three doses (low, middle, and high) of Cd, CPF, or their mixture for 90 days. No obvious symptom was observed in the treated animals except those treated with high-dose CPF. Histological results showed that middle and high doses of the chemicals caused neuronal cell damage in brains. GC-MS-based metabonomics analysis revealed that energy and amino acid metabolism were disturbed in the brains of rats exposed to the two chemicals and their combinations even at low doses. We further identified the unique brain metabolite biomarkers for rats treated with Cd, CPF, or both. Two amino acids, tyrosine and l-leucine, were identified as the biomarkers for Cd and CPF treatment, respectively. In addition, a set of five unique biomarkers (1,2-propanediol-1-phosphate, d-gluconic acid, 9H-purine, serine, and 2-ketoisovaleric acid) was identified for the mixtures of Cd and CPF. Therefore, the metabolomics analysis is more sensitive than regular clinical observation and pathological examination for detecting the neurotoxicity of the individual and combined Cd and CPF at low levels. Overall, these results identified the unique biomarkers for Cd and CPF exposure, which provide new insights into the mechanism of their joint toxicity.

Our previous in vivo studies showed that chlorpyrifos (CPF) and cypermethrin (CM) in a mixture dermally administered, strongly inhibited cholinesterase activity in plasma and the brain and were very toxic to the rat central nervous system. In this work, the mechanisms of neurotoxicity have not been elucidated. We used human undifferentiated SH-SY5Y cells to study mechanisms of pesticide-induced neuronal cell death. It was found that chlorpyrifos (CPF) and its mixture with cypermethrin (CPF+CM) induced cell death of SH-SY5Y cells in a dose- and time-dependent manner, as shown by MTT assays. Pesticide-induced SH-SY5Y cell death was characterized by concentration-dependent down-regulation of Bcl-2 and Bcl-xL as well as an increase in the caspase 3 activation. Pan-caspase inhibitor Q-VD-OPh produced a slight but significant reversal effect of pesticide-induced toxicity indicating that the major caspase pathways are not integral to CPF- and CPF+CM-induced cell death. Furthermore, signal transduction inhibitors PD98059, SL-327, SB202190, SP600125 and mecamylamine failed to attenuate pesticides effect. Atropine exhibited minimal ability to reverse toxicity. Finally, it was shown that inhibition of TNF-α by pomalidomide attenuated CPF-/CPF+CM-induced apoptosis. Overall, our data suggest that FAS/TNF signalling pathways may participate in CPF and CPF+CM toxicity., (© 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

This study aimed to compare three different methodologies (Adult Immersion Tests, field trials with naturally infected animals, and a Stall Test using artificially infested cattle) to evaluate the efficacy of two topical formulations that we administered as whole body sprays (15% Cypermethrin+30% Chlorpyriphos+15% Fenthion-Colosso(®) FC 30, Ouro Fino Agronegócios; and 60% Dichlorvos+20% Chlorpyriphos-Ectofós(®), Vallée Saúde Animal Ltd.), against a susceptible strain of Rhipicephalus (Boophilus) microplus. To achieve this objective, two natural infestation trials were conducted, as well as two artificial infestation trials (Stall Tests) and two Adult Immersion Tests (AIT). The AIT results showed that both spray formulations achieved 100% efficacy against R. (B.) microplus fully engorged females. However, when observing results obtained by field trials (natural infestations) and Stall Tests, none of these topically applied compounds reached 100% efficacy or affected the reproductive capacity of the fully engorged female ticks. Additional studies must be conducted to compare these in vivo methodologies with different in vitro techniques, such as the Larval Packet Test. However, based on results obtained here, we can conclude that depending on the spray formulations used, the AIT can overestimate acaricidal efficacy and values of reproductive efficiency of such compounds against R (B.) microplus. Specifically, when dealing with spray formulations in the Stall Tests, the period of residual action can increase because these animals are sheltered from contact with environmental factors that might interfere with the efficacy of the products tested. It may be necessary to take in vivo trial results into consideration (such as field trials with naturally infested animals or Stall Tests) to standardize a specific in vitro assay, such as the Adult Immersion Test., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Effects of Haematobia irritans infestation on weight gain of 18 to 20 months old non-castrated Nelore calves, were investigated, under field conditions, using different antiparasitic treatments. Sixty animals were divided in three groups, with 20 bovines each: T01 (untreated control); T02 (treated with Cypermethrin 15 g+Chlorpyriphos 25 g+Citronellal 1 g, as a whole body spray, on days 0, 30, 60, 90 and 120 post-treatment); and T03 (treated on day zero with an ear tag impregnated with Diazinon 6g on the left ear). Counts of H. irritans were conducted on day 30, 60, 90, 120 and 150 post-treatment (DPT). On the same experimental dates, animals were individually weighed, seeking to evaluate the effects of parasitism on the development of animals in each group. From this study it is concluded that T03 had significantly higher efficacy (>90%, till 90 DPT), based on H. irritans fly counts, compared to T02 which showed little or no effect. At the specific conditions of the present study, an average of approximately 90 flies (mean difference of flycounts between groups T01 and T03) was associated with a difference of 20 kg/animal in 150 days., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Chlorpyrifos (CPF) is an organophosphate pesticide. This pesticide induces cognitive impairments, oxidative stress and neuronal damage, which suggests a possible relationship between CPF exposure and Alzheimer's disease. In this study we examined long-term changes in behavior and brain levels of the amyloid beta (Aβ) protein after repeated CPF exposure in a mouse model of Alzheimer's disease. Tg2576 male mice between four and six months of age carrying the human Swedish mutation for Alzheimer's disease were exposed to eight doses of 25 mg/kg of CPF distributed over four weeks. Five months after exposure, general activity was measured in an open-field, while learning and memory were assessed in a Morris water maze task six months after treatment with CPF. Levels of the Aβ fragments (1-40 and 1-42) were also measured in the frontal cortex and hippocampal brain regions. Motor activity was increased in CPF-exposed mice. Although acquisition learning in a water maze task was not affected, retention was worsened in CPF-exposed mice. There were no significant increases of Aβ levels in the brains of CPF-treated mice six months after exposure. These findings raise concerns about the risk of developing neurodegenerative diseases in vulnerable subjects following repeated exposure to CPF., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Chlorpyrifos is a widely used insecticide of organophosphate group, which causes severe toxicological effects in non target aquatic organisms especially in fish. In the present study the genotoxic effects of sublethal concentrations of chlorpyrifos were observed in the erythrocytes and gill cells of Labeo rohita (commonly known as rohu) using the Alkaline Single-Cell Gel Electrophoresis (Comet) assay. Effects of chlorpyrifos on the behavior of the fish were also investigated. The 96 h LC50 value of chlorpyrifos, estimated by Trimmed Spearman-Karber (TSK) in static bioassay, was found to be 442.8 µg/L. On the basis of LC50 value, the fish were exposed to three sublethal concentrations of chlorpyrifos (SL-I ∼221.4 µg/L, SL- II ∼110.7 µg/L and SL-III ∼73.8 µg/L) for 96 h. Blood and gill samples were collected at every 24 h and were subjected to the Comet assay. The observed DNA damage was concentration dependent and time dependent and those levels of DNA damage in between the tested concentrations and times were significantly different (p < 0.01). It was also found that the gill cells are more sensitive to chlorpyrifos, though; it revealed more DNA damage as compared to the erythrocytes of fish. Fish exposed to different concentrations of chlorpyrifos showed different neurotoxic behavioral responses. It was concluded that chlorpyrifos is a genotoxic and neurotoxic insecticide causing DNA damage and neurotoxic effects in Labeo rohita.

The present study assessed the comparative responses on the specific growth rate, nitrogen metabolism and enzymes associated with nitrogen metabolism in two nitrogen fixing cyanobacteria-Nostoc muscorum and Phormidium foveolarum exposed to two UV-B doses (low; UV-BL: 0.5472kJm(-2) and high; UV-BH: 5.472kJm(-2)) and two doses of the insecticide chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate; low i.e. CPL, 1µgml(-1) and high i.e. CPH, 2µgml(-1)) singly and in combination. The specific growth rate, NO3(-) and NO2(-) uptake, nitrate assimilating enzymes - nitrate reductase and nitrite reductase and ammonium assimilating enzymes - glutamine synthetase and glutamate synthase were severely affected when treated either with CPH or/and UV-BH while glutamate dehydrogenase exhibited a stimulatory response. CPL also reduced all the measured parameters (except GDH activity) after 24h, however, a stimulatory effect was observed after 72h due to an increase in nitrogen metabolism (and other antioxidant) enzymes during this period. UV-BL did not cause significant alteration in the studied parameters while in combination with CP doses, it either alleviated the inhibitory effects or further enhanced the CPL induced activities of these enzymes (except GDH). Overall results indicate the resistant nature of P. foveolarum against the inhibitory doses of UV-B and chlorpyrifos in comparison to N. muscorum., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Many veterans of the 1991 Gulf War (GW) returned from that conflict with a widespread chronic pain affecting deep tissues. Recently, we have shown that a 60day exposure to the insecticides permethrin, chlorpyrifos, and pyridostigmine bromide (NTPB) had little influence on nociceptor action potential forming Nav1.8, but increased Kv7 mediated inhibitory currents 8weeks after treatment. Using the same exposure regimen, we used whole cell patch methods to examine whether the influences of NTPB could be observed on Nav1.9 expressed in muscle and vascular nociceptors. During a 60day exposure to NTPB, rats exhibited lowered muscle pain thresholds and increased rest periods, but these measures subsequently returned to normal levels. Eight and 12weeks after treatments ceased, DRG neurons were excised from the sensory ganglia. Whole cell patch studies revealed little change in voltage dependent activation and deactivation of Nav1.9, but significant increases in the amplitude of Nav1.9 were observed 8weeks after exposure. Cellular studies, at the 8week delay, revealed that NTPB also significantly prolonged action potential duration and afterhyperpolarization (22°C). Acute application of permethrin (10μM) also increased the amplitude of Nav1.9 in skin, muscle and vascular nociceptors. In conclusion, chronic exposure to Gulf War agents produced long term changes in the amplitude of Nav1.9 expressed in muscle and vascular nociceptors. The reported increases in Kv7 amplitude may have been an adaptive response to increased Nav1.9, and effectively suppressed behavioral pain measures in the post treatment period. Factors that alter the balance between Nav1.9 and Kv7 could release spontaneous discharge and produce chronic deep tissue pain., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Chlorpyrifos (CPF) is an organophosphate compound that is slowly delivered in the organism after subcutaneous injection, keeping acetylcholinesterase (AChE) activity mildly inhibited for weeks. We have previously reported reduced voluntary ethanol drinking 8 weeks post-CPF administration in Wistar rats when AChE activity was almost completely recovered. Additionally, the OPs disrupt the functioning of certain neurochemical systems and modify the formation and/or degradation of some neuropeptides with a known role in regulating voluntary consumption of alcohol. Moreover, chronic ethanol intake significantly alters the regional expression of some of these neurochemical systems. Thus, the present study explored whether a previous history with ethanol consumption modify the disturbance in the voluntary ethanol consumption induced by CPF administration. For this aim, we measured ethanol consumption in increasing concentrations (8%, 15% and 20% w/v) from 4 days to 8 weeks following a single dose of CPF. Two experiments were carried out; experiment 1 was conducted in ethanol-naïve rats and experiment 2, in animals with a previous history of ethanol drinking before CPF administration. Additionally, food and body weight measures were collected. We report here a significant increase in ethanol consumption and preference at high ethanol concentrations (15% and 20%) in CPF-treated animals with a previous history of ethanol consumption (experiment 1) and a long-lasting increase in food intake both in ethanol-exposed (experiment 1) and ethanol-naïve CPF-treated rats (experiment 2). Present data are discussed under the interesting idea that CPF targets neurobiological pathways critically involved with ethanol consumption. Additionally, we conclude that CPF effects on voluntary ethanol consumption are ethanol-experience dependent.

Background: Current studies have indicated many environmental factors, such as pesticides, that cause immune system disorders through inducing changes in humoral and cellular responses thereby increasing the risk of contracting infectious diseases and cancer. The literature suggests that low exposures to certain organophosphorus pesticides stimulate the immune system, whilst high exposures result in decreased function. Precise mechanisms for the fall in immunocompetence are often unclear, however it can be predicted that the intimate interaction between the nervous and immune systems can potentially lead to toxicity., Objectives: To determine the effects of organophosphorus pesticide, chlorpyrifos that is often used in Poland, on selected immunological responses, such as immune-competent cell proportions formed experimentally in-vivo by cells of Wistar rats during subchronic exposures after 45 and 90 days., Materials and Methods: The test was carried out on ten male and ten female Wistar rats in each of three test groups, who received 3 chlorpyrifos doses for 90 days intragastrically, according to OECD guidelines (No. 401). Two control groups were given olive oil. After completion, the animals were deeply anaesthetised by a mixture of ketamine (Vetaketam) and xylazine (Vetaxym). Immuno-competent cells were profiled by a commercial monoclonal antibody method. In order to measure the dynamics of any changes, the aforementioned immunological responses were investigated after 45 days using the same procedures for obtaining the relevant biological test material., Results: Test animals exposed to chlorpyrifos had altered number of white bood cells which were either increased or decreased relative to controls after 45 and 90 days for all exposure levels used., Conclusions: The study demonstrated changes in white-blood cell (lymphocyte) response profiles, reflecting an immunomodulation although such changes were equivocal, where both suppression and stimulation were observed., Key Words: immunomodulation, immune system, lymphocyte, organophosphorus pesticides, chlorpyrifos.

Chlorpyrifos (CPF) is an organophosphate (OP) insecticide extensively used in agricultural and domestic settings. Healthy adult female albino rats were divided into three groups of six rats in each. Two groups were dosed orally with CPF in vegetable oil (0.1 and 2.5 mg/kg/day) and third group was given vegetable oil for 8 weeks. Non-significant changes were observed for body weight and feed intake. A disruption in estrous cyclicity was observed with a prolonged metestrous. Erythrocyte osmotic fragility and lipid peroxidation levels increased significantly. Mammary gland whole mounts revealed a significant (P<0.05-0.0001) increase in the ductal thickness, number of branches, alveolar and terminal end bud number and terminal end bud diameter. A significant increase in ovarian surface epithelium height, follicular diameter and follicular atresia was observed in treated rats (P<0.05-0.0001). A similar significant increase in the uterine surface epithelium height, endometrial gland epithelium height and myometrium thickness in higher dose group was recorded (P<0.05-0.0001). Luminal epithelium height and endometrial gland diameter was increased significantly in both the treated groups (P<0.05-0.0001). The results indicate that sub-chronic exposure of CPF causes oxidative stress and negative effects on the reproductive organs of female rats, which may be a pointer towards beginning of cancer incidence., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Chlorpyrifos (CPF) is an organophosphate (OP) insecticide that is metabolically activated to the highly toxic chlorpyrifos oxon. Dietary exposure is the main route of intoxication for non-occupational exposures. However, only limited behavioral effects of chronic dietary exposure have been investigated. Therefore, male Wistar rats were fed a dose of 5mg/kg/day of CPF for thirty-one weeks. Animals were evaluated in spatial learning and impulsivity tasks after 21 weeks of CPF dietary exposure and one week after exposure ended, respectively. In addition, the degree of inhibition of brain acetylcholinesterase (AChE) was evaluated for both the soluble and particulate forms of the enzyme, as well as AChE gene expression. Also, brain acylpeptide hydrolase (APH) was investigated as an alternative target for OP-mediated effects. All variables were evaluated at various time points in response to CPF diet and after exposure ended. Results from behavioral procedures suggest cognitive and emotional disorders. Moreover, low levels of activity representing membrane-bound oligomeric forms (tetramers) were also observed. In addition, increased brain AChE-R mRNA levels were detected after four weeks of CPF dietary exposure. However, no changes in levels of brain APH were observed among groups. In conclusion, our data point to a relationship between cognitive impairments and changes in AChE forms, specifically to a high inhibition of the particulate form and a modification of alternative splicing of mRNA during CPF dietary exposure., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Organophosphates (OPs) are important toxic compounds commonly used for a variety of purposes in agriculture, industry and household settings. It has been well established that the main mechanism of acute toxic action of OP is the inhibition of acetylcholinesterase (AChE). However, we observed long term deficit after acute subcutaneous exposure to Chlorpyrifos (CPF) even when AChE activity is restored. In fact, besides AChE inhibition, non-AChE targets have also been proposed as an alternative mechanism involved in the acute lethal action and side effects of short or long-term exposure. In this context, our main aim in this research was to establish a dose-response curve of Acylpeptide hydrolase (APH) and AChE regional brain activity after acute CPF administration that could explain these long term effects observed in the literature. Moreover, since available data suggest that long term effects of OPs exposure could involve neuronal cell death, our second aim was to evaluate, assessing by Fluoro-Jade B (FJB) staining, whether CPF produces induced cell death. Our results show that an acute exposure to 250 mg/kg CPF does not induce neuronal death as measured by FJB but produces highest AChE regional brain inhibition after administration. In addition, APH seems to be more sensitive than AChE to CPF exposure because after 31 days of exposure, complete recovery was seen only for APH activity at Frontal Cortex, Cerebellum and Brain Stem.

Environmental factors are likely to interact with genetic determinants to influence prostate cancer progression. The Agricultural Health Study has identified an association between exposure to organophosphorous pesticides including chlorpyrifos, and increased prostate cancer risk in pesticide applicators with a first-degree family history of this disease. Exploration of this potential gene-environment interaction would benefit from the development of a suitable animal model. Utilizing a previously described mouse model that is genetically predisposed to prostate cancer through a prostate-specific heterozygous PTEN deletion, termed C57/Luc/Ptenp+/-, we used bioluminescence imaging and histopathological analyses to test whether chronic exposure to chlorpyrifos in a grain-based diet for 32 weeks was able to promote prostate cancer development. Chronic exposure to chlorpyrifos in the diet did not promote prostate cancer development in C57/Luc/Ptenp+/- mice despite achieving sufficient levels to inhibit acetylcholinesterase activity in plasma. We found no significant differences in numbers of murine prostatic intraepithelial neoplasia lesions or disease progression in chlorpyrifos versus control treated animals up to 32 weeks. The mechanistic basis of pesticide-induced prostate cancer may be complex and may involve other genetic variants, multiple genes, or nongenetic factors that might alter prostate cancer risk during pesticide exposure in agricultural workers.

This study investigated the effect of chlorpyrifos on thoracic aorta and on the level of NO in plasma and aorta. The effect of chlorpyrifos on thoracic aorta in organ bath was determined in 10 rats. Another 45 rats were assigned to 3 groups with 15 rats each: control group 1 received distilled water, control group 2 was given corn oil, and the last group was given 13.5 mg/kg chlorpyrifos dissolved in corn oil every other day for 8 weeks orally. Chlorpyrifos (10(-10) M-10(-5) M) showed no effect on isolated thoracic aorta. Plasma AChE activity was decreased, while LDH, ALT, GGT, and AST activities were increased in chlorpyrifos group compared to control groups. Plasma NO level was increased in chlorpyrifos group compared to control groups. iNOS expression was present in all groups in the cytoplasm of the endothelia and in the smooth muscle cells of aorta. According to semiquantitative histomorphological analysis, iNOS immunopositive reactions were seen in the decreasing order in chlorpyrifos, control 2, and control 1 groups. eNOS immunopositive reactions were observed in the endothelial cell cytoplasm, rarely in the subintimal layer, and the smooth muscle cells of aorta. There were no differences among the groups in terms of eNOS immunostaining. In conclusion, chlorpyrifos induced NO production in aorta following an increase in NOS expression.

Sensors have been developed for noninvasive biomonitoring of the organophosphate pesticide chlorpyrifos (CPF), and previous studies have suggested consistent partitioning of 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of CPF, into saliva after exposure to TCPy. The objective of this study was to quantitatively evaluate in vivo pharmacokinetics and pharmacodynamics of CPF and TCPy in saliva after CPF administration. Rats were coadministered CPF (0.5-5mg/kg) and pilocarpine (~13 mg/kg) iv. Saliva and blood were collected, and levels of CPF, TCPy, and cholinesterase (ChE) activity were quantified. Experimental results suggest that CPF is rapidly metabolized after iv administration. Formation of TCPy from administered CPF at the low dose (0.5 mg/kg) was slower than from higher CPF doses, potentially due to differences in plasma protein binding to CPF. CPF was measured in saliva only at the first time point sampled (0-15 min), indicating low partitioning and rapid metabolism. After formation, TCPy pharmacokinetics were very similar in blood and saliva. Saliva/blood TCPy concentration ratios were not affected by TCPy concentration in blood, saliva flow rate, or salivary pH and were consistent with previous studies. ChE activity in plasma demonstrated a dose-dependent decrease, and ChE activity in saliva was extremely variable and demonstrated no dose relationship. A physiologically based pharmacokinetic and pharmacodynamic model for CPF was modified and predicted the data reasonably well. It is envisioned that a combination of biomonitoring compounds like TCPy in saliva coupled with computational modeling will form an approach to measure pesticide exposure to susceptible human populations such as agricultural workers.

The genotoxic and mutagenic effects of two commonly used organochlorine pesticides, lindane (LND) and endosulfan (ENS), and two commonly used organophosphate pesticides, chlorpyrifos (CPF) and monocrotophos (MCP) were assessed using in vivo mouse bone marrow micronucleus test and in vitro Ames Salmonella/ microsome mutagenicity test. The results showed that these pesticides alone or in combination, induced significantly high frequency of micronuclei (MN) formation that increased with concentration of pesticides. All these four pesticides produced significant increase in the frequencies of micronucleated-polychromatic erythrocytes (MN-PCE) and decrease infrequencies of PCE in dose-dependent manner. The results indicate the suppression of proliferative activity of the bone marrow and increase in the extent of cell death. ENS and MCP showed mutagenic potential in Salmonella/ microsome assay. ENS induced mutagenic and nontoxic response only in TA98 tester strain of S.typhimurium at the dose of 500 μg/plate and in the absence of metabolic activation. MCP showed weak mutagenic and nontoxic effect only in TA100 tester strain at the dose of 5000 μg/plate in both assays, with or without metabolic activation when compared with negative control. MCP was toxic in TA98 tester strain at the dose of 5000 μg/plate in absence of metabolic activation while reduction in toxicity was seen on addition of S9 mixture. The study clearly showed the genotoxic potential of all these four pesticides and mutagenic response of endosulfan and monocrotophos.