Neurodevelopmental consequences of gestational and lactational exposure to pyrethroids in rats

Effects of daily exposure to pyrethroid pesticides during infancy on children neurodevelopment at age four: A prospective study in rural Yunnan, China

INTRODUCTION

Exposure to pyrethroid pesticides (PYRs) of children in infancy at ages 1 and 2 may affect their neurodevelopmental outcomes at age 4.

OBJECTIVES

The study aimed to explore the longitudinal association of infancy PYRs exposure with neurodevelopment at age 4.

METHODS

This study based on Xuanwei birth cohort study that started from January 2016 in rural Yunnan, China. Urine samples (n = 263) at ages 1 and 2 were tested for PYRs metabolites 3-phenoxybenzoic acid (3-PBA), 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), and cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DBCA). PYRs metabolites were classified as low and high exposure using the 75th percentile values. Neurodevelopment of children aged 4 was assessed by Griffiths Development Scales-Chinese Edition (GDS-C). The development quotient below 85 was defined as low development level. Multiple linear regression and logistic regression were used to analyze the association of children's PYRs exposure with their neurodevelopmental outcomes.

RESULTS

Children's PYRs metabolites detection rates were 98.48 % in infants at both age 1 and 2. The average levels of 3-PBA, 4-F-3-PBA and DBCA were 0.51 µg/L, 0.30 µg/L and < 0.09 µg/L, respectively at age 1; and 0.88 µg/L, 0.82 µg/L, and 0.52 µg/L at age 2. The levels of three metabolites in 2-year-olds were higher than those in 1-year-olds. The children aged 4 had a general developmental quotient of 90.87 ± 11.37, with 28.14 % classified in low development level. Multiple linear regression analysis showed that higher 3-PBA level at 2-year-old was negatively associated with the quotient in locomotor (β=-14.61, 95 % CI: -24.93, -4.30) and language (β=-10.89, 95 % CI: -19.38, -2.41). Logistic regression displayed that higher 3-PBA level aged 2 was positively correlated with low development level in the language domain (OR=3.23, 95 % CI: 1.33, 7.83), but negatively correlated with personal social domain (OR=0.23, 95 % CI: 0.07, 0.79).

CONCLUSION

Children were widely exposed to PYRs in infancy, which may impact on their neurodevelopment at age 4. Age 2 may be a sensitive window when PYRs exposure may negatively impact locomotor and language development. This study suggests that PYRs exposure should be minimized or avoided in child care, especially in children aged 2 years.

A Shotgun Proteomic-Based Approach with a Q-Exactive Hybrid Quadrupole-Orbitrap High-Resolution Mass Spectrometer for the Assessment of Pesticide Mixture-Induced Neurotoxicity on a 3D-Developed Neurospheroid Model from Human Brain Meningiomas: Identification of Trityl-Post-Translational Modification

The widespread use of pesticides, particularly in combinations, has resulted in enhanced hazardous health effects. However, little is known about their molecular mechanism of interactions. The aim of this study was to assess the neurotoxicity effect of pesticides in mixtures by adopting a 3D in vitro developed neurospheroid model, followed by treatment by increased concentrations of pesticides for 24 h and analysis by a shotgun proteomic-based approach with high-resolution tandem mass spectrometry. Three proteins, namely, glyceraldehyde-3-phosphate-dehydrogenase (GAPDH), α-enolase, and phosphoglycerate-kinase-1, were selected as key targets in the metabolic process. Only high doses of pesticides mitigated cell-density proliferation with the occurrence of apoptotic cells, which unlikely makes any neurological alterations in environmental regulatory exposures. The proteomic analysis showed that majority of altered proteins were implicated in cell metabolism. De novo peptide sequencing revealed ion losses and adduct formation, namely, a trityl-post-translational modification in the active site of 201-GAPDH protein. The study also highlights the plausible role of pyrethroids to be implicated in the deleterious effects of pesticides in a mixture. To the best of our knowledge, our finding is the first in toxicoproteomics to deeply elucidate pesticides' molecular interactions and their ability to adduct proteins as a pivotal role in the neurotoxicity mechanism.

Endocrine-Disrupting Effects of Transplacental and Translactational Exposure to Tembotrione on Hormone Status in Wistar Rat Offspring at Different Developmental Stages: A Pilot Study

Green agronomy promotes the implementation of natural and naturally derived substances in crop protection. In the present study, we evaluated the endocrine-disrupting potential of the allelopathic herbicide tembotrione in Wistar rats by studying the hormone status of offspring from the treated dams. Three doses of tembotrione (0.0004, 0.0007, and 4.0 mg/kg b.w./day) have been administered to dams during gestation and/or lactation. In the serum of newborn, weaning, and pubertal female and male offspring, 17β-estradiol and testosterone were determined using enzyme-linked immunosorbent assay. A decrease in 17β-estradiol and testosterone was observed in female and male weaning and pubertal offspring exposed to all doses of tembotrione during gestation and lactation. In weaning offspring exposed only during lactation, 17β-estradiol dropped significantly after exposure to the two lower doses and testosterone after exposure to the lowest dose of tembotrione. The greatest effect was observed at the lowest dose of tembotrione. In newborns, we observed increased 17β-estradiol after exposure to two lower doses of tembotrione and significantly increased testosterone after exposure to the lowest dose. The highest dose of tembotrione decreased 17β-estradiol significantly in newborn females. The obtained results suggest that tembotrione might be considered a pro-estrogenic or estrogen agonistic compound under the exposure conditions applied in this investigation.

Maternal exposure to deltamethrin during pregnancy and lactation impairs neurodevelopment of male offspring

Deltamethrin (DM) is a highly effective and widely used pyrethroid pesticide. It is an environmental factor affecting public and occupational health and exerts direct toxic effects on the central nervous system. As the major target organs for neurotoxicity of DM, the hippocampus and the cerebellum are critical to the learning and motor function. Pregnant Wistar rats were randomly divided into four groups and gavaged at doses of 0, 1, 4or 10 mg/kg/d DM from gestational day (GD) 0 to postnatal day (PN) 21. The PC12 cells were selected to further verify the regulatory mechanisms of DM on the neurodevelopmental injury. We found that maternal exposure to DM caused learning, memory and motor dysfunction in male offspring. Maternal exposure to DM induced the decrease in the density of hippocampal dendritic spines in male offspring through the reduced expression of M1 mAchRs, which in turn reduced the mediated AKT/mTOR signaling pathway, contributing to the inhibition of dynamic changes of GluA1. Meanwhile, DM exposure inhibited the BDNF/TrkB signaling pathway, thereby reducing phosphorylation of stathmin and impairing cerebellar purkinje cell dendrite growth and development. Taken together, maternal exposure to DM during pregnancy and lactation could impair neurodevelopment of male offspring.

Echinacea purpurea extract intervention for counteracting neurochemical and behavioral changes induced by bifenthrin

This study was conducted to elucidate the possible protective efficiency of Echinacea purpurea hydroethanolic extract (EchEE) against bifenthrin (BIF)-induced neuro-chemical and behavioral changes in rats. Total phenolics content, reducing power and radical scavenging activity of EchEE were estimated. Four groups of adult male albino rats were used (10 rats each) as follows: 1) Control healthy rats ingested with placebo, 2) Healthy rats orally received EchEE (465 mg/kg/day), 3) Rats intoxicated with BIF (7mg/kg/day) dissolved in olive oil, and 4) Rats co-treated with EchEE (465 mg/kg/day) besides to BIF (7mg/kg/day) intoxication. After 30 days, some neuro-chemical and behavioral tests were assessed. The behavioral tests revealed that rats received BIF exhibited exploratory behavior and spatial learning impairments, memory and locomotion dysfunction, and enhanced anxiety level. Biochemical findings revealed that BIF induced-oxidative stress in the cortex and hippocampus; this was appeared from the significant rise in malondialdehyde (MDA) and nitric oxide (NO) levels, coupled with decreased catalase (CAT), superoxide dismutase (SOD), paraoxonase-1 (PON-1) activities, and reduced glutathione (GSH) level in both brain areas. Also, BIF induced a significant increase caspas-3, tumor necrosis factor alpha (TNF), and interleukin-1beta (IL-1ß) in both areas; dopamine and serotonin levels, and ACh-ase activity were markedly decreased in both areas. Interestingly, treatment of rats with EchEE in combination with BIF resulted in a significant decrease in oxidative stress damage, and modulation of the apoptotic and pro-inflammatory markers. Also, EchEE markedly improved behavioral activities and neurotransmitters level that were impaired by BIF. In conclusion, the present study clearly indicated that EchEE can attenuate brain dysfunction induced by pesticides exposure through preventing the oxidative stress. This may be attributed to its high antioxidant component.

Shotgun Proteomic-Based Approach with a Q-Exactive Hybrid Quadrupole-Orbitrap High-Resolution Mass Spectrometer for Protein Adductomics on a 3D Human Brain Tumor Neurospheroid Culture Model: The Identification of Adduct Formation in Calmodulin-Dependent Protein Kinase-2 and Annexin-A1 Induced by Pesticide Mixture

Pesticides are increasingly used in combinations in crop protection, resulting in enhanced toxicities for various organisms. Although protein adductomics is challenging, it remains a powerful bioanalytical tool to check environmental exposure and characterize xenobiotic adducts as putative toxicity biomarkers with high accuracy, facilitated by recent advances in proteomic methodologies and a mass spectrometry high-throughput technique. The present study aims to predict the potential neurotoxicity effect of imidacloprid and λ-cyhalothrin insecticides on human neural cells. Our protocol consisted first of 3D in vitro developing neurospheroids derived from human brain tumors and then treatment by pesticide mixture. Furthermore, we adopted a bottom-up proteomic-based approach using nanoflow ultraperformance liquid chromatography coupled with a high-resolution mass spectrometer for protein-adduct analysis with prediction of altered sites. Two proteins were selected, namely, calcium-calmodulin-dependent protein kinase-II (CaMK2) and annexin-A1 (ANXA1), as key targets endowed with primordial roles. De novo sequencing revealed several adduct formations in the active site of 82-ANXA1 and 228-CaMK2 as a result of neurotoxicity, predicted by the added mass shifts for the structure of electrophilic precursors. To the best of our knowledge, our study is the first to adopt a proteomic-based approach to investigate in depth pesticide molecular interactions and their potential to adduct proteins which play a crucial role in the neurotoxicity mechanism.

Delayed in sensorimotor reflex ontogeny, slow physical growth, and impairments in behaviour as well as dopaminergic neuronal death in mice offspring following prenatally rotenone administration

The environment is varying day by day with the introduction of chemicals such as pesticides, most of which have not been effectively studied for their influence on a susceptible group of population involving infants and pregnant females. Rotenone is an organic pesticide used to prepare Parkinson's disease models. A lot of literature is available on the toxicity of rotenone on the adult brain, but to the best of our knowledge, effect of rotenone on prenatally exposed mice has never been investigated yet. Therefore, the recent work aims to evaluate the toxic effect of rotenone on mice, exposed prenatally. We exposed female mice to rotenone at the dose of 5 mg/Kg b.w. throughout the gestational period with oral gavage. We then investigated the effects of rotenone on neonate's central nervous systems as well as on postnatal day (PD) 35 offspring. In the rotenone group, we observed slow physical growth, delays in physical milestones and sensorimotor reflex in neonates and induction of anxiety and impairment in cognitive performances of offspring at PD-35. Additionally, immunohistochemical analysis revealed a marked reduction in TH-positive neurons in substantia nigra. Histological examination of the cerebellum revealed a decrease in Purkinje neurons in the rotenone exposed group as compared to the control. The data from the study showed that prenatally exposure to rotenone affects growth, physical milestones, neuronal population and behaviour of mice when indirectly exposed to the offspring through their mother. This study could provide a great contribution to researchers to find out the molecular mechanism and participating signalling pathway behind these outcomes.

Influence of bifenthrin exposure at different gestational stages on the neural development

Perinatal exposure to bifenthrin (BF) alters neurodevelopment. However, the most susceptible time period to BF exposure and the possible mechanisms are not clear. In the current study, pregnant female mice were treated with BF (0.5 mg/kg/d) at three different stages [gestational day (GD) 0-5, 6-15 and 16-birth (B)] and neurologic deficits were evaluated in offspring mice. BF exposure at GD 16-B significantly altered the locomotor activity and caused learning and memory impairments in 6-week-old offspring. Gestational BF exposure also caused neuronal loss in the region of cornu ammonis of hippocampi of 6-week-old offspring. Interestingly, neurobehavioral impairments and neuronal loss were not observed in offspring at 10-week-old. BF exposure at GD 16-B also decreased protein levels of VGluT1, NR1 and NR2A while increased the protein levels of NR2B and VGAT1, as well as the gene levels of Il-1β, Il-6 and Tnf-α in hippocampi of 6-week-old offspring. Collectively, these data demonstrate that gestational exposure to a low dose BF causes neurodevelopmental deficits that remit with the age and the late-stage of pregnancy is the most susceptible time window to BF exposure. Imbalance in excitatory/inhibitory neuronal transmission, altered expression levels of NMDA receptors and increased neural inflammation may be associated with BF prenatal exposure-triggered neurobehavioral impairments.

Detection methods, migration patterns, and health effects of pesticide residues in tea

Due to its rich health benefits and unique cultural charm, tea drinking is increasingly popular with the public in modern society. The safety of tea is the top priority that affects the development of tea industry and the health of consumers. During the process of tea growth, pesticides are used to prevent the invasion of pests and diseases with maintaining high quality and stable yield. Because hot water brewing is the traditional way of tea consumption, water is the main carrier for pesticide residues in tea into human body accompanied by potential risks. In this review, pesticides used in tea gardens are divided into two categories according to their solubility, among which water-soluble pesticides pose a greater risk. We summarized the methods of the sample pretreatment and detection of pesticide residues and expounded the migration patterns and influencing factors of tea throughout the process of growth, processing, storage, and consumption. Moreover, the toxicity and safety of pesticide residues and diseases caused by human intake were analyzed. The risk assessment and traceability of pesticide residues in tea were carried out, and potential eco-friendly improvement strategies were proposed. The review is expected to provide a valuable reference for reducing risks of pesticide residues in tea and ensuring the safety of tea consumption.

Effects of pyrethroids on the cerebellum and related mechanisms: a narrative review

Pyrethroids (PYRs) are a group of synthetic organic chemicals that mimic natural pyrethrins. Due to their low toxicity and persistence in mammals, they are widely used today. PYRs exhibit higher lipophilicity than other insecticides, which allows them to easily penetrate the blood-brain barrier and directly induce toxic effects on the central nervous system. Several studies have shown that the cerebellum appears to be one of the regions with the largest changes in biomarkers. The cerebellum, which is extremely responsive to PYRs, functions as a crucial region for storing motor learning memories. Exposure to low doses of various types of PYRs during rat development resulted in diverse long-term effects on motor activity and coordination functions. Reduced motor activity may result from developmental exposure to PYRs in rats, as indicated by delayed cerebellar morphogenesis and maturation. PYRs also caused adverse histopathological and biochemical changes in the cerebellum of mothers and their offspring. By some studies, PYRs may affect granule cells and Purkinje cells, causing damage to cerebellar structures. Destruction of cerebellar structures and morphological defects in Purkinje cells are known to be directly related to functional impairment of motor coordination. Although numerous data support that PYRs cause damage to cerebellar structures, function and development, the mechanisms are not completely understood and require further in-depth studies. This paper reviews the available evidence on the relationship between the use of PYRs and cerebellar damage and discusses the mechanisms of PYRs.

Gestational Exposure to Cyfluthrin through Endoplasmic Reticulum (ER) Stress-Mediated PERK Signaling Pathway Impairs Placental Development

Cyfluthrin, a typical type II pyrethroid pesticide, is widely used in house hygiene and agricultural pest control. Several epidemiological investigations have found that maternal pyrethroid exposure is connected to adverse pregnancy outcomes. However, the underlying mechanisms remain to be elucidated. Thus, we evaluated the effect of cyfluthrin exposure during pregnancy on placenta development in vivo. In the current study, Pregnant SD rats were randomly divided into four groups and administered 6.25, 12.5, and 25 mg/kg body weight cyfluthrin or an equivalent volume of corn oil by gavage from GD0 to GD19. The results have shown that gestational exposure to cyfluthrin exerted no effect on the fetal birth defect, survival to PND4, or fetal resorption and death. However, live fetuses and implantation sites significantly decreased in the high-dose cyfluthrin-treated group. Moreover, a significant reduction in placenta weight and diameter was observed in rats. Correspondingly, the fetal weight and crown-rump length from dams exposed to cyfluthrin were reduced. Cyfluthrin-treat groups, the total area of the placenta, spongiotrophoblast area, and labyrinth area had abnormal changes. Meanwhile, the area of blood sinusoid and CD34-positive blood vessel numbers in the placenta were considerably reduced, as well as abnormal expression of placental pro-angiogenic and anti-angiogenic factors in dams exposed to cyfluthrin. Further observation by transmission electron microscopy revealed significant changes in the ultrastructure of the medium-dose and high-dose groups. Additional experiments showed gestational exposure to cyfluthrin inhibited proliferation and induced apoptosis of placentas, as decreased PCNA-positive cells and increased TUNEL-positive cells. Furthermore, western blot and qPCR analysis revealed that gestational exposure to medium-dose and high-dose cyfluthrin increased the expression of GRP78, and three downstream mRNA and proteins (p-eIF2α, ATF4, and CHOP) of the PERK signaling, indicating that endoplasmic reticulum (ER) stress-mediated PERK/eIF2α/ATF4/CHOP signaling pathway in rat placentas was activated. Our study demonstrated that gestational exposure to cyfluthrin leads to placental developmental disorder, which might be associated with ER stress-mediated PERK signaling pathway.

In utero alcohol exposure impairs vessel-associated positioning and differentiation of oligodendrocytes in the developing neocortex

Prenatal alcohol exposure (PAE) is a major cause of nongenetic mental retardation and can lead to fetal alcohol syndrome (FAS), the most severe manifestation of fetal alcohol spectrum disorder (FASD). FASD infants present behavioral disabilities resulting from neurodevelopmental defects. Both grey and white matter lesions have been characterized and are associated with apoptotic death and/or ectopic migration profiles. In the last decade, it was shown that PAE impairs brain angiogenesis, and the radial organization of cortical microvessels is lost. Concurrently, several studies have reported that tangential migration of oligodendrocyte precursors (OPCs) originating from ganglionic eminences is vascular associated. Because numerous migrating oligodendrocytes enter the developing neocortex, the present study aimed to determine whether migrating OPCs interacted with radial cortical microvessels and whether alcohol-induced vascular impairments were associated with altered positioning and differentiation of cortical oligodendrocytes. Using a 3D morphometric analysis, the results revealed that in both human and mouse cortices, 15 to 40% of Olig2-positive cells were in close association with radial cortical microvessels, respectively. Despite perinatal vascular disorganization, PAE did not modify the vessel association of Olig2-positive cells but impaired their positioning between deep and superficial cortical layers. At the molecular level, PAE markedly but transiently reduced the expression of CNPase and MBP, two differentiation markers of immature and mature oligodendrocytes. In particular, PAE inverted their distribution profiles in cortical layers V and VI and reduced the thickness of the myelin sheath of efferent axons. These perinatal oligo-vascular defects were associated with motor disabilities that persisted in adults. Altogether, the present study provides the first evidence that Olig2-positive cells entering the neocortex are associated with radial microvessels. PAE disorganized the cortical microvasculature and delayed the positioning and differentiation of oligodendrocytes. Although most of these oligovascular defects occurred in perinatal life, the offspring developed long-term motor troubles. Altogether, these data suggest that alcohol-induced oligo-vascular impairments contribute to the neurodevelopmental issues described in FASD.

Beneficial effects of kebar grass (Biophytum petersianum klotzsch) ethanol extract to increase motor reflex and spatial memory in mice offspring (Mus musculus) from lactating mothers exposed to carbofuran

BACKGROUND AND PURPOSE

This study aimed to determine the potency of kebar grass ethanol extract to overcome an increase in cerebellar neuronal cell necrosis, which has an impact on decreasing motor reflex function and spatial memory of mice from lactating mothers exposed to carbofuran.

EXPERIMENTAL APPROACH

Forty lactating mice were divided into four groups, 10 each; including control, T1 (carbofuran 0.0125 mg/day), T2 (vitamin C 5 mg + carbofuran 0.0125 mg/day), T3 (kebar grass extract 3.375 mg + carbofuran 0.0125 mg/day). The mice were orally administered with carbofuran, vitamin C, and kebar grass extract on days 0 to 14 postnatal. On the 15th day, brains of the mice were necropsied to measure the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH), H&E staining; motor reflex tests were performed on 10-day-old mice, and the mice aged 30 days were tested on their swimming and spatial memory.

FINDINGS / RESULTS

Carbofuran caused an increase in MDA, GSH, neuronal cell necrosis, surface righting reflex, a decrease in SOD, swimming ability, and spatial memory. Kebar grass extract and vitamin C administration decreased MDA, GSH, neuron necrosis, surface righting reflex, and increased SOD, swimming ability, and spatial memory.

CONCLUSION AND IMPLICATIONS

Exposing to carbofuran in lactating mice caused brain oxidative stress, impaired motor reflexes, and spatial memory in mice offspring. Kebar grass extract and vitamin C administration prevented brain oxidative stress and inhibited disorders in motor reflexes, and spatial memory in mice offspring. Kebar grass extract administration was more effective than vitamin C.

Analysis of six pyrethroid insecticide metabolites in cord serum using a novel gas chromatography-ion trap mass spectrometry method

Pyrethroid insecticides are commonly used for residential and commercial pest control in the US. Pregnant women and their fetuses are vulnerable to pesticide exposures during critical windows of neurodevelopment. Biomonitoring for exposure requires accurate and sensitive methods to assess exposures during pregnancy. The objective of this study was to develop a sensitive analytical method to measure pyrethroid metabolite concentrations in cord serum. Six pyrethroid metabolites, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid (c/t-DCCA), trans-chrysanthemum dicarboxylic acid (t-CDCA), cis-3-(2,2-dibromovinyl)-2,2-dimethyl-cyclopropane carboxylic acid (c-DBCA), 4-fluoro-3-phenoxybenzoic acid (FPBA), and 3-phenoxybenzoic acid (3PBA) were extracted from cord serum by a dichloromethane liquid-liquid extraction, derivatized by 1,1,1,3,3,3-hexafluoro-2-propanol carboxylic acid esterification, and then measured by gas chromatography/ion trap mass spectrometry. Limits of detection ranged from 0.02 to 0.6 ng/mL. Sixty-three cord serum samples were collected from maternal-fetal dyads in central New Jersey to test for pyrethroid metabolites. Non-specific metabolites, 3PBA, t-DCCA, and t-CDCA, were detected most frequently, present in 29%, 6.3% and 6.3% of samples, respectively. Sensitivities were comparable or greater than other published studies assessing pyrethroid metabolites in cord blood. Comparisons with other literature-reported studies emphasize the importance of method sensitivity when assessing exposures at biologically relevant concentrations.

Bifenthrin impairs the functions of Leydig and Sertoli cells in mice via mitochondrion-endoplasmic reticulum dysregulation

Bifenthrin (BF) is a synthetic insecticide that is widely used in fields, resulting in an increase in its exposure to animals. However, reports on the toxic effects of BF on mammalian species and the underlying mechanism are still lacking. Here, we elucidated the mechanism underlying the toxic effects of BF on mouse reproduction using cell lines of immature mouse Leydig (TM3) and Sertoli (TM4) cells, which are constituent cells of testes. Our results show that BF suppressed the proliferation and viability of TM3 and TM4 cells. Additionally, treatment with BF induced cell cycle arrest, apoptotic cell death, and DNA fragmentation. Mitochondrial dysfunction and disruption of calcium homeostasis were observed in BF-treated TM3 and TM4 cells. Further, bifenthrin modulated unfolded protein response and mitochondrion-associated membrane and mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) signaling pathways. The expression of the mRNAs related to cell cycle progression, steroidogenesis, and spermatogenesis was downregulated by BF, suggestive of testicular toxicity. Taken together, these results demonstrate the intracellular mechanism of action of BF to involve antiproliferative and apoptotic effects and testicular dysfunction in mouse testis.

Evaluation of Chemical Effects on Network Formation in Cortical Neurons Grown on Microelectrode Arrays

Thousands of chemicals to which humans are potentially exposed have not been evaluated for potential developmental neurotoxicity (DNT), driving efforts to develop a battery of in vitro screening approaches for DNT hazard. Here, 136 unique chemicals were evaluated for potential DNT hazard using a network formation assay (NFA) in cortical cells grown on microelectrode arrays. The effects of chemical exposure from 2 h postplating through 12 days in vitro (DIV) on network formation were evaluated at DIV 5, 7, 9, and 12, with cell viability assessed at DIV 12. Only 82 chemicals altered at least 1 network development parameter. Assay results were reproducible; 10 chemicals tested as biological replicates yielded qualitative results that were 100% concordant, with consistent potency values. Toxicological tipping points were determined for 58 chemicals and were similar to or lower than the lowest 50% effect concentrations (EC50) for all parameters. When EC50 and tipping point values from the NFA were compared to the range of potencies observed in ToxCast assays, the NFA EC50 values were less than the lower quartile for ToxCast assay potencies for a subset of chemicals, many of which are acutely neurotoxic in vivo. For 13 chemicals with available in vivo DNT data, estimated administered equivalent doses based on NFA results were similar to or lower than administered doses in vivo. Collectively, these results indicate that the NFA is sensitive to chemicals acting on nervous system function and will be a valuable contribution to an in vitro DNT screening battery.

Beneficial Effects of Remifentanil Against Excitotoxic Brain Damage in Newborn Mice

Background: Remifentanil, a synthetic opioid used for analgesia during cesarean sections, has been shown in ex vivo experiments to exert anti-apoptotic activity on immature mice brains. The present study aimed to characterize the impact of remifentanil on brain lesions using an in vivo model of excitotoxic neonatal brain injury. Methods: Postnatal day 2 (P2) mice received three intraperitoneal injections of remifentanil (500 ng/g over a 10-min period) or saline just before an intracortical injection of ibotenate (10 μg). Cerebral reactive oxygen species (ROS) production, cell death, in situ labeling of cortical caspase activity, astrogliosis, inflammation mediators, and lesion size were determined at various time points after ibotenate injection. Finally, behavioral tests were performed until P18. Results: In the injured neonatal brain, remifentanil significantly decreased ROS production, cortical caspase activity, DNA fragmentation, interleukin-1β levels, and reactive astrogliosis. At P7, the sizes of the ibotenate-induced lesions were significantly reduced by remifentanil treatment. Performance on negative geotaxis (P6-8) and grasping reflex (P10-12) tests was improved in the remifentanil group. At P18, a sex specificity was noticed; remifentanil-treated females spent more time in the open field center than did the controls, suggesting less anxiety in young female mice. Conclusions: In vivo exposure to remifentanil exerts a beneficial effect against excitotoxicity on the developing mouse brain, which is associated with a reduction in the size of ibotenate-induced brain lesion as well as prevention of some behavioral deficits in young mice. The long-term effect of neonatal exposure to remifentanil should be investigated.

Non-target toxicity of novel insecticides

Humans have used insecticides since ancient times. The spectrum and potency of available insecticidal substances has greatly expanded since the industrial revolution, resulting in widespread use and unforeseen levels of synthetic chemicals in the environment. Concerns about the toxic effects of these new chemicals on non-target species became public soon after their appearance, which eventually led to the restrictions of use. At the same time, new, more environmentally-friendly insecticides have been developed, based on naturally occurring chemicals, such as pyrethroids (derivatives of pyrethrin), neonicotinoids (derivatives of nicotine), and insecticides based on the neem tree vegetable oil (Azadirachta indica), predominantly azadirachtin. Although these new substances are more selective toward pest insects, they can still target other organisms. Neonicotinoids, for example, have been implicated in the decline of the bee population worldwide. This review summarises recent literature published on non-target toxicity of neonicotinoids, pyrethroids, and neem-based insecticidal substances, with a special emphasis on neonicotinoid toxicity in honeybees. We also touch upon the effects of pesticide combinations and documented human exposure to these substances.

Time- and sex-dependent efficacy of magnesium sulfate to prevent behavioral impairments and cerebral damage in a mouse model of cerebral palsy

Cerebral lesions acquired in the perinatal period can induce cerebral palsy (CP), a multifactorial pathology leading to lifelong motor and cognitive deficits. Several risk factors, including perinatal hypoxia-ischemia (HI), can contribute to the emergence of CP in preterm infants. Currently, there is no international consensus on treatment strategies to reduce the risk of developing CP. A meta-analysis showed that magnesium sulfate (MgSO₄) administration to mothers at risk of preterm delivery reduces the risk of developing CP (Crowther et al., 2017). However, only a few studies have investigated the long-term effects of MgSO₄ and it is not known whether sex would influence MgSO₄ efficacy. In addition, the search for potential deleterious effects is essential to enable broad use of MgSO₄ in maternity wards. We used a mouse model of perinatal HI to study MgSO₄ effects until adolescence, focusing on cognitive and motor functions, and on some apoptosis and inflammation markers. Perinatal HI at postnatal day 5 (P(5)) induced (1) sensorimotor deficits in pups; (2) increase in caspase-3 activity 24 h after injury; (3) production of proinflammatory cytokines from 6 h to 5 days after injury; (4) behavioral and histological alterations in adolescent mice with considerable interindividual variability. MgSO₄ prevented sensorimotor alterations in pups, with the same efficacy in males and females. MgSO₄ displayed anti-apoptotic and anti-inflammatory effects without deleterious side effects. Perinatal HI led to motor coordination impairments in female adolescent mice and cognitive deficits in both sexes. MgSO₄ tended to prevent these motor and cognitive deficits only in females, while it prevented global brain tissue damage in both sexes. Moreover, interindividual and intersexual differences appeared regarding the lesion size and neuroprotection by MgSO₄ in a region-specific manner. These differences, the partial prevention of disorders, as well as the mismatch between histological and behavioral observations mimic clinical observations. This underlines that this perinatal HI model is suitable to further analyze the mechanisms of sex-dependent perinatal lesion susceptibility and MgSO₄ efficacy.

Magnesium Sulfate Prevents Neurochemical and Long-Term Behavioral Consequences of Neonatal Excitotoxic Lesions: Comparison Between Male and Female Mice

Magnesium sulfate (MgSO4) administration to mothers at risk of preterm delivery is proposed as a neuroprotective strategy against neurological alterations such as cerebral palsy in newborns. However, long-term beneficial or adverse effects of MgSO4 and sex-specific sensitivity remain to be investigated. We conducted behavioral and neurochemical studies of MgSO4 effects in males and females, from the perinatal period to adolescence in a mouse model of cerebral neonatal lesion. The lesion was produced in 5-day-old (P5) pups by ibotenate intracortical injection. MgSO4 (600 mg/kg, i.p.) prior to ibotenate prevented lesion-induced sensorimotor alterations in both sexes at P6 and P7. The lesion increased glutamate level at P10 in the prefrontal cortex, which was prevented by MgSO4 in males. In neonatally lesioned adolescent mice, males exhibited more sequelae than females in motor and cognitive functions. In the perirhinal cortex of adolescent mice, the neonatal lesion induced an increase in vesicular glutamate transporter 1 density in males only, which was negatively correlated with cognitive scores. Long-term sequelae were prevented by neonatal MgSO4 administration. MgSO4 never induced short- or long-term deleterious effect on its own. These results also strongly suggest that sex-specific neuroprotection should be foreseen in preterm infants.

Developmental neurotoxicity of different pesticides in PC-12 cells in vitro

The detection of developmental neurotoxicity (DNT) of chemicals has high relevance for protection of human health. However, DNT of many pesticides is only little known. Furthermore, validated in vitro systems for assessment of DNT are not well established. Here we employed the rat phaeochromocytoma cell line PC-12 to evaluate DNT of 18 frequently used pesticides of different classes, including neonicotinoids, pyrethroids, organophosphates, organochlorines, as well as quaternary ammonium compounds, the organic compound used in pesticides, piperonyl butoxide, as well as the insect repellent diethyltoluamide (DEET). We determined the outgrowth of neurites in PC-12 cells co-treated with nerve growth factor and different concentrations of biocides for 5days. Furthermore, we determined transcriptional alterations of selected genes that may be associated with DNT, such as camk2α and camk2β, gap-43, neurofilament-h, tubulin-α and tubulin-β. Strong and dose- dependent inhibition of neurite outgrowth was induced by azamethiphos and chlorpyrifos, and dieldrin and heptachlor, which was correlated with up-regulation of gap-43. No or only weak effects on neurite outgrowth and transcriptional alterations occurred for neonicotinoids acetamiprid, clothianidin, imidacloprid and thiamethoxam, the pyrethroids λ-cyhalothrin, cyfluthrin, deltamethrin, and permethrin, the biocidal disinfectants C12-C14-alkyl(ethylbenzyl)dimethylammonium (BAC), benzalkonium chloride and barquat (dimethyl benzyl ammonium chloride), and piperonyl butoxide and DEET. Our study confirms potential developmental neurotoxicity of some pesticides and provides first evidence that azamethiphos has the potential to act as a developmental neurotoxic compound. We also demonstrate that inhibition of neurite outgrowth and transcriptional alterations of gap-43 expression correlate, which suggests the employment of gap-43 expression as a biomarker for detection and initial evaluation of potential DNT of chemicals.

Chemical Pesticides and Human Health: The Urgent Need for a New Concept in Agriculture

The industrialization of the agricultural sector has increased the chemical burden on natural ecosystems. Pesticides are agrochemicals used in agricultural lands, public health programs, and urban green areas in order to protect plants and humans from various diseases. However, due to their known ability to cause a large number of negative health and environmental effects, their side effects can be an important environmental health risk factor. The urgent need for a more sustainable and ecological approach has produced many innovative ideas, among them agriculture reforms and food production implementing sustainable practice evolving to food sovereignty. It is more obvious than ever that the society needs the implementation of a new agricultural concept regarding food production, which is safer for man and the environment, and to this end, steps such as the declaration of Nyéléni have been taken.

Chemical Pesticides and Human Health: The Urgent Need for a New Concept in Agriculture

The industrialization of the agricultural sector has increased the chemical burden on natural ecosystems. Pesticides are agrochemicals used in agricultural lands, public health programs, and urban green areas in order to protect plants and humans from various diseases. However, due to their known ability to cause a large number of negative health and environmental effects, their side effects can be an important environmental health risk factor. The urgent need for a more sustainable and ecological approach has produced many innovative ideas, among them agriculture reforms and food production implementing sustainable practice evolving to food sovereignty. It is more obvious than ever that the society needs the implementation of a new agricultural concept regarding food production, which is safer for man and the environment, and to this end, steps such as the declaration of Nyéléni have been taken.