A review of experimental evidence linking neurotoxic organophosphorus compounds and inflammation

The association of isocarbophos and isofenphos with different types of glucose metabolism: The role of inflammatory cells

To investigate the associations between isocarbophos and isofenphos with impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM), and to assess the mediation roles of inflammation cells. There were 2701 participants in the case-control study, including 896 patients with T2DM, 900 patients with IFG, 905 subjects with NGT. Plasma isocarbophos and isofenphos concentrations were measured using gas chromatography and triple quadrupole tandem mass spectrometry. Generalized linear models were used to calculate the relationships between plasma isofenphos and isocarbophos levels with inflammatory factor levels and T2DM. Inflammatory cell was used as mediators to estimate the mediating effects on the above associations. Isocarbophos and isofenphos were positively related with T2DM after adjusting for other factors. The odds ratio (95% confidence interval) (OR (95%CI)) for T2DM was 1.041 (1.015, 1.068) and for IFG was 1.066 (1.009, 1.127) per unit rise in ln-isocarbophos. The prevalence of T2DM increased by 6.4% for every 1 unit more of ln-isofenphos (OR (95% CI): 1.064 (1.041, 1.087)). Additionally, a 100% rise in ln-isocarbophos was linked to 3.3% higher ln-HOMA2IR and a 0.029 mmol/L higher glycosylated hemoglobin (HbA1c) (95% CI: 0.007, 0.051). While a 100% rise in ln-isofenphos was linked to increase in ln-HOMA2 and ln-HOMA2IR of 5.8% and 3.4%, respectively. Furthermore, white blood cell (WBC) and neutrophilic (NE) were found to be mediators in the relationship between isocarbophos and T2DM, and the corresponding proportions were 17.12% and 17.67%, respectively. Isofenphos and isocarbophos are associated with IFG and T2DM in the rural Chinese population, WBC and NE have a significant role in this relationship.

Exposure to agricultural pesticides and wheezing among 5-12-year-old children in the Imperial Valley, CA, USA

Background

Exposure to pesticides has been linked to adverse respiratory health outcomes in children.

Methods

We leveraged the Children's Assessing Imperial Valley Respiratory Health and the Environment cohort located in the rural community of Imperial Valley near the US-Mexico border. We calculated the kilograms of total pesticides applied within 400 m of children's residential addresses for the years 2016-2020. Estimated pesticide usage near homes was categorized into three groups (none vs. low vs. high [split at the median]). All health variables (i.e., asthma status and wheezing) were derived from a parent-reported questionnaire on respiratory health. We used generalized linear models, controlling for child sex, the language of survey, health insurance, respondents' highest education, and exposure to environmental secondhand smoking, to calculate prevalence differences between none versus low and high exposure to agricultural pesticides.

Results

Approximately 62% of the 708 children (aged 5-12 years) lived within 400 m of at least one pesticide application within 12 months prior to survey administration. Exposure to pesticides within 400 m of children's residences was associated with 12-month prior wheeze. Those in the "high" exposure group had a prevalence of wheezing that was 10 (95% confidence interval: 2%, 17%) percentage points higher than among children not exposed to pesticide applications. Associations for high exposure to specific categories of pesticide applications, sulfur only, all pesticides except sulfur, chlorpyrifos, and glyphosate, also were observed with a higher prevalence of wheezing than among children not exposed to pesticide applications.

Conclusions

We observed associations between living near pesticide applications and more wheeze symptoms among children.

Biphasic response of human iPSC-derived neural network activity following exposure to a sarin-surrogate nerve agent

Organophosphorus nerve agents (OPNA) are hazardous environmental exposures to the civilian population and have been historically weaponized as chemical warfare agents (CWA). OPNA exposure can lead to several neurological, sensory, and motor symptoms that can manifest into chronic neurological illnesses later in life. There is still a large need for technological advancement to better understand changes in brain function following OPNA exposure. The human-relevant in vitro multi-electrode array (MEA) system, which combines the MEA technology with human stem cell technology, has the potential to monitor the acute, sub-chronic, and chronic consequences of OPNA exposure on brain activity. However, the application of this system to assess OPNA hazards and risks to human brain function remains to be investigated. In a concentration-response study, we have employed a human-relevant MEA system to monitor and detect changes in the electrical activity of engineered neural networks to increasing concentrations of the sarin surrogate 4-nitrophenyl isopropyl methylphosphonate (NIMP). We report a biphasic response in the spiking (but not bursting) activity of neurons exposed to low (i.e., 0.4 and 4 μM) versus high concentrations (i.e., 40 and 100 μM) of NIMP, which was monitored during the exposure period and up to 6 days post-exposure. Regardless of the NIMP concentration, at a network level, communication or coordination of neuronal activity decreased as early as 60 min and persisted at 24 h of NIMP exposure. Once NIMP was removed, coordinated activity was no different than control (0 μM of NIMP). Interestingly, only in the high concentration of NIMP did coordination of activity at a network level begin to decrease again at 2 days post-exposure and persisted on day 6 post-exposure. Notably, cell viability was not affected during or after NIMP exposure. Also, while the catalytic activity of AChE decreased during NIMP exposure, its activity recovered once NIMP was removed. Gene expression analysis suggests that human iPSC-derived neurons and primary human astrocytes resulted in altered genes related to the cell's interaction with the extracellular environment, its intracellular calcium signaling pathways, and inflammation, which could have contributed to how neurons communicated at a network level.

N-methyl-d-aspartate receptors: Structure, function, and role in organophosphorus compound poisoning

Acute organophosphorus compound (OP) poisoning induces symptoms of the cholinergic crises with the occurrence of severe epileptic seizures. Seizures are induced by hyperstimulation of the cholinergic system, but are enhanced by hyperactivation of the glutamatergic system. Overstimulation of muscarinic cholinergic receptors by the elevated acetylcholine causes glutamatergic hyperexcitation and an increased influx of Ca2+ into neurons through a type of ionotropic glutamate receptors, N-methyl-d-aspartate (NMDA) receptors (NMDAR). These excitotoxic signaling processes generate reactive oxygen species, oxidative stress, and activation of the neuroinflammatory response, which can lead to recurrent epileptic seizures, neuronal cell death, and long-term neurological damage. In this review, we illustrate the NMDAR structure, complexity of subunit composition, and the various receptor properties that change accordingly. Although NMDARs are in normal physiological conditions important for controlling synaptic plasticity and mediating learning and memory functions, we elaborate the detrimental role NMDARs play in neurotoxicity of OPs and focus on the central role NMDAR inhibition plays in suppressing neurotoxicity and modulating the inflammatory response. The limited efficacy of current medical therapies for OP poisoning concerning the development of pharmacoresistance and mitigating proinflammatory response highlights the importance of NMDAR inhibitors in preventing neurotoxic processes and points to new avenues for exploring therapeutics for OP poisoning.

Degranulation and expression of cytokines were modulated by diazinon in activated mast cells

Diazinon is an organophosphorus (OP) insecticides used in agriculture, home gardening and indoor pest control in Japan. It can activate macrophages and induce pro-inflammatory responses and has been reported to cause airway hyper-reactivity, suggesting the possibility of asthma exacerbation from exposure to OP insecticides. Despite the correlation between insecticide use and the pathogenesis of allergic diseases, there have been no reports on the effects of diazinon on mast cell function. Therefore, in this study, we investigated the effects of diazinon on mast cell function in rat basophilic leukemia (RBL)-2H3 cells. Surprisingly, we found that diazinon inhibited mast cell activation, although the degree of inhibition varied with concentration. Diazinon induced reactive oxygen species (ROS) generation and HO-1 expression at a concentration of 150 µM without affecting cell viability. Diazinon inhibited A23187-mediated degranulation and Tnf and Il4 expression in RBL-2H3 cells but did not affect calcium influx. Suppression of degranulation by diazinon was reversed when the culture supernatant was removed. As a signaling event downstream of calcium influx, diazinon inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) induced by A23187, whereas the phosphorylation of p38 had little effect. IgE cross-linking-mediated degranulation as well as the induction of Tnf and IL4 expression was significantly inhibited by diazinon, while diazinon had little effect on calcium influx. In conclusion, diazinon inhibited mast cell activation, including degranulation and cytokine expression. When evaluating the in vivo effects of diazinon, its potential to inhibit mast cell activation should be considered in the pathophysiology and development of allergic diseases in terms of basic and clinical aspects, respectively, although the effect of diazinon varies depending on the cell type.

Association between organophosphorus insecticides exposure and osteoarthritis in patients with arteriosclerotic cardiovascular disease

BACKGROUND

Organic phosphorus insecticides (OPPs) are a class of environmental pollutants widely used worldwide with potential human health risks. We aimed to assess the association between exposure to OPPs and osteoarthritis (OA) particularly in participants with atherosclerotic cardiovascular disease (ASCVD).

METHODS

Participants' information was obtained from data in the National Health and Nutrition Examination (NHANES). Weighted logistic regression models were utilized to detect associations between OPPs metabolites and OA. Restricted cubic spline plots (RCS) were drawn to visualize the dose-response relationship between each metabolite and OA prevalence. Weighted quantile sum (WQS) regression and Bayesian kernel-machine regression (BKMR), were applied to investigate the joint effect of mixtures of OPPs on OA.

RESULTS

A total of 6871 samples were included in our study, no significant associations between OPPs exposure and OA incidence were found in whole population. However, in a subset of 475 individuals with ASCVD, significant associations between DMP (odds ratio [OR] as a continuous variable = 1.22, 95% confidence interval [CI]: 1.07,1.28), DEP ((odds ratio [OR] of the highest tertile compared to the lowest = 2.43, 95% confidence interval [CI]: 1.21,4.86), and OA were observed. DMP and DEP showed an increasing dose-response relationship to the prevalence of OA, while DMTP, DETP, DMDTP and DEDTP showed a nonlinear relationship. Multi-contamination modeling revealed a 1.34-fold (95% confidence intervals:0.80, 2.26) higher prevalence of OA in participants with high co-exposure to OPPs compared to those with low co-exposure, with a preponderant weighting (0.87) for the dimethyl dialkyl phosphate metabolites (DMAPs). The BKMR also showed that co-exposure of mixed OPPs was associated with an increased prevalence of OA, with DMP showing a significant dose-response relationship.

CONCLUSION

High levels of urine dialkyl phosphate metabolites (DAP) of multiple OPPs are associated with an increased prevalence of OA in patients with ASCVD, suggesting the need to prevent exposure to OPPs in ASCVD patients to avoid triggering OA and further avoid the occurrence of cardiovascular events caused by OA.

Coupling Peptide-Based Encapsulation of Enzymes with Bacteria for Paraoxon Bioremediation

The catalytic efficiency of enzymes can be harnessed as an environmentally friendly solution for decontaminating various xenobiotics and toxins. However, for some xenobiotics, several enzymatic steps are needed to obtain nontoxic products. Another challenge is the low durability and stability of many native enzymes in their purified form. Herein, we coupled peptide-based encapsulation of bacterial phosphotriesterase with soil-originated bacteria, Arthrobacter sp. 4Hβ as an efficient system capable of biodegradation of paraoxon, a neurotoxin pesticide. Specifically, recombinantly expressed and purified methyl parathion hydrolase (MPH), with high hydrolytic activity toward paraoxon, was encapsulated within peptide nanofibrils, resulting in increased shelf life and retaining ∼50% activity after 132 days since purification. Next, the addition of Arthrobacter sp. 4Hβ, capable of degrading para-nitrophenol (PNP), the hydrolysis product of paraoxon, which is still toxic, resulted in nondetectable levels of PNP. These results present an efficient one-pot system that can be further developed as an environmentally friendly solution, coupling purified enzymes and native bacteria, for pesticide bioremediation. We further suggest that this system can be tailored for different xenobiotics by encapsulating the rate-limiting key enzymes followed by their combination with environmental bacteria that can use the enzymatic step products for full degradation without the need to engineer synthetic bacteria.

A longitudinal MRI and TSPO PET-based investigation of brain region-specific neuroprotection by diazepam versus midazolam following organophosphate-induced seizures

Acute poisoning with organophosphorus cholinesterase inhibitors (OPs), such as OP nerve agents and pesticides, can cause life threatening cholinergic crisis and status epilepticus (SE). Survivors often experience significant morbidity, including brain injury, acquired epilepsy, and cognitive deficits. Current medical countermeasures for acute OP poisoning include a benzodiazepine to mitigate seizures. Diazepam was long the benzodiazepine included in autoinjectors used to treat OP-induced seizures, but it is now being replaced in many guidelines by midazolam, which terminates seizures more quickly, particularly when administered intramuscularly. While a direct correlation between seizure duration and the extent of brain injury has been widely reported, there are limited data comparing the neuroprotective efficacy of diazepam versus midazolam following acute OP intoxication. To address this data gap, we used non-invasive imaging techniques to longitudinally quantify neuropathology in a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP) with and without post-exposure intervention with diazepam or midazolam. Magnetic resonance imaging (MRI) was used to monitor neuropathology and brain atrophy, while positron emission tomography (PET) with a radiotracer targeting translocator protein (TSPO) was utilized to assess neuroinflammation. Animals were scanned at 3, 7, 28, 65, 91, and 168 days post-DFP and imaging metrics were quantitated for the hippocampus, amygdala, piriform cortex, thalamus, cerebral cortex and lateral ventricles. In the DFP-intoxicated rat, neuroinflammation persisted for the duration of the study coincident with progressive atrophy and ongoing tissue remodeling. Benzodiazepines attenuated neuropathology in a region-dependent manner, but neither benzodiazepine was effective in attenuating long-term neuroinflammation as detected by TSPO PET. Diffusion MRI and TSPO PET metrics were highly correlated with seizure severity, and early MRI and PET metrics were positively correlated with long-term brain atrophy. Collectively, these results suggest that anti-seizure therapy alone is insufficient to prevent long-lasting neuroinflammation and tissue remodeling.

Quantitative T2 mapping-based longitudinal assessment of brain injury and therapeutic rescue in the rat following acute organophosphate intoxication

Acute intoxication with organophosphate (OP) cholinesterase inhibitors poses a significant public health risk. While currently approved medical countermeasures can improve survival rates, they often fail to prevent chronic neurological damage. Therefore, there is need to develop effective therapies and quantitative metrics for assessing OP-induced brain injury and its rescue by these therapies. In this study we used a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP), to test the hypothesis that T2 measures obtained from brain magnetic resonance imaging (MRI) scans provide quantitative metrics of brain injury and therapeutic efficacy. Adult male Sprague Dawley rats were imaged on a 7T MRI scanner at 3, 7 and 28 days post-exposure to DFP or vehicle (VEH) with or without treatment with the standard of care antiseizure drug, midazolam (MDZ); a novel antiseizure medication, allopregnanolone (ALLO); or combination therapy with MDZ and ALLO (DUO). Our results show that mean T2 values in DFP-exposed animals were: (1) higher than VEH in all volumes of interest (VOIs) at day 3; (2) decreased with time; and (3) decreased in the thalamus at day 28. Treatment with ALLO or DUO, but not MDZ alone, significantly decreased mean T2 values relative to untreated DFP animals in the piriform cortex at day 3. On day 28, the DUO group showed the most favorable T2 characteristics. This study supports the utility of T2 mapping for longitudinally monitoring brain injury and highlights the therapeutic potential of ALLO as an adjunct therapy to mitigate chronic morbidity associated with acute OP intoxication.

Recent advances in cholinergic mechanisms as reactions to toxicity, stress, and neuroimmune insults

This review presents recent studies of the chemical and molecular regulators of acetylcholine (ACh) signaling and the complexity of the small molecule and RNA regulators of those mechanisms that control cholinergic functioning in health and disease. The underlying structural, neurochemical, and transcriptomic concepts, including basic and translational research and clinical studies, shed new light on how these processes inter-change under acute states, age, sex, and COVID-19 infection; all of which modulate ACh-mediated processes and inflammation in women and men and under diverse stresses. The aspect of organophosphorus (OP) compound toxicity is discussed based on the view that despite numerous studies, acetylcholinesterase (AChE) is still a vulnerable target in OP poisoning because of a lack of efficient treatment and the limitations of oxime-assisted reactivation of inhibited AChE. The over-arching purpose of this review is thus to discuss mechanisms of cholinergic signaling dysfunction caused by OP pesticides, OP nerve agents, and anti-cholinergic medications; and to highlight new therapeutic strategies to combat both the acute and chronic effects of these chemicals on the cholinergic and neuroimmune systems. Furthermore, OP toxicity was examined in view of cholinesterase inhibition and beyond in order to highlight improved small molecules and RNA therapeutic strategies and assess their predicted pitfalls to reverse the acute toxicity and long-term deleterious effects of OPs.

Investigating the prevalence of erectile dysfunction among men exposed to organophosphate insecticides

INTRODUCTION

Erectile dysfunction (ED) poses a significant disease morbidity and contributor to male infertility, where an estimated 20-40% of men are affected annually. While several risk factors have been identified in the etiology of ED (e.g., aging, heart disease, diabetes, and obesity), the complete pathogenesis remains to be elucidated. Over the last few decades, the contribution of environmental exposures to the pathogenesis of ED has gained some attention, though population studies are limited and results are mixed. Among environmental contaminants, organophosphate (OP) insecticides represent one of the largest chemical classes, and chlorpyrifos is the most commonly used OP in the U.S. OP exposure has been implicated in driving biological processes, including inflammation, reactive oxygen species production, and endocrine and metabolism disruption, which have been demonstrated to adversely affect the hypothalamus and testes and may contribute to ED. Currently, studies evaluating the association between OPs and ED within the U.S. general population are sparse.

METHODS

Data were leveraged from the National Health and Nutrition Examination Survey (NHANES), which is an annually conducted, population-based cross-sectional study. Urinary levels of 3,5,6-trichloro-2-pyridinol (TCPy), a specific metabolite of the most pervasive OP insecticide chlorpyrifos, were quantified as measures of OP exposure. ED was defined by responses to questionnaire data, where individuals who replied "sometimes able" or "never able" to achieve an erection were classified as ED. Chi-square, analysis of variance (ANOVA), and multivariable, weighted linear and logistic regression analyses were used to compare sociodemographic variables between quartiles of TCPy exposure, identify risk factors for TCPy exposure and ED, and to analyze the relationship between TCPy and ED.

RESULTS

A total of 671 adult men were included in final analyses, representing 28,949,379 adults after survey weighting. Approximately 37% of our cohort had ED. Smoking, diabetes, aging, Mexican-American self-identification, and physical inactivity were associated with higher ED prevalence. Analysis of TCPy modeled as a continuous variable revealed nonsignificant associations with ED (OR = 1.02 95% CI [0.95, 1.09]). Stratification of total TCPy into quartiles revealed increased odds of ED among adults in the second and fourth quartiles, using the first quartile as the reference (OR = 2.04 95% CI [1.11, 3.72], OR = 1.51 95% CI [0.58, 3.93], OR = 2.62 95% CI [1.18, 5.79], for quartiles 2, 3, and 4, respectively).

CONCLUSIONS

The results of our study suggest a potential role for chlorpyrifos and other OPs the pathogenesis of ED. Future studies are warranted to validate these findings, determine clinical significance, and to investigate potential mechanisms underlying these associations.

Neurosteroids as Novel Anticonvulsants for Refractory Status Epilepticus and Medical Countermeasures for Nerve Agents: A 15-Year Journey to Bring Ganaxolone from Bench to Clinic

This article describes recent advances in the use of neurosteroids as novel anticonvulsants for refractory status epilepticus (RSE) and as medical countermeasures (MCs) for organophosphates and chemical nerve agents (OPNAs). We highlight a comprehensive 15-year journey to bring the synthetic neurosteroid ganaxolone (GX) from bench to clinic. RSE, including when caused by nerve agents, is associated with devastating morbidity and permanent long-term neurologic dysfunction. Although recent approval of benzodiazepines such as intranasal midazolam and intranasal midazolam offers improved control of acute seizures, novel anticonvulsants are needed to suppress RSE and improve neurologic function outcomes. Currently, few anticonvulsant MCs exist for victims of OPNA exposure and RSE. Standard-of-care MCs for postexposure treatment include benzodiazepines, which do not effectively prevent or mitigate seizures resulting from nerve agent intoxication, leaving an urgent unmet medical need for new anticonvulsants for RSE. Recently, we pioneered neurosteroids as next-generation anticonvulsants that are superior to benzodiazepines for treatment of OPNA intoxication and RSE. Because GX and related neurosteroids that activate extrasynaptic GABA-A receptors rapidly control seizures and offer robust neuroprotection by reducing neuronal damage and neuroinflammation, they effectively improve neurologic outcomes after acute OPNA exposure and RSE. GX has been selected for advanced, Biomedical Advanced Research and Development Authority-supported phase 3 trials of RSE and nerve agent seizures. In addition, in mechanistic studies of neurosteroids at extrasynaptic receptors, we identified novel synthetic analogs with features that are superior to GX for current medical needs. Development of new MCs for RSE is complex, tedious, and uncertain due to scientific and regulatory challenges. Thus, further research will be critical to fill key gaps in evaluating RSE and anticonvulsants in vulnerable (pediatric and geriatric) populations and military persons. SIGNIFICANCE STATEMENT: Following organophosphate and nerve agent intoxication, refractory status epilepticus (RSE) occurs despite benzodiazepine treatment. RSE occurs in 40% of status epilepticus patients, with a 35% mortality rate and significant neurological morbidity in survivors. To treat RSE, neurosteroids are better anticonvulsants than benzodiazepines. Our pioneering use of neurosteroids for RSE and nerve agents led us to develop ganaxolone as a novel anticonvulsant and neuroprotectant with significantly improved neurological outcomes. This article describes the bench-to-bedside journey of bringing neurosteroid therapy to patients, with ganaxolone leading the way.

Amelioration of acetic acid-induced ulcerative colitis in rats by cetirizine and loratadine via regulation of the PI3K/Akt/Nrf2 signalling pathway and pro-inflammatory cytokine release

Objectives

Ulcerative colitis is a chronic inflammatory bowel disease (IBD) that causes inflammation and ulcers in the rectum and the innermost layer of the large intestine. Our study aimed to elucidate the ameliorative effect of cetirizine (CTZ) and loratadine (LOR) against acetic acid-induced ulcerative colitis in rats via assessment of the PI3K/p-Akt/Nrf2 signaling pathway and proinflammatory cytokine release.

Materials and Methods

Thirty-two rats were allocated into four groups (n=8). Group (I) was considered normal control. Acetic acid (AA) was injected intrarectally in groups (2-4). Group (2) was kept untreated. Group (3) was administered CTZ (20 mg/kg/day) for 7 days. Group (4) was administered LOR (10 mg/kg/day) for 7 days.

Results

AA showed severe macroscopic colonic lesions associated with increased ulcer number, area, and severity with significantly elevated PI3K, p-Akt, Nrf2, TNF-α, and IL-6 in colorectal tissue as compared to the normal control group. All the aforementioned indicators were greatly improved by CTZ and LOR therapy.

Conclusion

This is the first study to elucidate the ameliorative effect of CTZ and LOR against AA-induced UC in rats. CTZ and LOR treatment mitigates UC via amelioration of the PI3K/p-Akt/Nrf2 pathway and proinflammatory cytokine release.

The early life exposome and autism risk: a role for the maternal microbiome?

Autism spectrum disorders (ASD) are highly heritable, heterogeneous neurodevelopmental disorders characterized by clinical presentation of atypical social, communicative, and repetitive behaviors. Over the past 25 years, hundreds of ASD risk genes have been identified. Many converge on key molecular pathways, from translational control to those regulating synaptic structure and function. Despite these advances, therapeutic approaches remain elusive. Emerging data unearthing the relationship between genetics, microbes, and immunity in ASD suggest an integrative physiology approach could be paramount to delivering therapeutic breakthroughs. Indeed, the advent of large-scale multi-OMIC data acquisition, analysis, and interpretation is yielding an increasingly mechanistic understanding of ASD and underlying risk factors, revealing how genetic susceptibility interacts with microbial genetics, metabolism, epigenetic (re)programming, and immunity to influence neurodevelopment and behavioral outcomes. It is now possible to foresee exciting advancements in the treatment of some forms of ASD that could markedly improve quality of life and productivity for autistic individuals. Here, we highlight recent work revealing how gene X maternal exposome interactions influence risk for ASD, with emphasis on the intrauterine environment and fetal neurodevelopment, host-microbe interactions, and the evolving therapeutic landscape for ASD.

Associations between pesticide exposure with biomarkers of stroke risk factors in farmers

The extensive use of pesticides may cause acute and chronic intoxication. Therefore, this study aimed to reveal the associations between pesticide exposure and serum markers for stroke risk factors in farmers. A cross-sectional study was conducted with farmers, who used chemical pesticides in Seloprojo Village, Ngablak District, Magelang Regency, Central Java Province, Indonesia. A questionnaire containing demographics, pesticide use, and aspects related to work was employed. Measurements of serum cholesterol, uric acid, glucose, cholinesterase, and fibrinogen levels were also conducted. Of the 106 subjects, 31 (29.2%) used organophosphates as chemical pesticides. There was a significant difference between organophosphate and nonorganophosphate groups in plasma fibrinogen levels. The organophosphate group had higher levels of fibrinogen (292.29 ± 67.56 mg/dL) than the non-organophosphate group (255.24 ± 38.90 mg/dL). Of the studied risk factors for stroke, there is a significant association between organophosphate exposure and increased plasma fibrinogen levels.

An updated systematic review on the maternal exposure to environmental pesticides and involved mechanisms of autism spectrum disorder (ASD) progression risk in children

Autism spectrum disorder (ASD) increased dramatically over the past 25 years because of genetic and environmental factors. This systematic review (SR) aimed to determine the association between maternal exposure during pregnancy to environmental pesticides and other associations with the risk of ASD progression in children. PubMed (MEDLINE), Scopus (Elsevier) and the Institute for Scientific Information (ISI) Web of Science were searched using appropriate keywords up to March 2021. Twenty-four studies met the inclusion/exclusion criteria and were selected. Most studies reported that ASD increases the risk of offspring after prenatal exposure to environmental pesticides in pregnant mother's residences, against offspring of women from the same region without this exposure. The main potential mechanisms inducing ASD progressions are ROS and prostaglandin E2 synthesis, AChE inhibition, voltage-gated sodium channel disruption, and GABA inhibition. According to the included studies, the highest rates of ASD diagnosis increased relative to organophosphates, and the application of the most common pesticides near residences might enhance the prevalence of ASD.

Mechanisms of Organophosphate Toxicity and the Role of Acetylcholinesterase Inhibition

Organophosphorus compounds (OPs) have applications in agriculture (e.g., pesticides), industry (e.g., flame retardants), and chemical warfare (nerve agents). In high doses or chronic exposure, they can be toxic or lethal. The primary mechanism, common among all OPs, that initiates their toxic effects is the inhibition of acetylcholinesterase. In acute OP exposure, the subsequent surge of acetylcholine in cholinergic synapses causes a peripheral cholinergic crisis and status epilepticus (SE), either of which can lead to death. If death is averted without effective seizure control, long-term brain damage ensues. This review describes the mechanisms by which elevated acetylcholine can cause respiratory failure and trigger SE; the role of the amygdala in seizure initiation; the role of M1 muscarinic receptors in the early stages of SE; the neurotoxic pathways activated by SE (excitotoxicity/Ca++ overload/oxidative stress, neuroinflammation); and neurotoxic mechanisms linked to low-dose, chronic exposure (Ca++ dyshomeostasis/oxidative stress, inflammation), which do not depend on SE and do not necessarily involve acetylcholinesterase inhibition. The evidence so far indicates that brain damage from acute OP exposure is a direct result of SE, while the neurotoxic mechanisms activated by low-dose chronic exposure are independent of SE and may not be associated with acetylcholinesterase inhibition.

Cell-Free DNA as a Biomarker in a Rodent Model of Chlorpyrifos Poisoning Causing Mitochondrial Dysfunction

INTRODUCTION

Organophosphates (OPs) are a major public health problem worldwide due to ease of access and high toxicity lacking effective biomarkers and treatment. Cholinergic agents such as OPs and carbamates are responsible for many pesticide-related deaths. While the inhibition of AChE is thought to be the main mechanism of injury, there are other important pathways that contribute to the overall toxicity of OPs such as mitochondrial dysfunction. An existing gap in OP poisoning are biomarkers to gauge severity and prognosis. Cell-free DNA (cfDNA) are novel biomarkers that have gained increased attention as a sensitive biomarker of disease with novel use in acute poisoning. This study investigates alterations in cerebral mitochondrial function in a rodent model of chlorpyrifos poisoning with the use of cfDNA as a potential biomarker.

METHODS

Twenty rodents were divided into two groups: Control (n = 10) and Chlorpyrifos (n = 10). Chlorpyrifos was administered through the venous femoral line with a Harvard Apparatus 11 Elite Syringe pump (Holliston, MA, USA) at 2 mg/kg. Animals were randomized to receive chlorpyrifos versus the vehicle (10% DMSO) for 60 min which would realistically present an acute exposure with continued absorption. At the end of the exposure (60 min), isolated mitochondria were measured for mitochondrial respiration along with measures of acetylcholinesterase activity, cfDNA, cytokines and western blot.

RESULTS

The Chlorpyrifos group showed a significant decrease in heart rate but no change in the blood pressure. There was a significant increase in bulk cfDNA concentrations and overall decrease in mitochondrial respiration from brain tissue obtained from animals in the Chlorpyrifos group when compared to the Control group with no difference in acetylcholinesterase activity. In addition, there was a significant increase in both IL-2 and IL-12 in the Chlorpyrifos group.

CONCLUSIONS

In our study, we found that the total cfDNA concentration may serve as a more accurate biomarker of OP exposure compared to acetylcholinesterase activity. In addition, there was an overall decrease in cerebral mitochondrial function in the Chlorpyrifos group when compared to the Control group.

Pesticides at brain borders: Impact on the blood-brain barrier, neuroinflammation, and neurological risk trajectories

Pesticides are omnipresent, and they pose significant environmental and health risks. Translational studies indicate that acute exposure to high pesticide levels is detrimental, and prolonged contact with low concentrations of pesticides, as single and cocktail, could represent a risk factor for multi-organ pathophysiology, including the brain. Within this research template, we focus on pesticides' impact on the blood-brain barrier (BBB) and neuroinflammation, physical and immunological borders for the homeostatic control of the central nervous system (CNS) neuronal networks. We examine the evidence supporting a link between pre- and postnatal pesticide exposure, neuroinflammatory responses, and time-depend vulnerability footprints in the brain. Because of the pathological influence of BBB damage and inflammation on neuronal transmission from early development, varying exposures to pesticides could represent a danger, perhaps accelerating adverse neurological trajectories during aging. Refining our understanding of how pesticides influence brain barriers and borders could enable the implementation of pesticide-specific regulatory measures directly relevant to environmental neuroethics, the exposome, and one-health frameworks.

Toxic External Exposure Leading to Ocular Surface Injury

The surface of the eye is directly exposed to the external environment, protected only by a thin tear film, and may therefore be damaged by contact with ambient particulate matter, liquids, aerosols, or vapors. In the workplace or home, the eye is subject to accidental or incidental exposure to cleaning products and pesticides. Organic matter may enter the eye and cause infection. Ocular surface damage can trigger a range of symptoms such as itch, discharge, hyperemia, photophobia, blurred vision, and foreign body sensation. Toxin exposure can be assessed clinically in multiple ways, including via measurement of tear production, slit-lamp examination, corneal staining, and conjunctival staining. At the cellular level, environmental toxins can cause oxidative damage, apoptosis of corneal and conjunctival cells, cell senescence, and impaired motility. Outcomes range from transient and reversible with complete healing to severe and sight-compromising structural changes. Classically, evaluation of tolerance and safety was carried out using live animal testing; however, new in vitro and computer-based, in silico modes are superseding the gold standard Draize test. This review examines how environmental features such as pollutants, temperature, and seasonality affect the ocular surface. Chemical burns to the eye are considered, and approaches to protect the ocular surface are detailed.

Exposure to Insecticides Modifies Gene Expression and DNA Methylation in Hematopoietic Tissues In Vitro

The evidence supporting the biological plausibility of the association of permethrin and malathion with hematological cancer is limited and contradictory; thus, further studies are needed. This study aimed to investigate whether in vitro exposure to 0.1 μM permethrin and malathion at 0, 24, 48 and 72 h after cell culture initiation induced changes in the gene expression and DNA methylation in mononuclear cells from bone marrow and peripheral blood (BMMCs, PBMCs). Both pesticides induced several gene expression modifications in both tissues. Through gene ontology analysis, we found that permethrin deregulates ion channels in PBMCs and BMMCs and that malathion alters genes coding proteins with nucleic acid binding capacity, which was also observed in PBMCs exposed to permethrin. Additionally, we found that both insecticides deregulate genes coding proteins with chemotaxis functions, ion channels, and cytokines. Several genes deregulated in this study are potentially associated with cancer onset and development, and some of them have been reported to be deregulated in hematological cancer. We found that permethrin does not induce DNA hypermethylation but can induce hypomethylation, and that malathion generated both types of events. Our results suggest that these pesticides have the potential to modify gene expression through changes in promoter DNA methylation and potentially through other mechanisms that should be investigated.

Degradation of mevinphos and monocrotophos by OH radicals in the environment: A computational investigation on mechanism, kinetic, and ecotoxicity

Known organophosphorus pesticides are used widely in agriculture to improve the production of crops. Based on the literature, the degradation of some organophosphorus pesticides was studied theoretically. However, the mechanisms and variation of toxicity during the degradation of mevinphos and monocrotophos are still unclear in the environment, especially in wastewater. In this study, the reaction mechanisms for the degradation of the two representative organophosphorus pesticides (i.e., mevinphos and monocrotophos) in presence of OH radicals in the atmosphere and water are proposed using quantum chemical methods wB97-XD/6-311 + +G(3df,2pd)//wB97-XD/6-311 + +G(d,p). Result shows that the dominant channel is OH-addition to the C atom in CC bond with energy barriers being 15.6 and 14.7 kJ/mol, in the atmosphere and water, respectively, for mevinphos. As for monocrotophos, H-abstraction from NH group via barriers of 8.2 and 10.6 kJ/mol is more feasible in both the atmosphere and water. Moreover, the subsequent reactions of the major products in the atmosphere with NO and O₂ were also studied to evaluate the atmospheric chemistry of mevinphos and monocrotophos. Kinetically, the total rate constant is 2.68 × 10^-9 and 3.86 × 10^-8 cm³ molecule^-1·s^-1 for mevinphos and monocrotophos in the atmosphere and 4.91 × 10¹⁰ and 7.77 × 10¹¹ M^-1 s^-1 in the water at 298 K, thus the lifetime is estimated to be 36.46-364.60 s (2.53-25.31 s) in the atmosphere, and 1.41 × 10^-2 - 1.41 × 10^-1 s (8.92 ×10^-4 - 8.92 ×10^-3 s) in the advanced oxidation processes (AOPs) system. Furthermore, ecotoxic predictions for rats and three aqueous organisms imply their toxicity are reduced during degradation by using ECOSAR and T.E.S.T program based quantitative structure and activity relationship (QSAR) method.

Hematological indices as indicators of inflammation induced by exposure to pesticides

Pesticide toxicity, both acute and chronic, is a global public health concern. Pesticides are involved in abnormal inflammatory responses by interfering with the normal physiology and metabolic status of cells. In this regard, inflammatory indices aggregate index of systemic inflammation (AISI), monocyte-to-high-density lipoprotein ratio, monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte platelet ratio (NLPR), neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune inflammation index, and systemic inflammation response index (SIRI) have been used as predictive markers of inflammatory status in several diseases and also in acute poisoning events. This study aimed to determine systemic inflammation indices and their relationship with pesticide exposure from urban sprayers in 302 individuals categorized into three groups (reference group and moderate and high exposure groups). The data suggest that the AISI, MLR, NLPR, and SIRI indices were significantly higher in the exposed groups compared with the reference group. In conclusion, this study proposes that inflammation indices warrant further attention in order to assess their value as early biomarkers of acute and chronic pesticide intoxication.

Neurotoxicity evoked by organophosphates and available countermeasures

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABA_AR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.

Organophosphorus Pesticide Exposure at 17 Weeks' Gestation and Odds of Offspring Attention-Deficit/Hyperactivity Disorder Diagnosis in the Norwegian Mother, Father, and Child Cohort Study

Prenatal organophosphorus pesticides (OPs) are ubiquitous and have been linked to adverse neurodevelopmental outcomes. However, few studies have examined prenatal OPs in relation to diagnosed attention-deficit/hyperactivity disorder (ADHD), with only two studies exploring this relationship in a population primarily exposed through diet. In this study, we used a nested case-control study to evaluate prenatal OP exposure and ADHD diagnosis in the Norwegian Mother, Father, and Child Cohort Study (MoBa). For births that occurred between 2003 and 2008, ADHD diagnoses were obtained from linkage of MoBa participants with the Norwegian Patient Registry (N = 297), and a reference population was randomly selected from the eligible population (N = 552). Maternal urine samples were collected at 17 weeks' gestation and molar sums of diethyl phosphates (ΣDEP) and dimethyl phosphates metabolites (ΣDMP) were calculated. Multivariable adjusted logistic regression models were used to estimate the association between prenatal OP metabolite exposure and child ADHD diagnosis. Additionally, multiplicative effect measure modification (EMM) by child sex was assessed. In most cases, mothers in the second and third tertiles of ΣDMP and ΣDEP exposure had slightly lower odds of having a child with ADHD, although confidence intervals were wide and included the null. EMM by child sex was not observed for either ΣDMP or ΣDEP. In summary, we did not find evidence that OPs at 17 weeks' gestation increased the odds of ADHD in this nested case-control study of ADHD in MoBa, a population primarily experiencing dietary exposure.

Association between organophosphorus flame retardants exposure and cognitive impairment among elderly population in southern China

The wide application of organophosphorus flame retardants (OPFRs) in consumer products leads to their ubiquitous occurrence. The neurotoxicity of OPFRs has been raised, whereas evidence from the elderly population were rather scarce. Hence, a case-control study was conducted based on the Shenzhen Aging-related Disorder Cohort. A total of 184 cases [Mini-mental State Examination (MMSE) < 24] and 795 participants as controls (MMSE ≥24) were recruited. Eight metabolites of OPFRs (m-OPFRs) in urine samples were measured, including bis(2-butoxyethyl) phosphate (BBOEP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), dibutyl phosphate (DBP), di-o-cresyl phosphate (DOCP), di-p-cresyl phosphate (DPCP) and diphenyl phosphate (DPHP). The detection frequencies of m-OPFRs ranged from 88.8 % to 95.4 %. BCEP had the highest median concentration (0.93 μg/L), followed by BCIPP (0.32 μg/L), DPHP (0.27 μg/L) and DBP (0.20 μg/L). Significant correlations were found between all pairs of urinary m-OPFRs with correlation coefficients ranging from 0.22 to 0.71 (p< 0.05). Logistic regression models showed that urinary concentrations of BDCIPP (adjusted odds ratio [OR]: 1.25, 95 % confidential interval [CI]: 1.04-1.50) and DBP (adjusted OR: 1.10, 95 % CI: 1.01-1.20) were positively associated with lower cognitive functions. Furthermore, a nonlinear dose-response relationship was found between urinary BDCIPP concentration and cognitive decline. To our knowledge, this is the first report on OPFR exposure and cognitive impairment among elderly population. Further toxicological tests of BDCIPP and DBP are needed to illustrate these results.

Exposure to organophosphate insecticides, inappropriate personal protective equipment use, and cognitive performance among pesticide applicators

Inappropriate use of personal protective equipment (PPE) among pesticide applicators may increase urinary organophosphate (OP) metabolite levels and subsequently increase risks of cognitive performance. Therefore, this study aims to (1) compare urinary OP metabolite levels and cognitive performance between pre-and post-pesticide application seasons; (2) PPE use and factors associated with PPE use linked to increased urinary OP metabolite levels during pesticide application; and (3) the association between urinary OP metabolite levels and cognitive performance. This longitudinal follow-up study on 79 pesticide applicators was carried out between October 2021 and January 2022. The applicators were interviewed, collected urine samples, and tested for cognitive performance in pre-and post-pesticide application seasons. The results found that the levels of urinary OP metabolites in post-application season were significantly higher than those in pre-application season (p < 0.001). Multiple linear regression analysis found that increased total diethylphosphate (DEP) and total dialkylphosphate (DAP) levels were associated with not wearing gloves while mixing pesticides [beta (β) ± standard error (SE) = -43.74 ± 18.52, 95% confidence interval (95% CI) = -80.84, -6.64 for total DEP and -50.84 ± 19.26, 95% CI = -89.41, -12.26 for total DAP] and also with not wearing a mask while spraying pesticides (β ± SE = -31.76 ± 12.24, 95% CI = -56.28, -7.24 for total DEP and -33.20 ± 12.63, 95% CI = -58.49, -7.92 for total DAP) after adjusting for covariates. The scores of Montreal Cognitive Assessment-Thai, Thai Mental State Examination, and Mini-Cognitive test in post-pesticide application were significantly lower than those in pre-pesticide application (p < 0.001). However, no association was found between urinary OP metabolite levels and cognitive decline. Our findings indicate that inappropriate PPE use during pesticide application was the major factor affecting urinary OP metabolite levels among pesticide applicators. Wearing gloves when mixing pesticides and a mask when spraying pesticides were key factors in reducing occupational exposure to OP. Exposure to OP at low levels and for short periods of exposure may not affect cognitive performance significantly. Therefore, long-term exposure and exposure to high levels of OP should be investigated further.

A new theoretical investigation on ·OH initiated oxidation of acephate in the environment: mechanism, kinetics, and toxicity

Acephate (O,S-dimethyl acetylphosphoramidothioate) is a typical organophosphorus pesticide used widely in agriculture. It can be released into the atmosphere and water during production and application. In this work, mechanisms in the ·OH initiated degradation of acephate were investigated using quantum chemical methods. Results show that addition, substitution and H-abstraction mechanisms can take place, with the latter being dominant. Moreover, the subsequent reactions of dominant products with O₂ and NO in the atmosphere were considered, as well. The rate constant in the atmosphere and aqueous phase was calculated by transition state theory (TST) with the Wigner tunneling contribution. The total rate constant in the atmosphere and aqueous phase is 7.86 × 10^-10 and 1.83 × 10^-12 cm³ per molecule per s, respectively, the latter being in accordance with the available experimental value of 1.50 × 10^-12 cm³ per molecule per s. Moreover, the ecotoxicity of acephate and degradation products was assessed in fish, daphnia, green algae and rats.

Respiratory and allergic health effects in children living near agriculture: A review

BACKGROUND

Exposure to pesticides and agricultural burning are likely to co-occur in agricultural communities, but these exposures have remained distinct bodies of research. We reviewed epidemiological studies to identify the respiratory health effects of children exposed to pesticides and agricultural burning through a systematic evaluation of peer-reviewed publications of children living in industrial agricultural areas.

METHODS

Two academic search databases (PubMed and Scopus) were queried for all available studies published in English before May 31st, 2021. The initial search combining both exposure metrics (pesticides and agricultural burning) yielded zero publications and thus the queries were performed and presented separately.

RESULTS

Studies were categorized based on main exposure of interest (i.e., pesticides or agricultural burning) and by respiratory health outcome assessment (i.e., self-reported asthma, acute respiratory symptoms, and lung function measurements). In total we identified 25 studies that focused on pesticide exposures and children's respiratory health, and 12 studies that focused on exposure to agricultural burning and children's respiratory health. A majority of the pesticide studies (18/25) reported a positive association between exposure to pesticides and adverse childhood respiratory health effects. Similarly, most (11/12) of the agricultural burning studies also reported a positive association between exposure to agricultural burning and adverse respiratory health effects.

CONCLUSION

The most frequently studied health outcomes in these publications were acute respiratory symptoms (n = 11 pesticides, n = 3 agricultural burning), followed by asthma (n = 9 pesticides, n = 3 agricultural burning), and lung function measurements (n = 5 pesticides, n = 6 agricultural burning). Although health outcome assessment differed between pesticide studies and agricultural burning studies, similar adverse respiratory health effects were observed across the majority of studies.

Toxicological effects of tris(1,3-dichloro-2-propyl) phosphate in oyster Crassostrea gigas using proteomic and phosphoproteomic analyses

As a typical organophosphorus pollutant, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) has been widely detected in aquatic environment. Previous studies showed that protein phosphorylation might be a vital way of TDCIPP to exert multiple toxic effects. However, there is a lack of high-throughput investigations on how TDCIPP affected protein phosphorylation. In this study, the toxicological effects of TDCIPP were explored by proteomic and phosphoproteomic analyses together with traditional means in oysters Crassostrea gigas treated with 0.5, 5 and 50 μg/L TDCIPP for 28 days. Integration of omic analyses revealed that TDCIPP dysregulated transcription, energy metabolism, and apoptosis and cell proliferation by either directly phosphorylating pivotal proteins or phosphorylating their upstream signaling pathways. The U-shaped response of acetylcholinesterase activities suggested the neurotoxicity of TDCIPP in a hormesis manner. What's more, the increase in caspase-9 activity as well as the expression or phosphorylation alterations in eukaryotic translation initiation factor 4E, cell division control protein 42 and transforming growth factor-β1-induced protein indicated the disruption of homeostasis between apoptosis and cell proliferation, which was consistent with the observation of shedding of digestive cells. Overall, combination of proteomic and phosphoproteomic analyses showed the capability of identifying molecular events, which provided new insights into the toxicological mechanisms of TDCIPP.

Neurobehavioral Toxicity Induced by Carbendazim in Rats and the Role of iNOS, Cox-2, and NF-κB Signalling Pathway

Carbendazim (CBZ) is one of the most common fungicides used to fight plant fungal diseases, otherwise, it leaves residue on fruits, vegetables, and soil that contaminate the environment, water, animal, and human causing serious health problems. Several studies have reported the reproductive and endocrine pathological disorders induced by CBZ in several animal models, but little is known about its neurotoxicity. So that, the present study aimed to explain the possible mechanisms of CBZ induced neurotoxicity in rats. Sixty male Wistar rats were divided into 4 groups (n = 15). Group (1) received normal saline and was kept as the negative control group, whereas groups (2, 3, 4) received CBZ at 100, 300, 600 mg/kg b.wt respectively. All rats received the aforementioned materials daily via oral gavage. Brain tissue samples were collected at 7, 14, 28 days from the beginning of the experiment. CBZ induced oxidative stress damage manifested by increasing MDA levels and reducing the levels of TAC, GSH, CAT in some brain areas at 14 and 28 days. There were extensive neuropathological alterations in the cerebrum, hippocampus, and cerebellum with strong caspase-3, iNOS, Cox-2 protein expressions mainly in rats receiving 600 mg/kg CBZ at each time point. Moreover, upregulation of mRNA levels of NF-κB, TNF-α, IL-1B genes and downregulation of the transcript levels of both AchE and MAO genes were recorded in all CBZ receiving groups at 14 and 28 days especially those receiving 600 mg/kg CBZ. Our results concluded that CBZ induced dose- and time-dependent neurotoxicity via disturbance of oxidant/antioxidant balance and activation of NF-κB signaling pathway. We recommend reducing the uses of CBZ in agricultural and veterinary fields or finding other novel formulations to reduce its toxicity on non-target organisms and enhance its efficacy on the target organisms.

Organophosphorus Pesticides as Modulating Substances of Inflammation through the Cholinergic Pathway

Organophosphorus pesticides (OPs) are widespread insecticides used for pest control in agricultural activities and the control of the vectors of human and animal diseases. However, OPs’ neurotoxic mechanism involves cholinergic components, which, beyond being involved in the transmission of neuronal signals, also influence the activity of cytokines and other pro-inflammatory molecules; thus, acute and chronic exposure to OPs may be related to the development of chronic degenerative pathologies and other inflammatory diseases. The present article reviews and discusses the experimental evidence linking inflammatory process with OP-induced cholinergic dysregulation, emphasizing the molecular mechanisms related to the role of cytokines and cellular alterations in humans and other animal models, and possible therapeutic targets to inhibit inflammation.

Acute and long-term effects of VX in rat brain cell aggregate culture

The contact poison VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) is a chemical warfare agent that is one of the most toxic organophosphorus compounds known. Its primary mechanism of toxic action is through the inhibition of acetylcholinesterase and resultant respiratory paralysis. The majority of work on VX has thus concentrated on its potent anticholinesterase activity and acute toxicity, with few studies investigating potential long-term effects. In this report we describe the effects of VX in aggregating rat brain cell cultures out to 28 days post-exposure. Cholinesterase activity was rapidly inhibited (60 min IC50 = 0.73 +/- 0.27 nM), but recovered towards baseline values over the next four weeks. Apoptotic cell death, as measured using caspase-3 activity was evident only at 100 μM concentrations. Cell type specific enzymatic markers (glutamine synthase, choline acetyltransferase and 2',3'-cyclic nucleotide 3'-phosphodiesterase) showed no significant changes. Total Akt levels were unchanged, while an increased phosphorylation of this protein was noted only at the highest VX concentration on the first day post-exposure. In contrast, significant and delayed (28 days post-exposure) decreases were noted in vascular endothelial growth factor (VEGF) levels, a protein whose reduced levels are known to contribute to neurodegenerative disorders. These observations may indicate that the long-term effects noted in some survivors of nerve agent intoxication may be due to VX-induced declines in brain VEGF levels.

A subchronic low-dose exposure of a glyphosate-based herbicide induces depressive and anxious-like behavior in mice: quercetin therapeutic approach

In this study, we investigated the possible role of pesticide exposure in contributing to neurological diseases such as depression. Here, we evaluated whether a subchronic low dose of a glyphosate-based herbicide (GBH) could induce alterations in the central nervous system, using the flavonoid quercetin as a therapeutic strategy. Forty mice were divided into four treatment groups: control, GBH, quercetin, and GBH+Quer groups and received 50 mg/kg of GBH solution, 30 mg/kg of quercetin, and/or vehicles for 30 days via gavage. After performing behavioral tests, such as the open field (OF), elevated plus maze (EPM), forced swim test (FST), and sucrose preference test (SPT), the mice were euthanized and their hippocampal tissues were collected to measure the levels of oxidative stress markers such as reactive species (RS), total antioxidant capacity (FRAP), reduced glutathione (GSH), and acetylcholinesterase activity (AChE), as well as for histological evaluation. The GBH group showed anxious and depressive-like behavior in the EPM and FST tests, as well as increased levels of RS and decreased GSH levels in the hippocampus. Quercetin treatment in the GBH+Quer group allowed partial or total improvement in behavioral tests (EPM and FST) and in the levels of oxidative stress markers (RS and GSH). However, the quercetin group showed similar behavior to the GBH group after treatment. The results revealed that oral exposure to a subchronic low dose of GBH was capable of promoting effects on behavior and oxidative stress in the hippocampus of mice. In addition, despite quercetin having a neuroprotective role, caution is needed when considering the possible per se effects of its continuous supplementation.

Autism Spectrum Disorder and Prenatal or Early Life Exposure to Pesticides: A Short Review

Background: Autism spectrum disorder (ASD) diagnoses have rapidly increased globally. Both environmental and genetic factors appear to contribute to the development of ASD. Several studies have shown a potential association between prenatal or postnatal pesticide exposure and the risk of developing ASD. Methods: We reviewed the available literature concerning the relationship between early life exposure to pesticides used in agriculture, such as organochlorines, organophosphates and pyrethroids, and ASD onset in childhood. We searched on Medline and Scopus for cohort or case–control studies published in English from 1977 to 2020. Results: A total of seven articles were selected for the review. We found a remarkable association between the maternal exposure to pyrethroid, as well as the exposure to organophosphate during pregnancy or in the first years of childhood, and the risk of ASD onset. This association was found to be less evident with organochlorine pesticides. Pregnancy seems to be the time when pesticide exposure appears to have the greatest impact on the onset of ASD in children. Conclusions: Among the different environmental pollutants, pesticides should be considered as emerging risk factors for ASD. The potential association identified between the exposure to pesticides and ASD needs to be implemented and confirmed by further epidemiological studies based on individual assessment both in outdoor and indoor conditions, including multiple confounding factors, and using statistical models that take into account single and multiple pesticide residues.

[Progress of sample preparation and analytical methods of dried fruit foods]

坚果、果脯等干果类食品含有丰富的营养成分,深受国内外广大消费者的喜爱。但这些食品在果实生产、加工、储运时会使用农药或产生霉变等,造成干果中农药、重金属、霉菌毒素或添加剂等有害成分残留,甚至超过国家限量要求,带来严重的食品安全问题。因此,加强干果类食品的质量监督具有重要的经济和社会意义。但干果类食品基质复杂,有害物质种类多,结构和性质差异大,含量低,其分析检测需要快速高效的样品前处理技术和准确灵敏的分析检测方法。该文主要综述了近十年来干果类食品中有害物质的样品前处理及分析检测方法研究进展。其中样品前处理方法主要包括各种场辅助萃取法、相分离法和衍生化萃取方法等。场辅助萃取法主要是借助超声波和微波场等外场(协同)作用加快干果中有害物质的溶出速度,提高其萃取效率。相分离法,包括固相(微)萃取、分散固相萃取和液相(微)萃取法等,具有溶剂消耗少、分离富集效率高的优势,是干果样品分析中较常使用的前处理方法。该文还重点介绍了干果中各类有害成分分析检测技术,主要包括色谱、原子光谱、无机质谱、电化学分析等常规实验室方法,以及一些适用于现场分析的快速检测技术,并以此为基础,展望了干果类食品中有害物质分析检测技术的发展趋势。

Chlorpyrifos pesticide promotes oxidative stress and increases inflammatory states in BV-2 microglial cells: A role in neuroinflammation

The exposure to environmental stressors, such as organophosphate (OP) pesticides, has been associated with the development of neurodegenerative diseases. Chlorpyrifos (CPF) is the worldwide most used OP pesticide and one of the most hazardous pesticides as it can cross the blood-brain barrier. Since studies evaluating the effects of CPF on brain immune cells are scarce, this research investigated the oxidative and inflammatory responses of CPF exposure in murine microglial cells. BV-2 cells were exposed to different concentrations of CPF pesticide (0.3-300 μM). CPF induced activation of microglial cells, confirmed by Iba-1 and CD11b marking, and promoted microglial proliferation and cell cycle arrest at S phase. Moreover, CPF exposure increased oxidative stress production (NO, MDA, and O₂∙), and upregulated pro-inflammatory cytokines (IL-1β and NLRP3) genes expression in BV-2 cells. Overall, data showed that CPF exposure, at the lowest concentrations, acted by promoting pro-oxidative and pro-inflammatory states in microglial cells. These results provide important information on the potential role of microglial activation in CPF-induced neuroinflammation and add to the expanding knowledge on the neurotoxicity of OP.

Occurrence and risk assessment of currently used organophosphate pesticides in overlying water and surface sediments in Guangzhou urban waterways, China

Organophosphate pesticides (OPPs) are one type of the most massively used pesticides and ubiquitously detected in aquatic environments, which may pose potential risks to the aquatic organisms and human health. In the present study, the spatiotemporal distribution and potential risks of OPPs were investigated in overlying water and surficial sediments from urban waterways of Guangzhou. For all studied sites, in general, four target OPPs (i.e., malathion, chlorpyrifos, terbufos, and diazinon) were present in the overlying water, with malathion and chlorpyrifos as major components. Higher concentrations of the four OPPs were found for the water and sediments collected in the dry season compared to the wet season, possibly because of the dilution effect of heavy rains. The results of Pearson's analyses and principal coordinate analyses (PCoA) suggested similar sources for target OPPs in the water and sediments across the Guangzhou urban waterways. Potential ecological risks of the OPPs to three representative taxons (algae, aquatic invertebrates, and fish) were evaluated via toxic units (TUs) and risk quotients (RQs), while risk assessment on human health was performed using hazard index (HI). Although TU results showed no acute risks to the aquatic organisms in the overlying water and surface sediments, RQ results of the mixture showed high risks to the aquatic invertebrate and fish in all water samples. Individual HI values and cumulative HI values were on the order of 10^-6-10^-3 for children and adults, suggesting no potential risks to either children or adults through drinking and bathing.

Conserved Metabolic and Evolutionary Themes in Microbial Degradation of Carbamate Pesticides

Carbamate pesticides are widely used as insecticides, nematicides, acaricides, herbicides and fungicides in the agriculture, food and public health sector. However, only a minor fraction of the applied quantity reaches the target organisms. The majority of it persists in the environment, impacting the non-target biota, leading to ecological disturbance. The toxicity of these compounds to biota is mediated through cholinergic and non-cholinergic routes, thereby making their clean-up cardinal. Microbes, specifically bacteria, have adapted to the presence of these compounds by evolving degradation pathways and thus play a major role in their removal from the biosphere. Over the past few decades, various genetic, metabolic and biochemical analyses exploring carbamate degradation in bacteria have revealed certain conserved themes in metabolic pathways like the enzymatic hydrolysis of the carbamate ester or amide linkage, funnelling of aryl carbamates into respective dihydroxy aromatic intermediates, C1 metabolism and nitrogen assimilation. Further, genomic and functional analyses have provided insights on mechanisms like horizontal gene transfer and enzyme promiscuity, which drive the evolution of degradation phenotype. Compartmentalisation of metabolic pathway enzymes serves as an additional strategy that further aids in optimising the degradation efficiency. This review highlights and discusses the conclusions drawn from various analyses over the past few decades; and provides a comprehensive view of the environmental fate, toxicity, metabolic routes, related genes and enzymes as well as evolutionary mechanisms associated with the degradation of widely employed carbamate pesticides. Additionally, various strategies like application of consortia for efficient degradation, metabolic engineering and adaptive laboratory evolution, which aid in improvising remediation efficiency and overcoming the challenges associated with in situ bioremediation are discussed.

[Uncontrolled asthma in children and adolescents exposed to pesticides in an area of intense agribusiness activity]

The study aimed to analyze factors associated with uncontrolled asthma in schoolchildren exposed to pesticides in a medium-sized municipality in the state of Mato Grosso, Brazil. This was a case-control study of children 6 to 7 and 13 to 14 years old in Primavera do Leste, in 2016. Cases were defined as schoolchildren that met the criteria for uncontrolled asthma based on International Study of Asthma and Allergies in Childhood (ISAAC) questions, and controls were selected from the same schools as the cases, after randomization, at a 1:1 ratio. Data collection used the questionnaires from Phases I and II of ISAAC and an additional questionnaire on pesticide exposure. Descriptive, bivariate, and logistic da e regression analyses were performed with the individual and environmental sociodemographic, and economic variables. 319 cases and 319 controls were selected, totaling 638 participants in the study. In the final da logistic model, the variables family income greater than 4 minimum wages (OR = 14.36; 95%CI: 8.89-23.20), maternal schooling up to incomplete secondary (OR = 16.32; 95%CI: 8.96-29.75), prematurity (OR = 13.25; 95%CI: 4.83-36.41), and low birthweight (OR = 17.08; 95%CI: 5.52-52.90) remained associated with uncontrolled asthma. Of the pesticide exposure variables, presence of household member working in agriculture (OR = 5.91; 95%CI: 2.11-16.53), living near farming activities (OR = 3.98; 95%CI: 1.47-11.76), and spraying areas near the household (OR = 4.20; 95%CI: 1.49-11.87) were related to the outcome. In this study, pesticides and sociodemographic, neonatal, and childhood conditions proved related to uncontrolled asthma in schoolchildren.

BIMP affects tubulin structure and causes abnormalities in cell division

Although organophosphorus agents are used worldwide as pesticides, there have been many reports of pesticide poisoning. Nerve agents are organophosphorus agents that interfere with neurotransmission and have been used as chemical weapons in wars. These agents mainly irreversibly inhibit the action of acetylcholinesterase, an enzyme that breaks down acetylcholine, a neurotransmitter, and are believed to cause acute symptoms of poisoning. However, in recent years, the presence of subacute, delayed toxicity independent of acetylcholinesterase inhibition has been reported for some organophosphorus agents. We analyzed the subacute and delayed toxicity of bis(isopropylmethyl)phosphonate (BIMP), which has the same phosphonate group as sarin. BIMP rounded out the morphology of the cells and reduced the proportion of cells in the G1 phase of the cell cycle over time. No DNA damage was observed, suggesting that BIMP may affect cell division.

Varying modalities of perinatal exposure to a pesticide cocktail elicit neurological adaptations in mice and zebrafish

Epidemiological indications connect maternal and developmental presence or exposure to pesticides with an increased risk for a spectrum of neurological trajectories. To provide pre-clinical data in support of this hypothesis, we used two distinct experimental models. First, female and male mice were fed immediately prior to mating, and the resulting pregnant dams were continously fed during gestation and lactation periods using chow pellets containing a cocktail of six pesticides at tolerable daily intake levels. Male and female offspring were then tracked for behavioral and in vivo electrophysiological adaptations. Second, a zebrafish model allowed us to screen toxicity and motor-behavior outcomes specifically associated with the developmental exposure to a low-to-high concentration range of the cocktail and of each individual pesticide. Here, we report anxiety-like behavior in aging male mice maternally exposed to the cocktail, as compared to age and gender matched sham animals. In parallel, in vivo electrocorticography revealed a decrease in gamma (40-80 Hz) and an increase of theta (6-9 Hz) waves, delineating a long-term, age-dependent, neuronal slowing. Neurological changes were not accompanied by brain structural malformations. Next, by using zebrafish larvae, we showed an increase of all motor-behavioral parameters resulting from the developmental exposure to 10 μg/L of pesticide cocktail, an outcome that was not associated with midbrain structural or neurovascular modifications as assessed by in vivo 2-photon microscopy. When screening each pesticide, chlorpyrifos elicited modifications of swimming parameters at 0.1 μg/L, while other components provoked changes from 0.5 μg/L. Ziram was the single most toxic component inducing developmental malformations and mortality at 10 μg/L. Although we have employed non-equivalent modalities and timing of exposure in two dissimilar experimental models, these outcomes indicate that presence of a pesticide cocktail during perinatal periods represents an element promoting behavioral and neurophysiological modifications. The study limitations and the possible pertinence of our findings to ecotoxicology and public health are critically discussed.

Neurotoxicant exposures and rates of Chronic Multisymptom Illness and Kansas Gulf War Illness criteria in Gulf War deployed women veterans

AIMS

This study analyzed deployment-related exposures and risk of Persian Gulf War Illness (GWI) in women veterans from the Veterans Affairs (VA) Cooperative Studies Program 585 Gulf War Era Cohort and Biorepository (GWECB CSP#585).

MAIN METHODS

We examined the associations between GW deployment-related exposures and case definitions for GWI in deployed GW women. Multivariate regression analyses controlling for demographic outcomes were performed.

KEY FINDINGS

Surveys were obtained from 202 GW deployed women veterans. Self-reported exposure to smoke from oil well fires as well as chemical and biological warfare were the only exposures significantly associated with the Center for Disease Control and Prevention (CDC) GWI criteria. Seventy-nine women were excluded from the rest of the analyses as they met Kansas GW illness exclusion criteria. Eligible women who self-reported deployment-related exposure to smoke from oil wells, pyridostigmine bromide (PB) pills, pesticide cream, pesticide treated uniforms, and insect baits were significantly more likely to meet the Kansas GWI criteria (n = 123) than those unexposed and exposures were related to Kansas symptom subdomain endorsements.

SIGNIFICANCE

These results suggest that women GW veterans reporting deployment related exposures of pesticide, oil well fire and PB pills are significantly more likely to meet the Kansas GWI criteria in this national cohort of GW women suggesting its utility in future studies. In addition, based on these results it appears that women exposed to particular toxicants during the war may benefit from more targeted treatment strategies dependent upon the mechanism of exposure of their toxicant induced outcomes.

Neuroprotection by delayed triple therapy following sarin nerve agent insult in the rat

The development of refractory status epilepticus (SE) induced by sarin intoxication presents a therapeutic challenge. In our current research we evaluate the efficacy of a delayed combined triple treatment in ending the abnormal epileptiform seizure activity (ESA) and the ensuing of long-term neuronal insult. SE was induced in male Sprague-Dawley rats by exposure to 1.2LD50 sarin insufficiently treated by atropine and TMB4 (TA) 1 min later. Triple treatment of ketamine, midazolam and valproic acid was administered 30 min or 1 h post exposure and was compared to a delayed single treatment with midazolam alone. Toxicity and electrocorticogram activity were monitored during the first week and behavioral evaluation performed 3 weeks post exposure followed by brain biochemical and immunohistopathological analyses. The addition of both single and triple treatments reduced mortality and enhanced weight recovery compared to the TA-only treated group. The triple treatment also significantly minimized the duration of the ESA, reduced the sarin-induced increase in the neuroinflammatory marker PGE2, the brain damage marker TSPO, decreased the gliosis, astrocytosis and neuronal damage compared to the TA+ midazolam or only TA treated groups. Finally, the triple treatment eliminated the sarin exposed increased open field activity, as well as impairing recognition memory as seen in the other experimental groups. The delayed triple treatment may serve as an efficient therapy, which prevents brain insult propagation following sarin-induced refractory SE, even if treatment is postponed for up to 1 h.

Neuroinflammation as a Therapeutic Target for Mitigating the Long-Term Consequences of Acute Organophosphate Intoxication

Acute intoxication with organophosphates (OPs) can cause a potentially fatal cholinergic crisis characterized by peripheral parasympathomimetic symptoms and seizures that rapidly progress to status epilepticus (SE). While current therapeutic countermeasures for acute OP intoxication significantly improve the chances of survival when administered promptly, they are insufficient for protecting individuals from chronic neurologic outcomes such as cognitive deficits, affective disorders, and acquired epilepsy. Neuroinflammation is posited to contribute to the pathogenesis of these long-term neurologic sequelae. In this review, we summarize what is currently known regarding the progression of neuroinflammatory responses after acute OP intoxication, drawing parallels to other models of SE. We also discuss studies in which neuroinflammation was targeted following OP-induced SE, and explain possible reasons why such therapeutic interventions have inconsistently and only partially improved long-term outcomes. Finally, we suggest future directions for the development of therapeutic strategies that target neuroinflammation to mitigate the neurologic sequelae of acute OP intoxication.

21-Day dermal exposure to aircraft engine oils: effects on esterase activities in brain and liver tissues, blood, plasma, and clinical chemistry parameters for Sprague Dawley rats

This dermal study tested the potential toxicity of grade 3 (G3) and 4 (G4) organophosphate-containing aircraft engine oils in both new (G3-N, G4-N) and used states (G3-U, G4-U) to alter esterase activities in blood, brain and liver tissues, clinical chemistry parameters, and electrophysiology of hippocampal neurons. A 300 µl volume of undiluted oil was applied in Hill Top Chamber Systems®, then attached to fur-free test sites on backs of male and female Sprague Dawley rats for 6 hr/day, 5 days/week for 21 days. Recovery rats received similar treatments and kept for 14 days post-exposure to screen for reversibility, persistence, or delayed occurrence of toxicity. In brain, both versions of G3 and G4 significantly decreased (32-41%) female acetylcholinesterase (AChE) activity while in males only G3-N and G4-N reduced (33%) AChE activity. Oils did not markedly affect AChE in liver, regardless of gender. In whole blood, G3-U decreased female AChE (29%) which persisted during recovery (32%). G4-N significantly lowered (29%) butyrylcholinesterase (BChE) in male plasma, but this effect was resolved during recovery. For clinical chemistry indices, only globulin levels in female plasma significantly increased following G3-N or G4-N exposure. Preliminary electrophysiology data suggested that effects of both versions of G3 and G4 on hippocampal function may be gender dependent. Aircraft maintenance workers may be at risk if precautions are not taken to minimize long-term aircraft oil exposure.

High-Resolution Metabolomic Assessment of Pesticide Exposure in Central Valley, California

Pesticides are widely used in the agricultural Central Valley region of California. Historically, this has included organophosphates (OPs), organochlorines (OCs), and pyrethroids (PYRs). This study aimed to identify perturbations of the serum metabolome in response to each class of pesticide and mutual associations between groups of metabolites and multiple pesticides. We conducted high-resolution metabolomic profiling of serum samples from 176 older adults living in the California Central Valley using liquid chromatography with high-resolution mass spectrometry. We estimated chronic pesticide exposure (from 1974 to year of blood draw) to OPs, OCs, and PYRs from ambient sources at homes and workplaces with a geographic information system (GIS)-based model. Based on partial least-squares regression and pathway enrichment analysis, we identified metabolites and metabolic pathways associated with one or multiple pesticide classes, including mitochondrial energy metabolism, fatty acid and lipid metabolism, and amino acid metabolism. Utilizing an integrative network approach, we found that the fatty acid β-oxidation pathway is a common pathway shared across all three pesticide classes. The disruptions of the serum metabolome suggested that chronic pesticide exposure might result in oxidative stress, inflammatory reactions, and mitochondrial dysfunction, all of which have been previously implicated in a wide variety of diseases. Overall, our findings provided a comprehensive view of the molecular mechanisms of chronic pesticide toxicity, and, for the first time, our approach informs exposome research by moving from macrolevel population exposures to microlevel biologic responses.

The Links between ALS and NF-κB

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease wherein motor neuron degeneration leads to muscle weakness, progressive paralysis, and death within 3-5 years of diagnosis. Currently, the cause of ALS is unknown but, as with several neurodegenerative diseases, the potential role of neuroinflammation has become an increasingly popular hypothesis in ALS research. Indeed, upregulation of neuroinflammatory factors have been observed in both ALS patients and animal models. One such factor is the inflammatory inducer NF-κB. Besides its connection to inflammation, NF-κB activity can be linked to several genes associated to familial forms of ALS, and many of the environmental risk factors of the disease stimulate NF-κB activation. Collectively, this has led many to hypothesize that NF-κB proteins may play a role in ALS pathogenesis. In this review, we discuss the genetic and environmental connections between NF-κB and ALS, as well as how this pathway may affect different CNS cell types, and finally how this may lead to motor neuron degeneration.

Effects of novel brain-penetrating oxime acetylcholinesterase reactivators on sarin surrogate-induced changes in rat brain gene expression

Past assassinations and terrorist attacks demonstrate the need for a more effective antidote against nerve agents and other organophosphates (OP) that cause brain damage through inhibition of acetylcholinesterase (AChE). Our lab has invented a platform of phenoxyalkyl pyridinium oximes (US patent 9,277,937) that demonstrate the ability to cross the blood-brain barrier in in vivo rat tests with a sarin surrogate nitrophenyl isopropyl methylphosphonate (NIMP) and provide evidence of brain penetration by reducing cessation time of seizure-like behaviors, accumulation of glial fibrillary acidic protein (GFAP), and hippocampal neuropathology, as opposed to the currently approved oxime, 2-pyridine aldoxime methyl chloride (2-PAM). Using two of the novel oximes (Oximes 1 and 20), this project examined whether gene expression changes might help explain this protection. Expression changes in the piriform cortex were examined using polymerase chain reaction arrays for inflammatory cytokines and receptors. The hippocampus was examined via quantitative polymerase chain reaction for the expression of immediate-early genes involved in brain repair (Bdnf), increasing neurotoxicity (Fos), and apoptosis control (Jdp2, Bcl2l1, Bcl2l11). In the piriform cortex, NIMP significantly stimulated expression for the macrophage inflammatory proteins CCL4, IL-1A, and IL-1B. Oxime 20 by itself elicited the most changes. When it was given therapeutically post-NIMP, the largest change occurred: a 310-fold repression of the inflammatory cytokine, CCL12. In the hippocampus, NIMP increased the expression of the neurotoxicity marker Fos and decreased the expression of neuroprotective Bdnf and antiapoptotic Bcl2l1. Compared with 2-PAM, Oxime 20 stimulated Bcl2l1 expression more and returned expression closer to the vehicle control values.

Alterations in the non-neuronal cholinergic system induced by in-vitro exposure to diazoxon in spleen mononuclear cells of Nile tilapia (O. niloticus)

Organophosphate pesticides as diazinon disrupt the neuroimmune communication, affecting the innate and adaptive immune response of the exposed organisms. Since the target molecule of diazinon is typically the acetylcholinesterase enzyme (AChE), the existence of a non-neuronal cholinergic system in leukocytes makes them susceptible to alterations by diazinon. Therefore, the aim of this work was to evaluate the activity of AChE, acetylcholine (ACh) concentration, and the expression of nicotinic ACh receptors (nAChR) and muscarinic ACh receptors (mAChR) in spleen mononuclear cells (SMNC) of Nile tilapia (O. niloticus) exposed in vitro to diazoxon, a diazinon metabolite. SMNC were exposed in-vitro to 1 nM, 1 μM, and 10 μM diazoxon for 24 h. The enzyme activity of AChE was then evaluated by spectrophotometry, followed by ACh quantification by ultra-performance liquid chromatography. Finally, mAChR and nAChR expression was evaluated by RT-qPCR. The results indicate that AChE levels are significantly inhibited at 1 and 10 μM diazoxon, while the relative expression of (M3, M4, and M5) mAChR and (β2) nAChR is reduced significantly as compared against SMNC not exposed to diazoxon. However, ACh levels show no significant difference with respect to the control group. The data indicate that diazoxon directly alters elements in the cholinergic system of SMNC by AChE inhibition or indirectly through the interaction with AChR, which is likely related to the immunotoxic properties of diazinon and its metabolites.