Tefluthrin induced toxicities in zebrafish: Focusing on enantioselectivity.

Tefluthrin is one of widely used chiral pyrethroid pesticides. The potential enantioselective risk posed by tefluthrin to the aquatic ecosystem is still unclear. In this study, the toxicity differences and corresponding mechanism of tefluthrin on zebrafish were investigated at the enantiomeric level. The results indicated that two tefluthrin enantiomers showed different acute toxicity, developmental toxicity and oxidative stress to zebrafish. The acute toxicity of (1R,3R)-tefluthrin was 130-176 fold as that of (1S,3S)-tefluthrin on zebrafish embryos, larvae and adults. (1R,3R)-Tefluthrin presented approximately 10, 3 and 2 times inhibition effect on the deformity rate, hatching rate and spontaneous movements on embryos as that of (1S,3S)-tefluthrin. Meanwhile, (1R,3R)-tefluthrin caused stronger oxidative stress on zebrafish embryo than (1S,3S)-tefluthrin. The molecular docking results revealed that there were stereospecific binding affinities between tefluthrin enantimers and sodium channel protein (Nav1.6), which may lead to acute toxicity differences. Transcriptome analysis showed that the two tefluthrin enantiomers markedly disturbed differential embryonic genes expression, thereby potentially causing the chronic enantioselective toxicity. The findings of the study reveal the toxicity differences and potential mechanism of tefluthrin enantiomers on zebrafish. These results also provides a foundation for a systematic evaluation of tefluthrin at enantiomer level.

Effects of used and under-used doses of Transfluthrin-based insecticide on Caenorhabditis elegans metabolism.

Different classes of insecticide compounds have been employed to control insects and mosquitoes; Pyrethroids are one of the most common used in both urban and rural household environments. This study investigated the effects of exposure of two doses of commercial transfluthrin-based insecticide (T-BI) on behavior (body bends, pharyngeal pumping rate, and feeding attributes) and biochemical biomarkers (AChE, PolyQ40 aggregations, HSP, antioxidative SOD, CTL, and GST) following three different protocols (transgenerational, neonatal, and lifespan) in Caenorhabditis elegans model system. The relative calculated dose (RCD) and relative calculated half dose (RCHD) of T-BI were compared with those of the control (water). T-BI reduced the health span of worms treated during their whole life and changed biochemical and behavioral patterns due to progenitors' uterine (transgenerational) and neonatal exposures. It was inferred that the effects of T-BI are transgenerational and persistent and can be harmful to non-target species, including humans. In addition, our findings highlight that T-BI contact by progenitors accelerates the establishment of Huntington's disease and causes a cholinergic outbreak in offspring adulthood.

Long-term efavirenz exposure induced neuroinflammation and cognitive deficits in C57BL/6 mice.

Efavirenz (EFV) is a non-nucleoside reverse transcriptase inhibitor (NNRTI), which is widely used for anti-HIV-1. Evidences revealed that several central nervous system side effects could be observed in mice and patients with administration of EFV. However, the detailed mechanisms are still unknown. In this study, we investigated the effects of long-term EFV treatment on cognitive functions and the potential underlying mechanisms in mice. We maintained C57BL/6 mice aged 2 months with treatment containing 40 or 80 mg/kg/day EFV for 5 months, while control group treated with saline. The cognitive functions were evaluated by novel object recognition test, Barnes maze test and Morris water maze. The results showed significant short-term memory impairment in 40 and 80 mg/kg groups, and notable spatial learning and memory impairments in 80 mg/kg group, without any spontaneous activity alteration. Moreover, EFV induced impairments in dendritic integrity and synaptic plasticity in hippocampus. Furthermore, Significant increases were observed in the expression levels of pro-IL-1ß, a similar tendency of TNF-α and phosphorylation of p65 of the 80 mg/kg group compared with control group. These results imply that long-term EFV treatment causes synaptic dysfunction resulting in cognitive deficits, which might be induced by the enhanced pro-inflammatory cytokines IL-1ß and TNF-α via activating NF-κB pathway.

Cytotoxicity, metabolism, and isozyme mapping of the synthetic cannabinoids JWH-200, A-796260, and 5F-EMB-PINACA studied by means of in vitro systems.

Intake of synthetic cannabinoids (SC), one of the largest classes of new psychoactive substances, was reported to be associated with acute liver damage but information about their hepatotoxic potential is limited. The current study aimed to analyze the hepatotoxicity including the metabolism-related impact of JWH-200, A-796260, and 5F-EMB-PINACA in HepG2 cells allowing a tentative assessment of different SC subclasses. A formerly adopted high-content screening assay (HCSA) was optimized using a fully automated epifluorescence microscope. Metabolism-mediated effects in the HCSA were additionally investigated using the broad CYP inhibitor 1-aminobenzotriazole. Furthermore, phase I metabolites and isozymes involved were identified by in vitro assays and liquid chromatography-high-resolution tandem mass spectrometry. A strong cytotoxic potential was observed for the naphthoylindole SC JWH-200 and the tetramethylcyclopropanoylindole compound A-796260, whereas the indazole carboxamide SC 5F-EMB-PINACA showed moderate effects. Numerous metabolites, which can serve as analytical targets in urine screening procedures, were identified in pooled human liver microsomes. Most abundant metabolites of JWH-200 were formed by N-dealkylation, oxidative morpholine cleavage, and oxidative morpholine opening. In case of A-796260, most abundant metabolites included an oxidative morpholine cleavage, oxidative morpholine opening, hydroxylation, and dihydroxylation followed by dehydrogenation. Most abundant 5F-EMB-PINACA metabolites were generated by ester hydrolysis plus additional steps such as oxidative defluorination and hydroxylation. To conclude, the data showed that a hepatotoxicity of the investigated SC cannot be excluded, that metabolism seems to play a minor role in the observed effects, and that the extensive phase I metabolism is mediated by several isozymes making interaction unlikely.

Toxicity Assessment of Transfluthrin, Benzyl Butyl Phthalate, and 17ß-Estradiol on the Primary Fibroblast of the Striped Field Mouse, Apodemus agrarius.

Environmental pollution (EP) is a well-known threat to wild animals, but its toxicological impact is poorly understood. In vitro toxicity evaluation using cells of lower predators could be a promising way to assess and monitor the effects of EPs on whole wildlife populations that are related in the food web. Here, we describe EPs' toxic effect and mechanism in the primary fibroblast derived from the embryo of the striped field mouse, Apodemus agrarius. Characterization of the primary fibroblast was via morphology, genetics, immunocytochemistry, and stable culture conditions for optimal toxicity screening. Cell viability assays-MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and lactate dehydrogenase (LDH)-were performed to observe cytotoxicity, and quantitative PCR was conducted to confirm gene alteration by EP exposure. MTT and LDH assays confirmed the cytotoxicity of transfluthrin (TF), benzyl butyl phthalate (BBP), and 17ß-estradiol (E2) with IC50 values of 10.56 µM, 10.82 µM, and 24.08 µM, respectively, following 48-h exposures. mRNA expression of androgen-binding protein, growth hormone receptor, cytochrome C oxidase, and cytochrome P450-1A1 was induced after exposure to TF, BBP, and E2. We unveiled new EP mechanisms at the mammalian cellular level and discovered potential biomarker genes for monitoring of EPs. Based on our findings, we propose the primary fibroblast of A. agrarius as a valuable model to assess the toxicological effects of EP on wildlife.

A recurring disease outbreak following litchi fruit consumption among children in Muzaffarpur, Bihar-A comprehensive investigation on factors of toxicity.

Litchi fruits are a nutritious and commercial crop in the Indian state of Bihar. Litchi fruit contains a toxin, methylene cyclopropyl-glycine (MCPG), which is known to be fatal by causing encephalitis-related deaths. This is especially harmful when consumed by malnourished children. The first case of litchi toxicity was reported in Bihar in 2011. A similar event was recorded in 2014 among children admitted to the Muzaffarpur government hospital, Bihar. Litchi samples sent to ICMR-NIN were analyzed and MCPG was found to be present in both the pulp and seed of the fruit. Diethyl phosphate (DEP) metabolites were found in the urine samples of children who had consumed litchi fruit from this area indicating exposure to pesticide. The presence of both MCPG in litchi and DEP metabolites in urine samples highlights the need to conduct a comprehensive investigation that examines all factors of toxicity.

Study on the Metabolic Effects of Repeated Consumption of Canned Ackee.

Ackee fruits (Blighia sapida), an important food source in some tropical countries, can be the cause of serious poisoning. Ackees contain hypoglycin A and methylenecyclopropylglycine. Experiments were undertaken by a volunteer to elucidate the metabolic details of poisoning. Rapid intestinal absorption of the toxins was followed by their slow degradation to methylenecyclopropylacetyl and methylenecyclopropylformyl conjugates. Impairment of the metabolism of branched chain amino acids and ß-oxidation of fatty acids was found. Reduced enzyme activities were observed for several days after ingestion. A defined dose of fruit material caused significantly higher concentrations of metabolites when consumed 24 h after a previous ingestion than when consumed only once. The accumulation of toxins, toxin metabolites, and products of the intermediate metabolism after repeated consumption may, at least partly, explain the high frequency of fatal cases observed during harvesting. No inhibition of enzymes that degrade long-chain acyl compounds was observed in the experiments.

Perampanel attenuates scratching behavior induced by acute or chronic pruritus in mice.

An itch is defined as an unpleasant sensation that evokes a desire to scratch. Glutamate is a major excitatory neurotransmitter in the mammalian central nervous system and has a crucial role in pruriceptive processing in the spinal dorsal horn. It is well known that glutamate exerts its effects by binding to various glutamate receptors including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, and that AMPA/kainate receptors play a crucial role in pruriceptive processing; however, the precise role of AMPA receptors remains uncertain. Perampanel, an antiepileptic drug, is an antagonist of AMPA receptors. Pretreatment with perampanel dose-dependently attenuated the induction of scratching, a behavior typically associated with pruritus, by intradermal administration of the pruritogen chloroquine. In addition, the induction of scratching in mice painted with diphenylcyclopropenone and NC/Nga mice treated with Biostir AD, animal models of contact dermatitis and atopic dermatitis, respectively, was dose-dependently alleviated by administration of perampanel. These findings indicate that AMPA receptors play a crucial role in pruriceptive processing in mice with acute or chronic pruritus.

Efavirenz-Associated Retinal Toxicity Presenting with Night Vision Defects in Patients with Human Immunodeficiency Virus.

Ocular lesions in patients with human immunodeficiency virus (HIV) are commonly due to underlying opportunistic infections. With highly active antiretroviral therapy (HAART), infectious lesions have reduced and noninfectious ocular manifestations including drug-related side effects have been noted. While retinal toxicity has been noted with few other HAART drugs, there are not many on the same with Efavirenz usage. We report a series of five patients with possible efavirenz-related retinal toxicity, visual function abnormalities, and its management. Efavirenz was replaced with alternate anti-retroviral drug. Reversal of ocular side effects were noted subjectively in the form of symptom amelioration of the patients. Objectively, it could be documented with electroretinogram changes and other visual function tests reverting back to normal after change in HAART regime. Early identification of this uncommon side effect in select patients can prevent irreversible vision loss due to efavirenz-associated retinal toxicity.

A review of the potential mechanisms of neuronal toxicity associated with antiretroviral drugs.

Highly active antiretroviral treatment has led to unprecedented efficacy and tolerability in people living with HIV. This effect was also observed in the central nervous system with the nowadays uncommon observation of dementias; yet in more recent works milder forms are still reported in 20-30% of optimally treated individuals. The idea of a subclinical neuronal toxicity induced by antiretrovirals has been proposed and was somehow supported by the late-emerging effects associated with efavirenz use. In this manuscript we are reviewing all the potential mechanisms by which antiretroviral drugs have been associated with in vitro, ex vivo, or in vivo toxicity to cells pertaining to the central nervous system (neurons, astrocytes, oligodendrocytes, and endothelial cells). These include direct or indirect effects and pathological pathways such as amyloid deposition, damage to small cerebral vessels, and impairment in neurotransmission. The aim of this review is therefore to provide a detailed description of the available literature in order to guide further clinical research for improving patients' neurocognition and quality of life.

The Pharmacogenetics of Efavirenz Metabolism in Children: The Potential Genetic and Medical Contributions to Child Development in the Context of Long-Term ARV Treatment.

Efavirenz (EFV) is a well-known, effective anti-retroviral drug long used in first-line treatment for children and adults with HIV and HIV/AIDS. Due to its narrow window of effective concentrations, between 1 and 4 µg/mL, and neurological side effects at supratherapeutic levels, several investigations into the pharmacokinetics of the drug and its genetic underpinnings have been carried out, primarily with adult samples. A number of studies, however, have examined the genetic influences on the metabolism of EFV in children. Their primary goal has been to shed light on issues of appropriate pediatric dosing, as well as the manifestation of neurotoxic effects of EFV in some children. Although EFV is currently being phased out of use for the treatment of both adults and children, we share this line of research to highlight an important aspect of medical treatment that is relevant to understanding the development of children diagnosed with HIV.

Ultraviolet-Visible and High-Resolution Mass Spectrometry for the Identification of Cyclopropyl-Fentanyl in the First Fatal Case in Spain.

Here we report the identification and quantitation of cyclopropyl-fentanyl in a fatality casework occurred due to a poly-drug toxicity in Spain in December 2017. The cyclopropyl-fentanyl was identified in non-biological (paraphernalia) and biological samples (whole-blood, vitreous humor and urine). Conventional techniques (GC-MS) and the UV-Vis spectral allowed differencing between the two structural isomer compounds of fentanyl (cyclopropyl and crotonyl) when the CRM was not available at the laboratory. Both of the drugs have the same MS spectra but different UV-Vis spectra due to the presence of an additional chromophore group in the case of crotonyl. The cyclopropyl-fentanyl detection allowed generating an alert and contributing to the surveillance and detection of this dangerous substance found mixed in doses of clandestine sale heroin. Then, high-resolution analytical techniques (LC-HRMS-MS), showed limitations for the identification of the isobaric fentanyl compounds but they had a high potential for fentanyl metabolites identification. Two tentative metabolites were identified in urine samples: cyclopropyl-norfentanyl and N-methyl cyclopropyl-norfentanyl. Finally, the systematic routine method (LC-MS-MS) was validated and applied to the quantification of cyclopropyl-fentanyl in a blood sample. A obtained value (20.4 ng/mL) was in the range of those reported in other cases in different countries (from 8 to 30 mg/ mL), being the determined concentration of cyclopropyl-fentanyl high enough to infer that this fentanyl analog had a main role as cause of death. As far as we know, this is the first fatality reported in Spain involving cyclopropyl-fentanyl.

Perinatal exposure of rats to the HIV drug efavirenz affects medial prefrontal cortex cytoarchitecture.

Efavirenz (EFV) is used for antiretroviral treatment of HIV infection, and successfully inhibits viral replication and mother-to-child transmission of HIV during pregnancy and childbirth. Unfortunately, the drug induces neuropsychiatric symptoms such as anxiety and depressed mood and potentially affects cognitive performance. EFV acts on, among others, the serotonin transporter and serotonin receptors that are expressed in the developing brain. Yet, how perinatal EFV exposure affects brain cytoarchitecture remains unclear. Here, we exposed pregnant and lactating rats to EFV, and examined in the medial prefrontal cortex (mPFC) of their adult offspring the effects of the maternal EFV exposure on cortical architecture. We observed a significant decrease in the number of cells, mainly mature neurons, in the infra/prelimbic and cingulate cortices of adult offspring. Next, we found an altered cortical cytoarchitecture characterized by a significant reduction in deep- and superficial-layer cells. This was accompanied by a sharp increase in programmed cell death, as we identified a significantly higher number of cleaved Caspase-3-positive cells. Finally, the serotonergic and dopaminergic innervation of the mPFC subdomains was increased. Thus, the perinatal exposure to EFV provoked in the mPFC of adult offspring cell death, significant changes in cytoarchitecture, and disturbances in serotonergic and dopaminergic innervation. Our results are important in the light of EFV treatment of HIV-positive pregnant women, and its effect on brain development and cognitive behavior.

GRP receptor and AMPA receptor cooperatively regulate itch-responsive neurons in the spinal dorsal horn.

Gastrin-releasing peptide (GRP) receptor-expressing (GRPR)+ neurons have a central role in the spinal transmission of itch. Because their fundamental regulatory mechanisms are not yet understood, it is important to determine how such neurons are excited and integrate itch sensation. In this study, we investigated the mechanisms for the activation of itch-responsive GRPR+ neurons in the spinal dorsal horn (SDH). GRPR+ neurons expressed the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) containing the GluR2 subunit. In mice, peripherally elicited histaminergic and non-histaminergic itch was prevented by intrathecal (i.t.) administration of the AMPAR antagonist NBQX, which was consistent with the fact that firing of GRPR+ neurons in SDH under histaminergic and non-histaminergic itch was completely blocked by NBQX, but not by the GRPR antagonist RC-3095. Because GRP+ neurons in SDH contain glutamate, we investigated the role of GRP+ (GRP+/Glu+) neurons in regulating itch. Chemogenetic inhibition of GRP+ neurons suppressed both histaminergic and non-histaminergic itch without affecting the mechanical pain threshold. In nonhuman primates, i.t. administration of NBQX also attenuated peripherally elicited itch without affecting the thermal pain threshold. In a mouse model of diphenylcyclopropenone (DCP)-induced contact dermatitis, GRP, GRPR, and AMPAR subunits were upregulated in SDH. DCP-induced itch was prevented by either silencing GRP+ neurons or ablation of GRPR+ neurons. Altogether, these findings demonstrate that GRP and glutamate cooperatively regulate GRPR+ AMPAR+ neurons in SDH, mediating itch sensation. GRP-GRPR and the glutamate-AMPAR system may play pivotal roles in the spinal transmission of itch in rodents and nonhuman primates.

Proteomic analysis of haptenation by skin sensitisers: Diphencyprone and ethyl acrylate.

The potential risk of skin sensitisation, associated with the development of allergic contact dermatitis (ACD), is a consideration in the safety assessment of new ingredients for use in personal care products. Protein haptenation in skin by sensitising chemicals is the molecular initiating event causative of skin sensitisation. Current methods for monitoring skin sensitisation rely on limited reactivity assays, motivating interest in the development of proteomic approaches to characterise the skin haptenome. Increasing our mechanistic understanding of skin sensitisation and ACD using proteomics presents an opportunity to develop non-animal predictive methods and/or risk assessment approaches. Previously, we have used a novel stable isotope labelling approach combined with data independent mass spectrometry (HDMSE) to characterise the haptenome for a number of well-known sensitisers. We have now extended this work by characterising the haptenome of the sensitisers Diphenylcyclopropenone (DPCP) and Ethyl Acrylate (EA) with the model protein Human Serum Albumin (HSA) and the complex lysates of the skin keratinocyte, HaCaT cell line. We show that haptenation in complex nucleophilic models is not random, but a specific, low level and reproducible event. Proteomic analysis extends our understanding of sensitiser reactivity beyond simple reactivity assays and offers a route to monitoring haptenation in living cells.

Relationship Between the Dose Administered, Target Tissue Dose, and Toxicity Level After Acute Oral Exposure to Bifenthrin and Tefluthrin in Young Adult Rats.

Most pyrethroid insecticides (PYRs) share a similar primary target site in mammals. However, the potency estimates of the lethal and sublethal effects of these compounds differ up to 103-fold. The aim of this study was to evaluate the relationship between the dose administered, the target tissue dose, and the effect of 2 highly toxic PYRs, tefluthrin (TEF; 0.1-9 mg/kg) and bifenthrin (BIF; 0.5-12 mg/kg), by using the oral route, a corn oil vehicle (1 ml/kg) and subcutaneous temperature (Tsc) monitoring assays in adult rats. The Tsc was determined at 30-min intervals for 5 h (TEF) or 4.5 h (BIF) after dosing. Rats were sacrificed at 6 h after dosing, and BIF and TEF concentrations were determined in blood (Bd), liver (Lv), and cerebellum (Cb) by using a GC-ECD system. The minimal effective dose of BIF (3 mg/kg) affecting Tsc was similar to that found in prior studies using other testing paradigms. Regarding TEF, a very steep relationship between the dose administered and toxicity was observed, with a near-threshold to low-effective range for Tsc at 0.1-6 mg/kg, and a near lethal syndrome at ≥ 7.5 mg/kg. At 6-7.5 mg/kg TEF, the Cb/Bd and Cb/Lv concentration ratios were both > 1. Conversely, for BIF, the Cb concentration was barely over the Bd concentration and the Cb/Lv concentration ratio remained < 1. Our results and previous findings call for more comprehensive consideration to establish the relevance of the distribution into target tissues and the tissue dosimetry for health risks through the exposure to PYRs in humans.

Gone in 60 seconds: Sub-lethal Effects of Metofluthrin Vapors on Behavior and Fitness of Resistant and Field Strains of Aedes aegypti (Diptera: Culicidae).

Spatial repellents can reduce fecundity and interrupt oviposition behavior in Aedes aegypti. Yet, it is unclear if short exposure times, resistant phenotypes, and other aspects of spatial repellents can impact these effects on mosquito reproduction. To address these issues, pyrethroid susceptible, pyrethroid resistant, and field strains of Ae. aegypti were used to evaluate the extent to which fecundity and oviposition behavior are affected following metofluthrin exposure. Mosquitoes were exposed for 60 s to a sub-lethal dose (LC30) of metofluthrin before blood feeding and allowed 72 h to become gravid before evaluation in an oviposition bioassay for an additional 72 h. Metofluthrin-exposed susceptible, field, and to a lesser extent resistant strain Ae. aegypti showed oviposition across fewer containers, less egg yield, less egg viability, and reduced larval survivorship in hatched eggs compared to unexposed cohorts. Susceptible mosquitoes retained some eggs at dissection following bioassays, and in one case, melanized eggs retained in the female. Treated resistant and field strain F1 larvae hatched significantly earlier than unexposed cohorts and resulted in increased larval mortality in the first 3 d after oviposition. Upon laying, the treated field strain had incompletely melanized eggs mixed in with viable eggs. The treated field strain also had the lowest survivorship of larvae reared from bioassay eggs. These results indicate that metofluthrin could succeed in reducing mosquito populations via multiple mechanisms besides acute lethality. With the available safety data, pre-existing spatial repellent registration, and possibilities for other outdoor delivery methods, metofluthrin is a strong candidate for transition into broader mosquito abatement operations.