Lysosomal disruption, mitochondrial impairment, histopathological and oxidative stress in rat's nervous system after exposure to a neonicotinoid (imidacloprid).

Imidacloprid (IMI), a neonicotinoid pesticide, has been widely used due to its high efficiency against insect pests. However, its prolonged exposure may pose significant risks to non-target organisms, including mammals. Recent studies have raised concerns about its potential neurotoxicity, yet the underlying mechanisms remain poorly understood. This study aimed to assess the neurotoxic effects of chronic Imidacloprid exposure in Wistar rats, focusing on oxidative stress, mitochondrial dysfunction, and lysosomal disruption. Wistar rats were orally administered two doses of Imidacloprid (5 mg/kg and 50 mg/kg body weight) for three months. Neurotoxic effects were assessed by measuring key biochemical markers such as the enzymatic activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), and glutathione S-transferase (GST). Non-enzymatic markers, including glutathione (GSH) levels and malondialdehyde (MDA) index, were also evaluated. Mitochondrial function was assessed by analyzing oxygen consumption, swelling, and membrane permeability and histopathological changes. Lysosomal stability was examined using the Neutral Red Retention Time (NRRT) assay. Neutral red is a dye that accumulates in the acidic environment of lysosomes. Healthy lysosomes retain the dye, while compromised lysosomes lose it, indicating destabilization. By measuring the amount of neutral red retained in lysosomes, the NRRT assay assesses lysosomal integrity. Lysosomal pH variations were also monitored to evaluate functional changes. Microscopic analysis provided insight into structural changes in lysosomes and other cell components. Lysosomal destabilization was further confirmed by morphological alterations observed through light microscopy, revealing a progressive, time-dependent degeneration of lysosomal structures, including lysosomal expansion, neutral red dye leakage, and cell rounding. These changes reflected a temporal evolution of lysosomal damage, progressing from minor structural disruptions to more severe alterations as exposure continued, observable at the microscopic level. During the study, clinical observations of intoxicated rats included symptoms such as lethargy, reduced activity levels, and impaired motor coordination. High-dose Imidacloprid exposure led to noticeable behavioral changes, including decreased exploratory behavior and altered grooming patterns. Additionally, signs of neurotoxic effects, such as tremors or ataxia, were observed in the rats exposed to the higher dose, reflecting the systemic impact of chronic pesticide exposure. The results revealed a significant decrease in the enzymatic activities of CAT, GPx, and SOD, accompanied by an increase in GST activity. A notable reduction in glutathione levels and a rise in MDA index were observed, indicating enhanced oxidative stress in the brain. Mitochondrial impairment was evidenced by disturbances in oxygen consumption, increased swelling, and altered membrane permeability. Lysosomal destabilization was confirmed by reduced retention of neutral red dye, structural changes in lysosomes, and a significant rise in lysosomal pH in the IMI-exposed groups. In addition, the histopathological features indicate that imidacloprid at the given dose and exposure duration may have caused notable neurotoxic effects in Wistar rat brain tissue. Chronic exposure to Imidacloprid induces oxidative stress, mitochondrial dysfunction, lysosomal disruption and histopathological alterations in the central nervous system of Wistar rats. These findings provide valuable insights into the neurotoxic mechanisms of neonicotinoid pesticides, highlighting the need for further research to understand the long-term effects of Imidacloprid exposure on mammalian health.

Cocktail effects of clothianidin and imidacloprid in zebrafish embryonic development, with high and low concentrations of mixtures.

There is growing concern that sprayed neonicotinoid pesticides (neonics) persist in mixed forms in the environmental soil and water systems, and these concerns stem from reports of increase in both the detection frequency and concentration of these pollutants. To confirm the toxic effects of neonics, we conducted toxicity tests on two neonics, clothianidin (CLO) and imidacloprid (IMD), in embryos of zebrafish. Toxicity tests were performed with two different types of mixtures: potential mixture compounds and realistic mixture compounds. Potential mixtures of CLO and IMD exhibited synergistic effects, in a dose-dependent manner, in zebrafish embryonic toxicity. Realistic mixture toxicity tests that are reflecting the toxic effects of mixture in the aquatic environment were conducted with zebrafish embryos. The toxicity of the CLO and IMD mixture at environmentally-relevant concentrations was confirmed by the alteration of the transcriptional levels of target genes, such as cell damage linked to oxidative stress response and thyroid hormone synthesis related to zebrafish embryonic development. Consequently, the findings of this study can be considered a strategy for examining mixture toxicity in the range of detected environmental concentrations. In particular, our results will be useful in explaining the mode of toxic action of chemical mixtures following short-term exposure. Finally, the toxicity information of CLO and IMD mixtures will be applied for the agricultural environment, as a part of chemical regulation guideline for the use and production of pesticides.

Molecular Recognition Properties of Nicotinic Ligands Determining Selectivity Between Insect and Mammalian Receptors.

This investigation defines the roles of various amino acids, neighboring key conserved amino acids in loops C and D of the nicotinic acetylcholine (ACh) receptor (nAChR), in the selective molecular recognition of nicotinic ligands with diverse pharmacophores using Aplysia californica ACh binding protein Y55W (Ac-AChBP) mutants (+Q57R; + Q57R+S189 V; + Q57R+S189E; + Q57T; + Q57T+S189 V; + Q57T+S189E) and Lymnaea stagnalis AChBP (Ls-AChBP) mutants (Q55T; Q55T+S186E; Q55R) as insect and mammalian nAChR structural surrogates, respectively. N-nitro/cyanoimine insecticides show high affinity to four Ac-AChBPs containing Arg57 or Thr57 and Ser189 or Val189, except for those with Glu189. Pyrazinoyl compound selectively interacts with the three Ac-AChBPs containing Arg57 and Ser189, Val189, or Glu189. Cationic ligands prefer three Ac-AChBPs with Thr57 and Ser189, Val189, or Glu189 and two Ls-AChBPs providing Thr55 ± Glu186 over the four Ac- and Ls-AChBPs with Arg57/55. Accordingly, loop C contributes to N-nitro/cyanoimine insecticide action, and loop D controls the affinity of the pyrazinoyl or cationic ligand.

Dual-assist heterologous antigens screening: An effective strategy to improve the sensitivity of lateral flow immunoassay.

Heterologous strategy has promising applications in improving the sensitivity of competitive immunoassay. In this study, the potential heterologous coating antigens (HEA) were screened from eight imidacloprid (IMI) structural analogs based on the cross-reactivity (CR) of a prepared antibody. Computer-aided molecular modeling was used to predict the optimal HEA. Compared with the homologous coating antigen (HOA), the predicted HEA prepared from acetamiprid (CR = 0.23 %) increased the detection sensitivity of the enzyme-linked immunoassay and colloidal gold nanoparticle-based lateral flow immunoassay (HOA-Au-LFIA) by 5.6 and 4.1 times, respectively. Subsequently, the HEA and aggregation-induced emission fluorescent labels were integrated into a lateral flow immunoassay platform (HEA-AIE-LFIA). The limit of detection was 0.12 ng mL-1 for HEA-AIE-LFIA, which was 7.7-fold lower than that of HOA-Au-LFIA. Furthermore, HEA-AIE-LFIA was applied to detect IMI in food samples with excellent recoveries (86.41 %-111.25 %). Overall, this strategy of screening for superior HEA has great potential for improving LFIA sensitivity.

Imidacloprid unique and repeated treatment produces cholinergic transmission disruption and apoptotic cell death in SN56 cells.

Imidacloprid (IMI), the most widely used worldwide neonicotinoid biocide, produces cognitive disorders after repeated and single treatment. However, little was studied about the possible mechanisms that produce this effect. Cholinergic neurotransmission regulates cognitive function. Most cholinergic neuronal bodies are present in the basal forebrain (BF), regulating memory and learning process, and their dysfunction or loss produces cognition decline. BF SN56 cholinergic wild-type or acetylcholinesterase (AChE), ß-amyloid-precursor-protein (ßAPP), Tau, glycogen-synthase-kinase-3-beta (GSK3ß), beta-site-amyloid-precursor-protein-cleaving enzyme 1 (BACE1), and/or nuclear-factor-erythroid-2-related-factor-2 (NRF2) silenced cells were treated for 1 and 14 days with IMI (1 µM-800 µM) with or without recombinant heat-shock-protein-70 (rHSP70), recombinant proteasome 20S (rP20S) and with or without N-acetyl-cysteine (NAC) to determine the possible mechanisms that mediate this effect. IMI treatment for 1 and 14 days altered cholinergic transmission through AChE inhibition, and triggered cell death partially through oxidative stress generation, AChE-S overexpression, HSP70 downregulation, P20S inhibition, and Aß and Tau peptides accumulation. IMI produced oxidative stress through reactive oxygen species production and antioxidant NRF2 pathway downregulation, and induced Aß and Tau accumulation through BACE1, GSK3ß, HSP70, and P20S dysfunction. These results may assist in determining the mechanisms that produce cognitive dysfunction observed following IMI exposure and provide new therapeutic tools.

Physiological and gene expression responses of Protohermes xanthodes (Megaloptera: Corydalidae) larvae to imidacloprid.

Megaloptera larvae are important bioindicator species and potential resource insects. To further cultivate their economic role, their living environment must be examined in more detail. In this study, we analyzed the physiological and biochemical effects of a sublethal dose of imidacloprid, a widely used neonicotinoid insecticide, on the larvae of Protohermes xanthodes. After treatment with imidacloprid, P. xanthodes larvae exhibited clear symptoms of poisoning, including the head curling up toward the ventral surface. Additionally, the activity of acetylcholinesterase was significantly inhibited following exposure. The activities of glutathione S-transferases initially continuously increased but showed a slight decrease after 8 days. Catalase activity initially increased and then decreased following imidacloprid treatment; superoxide dismutase activity fluctuated over time, and peroxidase activity continuously increased. The expression levels of HSP70s genes were evaluated using qRT-PCR. These results indicate that P. xanthodes larvae exhibit a toxic response to imidacloprid exposure, manifested as oxidative stress, as observed through behavioral and physiological indicators.

Carboxymethyl cellulose-coated iron-doped hollow silica carriers with erythrocyte-like structure for improved foliar adhesion and responsive pesticide delivery.

The development of nanopestcide carriers with high foliage adhesion remains a challenging task. Erythrocytes are double concave disc structure with thinner center and thicker rim and erythrocyte-like carriers would present enhanced foliar affinity. In this study, we fabricated novel rough-surfaced erythrocyte-like carriers for pesticide delivery. Firstly, erythrocyte-like silica (ES) nanoparticles were prepared by sol-gel method. Subsequently, the ES nanoparticles were further hydrothermal treated to obtain rough-surfaced iron-doped hollow ES (Fe-EHS) nanocarriers. The Fe-EHS nanocarriers could increase contact area and form a topological effect between the pesticide carriers and the micro/nanostructures on plant foliage, effectively enhancing the retention and rain fastness on foliage. Fe-EHS nanocarriers presented a loading capacity of 38.1 % for imidacloprid (IMI). After loading IMI, carboxymethyl cellulose (CMC) was encapsulated to generate nanopesticide delivery system (IMI@Fe-EHS-CMC). The obtained IMI@Fe-EHS-CMC exhibited good foliar adhesion, biosafety, and excellent UV shielding. Additionally, the IMI@Fe-EHS-CMC system possessed pH/cellulase responsive release behavior and could be bidirectionally transported through vascular bundles in tobacco plants. Furthermore, the IMI@Fe-EHS-CMC system showed potent insecticidal activity. This work offers valuable insights for enhancing the effective utilization of pesticides.

Human health risk assessment on pesticide residues in fishes of kuttanad wetland, a globally important agricultural heritage system.

Kuttanad is a unique wetland agriculture system featuring polder-based rice cultivation below sea level. Facing increasing pollution threats from agrochemicals, this FAO-recognized Globally Important Agricultural Heritage System (GIAHS) needs constant monitoring and risk assessment. The present study investigated the seasonal dynamics of agricultural pesticide residues in fish cultured in the wetland system. A total of 217 fish samples were analyzed, spanning three different sampling stations of Kuttanad, viz., Vaikom, Ramankari, and Edathua, during pre-monsoon, monsoon, and post-monsoon seasons. The results revealed the presence of 14 pesticides across locations and seasons. The pesticides found in the highest concentrations were propetamphos (54.64 mg L-1), thiacloprid (46.78 mg L-1), and diphenylamine (24.70 mg L-1). The most frequently detected pesticides were propoxur, fenuron, and thiacloprid. Contaminants were detected more frequently during the post-monsoon season (49%) compared to the monsoon (38%) and pre-monsoon (13%) seasons, with imidacloprid being present in all three seasons. The target hazard quotients (THQ) for propetamphos, thiacloprid, and diphenylamine were determined to be 0.04, 0.004, and 0.0002, respectively. The hazard index (HI) calculated as the sum of THQ of quantified pesticides was 0.056, indicating a low to moderate risk. However, consistent monitoring of pesticides in the Kuttanad wetland agriculture system is important to ensure timely intervention to protect biodiversity and human health.

Kill two birds with one stone: colorimetric/fluorescence immunosensor based on Au@Pt nanozyme for sensitive detection of imidacloprid.

Gold-platinum (Au@Pt) nanozymes with high catalytic activity and stability were designed to improve the stability of the enzyme-linked immunosorbent assay (ELISA), and a two-mode signal output was used to enhance the sensitivity and confidence of the assay. This study reports the two-mode signal output based on Au@Pt nanozyme to catalyzed 3,3',5,5'-tetramethylbenzidine (TMB) reaction. Oxidized 3,3',5,5'-tetramethylbenzidine (ox-TMB) has wide absorption spectrum, providing excellent optical density capabilities and fluorescence quenching. The detection limits of imidacloprid were 0.88 µg/L and 1.14 µg/L in colorimetric and fluorescence modes, respectively. Multiple-mode strategy improves detection accuracy, increases the confidence of experimental results, and broadens detection modes. Two modes can meet the requirements of accurate and flexible multi-mode sensing in different application situations.

Metabolomics and microbiomics revealed the combined effects of different-sized polystyrene microplastics and imidacloprid on earthworm intestinal health and function.

The coexistence of pesticides and plastic film residues in agricultural soils poses a significant threat to soil organisms due to their potential long-term contamination and combined toxic effects. Specifically, earthworms are at risk of simultaneously ingesting residual pesticides and microplastics, yet the impact of this combined exposure on their intestinal health and function remains poorly understood. In this study, earthworm (Eisenia fetida) were single and combined exposed to three particle sizes (10 µm, 500 µm, and 2 mm) of polyethylene microplastics (PE MPs) and imidacloprid (IMI) for 28 days, respectively. Our findings underscore that compared to single exposures, the combined exposure inflicted more profound injuries on intestinal tissues and elicited a heightened activation of intestinal digestive enzymes. Furthermore, the combined exposure significantly perturbed the relative abundance of several pivotal metabolic-associated gut microbiota, fostering an enrichment of pathogenic species. Metabolomics analysis showed combined exposure increased differential metabolites, disrupting amino acid, fatty acid, and carbohydrate metabolism in earthworm intestines, potentially hindering nutrient absorption and causing toxic metabolite accumulation. An integrated omics analysis implies that combined exposures have the potential to disrupt the relative abundance of crucial gut microbiota in earthworms, thereby altering their intestinal metabolism and subsequently impacting intestinal health and functionality. Overall, the results reveal that combined exposure of IMI and PE MPs exacerbate the negative effects on earthworm gut health, and this study holds significant implications for the holistic understanding of the combined toxic effects of microplastics and pesticide on soil ecosystems.

Treatment of an accident of imidacloprid poisoning.

Objective: Accidental oral imidacloprid poisoning occurred in a family in Shandong, China, in May 2023. This study aimed to analyze the clinical characteristics of this imidacloprid poisoning event and investigated the detection of toxicants. Methods: Clinical data of four patients with oral imidacloprid poisoning were collected and retrospectively analyzed. The relevant literature was then reviewed. Results: Four patients from the same family received different oral doses of imidacloprid. The main clinical manifestations were digestive and neurological symptoms, including nausea, vomiting, and varying degrees of consciousness. Laboratory tests showed an increased white blood cell count, neutrophil proportion, and mild elevation of transaminase and urea nitrogen levels in some patients. Following comprehensive treatment, which included hemoperfusion, gastric lavage, total gastrointestinal decontamination, and drug symptomatic treatment, the patient's symptoms were quickly relieved, and the concentration of imidacloprid in the blood rapidly decreased. Conclusion: Toxicant detection is an important criterion for the differential diagnosis of poisoning and is helpful for disease assessment, treatment plan formulation, and in determining patient prognosis.

Fluorometric detection of copper and imidacloprid using nitrogen-doped graphitic carbon dots: A promising method for environmental monitoring.

Pesticides in environmental samples pose significant risks to ecosystems and human health since they require precise and efficient detection methods. Imidacloprid (IMI), a widely used neonicotinoid insecticide, exemplifies these hazards due to its potential toxicity. This study addresses the urgent need for improved monitoring of such contaminants by introducing a novel fluorometric method for detecting IMI using nitrogen-doped graphite carbon dots (N-GCDs). The sensor operates by quenching fluorescence through the interaction of Cu2+ ions with N-GCDs. Subsequently, IMI binds to the imidazole group, chelates with Cu2+, and restores the fluorescence of N-GCDs. This alternating fluorescence behavior allows for the accurate identification of both Cu2+ and IMI. The sensor exhibits linear detection ranges of 20-100 nM for Cu2+ and 10-140 µg/L for IMI, with detection limits of 18 nM and 1.2 µg/L, respectively. The high sensitivity of this sensor enables the detection of real-world samples, which underscores its potential for practical use in environmental monitoring and agricultural safety.

Imidacloprid Uptake and Accumulation in Lettuce Plant (Lactuca sativa L. var. longipolia) and Its Effects on Abundance of Microbial Communities in Cultivated and Non-Cultivated Arid Soil.

Systemic plant protection products, such as neonicotinoids (NIs), are capable of being translocated throughout a plant. Although NIs are less toxic to mammals, fish, and birds, their impact on microbial and non-target insects is of concern. This study investigates the uptake, translocation, and accumulation of the NI, imidacloprid (IMI), in romaine lettuce (Lactuca sativa L. var. longipolia). Exposing 15-day-old seedlings to "10 mg/L" of IMI, the effects on microbial communities in both cultivated (CS) and non-cultivated soil (NCS) were studied along with IMI translocation within plant tissues. The concentrations of IMI in soil varied temporally and between soil types after initial application, with a decrease from 2.0 and 7.7 mg/kg on the first day of sampling to 0.5 and 2.6 mg/kg on the final sampling day (day 35) for CS and NCS, respectively. The half-life of IMI soil was 10.7 and 72.5 days in CS and NCS, respectively, indicating that IMI degraded more quickly in CS, possibly due to smaller grain size, aeration, microbial degradation, and water flow. The accumulated concentrations of IMI in lettuce tissues ranged from 12.4 ± 0.2 and 18.7± 0.9 mg/kg in CS and NCS, respectively. The highest concentration of IMI was found in the shoots, followed by the roots, whereas the soil showed the lowest IMI residuals at the end of the trial. Soil bacteria and fungi were altered by the application of IMI, with a lower abundance index within the bacterial community, indicating a negative impact on the distribution of bacteria in the soil.

Overexpression of SmUGGT1 Confers Imidacloprid Resistance to Sitobion miscanthi (Takahashi).

Sitobion miscanthi, the main species of wheat aphids, is one kind of harmful pest. Chemical insecticides are the important agrochemical products to effectively control wheat aphids. However, the broad application has led to serious resistance of pests to several insecticides, and understanding insecticide resistance mechanisms is critical for integrated pest management. In this study, SmUGGT1, a new uridine diphosphate (UDP)-glycosyltransferase (UGT) gene, was cloned and more strongly expressed in the SM-R (the resistant strain to imidacloprid) than in the SM-S (the susceptible strain to imidacloprid). The increased susceptibility to imidacloprid was observed after silencing SmUGGT1, indicating that it can be related to the resistance to imidacloprid. Subsequently, SmUGGT1 regulated post-transcriptionally in the coding sequences (CDs) by miR-81 was verified and involved in the resistance to imidacloprid in S. miscanthi. This finding is crucial in the roles of UGT involved in insecticide resistance management in pests.

A tiny sample rapid visual detection technology for imidacloprid resistance in Aphis gossypii by CRISPR/Cas12a.

Insecticide resistance monitoring is essential for guiding chemical pest control and resistance management policies. Currently, rapid and effective technology for monitoring the resistance of tiny insects in the field is absent. Aphis gossypii Glover is a typical tiny insect, and one of the most frequently reported insecticide-resistant pests. In this study, we established a novel CRISPR/Cas12a-based rapid visual detection approach for detecting the V62I and R81T mutations in the ß1 subunit of the nAChR in A. gossypii, to reflect target-site resistance to imidacloprid. Based on the nAChR ß1 subunit gene in A. gossypii, the V62I/R81T-specific RPA primers and crRNAs were designed, and the ratio of 10 µM/2 µM/10 µM for ssDNA/Cas12a/crRNA was selected as the optimal dosage for the CRISPR reaction, ensuring that Cas12a only accurately recognizes imidacloprid-resistance templates. Our data show that the field populations of resistant insects possessing V62I and R81T mutations to imidacloprid can be accurately identified within one hour using the RPA-CRISPR/Cas12a detection approach under visible blue light at 440-460 nm. The protocol for RPA-CRISPR detection necessitates a single less than 2 mm specimen of A. gossypii tissues to perform RPA-CRISPR detection, and the process only requires a container at 37 °C and a portable blue light at 440-460 nm. Our research represents the first application of RPA-CRISPR technology in insecticide resistance detection, offers a new method for the resistance monitoring of A. gossypii or other tiny insects, helps delay the development of resistance to imidacloprid, improves the sustainability of chemical control, and provides theoretical guidance for managing pest resistance.

Imidacloprid affects human cells through mitochondrial dysfunction and oxidative stress.

Given their relatively low persistence and mammalian toxicity, neonicotinoid pesticides have been extensively used worldwide and are omnipresent in the environment. Recent studies have shown that neonicotinoids may pose adverse effects on non-target organisms other than the known neurotoxicity, raising emerging concerns that these insecticides might pose human health risk through additional toxicity pathways. In the present study, the mitochondria function, oxidative stress, DNA damages, and genes transcription levels were examined in the human neuroblastoma SH-SY5Y cells after 48-h exposure to imidacloprid at concentrations from 0.05 to 200 µmol/L. Results showed that imidacloprid induced mitochondrial dysfunction with the degradation of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) levels. In addition, imidacloprid caused oxidative stress by stimulating the generation of reactive oxygen species (ROS) and hydrogen peroxide (H2O2) via the disruption of calcium ion level and mitochondrial function. Ultimately, the oxidative stress continued to produce DNA damage and apoptosis in SH-SY5Y cells at imidacloprid concentrations above 47.6 µmol/L. Among the evaluated endpoints, ATP was the most sensitive, with a median activity concentration of 0.74 µmol/L. The 5 % hazard concentration of imidacloprid was estimated to be 0.69 µmol/L, which can be used as a threshold for human health risk assessment for imidacloprid. Collectively, our results provide an important support for further research on potential toxicity of neonicotinoids related to mitochondrial toxicity in humans.

Sublethal Imidacloprid Administration to Honey Bee Workers is More Lethal to the Queen Larvae.

Imidacloprid and other neonicotinoid insecticides severely impact the performance and survival of honey bees and other pollinators. In the present study, we focused on the gene expression profile of newly emerged Apis mellifera queen bees after sublethal imidacloprid treatment during the larval stage. Royal jelly containing 1 ppb imidacloprid was provided to larvae for 3 consecutive days (2-4 days postemergence). Queen larvae treated with imidacloprid showed lower capping and emergence rates (35.5% and 24.22%, respectively) than did control larvae (61.68% and 52.95%, respectively), indicating a high failure rate of queen rearing associated with imidacloprid exposure during the larval stage. The molecular response to imidacloprid treatment was examined next. By comparing the gene expression profiles of imidacloprid-treated queen larvae and those of control queen larvae using DESeq2, we identified 215 differentially expressed genes, with 105 and 111 up- and downregulated genes, respectively. Gene Ontology results indicated that chitin binding- and calcium ion binding-related genes were upregulated, while phototransduction- and visual perception-related genes were downregulated. The high mortality rate and altered gene expression profiles suggest that treatment with even 1 ppb imidacloprid can severely impact queen bee survival. Environ Toxicol Chem 2024;43:2232-2242. © 2024 SETAC.

Sensitivity Variations in Developmental Toxicity of Imidacloprid to Zebrafish Embryos at Different Neurodevelopmental Stages.

Neonicotinoids are ubiquitous in global surface waters and pose a significant risk to aquatic organisms. However, information is lacking on the variations in sensitivity of organisms at different developmental stages to the neurotoxic neonicotinoids. We established a spectrum of toxicity to zebrafish embryos at four neurodevelopmental stages (1, 3, 6, and 8 h post fertilization [hpf]) and dechorionated embryos at 6 hpf based on external and internal exposure to imidacloprid as a representative neonicotinoid. Embryos at the gastrula stage (6 and 8 hpf) were more sensitive to imidacloprid than embryos at earlier developmental stages. Dechorionated embryos were more sensitive to imidacloprid than embryos with a chorion, suggesting that the chorion offers protection against pollutants. Nine sublethal effects were induced by imidacloprid exposure, among which uninflated swim bladder (USB) was the most sensitive. Water depth and air availability in the exposure chambers were critical factors influencing the occurrence of USB in zebrafish larvae. Internal residues of metabolites accounted for <10% of imidacloprid, indicating that imidacloprid was metabolized in a limited fashion in the embryos. In addition, acute toxicity of the main metabolite 5-hydroxy-imidacloprid was significantly lower than that of imidacloprid, indicating that the observed toxicity in embryos exposed to imidacloprid was mainly induced by the parent compound. Our research offers a fresh perspective on choosing the initial exposure time in zebrafish embryo toxicity tests, particularly for neurotoxicants. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC.

Temperature-dependent in vitro hepatocytotoxicity of insecticides in bats.

Heterothermic insectivorous bats are supposed to experience differential adverse effects of insecticidal pollutants depending on their seasonal and/or daily variation of metabolic and detoxification rates. Here, we investigated effects of imidacloprid, cypermethrin and fipronil on Nyctalus noctula bat-derived hepatocytes through cytotoxicity, cell inhibition and death at different concentrations (0.01, 0.1, 1, 10, 100, 1000 µg/ml), exposure times (10, 24, 48 hrs), incubation temperatures simulating hibernation (8 °C), daily torpor (20 °C), normothermy (37 °C) and active flight (40 °C), and cytochrome P450 addition. Toxic effects were significantly influenced by temperature (p < 0.05), with strong cytotoxicity after 10 hour exposure to fipronil or cypermethrin at 37 and 40 °C, cell replication inhibition (all insecticides at 8 °C) and cellular stimulation, with slight culture proliferation after 48 hours (all insecticides at 40 °C). Replacing protected chiropterans with cell cultures is a way to assess and extrapolate risks of insecticides for bats.

Berberine chloride loaded nano-PEGylated liposomes attenuates imidacloprid-induced neurotoxicity by inhibiting NLRP3/Caspase-1/GSDMD-mediated pyroptosis.

Concerns have been expressed about imidacloprid (IMI), one of the most often used pesticides, and its potential neurotoxicity to non-target organisms. Chronic neuroinflammation is central to the pathology of several neurodegenerative disorders. Hence, exploring the molecular mechanism by which IMI would trigger neuroinflammation is particularly important. This study examined the neurotoxic effects of oral administration of IMI (45 mg/kg/day for 30 days) and the potential neuroprotective effect of berberine (Ber) chloride loaded nano-PEGylated liposomes (Ber-Lip) (10 mg/kg, intravenously every other day for 30 days) using laboratory rat. The histopathological changes, anti-oxidant and oxidative stress markers (GSH, SOD, and MDA), proinflammatory cytokines (IL1ß and TNF-α), microglia phenotype markers (CD86 and iNOS for M1; CD163 for M2), the canonical pyroptotic pathway markers (NLRP3, caspase-1, GSDMD, and IL-18) and Alzheimer's disease markers (Neprilysin and beta amyloid [Aß] deposits) were assessed. Oral administration of IMI resulted in apparent cerebellar histopathological alterations, oxidative stress, predominance of M1 microglia phenotype, significantly upregulated NLRP3, caspase-1, GSDMD, IL-18 and Aß deposits and significantly decreased Neprilysin expression. Berberine reduced the IMI-induced aberrations in the measured parameters and improved the IMI-induced histopathological and ultrastructure alterations brought on by IMI. This study highlights the IMI neurotoxic effect and its potential contribution to the development of Alzheimer's disease and displayed the neuroprotective effect of Ber-Lip.