Neurodevelopmental toxicity in the mouse neocortex following prenatal exposure to acetamiprid

Acetamiprid-induced testicular toxicity in mice: ameliorative effect and potential mechanisms of morin

BACKGROUND

Acetamiprid (ACP) is a novel chloronicotinyl insecticide that has been extensively utilized in agricultural, domestic, and public health contexts for nearly two decades. However, its potential to induce organ damage, including reproductive toxicity in mammals, has emerged as a significant concern. Morin is a naturally occurring flavonol that has gained prominence as a food supplement in recent years due to its antioxidant and anti-inflammatory properties. The objective of this study was to evaluate the protective effect of morin against testicular damage in mice subjected to ACP exposure.

METHODS

Thirty male Balb/c mice were randomly assigned to one of five groups, with the following treatment allocations: control, ACP (20 mg/kg), ACP + morin (15 and 30 mg/kg), and only morin (30 mg/kg). ACP and morin applications were conducted orally over a period of 14 days. Hormonal analyses were conducted on serum samples obtained from the mice, while biochemical and histological evaluations were performed on testicular samples.

RESULTS

The biochemical results demonstrated that ACP elevated oxidative stress, inflammation, and ER stress in testicular tissue by inhibiting the Nrf2 pathway, a finding that was corroborated by histopathological analyses. However, morin treatments eliminated ACP-induced Nrf2 inhibition and to activate antioxidant and anti-inflammatory mechanisms. These findings were also corroborated by the restoration of serum testosterone and inhibin B levels and the diminution of histopathological lesions.

CONCLUSIONS

Overall, the findings indicated that morin may have potential protective properties against ACP-associated reproductive toxicity, however, further research is required to determine the detailed molecular mechanisms.

Relationships of residential distance to greenhouse floriculture and organophosphate, pyrethroid, and neonicotinoid urinary metabolite concentration in Ecuadorian Adolescents

BACKGROUND

Adolescents living in agricultural areas are at higher risk of secondary pesticide exposure; however, there is limited evidence to confirm exposure by pesticide drift for greenhouse floriculture, like rose production.

METHODS

525 adolescents (12-17, 49% male) living in Pedro Moncayo, Ecuador were assessed in 2016. Urinary concentrations of creatinine and pesticide biomarkers (organophosphates, neonicotinoids, and pyrethroids) were measured using mass-spectrometry. Home distance to the nearest greenhouse and surface area of greenhouses within various buffer sizes around the home were calculated. Linear regression assessed whether home distance and surface area of greenhouses was associated with creatinine-adjusted metabolite concentration, adjusting for demographic, socioeconomic, and anthropometric variables. Geospatially weighted regression (GWR) was conducted, adjusting for similar covariates. Getis-ord Gi* identified hot and cold spots using a 1994 m distance band.

RESULTS

The associations between residential distance to greenhouses and urinary pesticide metabolites differed by metabolite type. The adjusted mean concentrations of OHIM (neonicotinoid) were greater (p-difference = 0.02) among participants living within 200 m (1.08 ug/g of creatinine) vs > 200 m (0.64 ug/g); however, the opposite was observed for 3,5,6-Trichloro-2-pyridinol (TCPy, organophosphate; 0-200 m: 3.63 ug/g vs > 200 m: 4.30 ug/g, p-diff = 0.05). In linear models, greater distances were negatively associated with para-nitrophenol (PNP, organophosphate; percent difference per 50% greater distance [95% CI]: - 2.5% [- 4.9%, - 0.1%]) and somewhat with 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy, organophosphate; - 4.0% [- 8.3%, 0.4%]), among participants living within 200 m of greenhouses. Concurring with the adjusted means analyses, opposite (positive) associations were observed for TCPy (2.1% [95%CI 0.3%, 3.9%]). Organophosphate and pyrethroid hotspots were found in parishes with greater greenhouse density, whereas neonicotinoid hot spots were in parishes with the lowest greenhouse density.

CONCLUSION

We observed negative associations between residential distance to greenhouses with OHIM, PNP and to some extent IMPy, suggesting that imidacloprid, parathion and diazinon are drifting from floricultural greenhouses and reaching children living within 200 m. Positive TCPy associations suggest greenhouses weren't the chlorpyrifos source during this study period, which implies that non-floricultural open-air agriculture (e.g. corn, potatoes, strawberries, grains) may be a source. Further research incorporating diverse geospatial constructs of pesticide sources, pesticide use reports (if available), participant location tracking, and repeated metabolite measurements is recommended.

Highly sensitive chemiluminometric and colorimetric probes for acetamiprid assay based on Cu2SnS3 quantum dots with peroxide-mimicking activity

Cu2SnS3 quantum dots (QDs) were employed to create colorimetric and chemiluminometric probes for the detection of acetamiprid. We demonstrated that the chemiluminescence (CL) signal of the luminol-hydrogen peroxide system, as well as the absorbance of the oxidation product of TMB with H2O2, was enhanced by the catalytic effect of Cu2SnS3 QDs. Additionally, the enhanced signals from both probes (CL intensity and absorbance) were diminished upon the addition of acetamiprid to the reaction mixture owing to the decrease in the generation of reactive oxygen species (ROS) via the interaction of hydroxyl radicals with cyanide groups of acetamiprid during the reactions. Based on these findings, we developed a colorimetric sensor for acetamiprid with both spectrophotometer-based and smartphone-based detections (with detection limits of 3.6 nM and 14.2 nM, respectively), alongside a CL sensor with a detection limit of 2.7 nM. The sensors were employed for analyzing food and water samples, yielding satisfactory results. These probes combine the advantages of both techniques, including a low limit of detection and rapid response time of CL, as well as the simplicity, cost-effectiveness, and portable nature of smartphone-based colorimetry that also allows for in-field visual detection.

Embryonic exposure to acetamiprid insecticide induces CD68-positive microglia and Purkinje cell arrangement abnormalities in the cerebellum of neonatal rats

Concerns have been raised regarding acetamiprid (ACE), a neonicotinoid insecticide, due to its potential neurodevelopmental toxicity. ACE, which is structurally similar to nicotine, acts as an agonist of nicotinic acetylcholine receptors (nAChRs) and resists degradation by acetylcholinesterase. Furthermore, ACE has been reported to disrupt neuronal transmission and induce developmental neurotoxicity and ataxia in animal models. However, the prenatal ACE exposure and its pathological changes, including impacts on motor control, remains unclear. In this study, we investigated the effects of ACE exposure, focusing on the development of cerebellar neurons and glia, which are linked to motor impairment. ACE at doses of 20, 40-, and 60 mg/kg body weight was administered to Pregnant Wistar rats via feed on gestational day (G) 15. The developing cerebellum of the pups was examined on postnatal days (P) 7, 14, and 18, corresponding to the critical periods of cerebellar maturation in rodents. Our data revealed that ACE exposure at 40 and 60 mg/kg induced abnormal neuronal alignment on P14, and neuronal cell loss on P18. Additionally, ACE altered microglial behavior, with an increase in the number of CD68-positive microglia, suggesting that the exposure results in an increase in phagocytic microglia in response to neuronal abnormalities, ultimately leading to neuronal cell loss. Pups exposed to 60 mg/kg ACE exhibited hindlimb clasping during the hindlimb suspension test, indicating motor impairment. These findings suggest that ACE exposure causes neuronal cell loss of developing Purkinje cells and promotes a phase shift to the activate mode of microglia. This study further highlights the crucial role of neuron-glia interactions in ACE-induced motor impairment, thus contributing to our understanding of the potential risks associated with prenatal ACE exposure.

Associations between Neonicotinoid, Pyrethroid, and Organophosphate Insecticide Metabolites and Neurobehavioral Performance in Ecuadorian Adolescents

Background

Organophosphate and pyrethroid insecticides can affect children's neurodevelopment and increase inflammation. Limited evidence exists among adolescents and on whether inflammation may mediate pesticide-neurobehavior associations. We examined the associations between insecticide metabolite concentrations and neurobehavior among adolescents in Ecuadorian agricultural communities.

Methods

We included 520 participants aged 11-17 years. We measured urinary insecticide metabolites (mass spectrometry) and neurobehavior (NEPSY-II). Associations were adjusted for socio-demographic and anthropometric characteristics. The associations of insecticide mixtures with neurobehavior were evaluated using PLS regression, and mediation by inflammatory biomarkers (TNF-α, IL-6, CRP, SAA, sICAM-1, sVCAM-1 and sCD-14) was conducted.

Results

Among organophosphates, para-nitrophenol (PNP) and 3,5,6-Trichloro-2-pyridinol (TCPy) were inversely associated with Social Perception (score difference per 50% increase [β 50% ] = -0.26 [95%CI: - 1.07, -0.20] and -0.10 [-0.22, 0.01], respectively). PNP and TCPy also had significant inverse associations with Attention/Inhibitory Control at concentrations >60 th percentile (β 50% = -0.26 [95%CI: -0.51, -0.01] and β 50% = -0.22 [95%CI: -0.43, -0.00], respectively). The pyrethroid, 3-phenoxybenzoic acid (3-PBA), was inversely associated with Language (β 50% = -0.13 [95%CI: -0.19, -0.01]) and had a negative quadratic association with Attention/Inhibitory Control. The neonicotinoid 5-Hydroxy imidacloprid (OHIM) was positively associated with Memory/Learning (β 50% = 0.20 [95%CI: 0.04, 0.37]). Mixtures of all insecticides were significantly negatively related to all domains, except for Memory/Learning, which was positively associated. No mediation by inflammatory markers on these associations was observed.

Conclusions

Concurrent organophosphate, pyrethroid, and the mixtures of all metabolites were associated with lower performance in all domains except for Memory/Learning. Neonicotinoids were positively associated with Memory/Learning and Social Perception scores.

Neonicotinoid pesticides: evidence of developmental neurotoxicity from regulatory rodent studies

Neonicotinoids are the most widely used class of insecticides in the United States (U.S.). and the world. Consistent with their high use and persistence, neonicotinoids are often found contaminating drinking water and food. They are also detected in human urine, breast milk, amniotic and cerebrospinal fluids, as well as the brains of treated rodents. Neonicotinoids were once thought to pose little neurotoxic risk to humans, but a growing body of research challenges that assumption. In this study we provide the first comprehensive assessment of unpublished rodent developmental neurotoxicity (DNT) studies on five neonicotinoids that were submitted to the U.S. Environmental Protection Agency (EPA) by neonicotinoid manufacturers. Groups of female rats were administered three different doses of a neonicotinoid during pregnancy and lactation, and their offspring subjected to various neurological tests and brain measurements. We identified nicotine-like effects such as reduced brain size, indicative of neuronal cell loss. Statistically significant shrinkage of brain tissue was observed in high-dose offspring for five neonicotinoids: acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam. Two brain regions reduced in the rodent studies-the corpus callosum and caudate-putamen-tend to be smaller in people diagnosed with attention-deficit hyperactivity disorder (ADHD), and in children of mothers who smoked during pregnancy, suggesting a possible link between perinatal neonicotinoid exposure and ADHD. A decreased auditory startle reflex was reported for acetamiprid at all doses and was statistically significant in the mid- and high-dose offspring, and for clothianidin in juvenile high-dose females. No mid- or low-dose brain morphometric data were submitted for acetamiprid, imidacloprid, or thiacloprid. Thiamethoxam mid- and low-dose brain morphometric data were provided to EPA upon request. Only partial mid-dose brain morphometry data were submitted for clothianidin, but no low-dose data. Yet despite this lack of data, EPA concluded that only the high-dose brain morphometric effects were treatment-related-setting the mid-dose as the study's No Observed Adverse Effect Level (NOAEL) or failing to find a definitive NOAEL for acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam. We found numerous deficiencies in EPA's regulatory oversight and data analyses. EPA dismissed statistically significant adverse effects, accepted substandard DNT studies despite lack of valid positive control data, and allowed neonicotinoid registrants to unduly influence agency decision-making. We conclude that perinatal exposure to neonicotinoids and their metabolites induces adverse, nicotine-like neurotoxic effects in rodent bioassays, and that the exposure limits set by EPA for human exposure are either not protective or not supported by available neurotoxicity data. We propose regulatory changes to empower EPA to better protect public health from developmental neurotoxins like neonicotinoids.

Decreases in the number of microglia and neural circuit dysfunction elicited by developmental exposure to neonicotinoid pesticides in mice

Neonicotinoids are insecticides widely used in the world. Although neonicotinoids are believed to be toxic only to insects, their developmental neurotoxicity in mammals is a concern. Therefore, we examined the effects of developmental exposure to neonicotinoids on immune system in the brain and post-developmental behaviors in this study. Imidacloprid or clothianidin was orally administered to dams at a dosage of 0.1 mg/kg/day from embryonic day 11 to postnatal day 21. Imidacloprid decreased sociability, and both imidacloprid and clothianidin decreased locomotor activity and induced anxiety, depression and abnormal repetitive behaviors after the developmental period. There was no change in the number of neurons in the hippocampus of mice exposed to imidacloprid. However, the number and activity of microglia during development were significantly decreased by imidacloprid exposure. Imidacloprid also induced neural circuit dysfunction in the CA1 and CA3 regions of the hippocampus during the early postnatal period. Exposure to imidacloprid suppressed the expression of csf1r during development. Collectively, these results suggest that developmental exposure to imidacloprid decreases the number and activity of microglia, which can cause neural circuit dysfunction and abnormal behaviors after the developmental period. Care must be taken to avoid exposure to neonicotinoids, especially during development.

Sex and adrenal hormones in association with insecticide biomarkers among adolescents living in ecuadorian agricultural communities

BACKGROUND

Organophosphate, pyrethroid, and neonicotinoid insecticides have resulted in adrenal and gonadal hormone disruption in animal and in vitro studies; limited epidemiologic evidence exists in humans. We assessed relationships of urinary insecticide metabolite concentrations with adrenal and gonadal hormones in adolescents living in Ecuadorean agricultural communities.

METHODS

In 2016, we examined 522 Ecuadorian adolescents (11-17y, 50.7% female, 22% Indigenous; ESPINA study). We measured urinary insecticide metabolites, blood acetylcholinesterase activity (AChE), and salivary testosterone, dehydroepiandrosterone (DHEA), 17β-estradiol, and cortisol. We used general linear models to assess linear (β = % hormone difference per 50% increase of metabolite concentration) and curvilinear relationships (β2 = hormone difference per unit increase in squared ln-metabolite) between ln-metabolite or AChE and ln-hormone concentrations, stratified by sex, adjusting for anthropometric, demographic, and awakening response variables. Bayesian Kernel Machine Regression was used to assess non-linear associations and interactions.

RESULTS

The organophosphate metabolite malathion dicarboxylic acid (MDA) had positive associations with testosterone (βboys = 5.88% [1.21%, 10.78%], βgirls = 4.10% [-0.02%, 8.39%]), and cortisol (βboys = 6.06 [-0.23%, 12.75%]. Para-nitrophenol (organophosphate) had negatively-trending curvilinear associations, with testosterone (β2boys = -0.17 (-0.33, -0.003), p = 0.04) and DHEA (β2boys = -0.49 (-0.80, -0.19), p = 0.001) in boys. The neonicotinoid summary score (βboys = 5.60% [0.14%, 11.36%]) and the neonicotinoid acetamiprid-N-desmethyl (βboys = 3.90% [1.28%, 6.58%]) were positively associated with 17β-estradiol, measured in boys only. No associations between the pyrethroid 3-phenoxybenzoic acid and hormones were observed. In girls, bivariate response associations identified interactions of MDA, Para-nitrophenol, and 3,5,6-trichloro-2-pyridinol (organophosphates) with testosterone and DHEA concentrations. In boys, we observed an interaction of MDA and Para-nitrophenol with DHEA. No associations were identified for AChE.

CONCLUSIONS

We observed evidence of endocrine disruption for specific organophosphate and neonicotinoid metabolite exposures in adolescents. Urinary organophosphate metabolites were associated with testosterone and DHEA concentrations, with stronger associations in boys than girls. Urinary neonicotinoids were positively associated with 17β-estradiol. Longitudinal repeat-measures analyses would be beneficial for causal inference.

EFSA (European Food Safety Authority), Hernandez‐Jerez A, Coja T, Paparella M, Price A, Henri J, Focks A, Louisse J, Terron A, Binaglia M, Guajardo IM, Mangas I, Guajardo IM, Ferreira L, Kardassi D, De Lentdecker C, Molnar T, Vianello G. Statement on the toxicological properties and maximum residue levels of acetamiprid and its metabolites

Acetamiprid is a pesticide active substance with insecticidal action whose approval was renewed by Commission Implementing Regulation (EU) 2018/113. In January 2022, the EFSA PPR Panel published a statement following a request from the European Commission to advise on human health or the environment based on new scientific evidence presented by France during the decision-making phase. In July 2022, by means of a further mandate received from the European Commission, EFSA was requested to provide advice if new information and any other scientific evidence that has become available since the assessment conducted for the renewal in 2018 warrant re-evaluation of (i) toxicological parameters used for the risk assessment of acetamiprid during the renewal process, including toxicological endpoints; (ii) the residue definition for acetamiprid in products of plant origin; and (iii) the safety of existing maximum residue levels (MRLs). Meanwhile, the applicant of acetamiprid in the EU submitted new toxicology studies regarding the toxicological profile of the metabolite IM-2-1. Furthermore, the European Commission was made aware that several recent publications in scientific literature were made available after the literature searches conducted by EFSA. As the new data could affect the advice that EFSA was expected to deliver through the 2022 mandate, EFSA was further requested to consider this information by means of a revised mandate received in September 2023. As regards re-evaluation of point (i) in this statement, this was addressed by an EFSA Working Group integrating all the available evidence. The results of the weight of evidence indicated that there are major uncertainties in the body of evidence for the developmental neurotoxicity (DNT) properties of acetamiprid and further data are therefore needed to come to a more robust mechanistic understanding to enable appropriate hazard and risk assessment. In view of these uncertainties, the EFSA WG proposed to lower the acceptable daily intake (ADI) and acute reference dose (ARfD) from 0.025 to 0.005 mg/kg body weight (per day). A revised residue definition for risk assessment was proposed for leafy and fruit crops as sum of acetamiprid and N-desmethyl-acetamiprid (IM-2-1), expressed as acetamiprid. Regarding pulses/oilseeds, root crops and cereals, the new data received did not indicate a need to modify the existing residue definition for risk assessment, which therefore remains as parent acetamiprid. Regarding the residue definition for enforcement, the available data did not indicate a need to modify the existing definition because acetamiprid is still a sufficient marker of the residues in all crop groups. Considering the new health-based guidance values derived in the present statement, a risk for consumer has been identified for 38 MRLs currently in place in the EU Regulation. Consequently, EFSA recommended to lower the existing MRLs for 38 commodities based on the assessment of fall-back Good Agricultural Practices received within an ad hoc data call. Some fall-back MRLs proposals require further risk management considerations.

Non-acute exposure of neonicotinoids, health risk assessment, and evidence integration: a systematic review

Neonicotinoid pesticides are utilized against an extensive range of insects. A growing body of evidence supports that these neuro-active insecticides are classified as toxicants in invertebrates. However, there is limited published data regarding their toxicity in vertebrates and mammals. the current systematic review is focused on the up-to-date knowledge available for several neonicotinoid pesticides and their non-acute toxicity on rodents and human physiology. Oral lethal dose 50 (LD50) of seven neonicotinoids (i.e. imidacloprid, acetamiprid, clothianidin, dinotefuran, thiamethoxam, thiacloprid, and nitenpyram) was initially identified. Subsequently, a screening of the literature was conducted to collect information about non-acute exposure to these insecticides. 99 studies were included and assessed for their risk of bias and level of evidence according to the Office of Health and Translation (OHAT) framework. All the 99 included papers indicate evidence of reproductive toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, immunotoxicity, and oxidative stress induction with a high level of evidence in the health effect of rodents and a moderate level of evidence for human health. The most studied type of these insecticides among 99 papers was imidacloprid (55 papers), followed by acetamiprid (22 papers), clothianidin (21 papers), and thiacloprid (11 papers). While 10 of 99 papers assessed the relationship between clothianidin, thiamethoxam, dinotefuran, and nitenpyram, showing evidence of liver injury, dysfunctions of oxidative stress markers in the reproductive system, and intestinal toxicity. This systematic review provides a comprehensive overview of the potential risks caused by neonicotinoid insecticides to humans and rodents with salient health effects. However, further research is needed to better emphasize and understand the patho-physiological mechanisms of these insecticides, taking into account various factors that can influence their toxicity.

Long-lasting developmental effects in rat offspring after maternal exposure to acetamiprid in the drinking water during gestation

Neonicotinoids (NNTs) are a class of insecticides proposed to be safe for pest control in urban, suburban, and agricultural applications. However, little is known about their developmental effects after repeated low-dose exposures during gestation. Here, we tested a dose considered subthreshold for maternal toxicity in rats (6 mg/kg/day) by assessing several morphological, biochemical, and neurobehavioral features in preterm fetuses and developing pups after maternal administration of the NTT acetamiprid (ACP) dissolved in the drinking water during gestational days (GD) 2-19. The exploratory evaluation included monitoring maternal body weight gain, fetal viability, body weight and sex ratio, cephalic length, neonatal body weight and sex ratio, metabolic enzymes in the placenta, maternal blood and fetal liver, and anogenital distance and surface righting response during infancy. We also used the circling training test to study the integrity of the associative-spatial-motor response in adolescence. Results showed no consistent findings indicating maternal, reproductive or developmental toxicity. However, we found ACP effects on maternal body weight gain, placental butyrylcholinesterase activity, and neurobehavioral responses, suggestive of a mild toxic action. Thus, our study showed a trend for developmental susceptibility at a dose so far considered subtoxic. Although the ACP concentration in environmental samples of surface water and groundwater has been mostly reported to be much lower than that used in our study, our results suggest that the ACP point of departure used in current guidelines aimed to prevent developmental effects may need to be verified by complementary sensitive multiple-endpoint testing in the offspring.

Molecular Docking Analysis at the Human α7-nAChR and Proliferative and Evoked-Calcium Changes in SH-SY5Y Cells by Imidacloprid and Acetamiprid Insecticides

Acetamiprid (ACE) and Imidacloprid (IMI) are widely-used neonicotinoid insecticides (NNIs) with functional activity at human acetylcholine nicotinic receptors and, therefore, with putative toxic effects. The objective of this study was the evaluation of the interactions between NNIs and α7-nAChR, as this receptor keeps intracellular Ca2+ ([Ca2+]i) to an optimum for an adequate neuronal functioning. Possible interactions between NNIs and the cryo-EM structure of the human α-7 nAChR were identified by molecular docking. Additionally, NNI effects were analyzed in neuroblastoma SH-SY5Y cells, as they naturally express α-7 nAChRs. Functional studies included proliferative/cytotoxic effects (MTT test) in undifferentiated SH-SY-5Y cells and indirect measurements of [Ca2+]i transients in retinoic acid-differentiated SH-SY-5Y cells loaded with Fluo-4 AM. Docking analysis showed that the binding of IMI and ACE occurred at the same aromatic cage that the specific α-7 nAChR agonist EVP-6124. IMI showed a better docking strength than ACE. According to the MTT assays, low doses (10-50 µM) of IMI better than ACE stimulated neuroblastoma cell proliferation. At higher doses (250-500 µM), IMI also prevailed over ACE and dose-dependently triggered more abrupt fluorescence changes due to [Ca2+]i mobilization in differentiated SH-SY5Y neurons. Indeed, only IMI blunted nicotine-evoked intracellular fluorescence stimulation (i.e., nicotine cross-desensitization). Summarizing, IMI demonstrated a superior docking strength and more robust cellular responses compared to ACE, which were likely associated with a stronger activity at α-7nAChRs. Through the interaction with α-7nAChRs, IMI would demonstrate its high neurotoxic potential for humans. More research is needed for investigating the proliferative effects of IMI in neuroblastoma cells.

Noninvasive imaging of rat-derived microglia and its reactivity to inflammatory molecules via acoustic impedance microscopy

PURPOSE

Microglia, the brain's immune cells, play important roles in neuronal differentiation, survival, and death. The function of microglia is deeply related to the morphologies; however, it is too complex to observe conventionally and identify the condition of living microglia using optical microscopes. Herein, we proposed a new method to observe living cultured microglia and their reactivity to inflammation via the acoustic impedance mode of a scanning acoustic microscope.

METHODS

Primary cultured microglia collected from rat pups exposed to acetamiprid, an insecticide, in utero were observed with both acoustic interface impedance mode (C-mode) and transparent three-dimensional impedance mode (B-mode).

RESULTS

We characterized microglia into four types based on the results obtained from acoustic impedance, cytoskeletal information, and laser confocal imaging. Biphasic acoustic observation using B-mode and C-mode gave us information regarding the dynamic morphologies of living microglia treated with adenosine triphosphate (ATP) (600 μmol/L), which reflects distress signals from inflamed neurons. Acetamiprid exposure induced microglia response even in the neonatal period. ATP stimulus altered the shape and thickness of microglia with a change in the bulk modulus of the cell. Three-dimensional alteration with ATP stimulus could be observed only after biphasic acoustic observation using B-mode and C-mode. This acoustic observation was consistent with confocal observation using anti-Iba-1 and P2Y12 immunocytochemistry.

CONCLUSION

This study demonstrated the adequacy of using a scanning acoustic microscope in analyzing microglia's shape, motility, and response to inflammation.

Neurocytotoxicity of imidacloprid- and acetamiprid-based comercial insecticides over the differentiation of SH-SY5Y neuroblastoma cells

Neonicotinoids are effective insecticides with specificity for invertebrate nicotinic acetylcholine receptors. Neonicotinoids are chemically stable and tend to remain in the environment for long so concerns about their neurotoxicity in humans do nothing but increase. Herein, we evaluated the chronic toxic effects of acetamiprid- and imidacloprid-based insecticides over the differentiation of human neuroblastoma SH-SY5Y cells, which were exposed to these insecticides at a concentration range similar to that applied to crop fields (0.01-0.5 mM). Both insecticides did not have acute cytotoxic effects in both non-differentiated and in staurosporine-differentiated SH-SY5Y cells cytotoxicity as measured by the MTT and vital-dye exclusion tests. However, after a chronic (7-day) treatment, only imidacloprid dose-dependently decreased the viability of SH-SY5Y cells (F(4,39) = 43.05, P < 0.001), largely when administered-during cell differentiation (F(4,39) = 51.86, P < 0.001). A well-defined dose-response curve was constructed for imidacloprid on day 4 (R² = 0.945, EC₅₀ = 0.14 mM). During differentiation, either imidacloprid or acetamiprid dose-dependently caused neurite branch retraction on day 3, likely because of oxidative stress, to the extent that cells turned into spheres without neurites after 7-day treatment. Despite their apparent safety, the neurodevelopmental vulnerability of SH-SY5Y neurons to the chronic exposure to imidacloprid and to a lesser extent to acetamiprid points to a neurotoxic risk for humans.

Impact of endocrine disruptors from mother's diet on immuno-hormonal orchestration of brain development and introduction of the virtual human twin tool

Diet has long been known to modify physiology during development and adulthood. However, due to a growing number of manufactured contaminants and additives over the last few decades, diet has increasingly become a source of exposure to chemicals that has been associated with adverse health risks. Sources of food contaminants include the environment, crops treated with agrochemicals, inappropriate storage (e.g., mycotoxins) and migration of xenobiotics from food packaging and food production equipment. Hence, consumers are exposed to a mixture of xenobiotics, some of which are endocrine disruptors (EDs). The complex interactions between immune function and brain development and their orchestration by steroid hormones are insufficiently understood in human populations, and little is known about the impact on immune-brain interactions by transplacental fetal exposure to EDs via maternal diet. To help to identify the key data gaps, this paper aims to present (a) how transplacental EDs modify immune system and brain development, and (b) how these mechanisms may correlate with diseases such as autism and disturbances of lateral brain development. Attention is given to disturbances of the subplate, a transient structure of crucial significance in brain development. Additionally, we describe cutting edge approaches to investigate the developmental neurotoxicity of EDs, such as the application of artificial intelligence and comprehensive modelling. In the future, highly complex investigations will be performed using virtual brain models constructed using sophisticated multi-physics/multi-scale modelling strategies based on patient and synthetic data, which will enable a greater understanding of healthy or disturbed brain development.

Effects of insufficient serine on health and selenoprotein expression in rats and their offspring

Objective

To observe the impact of insufficient exogenous and/or endogenous serine on selenoprotein expression and health of pregnant rats and their offspring.

Method

Experiment 1 was conducted in male rats, in which the dose-dependent effects of serine on selenoprotein expression and thyroid hormones (T3, T4 and TSH) were investigated by feeding either a serine adequate diet (20C), serine-deprived diet (20CSD) or 20CSD with different serine levels (0.5, 1.0, and 2.0 times the amount of serine in 20C). In experiment 2, a PHGDH inhibitor was administrated to pregnant rats fed either 20C or 20CSD. Blood and organ tissues of pregnant rats and offspring were subjected to the analyses of thyroid hormone, serine and homocysteine and GPx3 and SELENOP in plasma and expression of GPx1 and DIO1, 2 in tissues respectively.

Result

In experiment 1, plasma SELENOP and GPx3 levels in adult male rats increased with the increasing dose of serine. Immunohistochemical results showed that GPx1 expression in liver and kidney of male rats also increased with increasing serine supplementation. Amongst all diet groups, only male rats fed 20CSD had significantly lower plasma TSH and T4 levels (P < 0.05). In experiment 2, GPx1 and DIO2 expression in the liver and kidney were suppressed in pregnant rats administered with a PHGDH compared to those who were not (P < 0.05). There were no significant differences in plasma T4 and T3 amongst all diet groups (P > 0.05). Also, offspring born to pregnant rats administered with a PHGDH inhibitor exhibited slower growth rates and hyperhomocysteinemia compared to offspring from mothers not administered with the inhibitor (P < 0.05). Conclusions: Insufficient exogenous serine through the diet decreased selenoprotein synthesis in adult male rats. However, this was not observed in pregnant rats, whereby exogenous or endogenous serine deficiency had no effect on the selenoprotein levels. A possible explanation is that dams may have an adaptive mechanism to limit maternal serine utilization and ensure adequate supply to the fetus.

Urinary neonicotinoid concentrations and pubertal development in Chinese adolescents: A cross-sectional study

BACKGROUND

Animal studies suggest that exposure to certain neonicotinoids may interfere with the normal function of endocrine system in mammals. However, evidence from human studies is limited.

OBJECTIVES

This study conducted a cross-sectional analysis to examine urinary neonicotinoids concentrations in Chinese adolescents and its association with pubertal development.

METHODS

774 urine samples from 439 boys (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) and 335 girls (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) were collected for determination of ten neonicotinoids (imidacloprid, nitenpyram, acetamiprid, thiacloprid, imidaclothiz, thiamethoxam, clothianidin, dinotefuran, flonicamid, sulfoxaflor) and one metabolite (N-desmethyl-acetamiprid). Urinary creatinine was detected for concentration adjustment. Pubertal development including pubic hair, axillary hair, genitalia (boys), testicular volume (boys) and breast (girls) assessed by Tanner stages and others (spermarche, facial hair for boys and menarche for girls) were obtained by physical examination and questionnaire. Logistic and bayesian kernel machine regression were used to investigate the association between neonicotinoids concentrations and pubertal developments.

RESULTS

High detection rates ranged from 72.0% to 100.0% for all neonicotinoids. Boys and girls with thiacloprid concentration at the >75th percentile had lower stage of genitalia development (OR: 0.83, 95% CI: 0.33-0.93) and higher stage of axillary hair development (OR: 1.46, 95% CI: 1.12-3.41), respectively, compared with those at the <25th percentile. The estimate change in genitalia stage was significantly different at or above the 75th percentile concentration of neonicotinoids mixture compared to the 50th percentile concentration. No associations were found between other urinary neonicotinoids and other indicators of puberty.

CONCLUSIONS

Higher thiacloprid concentration was associated with delayed genitalia development in boys and early axillary hair development in girls. Neonicotinoids mixture was negatively associated with genitalia stage in the joint effect. Given the characteristic of the cross-sectional study, our results need further confirmation of the causal relationship.

Prenatal neonicotinoid insecticides Exposure, oxidative Stress, and birth outcomes

BACKGROUND

An increasing number of studies have reported neonicotinoid insecticides (NEOs), the emerging alternatives to conventional insecticides, may increase oxidative stress and cause adverse health effects, but limited is known about the prenatal NEOs exposures and their impact on birth outcomes.

OBJECTIVES

We investigated the levels of prenatal exposure to NEOs/metabolites, to assess their associations with birth outcomes, and investigate whether these associations could be mediated by oxidative stress using 8-OHdG as the biomarker.

METHODS

We studied 296 mother-infant pairs recruited from Laizhou Wan Birth Cohort in 2010 - 2013. Two NEOs (IMI and ACE), three metabolites (6-CN, ND-ACE, and 2CTCA), and 8-OHdG were measured in maternal urine collected before delivery. Birth outcomes including birth weight, birth length, ponderal index (PI), head circumference, and gestational age, were acquired. We examined the associations between NEOs/metabolites and birth outcomes using multivariable linear regression. Mediation analysis was conducted to clarify the role of 8-OHdG on the association of NEOs/metabolites exposure and birth outcomes.

RESULTS

Highest detection rate was observed for ACE (100.0%), followed by IMI (98.3%) and 6-CN (98.0%), suggesting the common exposure of pregnant women. The highest median concentration was observed for 6-CN with creatinine-adjusted median levels of 9.58 μg/g creatinine. A decrease in newborns' head circumference was observed with a 10-fold increase in IMI (β = -1.83; 95% CI = -3.04, -0.62) and ACE (β = -2.27; 95% CI = -3.56, -0.98). An increase in newborns' PI was observed with a 10-fold increase in IMI (β = 0.40; 95% CI = 0.03, 0.75). Maternal 8-OHdG demonstrated 38.5-65.5% mediating effects in the negative association of IMI, ACE, 2-CTCA with head circumference. These associations might differ between boys and girls.

CONCLUSIONS

Pregnant women were widely exposed to NEOs/metabolites in China. Results suggested the potential impacts of prenatal exposure to certain neonicotinoid insecticides on head circumference. Urinary 8-OHdG may partly mediate these associations.

Ca2+ imaging with two-photon microscopy to detect the disruption of brain function in mice administered neonicotinoid insecticides

Neonicotinoid pesticides are a class of insecticides that reportedly have harmful effects on bees and dragonflies, causing a reduction in their numbers. Neonicotinoids act as neuroreceptor modulators, and some studies have reported their association with neurodevelopmental disorders. However, the precise effect of neonicotinoids on the central nervous system has not yet been identified. Herein, we conducted in vivo Ca²⁺ imaging using a two-photon microscope to detect the abnormal activity of neuronal circuits in the brain after neonicotinoid application. The oral administration of acetamiprid (ACE) (20 mg/kg body weight (BW) in mature mice with a quantity less than the no-observed-adverse-effect level (NOAEL) and a tenth or half of the median lethal dose (LD₅₀) of nicotine (0.33 or 1.65 mg/kg BW, respectively), as a typical nicotinic acetylcholine receptor (nAChR) agonist, increased anxiety-like behavior associated with altered activities of the neuronal population in the somatosensory cortex. Furthermore, we detected ACE and its metabolites in the brain, 1 h after ACE administration. The results suggested that in vivo Ca²⁺ imaging using a two-photon microscope enabled the highly sensitive detection of neurotoxicant-mediated brain disturbance of nerves.

Microbe mediated remediation of dyes, explosive waste and polyaromatic hydrocarbons, pesticides and pharmaceuticals

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Environmental pollutants dyes, pesticides, pharmaceuticals, explosive waste and polyaromatic hydrocarbons.

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Environmental pollutants toxicity.

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Possible microbial biodegradation pathways of environmental pollutants.

Industrialization and human activities have led to serious effects on environment. With the progress taking place in the biodegradation field, it is important to summarize the latest advancement. In this review, we intend to provide insights on the recent progress on the biodegradation of environmental contaminants such as dyes, pesticides, pharmaceuticals, explosive waste and polyaromatic hydrocarbons by microorganisms. Along with the biodegradation of environmental contaminants, toxicity effects have also been discussed.

Statement on the active substance acetamiprid

Acetamiprid is a pesticide active substance with insecticidal action currently under the third renewal (AIR3) of the Commission implementing regulation (EU) No 844/2012. Following concerns that this substance may pose high risks to humans and the environment, the French authorities asked the Commission to restrict its uses under Article 69 of Regulation (EC) No 1107/2009. To support this request, competent Authorities from France cited a series of literature papers investigating its hazards and/or exposure to humans and the environment. Consequently, the EFSA PPR Panel was mandated to advise on the likelihood that body of evidence would constitute proof of serious risks to humans or the environment. Therefore, the EFSA PPR Panel evaluated the likelihood of these studies indicating new or higher hazards and exposure to humans and the environment compared to previous EU assessments.A stepwise methodology was designed, including: (i) the initial screening; (ii) the data extraction and critical appraisal based on the principles of OHAT/NTP; (iii) the weight of evidence, including consideration of the previous EU assessments; (iv) the uncertainty analysis, followed, whenever relevant, by an expert knowledge elicitation process. For human health, no conclusive evidence of higher hazards compared to previous assessment was found for genotoxicity, developmental toxicity, neurotoxicity including developmental neurotoxicity and immunotoxicity. However, due to the lack of adequate assessment of the current data set, the PPR Panel recommends conducting an assessment of endocrine disrupting properties for acetamiprid in line with EFSA/ECHA guidance document for the identification of endocrine disruptors. For environment, no conclusive, robust evidence of higher hazards compared to the previous assessment was found for birds, aquatic organisms, bees and soil organisms. However, the potential of high inter-species sensitivity of birds and bees towards acetamiprid requires further consideration.

Neurotoxic Effects of Neonicotinoids on Mammals: What Is There beyond the Activation of Nicotinic Acetylcholine Receptors?-A Systematic Review

Neonicotinoids are a class of insecticides that exert their effect through a specific action on neuronal nicotinic acetylcholine receptors (nAChRs). The success of these insecticides is due to this mechanism of action, since they act as potent agonists of insect nAChRs, presenting low affinity for vertebrate nAChRs, which reduces potential toxic risk and increases safety for non-target species. However, although neonicotinoids are considered safe, their presence in the environment could increase the risk of exposure and toxicity. On the other hand, although neonicotinoids have low affinity for mammalian nAChRs, the large quantity, variety, and ubiquity of these receptors, combined with its diversity of functions, raises the question of what effects these insecticides can produce in non-target species. In the present systematic review, we investigate the available evidence on the biochemical and behavioral effects of neonicotinoids on the mammalian nervous system. In general, exposure to neonicotinoids at an early age alters the correct neuronal development, with decreases in neurogenesis and alterations in migration, and induces neuroinflammation. In adulthood, neonicotinoids induce neurobehavioral toxicity, these effects being associated with their modulating action on nAChRs, with consequent neurochemical alterations. These alterations include decreased expression of nAChRs, modifications in acetylcholinesterase activity, and significant changes in the function of the nigrostriatal dopaminergic system. All these effects can lead to the activation of a series of intracellular signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. Neonicotinoid-induced changes in nAChR function could be responsible for most of the effects observed in the different studies.

Maternal administration of bisphenol A alters the microglial profile in the neocortex of mouse weanlings

Bisphenol A (BPA) is known to cause abnormal neurogenesis in the developing neocortex. The mechanisms of BPA toxicity concerning neuroinflammatory-related endpoints are incompletely characterized. To evaluate the microglial morphology and the gene expression of pro-inflammatory cytokines in the newborn neocortex, ICR mice were exposed to BPA 200 μg/kg/d on gestational day 6 through post-partum day 21. Weanlings exposed during prenatal and postnatal period to BPA showed an increased number of amoeboid-type microglia, a microglial differentiation disruption (the M1/M2 microglial ratio), and an abnormal expression of genes encoding pro-inflammatory factors. These findings suggest that the well-known neurodevelopmental toxicity of BPA may be related to an increased microglial activation and neuroinflammation in the neocortex.

Laboratory scale UV-visible degradation of acetamiprid in aqueous marketed mixtures - Structural elucidation of photoproducts and toxicological consequences

Acetamiprid is a neonicotinoid pesticide, which is extensively used on agricultural crops, but has a high toxic effect on beneficial insects and the human body. It is exposed to sunlight irradiation on crops but also in surface waters where it is found at a high level due to its resistance to common water treatments. The aim of the present work was to study the UV-visible photodegradation of acetamiprid, alone and in two marketed mixtures (Polysect Ultra SL® and Roseclear Ultra®). Ten photoproducts were characterized using LC-HR-MS/MS analysis. Photodegradation pathways were proposed based on the chemical structures of photoproducts and kinetic measurements; a matrix effect has been evidenced for commercial mixtures. Most photoproducts exhibit potential developmental toxicity twice higher than that of the parent compound. Regarding potential mutagenicity, all photoproducts are less toxic than acetamiprid. Estimated oral rat LD50 values show that the potential toxicities of photoproducts are similar or lower than that of acetamiprid. In vitro tests on Vibrio fischeri bacteria showed that the ecotoxicities of marketed mixtures are significantly higher than that of acetamiprid in aqueous solution; they slightly increase after UV-light exposure.

An Overview on the Effect of Neonicotinoid Insecticides on Mammalian Cholinergic Functions through the Activation of Neuronal Nicotinic Acetylcholine Receptors

Neonicotinoid insecticides are used worldwide and have been demonstrated as toxic to beneficial insects such as honeybees. Their effectiveness is predominantly attributed to their high affinity for insect neuronal nicotinic acetylcholine receptors (nAChRs). Mammalian neuronal nAChRs are of major importance because cholinergic synaptic transmission plays a key role in rapid neurotransmission, learning and memory processes, and neurodegenerative diseases. Because of the low agonist effects of neonicotinoid insecticides on mammalian neuronal nAChRs, it has been suggested that they are relatively safe for mammals, including humans. However, several lines of evidence have demonstrated that neonicotinoid insecticides can modulate cholinergic functions through neuronal nAChRs. Major studies on the influence of neonicotinoid insecticides on cholinergic functions have been conducted using nicotine low-affinity homomeric α7 and high-affinity heteromeric α4β2 receptors, as they are the most abundant in the nervous system. It has been found that the neonicotinoids thiamethoxam and clothianidin can activate the release of dopamine in rat striatum. In some contexts, such as neurodegenerative diseases, they can disturb the neuronal distribution or induce oxidative stress, leading to neurotoxicity. This review highlights recent studies on the mode of action of neonicotinoid insecticides on mammalian neuronal nAChRs and cholinergic functions.

Maternal Nicotine Exposure During Gestation and Lactation Period Affects Behavior and Hippocampal Neurogenesis in Mouse Offspring

Cigarette smoking or nicotine exposure during pregnancy is associated with numerous obstetrical, fetal, and developmental complications, as well as an increased risk of adverse health consequences in the adult offspring. In this study, we examined the effects of maternal nicotine exposure during perinatal and lactation stages on behavioral performance and hippocampal neurogenesis in the adolescent stage of offspring mice. Female C57BL/mice received nicotine in drinking water (200 μg/ml nicotine) or vehicle (1% saccharin) starting from 2 weeks premating until the offspring were weaned on postnatal day 20. Experiments started on postnatal day 35. Female offspring with maternal nicotine exposure presented an increase in anxiety-like behavior in an open-field test. BrdU assay revealed that nicotine offspring presented an increase in cell proliferation in hippocampal dentate gyrus, but the number of BrdU⁺ cells was decreased in one week and further decreased in three weeks. The occurrence of disarray of DCX⁺ cells increased in both male and female nicotine offspring. The density of microglial marker protein Iba1 was significantly increased in the nicotine offspring. Furthermore, the expression of microglia marker Iba1, the CX3CL1, CX3CR1, and downstream molecules PKA and p-ErK were significantly increased in the nicotine group. In summary, maternal nicotine exposure affects both hippocampal neurogenesis and microglial activity in the adolescent offspring.

Exposure to neonicotinoid insecticides in the U.S. general population: Data from the 2015-2016 national health and nutrition examination survey

BACKGROUND

Neonicotinoids are used for insect control in agriculture, landscaping, and on household pets. Neonicotinoids have become popular replacements for organophosphate and carbamate insecticides, and use is on the rise.

OBJECTIVES

To assess human exposure to neonicotinoid insecticides in a representative sample of the U.S. general population 3 years and older from the 2015-2016 National Health and Nutrition Examination Survey (NHANES).

METHODS

We used online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry after enzymatic hydrolysis of conjugates to quantify in 3038 samples the urinary concentrations of six neonicotinoid biomarkers: four parent compounds (acetamiprid, clothianidin, imidacloprid, thiacloprid) and two metabolites (N-desmethyl-acetamiprid, 5-hydroxy-imidacloprid). We calculated distribution percentiles, and used regression models to evaluate associations of various demographic parameters and fasting time with urinary concentrations above the 95th percentile (a value selected to represent higher than average concentrations) of neonicotinoid biomarkers.

RESULTS

Weighted detection frequencies were 35% (N-desmethyl-acetamiprid), 19.7% (5-hydroxy imidacloprid), 7.7% (clothianidin), 4.3% (imidacloprid), and <0.5% (acetamiprid, thiacloprid). The weighted frequency of having detectable concentrations of at least one of the six biomarkers examined was 49.1%. The 95th percentile concentrations for N-desmethyl-acetamiprid, 5-hydroxy imidacloprid, and clothianidin were 1.29, 1.37, and 0.396 μg/L, respectively. For people who fasted <8 h, regardless of race/ethnicity and sex, 3-5 year old children were more likely to have N-desmethyl-acetamiprid concentrations above the 95th percentile than adolescents (adjusted odds ratio (OR) = 3.12; 95% confidence interval [CI], (0.98-9.98)) and adults (adjusted OR = 4.29; 95% CI, (2.04-9.0)); and children 6-11 years of age were more likely than adults to have N-desmethyl-acetamiprid concentrations above the 95th percentile (adjusted OR = 2.65; 95% CI, (1.2-5.84)). Asians were more likely than non-Asians to have concentrations above the 95th percentile of N-desmethyl-acetamiprid (adjusted OR = 1.94; 95% CI, (1.08-3.49)) and 5-hydroxy-imidacloprid (adjusted OR = 2.25; 95% CI, (1.44-3.51)). Samples collected during the summer were more likely to have metabolite concentrations above the 95th percentile than those collected in the winter (adjusted OR 1.55 for N-desmethyl-acetamiprid, and 2.43 for 5-hydroxy-imidacloprid).

CONCLUSIONS

The detection of neonicotinoid metabolites more frequently and at much higher concentrations than the corresponding parent compounds suggests that the metabolites may be suitable biomarkers to assess background exposures. About half of the U.S. general population 3 years of age and older was recently exposed to neonicotinoids. Compared to other age ranges and ethnicities, young children and Asians may experience higher exposures. At present, reasons for such differences remain unknown.

The neonicotinoids acetamiprid and imidacloprid impair neurogenesis and alter the microglial profile in the hippocampal dentate gyrus of mouse neonates

Acetamiprid (ACE) and imidacloprid (IMI) are widely used neonicotinoid pesticides. They bind selectively to insect nicotinic acetylcholine receptors (nAChRs) and are considered non-hazardous to mammals. Few studies have assessed the activation of vertebrate nAChRs and the neurodevelopmental toxicity following in utero or neonatal exposure to neonicotinoids; therefore, we evaluated the effects of ACE or IMI exposure on neurogenesis and microglial profiles in the developing hippocampal dentate gyrus (DG) of mouse neonates. Mice were exposed to ACE, IMI (both 5 mg/kg/day) or nicotine (0.5 mg/kg/day) from postnatal day (P)12 to P26 by oral gavage. On P27, brains were removed, and neurogenesis and microglial activation in the hippocampal DG were examined via immunohistochemistry. A reduction in neurogenesis in the hippocampal DG of neonates following ACE, IMI and nicotine treatment was found. Additionally, neonicotinoid-exposed newborns showed an increase in the number of amoeboid-type and activated M1-type microglia. These results suggest that exposure to ACE and IMI impairs neurogenesis and alters microglial profiles in the developing hippocampal DG following oral dosing in an early postnatal period. A better understanding of the potential effects of these pesticides on human infant health is an important goal of our research.