Cytotoxicity induced by deltamethrin and its metabolites in SH-SY5Y cells can be differentially prevented by selected antioxidants

The impact of repeated pyrethroid pulses on aquatic communities

Pesticides are considered to be one of the main causes of the decline in macroinvertebrate biodiversity in small streams. In particular, pyrethroids are detected in agricultural surface waters worldwide and pose a high risk to aquatic invertebrates. Due to their knock-down effect, even short pyrethroid exposure pulses can have significant short- and long-term effects on macroinvertebrate communities. Therefore, it is necessary to consider more realistic exposure scenarios for the environmental risk assessment of pyrethroids and, consequently, to obtain more realistic effect data by using multi-stressor test systems. In an experimental setup with artificial indoor streams (AIS), four pyrethroid pulses simulated the exposure scenario of heavy rainfall events. Effects of these 12 h-exposures at different concentrations of deltamethrin (0.64 ng/L, 4 ng/L, 16 ng/L, 64 ng/L) with intervening recovery periods of six days were assessed on an aquatic community consisting of Gammarus pulex, Ephemera danica, Lumbriculus variegatus and Potamopyrgus antipodarum with various lethal and sub-lethal endpoints. The mortality rate of G. pulex significantly increased with increasing deltamethrin concentrations, whereas the mean number of offspring significantly decreased (NOECoffspring: 16 ng/L, LOECoffspring: 64 ng/L). The biomass of L. variegatus decreased with increasing deltamethrin concentrations (NOECdry weight: 16 ng/L, LOECdry weight: 64 ng/L). The findings of this study clearly demonstrate that 12 h-deltamethrin pulses at environmentally relevant concentrations adversely affect an aquatic community. Based on the results of this study a RAC value of 5.33 ng/L is assumed, which is below the concentrations measured in rivers of up to 58.8 ng/L. Unacceptable effects on the entire freshwater environment can therefore not be ruled out. The experimental AIS approach is a useful tool for assessing the effects of repeated pulse exposures that occur during surface runoff events.

Single and combined effect of chrysin and N-acetylcysteine against deltamethrin exposure in rats

Effects of chrysin and N-acetylcysteine on deltamethrin exposure in rats were investigated. Eighty male Wistar Albino rats, weighing between 150 and 200 g and aged 2-3 months, were used and evenly allocated into eight groups. The control group of rats received a corn oil vehicle. Chrysin (50 mg/kg.bw), N-acetylcysteine (50 mg/kg.bw), a combination of chrysin and N-acetylcysteine, deltamethrin (10 mg/kg.bw), deltamethrin combined with chrysin, deltamethrin combined with N-acetylcysteine, and a combination of deltamethrin, chrysin, and N-acetylcysteine were administered via oral gavage for a duration of 21 days. Tissue (liver, kidney, brain, testis, heart, lung) and blood of oxidative stress markers (MDA, NO, GSH, SOD, CAT, GSH-Px, GR, GST, G6PD), hepatic caspase 3, 9 and p53 protein levels, biochemical parameters (glucose, triglyceride, cholesterol, BUN, creatinine, uric acid, total protein, albumin, LDH, AST, ALT, ALP, PChE activities/levels), as well as rat body/organ weights and plasma/liver deltamethrin concentrations. The administration of chrysin and N-acetylcysteine independently did not alter the assessed parameters. Significant differences were observed in most parameters assessed in the deltamethrin-alone group compared to the control group, whereas the parameter values in the groups treated with chrysin, NAC, or their combination with deltamethrin were similar to those of the control.

Investigation of the therapeutic effect of melatonin on deltamethrin applied mouse primary hepatocyte culture

OBJECTIVE

In recent years, it has been known that the melatonin hormone, secreted from the pineal gland, possesses significant antioxidant activity. This study explores the therapeutic effect of melatonin on the deleterious effects of deltamethrin, a pyrethroid pesticide extensively used worldwide, including in Türkiye, on mouse liver cells.

METHODS

Hepatocytes from Balb/C mice were isolated using a two-stage perfusion method, resulting in over 85% live hepatocytes. The isolated cells were cultured with different doses of deltamethrin (1 and 10 µM) and melatonin (100 µM) for 24 and 48 hours. At the conclusion of the culture period, hepatocytes were extracted at the 24th and 48th hours, and Malondialdehyde (MDA), Total Antioxidant Capacity (TAC), Total Oxidation Status (TOS), and DNA damages (8-hydroxy-2'-deoxyguanosine (8-OHdG)) were examined.

RESULTS

While an increase in MDA, TOS, and DNA damage was observed in the deltamethrin-administered groups of hepatocytes, a decrease in TAC level was noted. It was determined that the applied deltamethrin had no effect on cell viability throughout the application period.

CONCLUSION

Furthermore, it was observed that melatonin, when administered concurrently with deltamethrin, reduced the toxic effect of deltamethrin. This study suggests that melatonin has a protective effect against deltamethrin-induced damage in mouse hepatocyte cells.

Overview of deltamethrin residues and toxic effects in the global environment

Pyrethroids are synthetic organic insecticides. Deltamethrin, as one of the pyrethroids, has high insecticidal activity against pests and parasites and is less toxic to mammals, and is widely used in cities and urban areas worldwide. After entering the natural environment, deltamethrin circulates between solid, liquid and gas phases and enters organisms through the food chain, posing significant health risks. Increasing evidence has shown that deltamethrin has varying degrees of toxicity to a variety of organisms. This review summarized worldwide studies of deltamethrin residues in different media and found that deltamethrin is widely detected in a range of environments (including soil, water, sediment, and air) and organisms. In addition, the metabolism of deltamethrin, including metabolites and enzymes, was discussed. This review shed the mechanism of toxicity of deltamethrin and its metabolites, including neurotoxicity, immunotoxicity, endocrine disruption toxicity, reproductive toxicity, hepatorenal toxicity. This review is aim to provide reference for the ecological security and human health risk assessment of deltamethrin.

The application of human-derived cell lines in neurotoxicity studies of environmental pollutants

As industrial and societal advancements progress, an increasing number of environmental pollutants linked to human existence have been substantiated to elicit neurotoxicity and developmental neural toxicity. For research in this field, human-derived neural cell lines have become excellent in vitro models. This study examines the utilization of immortalized cell lines, specifically the SH-SY5Y human neuroblastoma cell line, and neural cells derived from human pluripotent stem cells, in the investigation of neurotoxicity and developmental neural toxicity caused by environmental pollutants. The study also explores the culturing techniques employed for these cell lines and provides an overview of the standardized assays used to assess various biological endpoints. The environmental pollutants involved include a variety of organic compounds, heavy metals, and microplastics. The utilization of cell lines derived from human sources holds significant significance in elucidating the neurotoxic effects of environmental pollutants and the underlying mechanisms. Finally, we propose the possibility of improving the in vitro model of the human nervous system and the toxicity detection methods.

Potential Protective Effects of Spirulina (Spirulina platensis) against In Vitro Toxicity Induced by Heavy Metals (Cadmium, Mercury, and Lead) on SH-SY5Y Neuroblastoma Cells

Spirulina, a filamentous microalga, is used all over the world as a nutraceutical dietary supplement. Recent studies have focused on examining its chelating activity and antioxidant properties, especially as a candidate for protection against neurotoxicity caused by heavy metals. The MTT test and LDH assay were used to examine the viability of the SH-SY5Y cells for 24, 48, and 72 h, to Cd, Hg, and Pb, individually or in combination with Spirulina, and the effects of necrotic cell death. In comparison to the control group, the viability of SH-SY5Y cells decreased after 24 h of exposure, with Cd being more toxic than Hg and Pb being less lethal. The effects of heavy metal toxicity on cell survival were ranked in order after 72 h under identical experimental circumstances as follows: Hg, Pb, and Cd. The viability of the cells was then tested after being exposed to Spirulina at doses of 5 at 50 (%v/v) for 24, 48, and 72 h, respectively. SH-SY5Y cells that had been treated with mixtures of heavy metals and Spirulina underwent the same assay. Cell viability is considerably increased by using Spirulina treatments at the prescribed periods and doses. Instead, the same procedure, when applied to SH-SY5Y cells, caused the release of LDH, which is consistent with the reduction in cell viability. We demonstrated for the first time, considering all the available data, that Spirulina 5, 25, and 50 (%v/v) enhanced the number of viable SH-SY5Y cells utilized as a model system for brain cells. Overall, the data from the present study provide a first insight into the promising positive role of Spirulina against the potentially toxic effects of metals.

The benefit of using in vitro bioassays to screen agricultural samples for oxidative stress: South Africa's case

Applied pesticides end up in non-target environments as complex mixtures. When bioavailable, these chemicals pose a threat to living organisms and can induce oxidative stress (OS). In this article, attention is paid to OS and the physiological role of the antioxidant defense system. South African and international literature was reviewed to provide extensive evidence of pesticide-induced OS in non-target organisms, in vivo and in vitro. Although in vitro approaches are used internationally, South African studies have only used in vivo methods. Considering ethical implications, the authors support the use of in vitro bioassays to screen environmental matrices for their OS potential. Since OS responses are initiated and measurable at lower cellular concentrations compared to other toxicity endpoints, in vitro OS bioassays could be used as an early warning sign for the presence of chemical mixtures in non-target environments. Areas of concern in the country could be identified and prioritized without using animal models. The authors conclude that it will be worthwhile for South Africa to include in vitro OS bioassays as part of a battery of tests to screen environmental matrices for biological effects. This will facilitate the development and implementation of biomonitoring programs to safeguard the South African environment.

Pyrethroid residues in Indonesian river Citarum: A simple analytical method applied for an ecological and human health risk assessment

Pyrethroid residues in the Citarum River, Indonesia, was first investigated based on their occurrences, water assimilative capacity, and risk assessment. In this paper, first, a relatively simple and efficient method was built and validated for analysis of seven pyrethroids in river water matrix: bifenthrin, fenpropathrin, permethrin, β-cyfluthrin, cypermethrin, fenvalerate, and deltamethrin. Next, the validated method was used to analyze pyrethroids in the Citarum River. Three pyrethroids, β-cyfluthrin, cypermethrin, and deltamethrin, were detected in some sampling points with concentration up to 0.01 mg/L. Water assimilative capacity evaluation shows that β-cyfluthrin and deltamethrin pollution exceed the Citarum river water capacity. However, due to hydrophobicity properties of pyrethroids, removal through binding to sediments are expected. Ecotoxicity risk assessment shows that β-cyfluthrin, cypermethrin and deltamethrin pose risks to the aquatic organisms in the Citarum River and its tributaries through bioaccumulation in food chain. Based on bioconcentration factors of the detected pyrethroids, β-cyfluthrin poses the highest adverse effect to humans while cypermethrin is the safest. Human risk assessment based on hazard index suggests that acute non-carcinogenic risk associated to consuming fish from the study location polluted with β-cyfluthrin, cypermethrin and deltamethrin is unlikely. However, hazard quotient shows that chronic non-carcinogenic risk associated to consuming fish from the study location polluted with β-cyfluthrin is likely. However, since the risk assessment was performed separately for each pyrethroid, further assessment on the impact of mixture pyrethroid to aquatic organisms and humans should be performed to explore the real impact of pyrethroids to the river system.

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.

β-Cyfluthrin-Mediated Cytotoxicity of Cultured Rat Primary Hepatocytes Ameliorated by Cotreatment with Luteolin

The current study was designed to evaluate the possible protective effects of luteolin against β-cyfluthrin-mediated toxicity on the primary culture of rat hepatocytes (RHs). In the first step, the exposure of RHs to β-cyfluthrin (10, 20, 40, and 80 μM) was assessed by MTT. Second, redox condition was evaluated in cotreatment of cells with luteolin (20, 40, and 60 μM) and β-cyfluthrin (40 μM) at both medium and intra levels. In comparison to control, viability was lower in 40 and 80 μM β-cyfluthrin-treated groups at 24 h and all β-cyfluthrin-treated groups at 48 h (P < 0.05). Cotreatment with 20 or 40 μM luteolin + 40 μM β-cyfluthrin resulted in a higher viability value compared to β-cyfluthrin alone at 24 and 48 h of incubation (P < 0.05). Administration of 20 or 40 μM luteolin with β-cyfluthrin led to the decrease of malondialdehyde and total nitrate/nitrite and the increase of total antioxidant capacity (TAC) values in both medium and intrahepatocyte levels compared to the β-cyfluthrin-treated group at 48 h (P < 0.05). It seems that low and medium doses of luteolin possess the potential to reduce β-cyfluthrin-mediated hepatotoxicity via attenuation of peroxidative/nitrosative reactions and augmentation of TAC levels.

The SH-SY5Y human neuroblastoma cell line, a relevant in vitro cell model for investigating neurotoxicology in human: focus on organic pollutants

Investigation of the toxicity triggered by chemicals on the human brain has traditionally relied on approaches using rodent in vivo models and in vitro cell models including primary neuronal cultures and cell lines from rodents. The issues of species differences between humans and rodents, the animal ethical concerns and the time and cost required for neurotoxicity studies on in vivo animal models, do limit the use of animal-based models in neurotoxicology. In this context, human cell models appear relevant in elucidating cellular and molecular impacts of neurotoxicants and facilitating prioritization of in vivo testing. The SH-SY5Y human neuroblastoma cell line (ATCC® CRL-2266^TM) is one of the most used cell lines in neurosciences, either undifferentiated or differentiated into neuron-like cells. This review presents the characteristics of the SH-SY5Y cell line and proposes the results of a systematic review of literature on the use of this in vitro cell model for neurotoxicity research by focusing on organic environmental pollutants including pesticides, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), flame retardants, PFASs, parabens, bisphenols, phthalates, and PAHs. Organic environmental pollutants are widely present in the environment and increasingly known to cause clinical neurotoxic effects during fetal & child development and adulthood. Their effects on cultured SH-SY5Y cells include autophagy, cell death (apoptosis, pyroptosis, necroptosis, or necrosis), increased oxidative stress, mitochondrial dysfunction, disruption of neurotransmitter homeostasis, and alteration of neuritic length. Finally, the inherent advantages and limitations of the SH-SY5Y cell model are discussed in the context of chemical testing.

Influence of perinatal deltamethrin exposure at distinct developmental stages on motor activity, learning and memory

BACKGROUND

Perinatal exposure to deltamethrin (DM) causes attention-deficit/ hyperactivity disorder-like behaviors. However, the vulnerable time window to DM exposure and the possible mechanism are obscure. We aimed to identify the critical window(s) at perinatal stages for DM exposure and the possible mechanism.

METHOD

Pregnant mice were exposed to DM (0.5 mg/kg) at three different prenatal stages [gestational day (GD) 0-5, 6-15 and 16-birth (16-B)] and early postnatal stage (PD 0-10). Locomotor activity, learning and memory were evaluated using open field and Y-maze test, respectively. Nissl staining and western blots were used to examine the neuronal loss and the protein expression, respectively.

RESULTS

Perinatal exposures to DM had no effect on reproductive and growth index of offspring. However, mice receiving DM exposure during GD 16-B displayed significantly higher mortality suggesting GD 16-B is the most vulnerable time window to DM exposure. Prenatal but not early postnatal DM exposure impaired locomotor activity, learning and memory, and caused neuron loss in the dentate gyrus of male offspring. However, neither prenatal nor postnatal DM exposure affected mouse behavior of female offspring. Prenatal DM exposures decreased the protein levels of NR2A and NR2B in both hippocampi and cerebral cortices of male offspring. However, female mice receiving DM exposure at GD 16-B but not other stages displayed increased expression levels of NR2A and NR2B in hippocampi.

CONCLUSION

Prenatal but not early postnatal DM exposure impairs the neuron development in male but not female mice. Altered NMDA receptor expression may correlate to DM-induced behavioral deficits.

Estrogen receptor: A potential linker of estrogenic and dopaminergic pathways in zebrafish larvae following deltamethrin exposure

Deltamethrin (DM), a type II pyrethroid insecticide, is widely used to control agricultural pests. However, its excessive use exerts a detrimental effect on the ecological environment and human health, indicating the need to study its potential risks in detail. In the present study, zebrafish embryos were exposed to varying concentrations of DM (0.1, 1, 10, and 25 μg/L) for 96 h to assess the alterations in the transcript levels of proteins of the estrogenic and dopaminergic pathways. In addition, its effect on zebrafish locomotor activity was studied. The mRNA expression of cyp19a1b, erα, erβ2, fshr, gnrh2, gnrhr3, vtg3, dat, and dr1 significantly changed after exposing the embryos to DM. Deltamethrin at 10 and 25 μg/L significantly reduced the average swimming speed of zebrafish larvae. In addition, embryos injected with zebrafish estrogen receptor α (erα) and β (erβ) morpholinos and co-exposed to 25 μg/L DM for 96 h showed reduced expression of vtg3 mRNA compared to embryos exposed to 25 μg/L DM only. The locomotor activity of erα and erβ knockdown zebrafish following DM exposure was increased significantly when compared with that of larvae exposed to 25 μg/L DM only. Our results demonstrated that DM altered the locomotor activity of zebrafish larvae and the transcript levels of the components of estrogenic and dopaminergic pathways; erα and erβ knockdown weakened these effects.

N-Acetylcysteine Reverses Monocrotophos Exposure-Induced Hepatic Oxidative Damage via Mitigating Apoptosis, Inflammation and Structural Changes in Rats

Oxidative stress-mediated tissue damage is primarily involved in hepatic injuries and dysfunctioning. Natural antioxidants have been shown to exert hepatoprotective, anti-inflammatory and antiapoptotic properties. The present study evaluated the effect of N-acetylcysteine (NAC) against monocrotophos (MCP) exposure-induced toxicity in the rat liver. Albino Wistar rats were divided into four groups: (1) control, (2) NAC-treated, (3) MCP-exposure, (4) NAC and MCP-coexposure group. The dose of MCP (0.9 mg/kg b.wt) and NAC (200 mg/kg b.wt) were administered orally for 28 days. Exposure to MCP caused a significant increase in lipid peroxidation, protein oxidation and decreased glutathione content along with the depletion of antioxidant enzyme activities. Further MCP exposure increased pro-inflammatory cytokines levels and upregulated Bax and Caspase-3 expressions. MCP exposure also caused an array of structural alternations in liver tissue, as depicted by the histological and electron microscopic analysis. Thepretreatment of NAC improved glutathione content, restored antioxidant enzyme activities, prevented oxidation of lipids and proteins, decreased pro-inflammatory cytokines levels and normalized apoptotic protein expression. Treatment of NAC also prevented histological and ultrastructural alternations. Thus, the study represents the therapeutic efficacy and antioxidant potential of NAC against MCP exposure in the rat liver.

Attenuative Role of Idebenone on Deltamethrin Mediated Peroxidative Toxicity of Ram Semen Stored at 4°C

The current study was conducted to evaluate the different concentrations of deltamethrin (DEL; Exp. 1) and the protective role of idebenone (IDB) supplemented with toxic dose of deltamethrin (Exp. 2) during chilled storage of ram semen. Collected samples were pooled and diluted at 500×106 spermatozoa per mL. In Exp. 1, effect of DEL at 1, 2.5, 5, 10, 20, 40, 80 μM levels was evaluated on different variables of spermatozoa motion characteristics. In Exp. 2, different amounts of IDB (2, 4, and 8 μM) concurrent with constant doses of DEL (10 μM) were examined on semen quality upon chilled preservation up to 72 h. Indices of spermatozoa kinematics, functionality of plasma membrane and viability were recorded. Biochemical metabolites were measured in spermatozoa and its medium (extender) at different time points. In Exp. 1, different parameters of spermatozoa kinematics were affected by exposure to DEL in a dose dependent manner. In Exp. 2, combination of IDB with DEL resulted in a significant (P<0.05) increase in total motility, forward progressive motility and curvilinear path velocity compared to DEL group at 24, 48 and 72 h. Simultaneous administration of IDB with DEL increased the percentage of spermatozoa with functional membrane and viability compared to DEL group at 72 h (P<0.05). The amounts of lipid peroxidation index were lower in medium of combination groups compared to DEL group at 48 h and 72 h (P<0.05). Antioxidant capacity was higher in spermatozoa and medium of IDB treated groups compared to DEL group at 72 h (P<0.05). Amounts of total nitrate-nitrite and superoxide dismutase activity of spermatozoa and medium were not affected by treatment (P>0.05). In conclusion, IDB could ameliorate oxidative and peroxidative damages induced by DEL mild toxicity upon cold preservation of ram semen.

Ameliorative role of trans-ferulic acid on induced oxidative toxicity of rooster semen by β-cyfluthrin during low temperature liquid storage

Current study was designed to evaluate the effects of β-cyfluthrin, as a toxicant substance, and trans-ferulic acid (trans-FA), as a protective agent, on different parameters of rooster semen upon liquid storage. For this purpose, semen samples of roosters (Ross 308, n = 10, 32-wk-old) were collected twice a week. Good quality samples (≥70% progressive motion) were diluted, pooled and then divided for the purposes of the study. In the first experiment, motility of spermatozoa was evaluated following exposure to different concentrations of β-cyfluthrin (1, 2.5, 5, 10, 20, 40, and 80 µM) at 0, 24, and 48 h of storage. In the second experiment, constant doses of β-cyfluthrin (10 µM) alone or in combination with trans-FA (10, 25 mM) were assessed on motility and viability of spermatozoa at 0, 24, and 48 h time points. Moreover, amounts of malondialdehyde (MDA), total antioxidant capacity (TAC), total nitrate-nitrite, total hydroperoxide (HPO), and activity of superoxide dismutase (SOD) were evaluated in the homogenate of spermatozoa-diluent at studied time points. Results of the first experiment showed that amounts of β-cyfluthrin greater than 5 µM, significantly reduced the motility of spermatozoa at 24 and 48 h of storage (P < 0.05). The second experiment demonstrated that, trans-FA especially at 10, 25 mM doses restored the motility and viability of spermatozoa compared to β-cyfluthrin treated group (P < 0.05). Amounts of MDA (10, 25 mM), hydroperoxide (10, 25, and 50 mM), and nitrate-nitrite (10, 25, and 50 mM) were lower and TAC (10 and 25 mM) were greater in trans-FA + β-cyfluthrin treated groups compared to β-cyfluthrin alone treated samples (P < 0.05). However, activity of SOD did not show significant changes by the treatment (P > 0.05). It seems that trans-FA could ameliorate toxic effect of β-cyfluthrin via reduction of peroxidative (as evident by measurement of MDA) and nitrosative (as evident by measurement of nitrate-nitrite) reactions over cold preservation of rooster semen.

Nerve Growth Factor Protects Against Pyrethroid-Induced Endoplasmic Reticulum (ER) Stress in Primary Hippocampal Neurons

Neurotrophins are a family of growth factors crucial for growth and survival of neurons in the developing and adult brain. Reduction in neurotrophin levels is associated with reduced neurogenesis and cognitive deficits in rodents. Recently, we demonstrated that long-term exposure to low levels of the pyrethroid pesticide deltamethrin causes hippocampal endoplasmic reticulum (ER) stress and learning deficits in mice. Here, we found that nerve growth factor (NGF) mRNA and protein were selectively reduced in the hippocampus of deltamethrin-treated mice. To explore potential mechanisms responsible for this observation, we employed mouse primary hippocampal neurons. Exposure of neurons to deltamethrin (1-5 μM) caused ER stress as indicated by increased levels of C/EBP-homologous protein (CHOP) and glucose-regulated protein 78 (GRP78). These changes were accompanied by increased levels of caspase-12, activated caspase-3, and decreased levels of NGF. Inhibition of ER stress with the eukaryotic initiation factor 2 alpha (eIF2α) inhibitor salubrinal abolished deltamethrin-induced activation of caspase-12 and caspase-3, and restored NGF levels. Furthermore, deltamethrin decreased Akt (protein kinase B) phosphorylation, which was significantly prevented by co-treatment with NGF or SC-79 in cells. Collectively, these results demonstrate that the loss of NGF following ER stress may contribute to deltamethrin-induced apoptosis in the hippocampus through the Akt signaling pathway, and that this may provide a plausible mechanism for impaired learning and memory observed following exposure of mice to deltamethrin.

Effects of pyrethroids on brain development and behavior: Deltamethrin

Deltamethrin (DLM) is a Type II pyrethroid pesticide widely used in agriculture, homes, public spaces, and medicine. Epidemiological studies report that increased pyrethroid exposure during development is associated with neurobehavioral disorders. This raises concern about the safety of these chemicals for children. Few animal studies have explored the long-term effects of developmental exposure to DLM on the brain. Here we review the CNS effects of pyrethroids, with emphasis on DLM. Current data on behavioral and cognitive effects after developmental exposure are emphasized. Although, the acute mechanisms of action of DLM are known, how these translate to long-term effects is only beginning to be understood. But existing data clearly show there are lasting effects on locomotor activity, acoustic startle, learning and memory, apoptosis, and dopamine in mice and rats after early exposure. The most consistent neurochemical findings are reductions in the dopamine transporter and the dopamine D1 receptor. The data show that DLM is developmentally neurotoxic but more research on its mechanisms of long-term effects is needed.

Bioallethrin enhances generation of ROS, damages DNA, impairs the redox system and causes mitochondrial dysfunction in human lymphocytes

Bioallethrin is a synthetic pesticide that is widely used to control insect pests. The wide use of bioallethrin has resulted in inevitable human exposure. In this study we report the effect of different concentrations of bioallethrin (10 to 200 µM, 2 h at 37 °C) on human lymphocytes under in vitro conditions. Bioallethrin treatment resulted in loss of cell viability (> 30% at 200 µM bioallethrin). Oxidative stress markers like lipid peroxidation and protein oxidation were significantly increased accompanied by lower ratio of reduced to oxidized glutathione. Enhanced ROS generation was observed through fluorescence spectroscopy and microscopy. Bioallethrin-induced oxidative stress also compromised the antioxidant defence as it reduced antioxidant capacity of cells and inhibited major antioxidant enzymes. Biomolecular modifications and systemic toxicity by bioallethrin resulted in plasma membrane damage with mitochondrial depolarization. Comet assay showed nuclear DNA fragmentation and strand scission with significant increase in tail length and olive tail moment. Apoptosis and necrosis of cells was confirmed through acridine orange/ethidium bromide dual staining and visualization under fluorescence microscope. Thus, bioallethrin causes oxidative damage and compromises the antioxidant system leading to DNA damage, cellular and organelle toxicity, resulting in apoptosis and necrosis of human lymphocytes.

Synthetic pyrethroids common metabolite 3-phenoxybenzoic acid induces caspase-3 and Bcl-2 mediated apoptosis in human hepatocyte cells

Synthetic pyrethroids are a group of insecticides frequently used in public health and agriculture, and 3-PBA is a common metabolite of them. Although the liver is the primary organ responsible for metabolizing many compounds including pesticides, to the authors' knowledge there have been no studies on the direct hepatotoxic effects of 3-PBA. Therefore, this study aimed to investigate the possible hepatotoxic effects of 3-PBA on a Human Hepatoma Cell Line (HepG2) and the underlying apoptotic mechanisms. Firstly, an LC₅₀ of 1041.242 µM was calculated for 3-PBA by using the WST-1 test with concentrations ranging between 1 µM and 10 mM. Following that, the HepG2 cells in the experimental group were exposed to 3 different concentrations of 3-PBA (1/5 LC₅₀, 1/10 LC₅₀ and 1/20 LC₅₀) for 24 hours. The apoptotic mechanism was evaluated by using flow cytometry, and immunofluorescence assays for Caspase 3 and Bcl-2. In the flow cytometry assay, the total number of apoptotic cells increased in a dose dependent manner (p < 0.05). In the immunofluorescence assay, the Caspase 3 protein showed strong immunoreactivity in the experimental groups, while the reaction to the Bcl-2 protein was minimal. These results demonstrated that 3-PBA has a significant hepatotoxic effect on HepG2 cells and induces apoptosis via the regulation of Caspase-3 and Bcl-2. Furthermore, our results could further the understanding of the fundamental molecular mechanisms of 3-PBA hepatotoxicity. More studies are needed to determine the effects of long-term exposure to 3-PBA and also the molecular mechanisms underlying hepatotoxicity.

Deltamethrin modulates the native structure of Hen Egg White Lysozyme and induces its aggregation at physiological pH

Deltamethrin, a type II pyrethroid pesticide was initially considered as safe for human use. Recent studies have reported several pathophysiological effects of deltamethrin on human and non-human species. However, its effect on structure and function of protein leading to progressive neurodegeneration is poorly understood. In present study, we investigated the interaction of deltamethrin with Hen Egg White Lysozyme (HEWL) at physiological pH and tried to understand the effect of pesticide on structure and function of protein. Employing different biophysical techniques, we shown that deltamethrin induces in vitro aggregation of HEWL in concentration dependent manner. Interaction of pesticide with different amino acids, followed by exposure of hydrophobic regions was driving force of aggregation process. Apart from modulating the hydrophobic domain, deltamethrin is observed to reduce α-helical and promote β-sheet content of lysozyme, eventually converting the globular protein into ThT sensitive amyloid fibrils and amorphous aggregates. Our study also indicate that deltamethrin induced aggregation reduces the catalytic activity of lysozyme.

Effects of deltamethrin and thiacloprid on cell viability, colony formation and DNA double-strand breaks in human bronchial epithelial cells

Deltamethrin (DEL) and thiacloprid (THIA) are commonly used insecticides applied either separately or as a mixture. We aimed to investigate the effects of DEL and THIA on cell viability, proliferation and DNA damage in human bronchial epithelial cells (BEAS-2B) because their effects in lung cells are not known. Our results indicate that all concentrations of DEL and THIA statistically decreased colony formation, plating efficiency and survival fraction in a concentration-dependent manner in BEAS-2B cells expect the lowest concentration for 24 h. MTT assay showed that treatment of DEL + THIA increased the cytotoxicity at higher concentrations. DEL + THIA significantly induced the foci formation of phosphorylated H2AX protein and p53 binding protein 1 at the highest concentration (44 μM DEL+666 μM THIA) for 120 h. Because gH2AX foci number was still higher in the recovery group given an additional 24 h after 120 h, the recovery period was not sufficient for DNA double-strand breaks repair.

Cytotoxicity and Oxidative Stress Responses of Imidacloprid and Glyphosate in Human Prostate Epithelial WPM-Y.1 Cell Line

Insecticide imidacloprid and herbicide glyphosate have a broad spectrum of applicable use in the agricultural sector of Egypt. Their ability to induce in vitro cytotoxic and oxidative stress on normal human cells (prostate epithelial WPM-Y.1 cell line) was evaluated with the methyl tetrazolium test (MTT) and histopathological investigation. Cell viability was evaluated with an MTT test for 24 h. The median inhibition concentration (IC50) values were 0.023 and 0.025 mM for imidacloprid and glyphosate, respectively. Sublethal concentrations: 1/10 and 1/50 of IC50 and IC50 levels significantly induced an increase in the lactate dehydrogenase (LDH) activity and malondialdehyde (MDA) level compared with the untreated cells. Rapid decrease in the glutathione (GSH) content and glutathione-S-transferase (GST) activity was induced. Significant increases were recorded in activities of catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), respectively, compared with the control group. Transmission electron microscopic (TEM) investigation showed significant defects in the cells following pesticide treatments for 24 h. Therefore, it is concluded that imidacloprid and glyphosate are very toxic in vitro assays and able to induce apoptotic effects as well as oxidative stress. So, these findings provide a scenario of multibiomarkers to achieve the imposed risks of pesticides at low doses.

Histological, ultrastructural, and biochemical study on the possible role of Panax ginseng in ameliorating liver injury induced by Lambda cyhalotherin

Background

Lambda-cyhalotherin (LCT) is a pyrithroid type 2 pesticide that is broadly utilized in pest control in public health, animal health, and agriculture. Although claiming that LCT has a low mammalian toxicity, several investigations reported its mammalian hepatotoxicity by mediating oxidative stress causes severe hepatotoxicity and liver damage.

Results

LCT significantly decreased catalase (CAT), superoxide dismutase (SOD), and total thiol (T. thiol) and increased lipid peroxidation (LPO). mRNA and protein expression levels of p53 were upregulated, whereas Bcl-2 mRNA and protein expression levels were downregulated in LCT-intoxicated animals. Also, light microscopic and ultrastructure studies for liver tissues of LCT-intoxicated animals showed mononuclear leukocytic infiltration in the parenchyma, congested portal vein with thickened wall, and proliferation of bile duct and hepatocytes with cytoplasmic vacuolations, fatty changes, and collagen fibers. Panax ginseng co-treatment attenuated oxidative stress biomarkers. Both tested doses of Panax ginseng (100 and 200 mg /kg b. wt./day) significantly decreased p53 and elevate Bcl-2 mRNA and protein expression levels and reveals significant amelioration and restoration of normal histology and ultrastructure of liver, but 200 mg/kg b. wt. of Panax ginseng seems to be more potent.

Conclusion

Panax ginseng exhibited ameliorative effect against hepatic oxidative stress, apoptosis, histopathological, and ultrastructural changes induced by LCT.

Acute and chronic toxicity of deltamethrin, permethrin, and dihaloacetylated heterocyclic pyrethroids in mice

BACKGROUND

Pyrethroids, a class of insecticides, that act on the nervous system of insects. Frequent consumption of foods with pyrethroid residues increase the risk of developmental and neurological diseases in humans. Assessing the toxicity of novel synthetic pyrethroids to mammals is also critical to the development of agrochemicals.

RESULTS

Using mice as models, the acute and chronic toxicity of deltamethrin, permethrin, dihaloacetylated pyrethroids to mammals was researched by gavage administration. Acute toxicity assessment displayed that the median lethal dose (LD₅₀ ) of deltamethrin, permethrin and dihaloacetylated heterocyclic pyrethroids DCA-O, DCA-01, and DCA-11 tested were greater than 500 mg/kg of weight. Furthermore, chronic toxicity assessment demonstrated that deltamethrin, permethrin caused epidermal damage near the genitals, while dihaloacetylated heterocyclic pyrethroids DCA-O, DCA-01, and DCA-11 showed no relevant symptoms. However, both the acute and chronic toxicity assessment suggested that pyrethroids exposure induced mice loss weight. Additionally, the elevated plus maze (EPM) test showed that pyrethroids caused anxiety-like behaviors and no motor defects in Kunming mice. Beside, during the sucrose preference test (SPT), 60-day pyrethroids exposure increased excitatory behaviors in mice. However, the neurochemical studies displayed that pyrethroids exposure increased the total amount of glutamate (Gln), glutamine (Glu) and γ-aminobutyric acid (GABA) in the mice's blood.

CONCLUSION

Pyrethroids exposure induced weight loss in mice, although the acute oral toxicity of deltamethrin, permethrin and dihaloacetylated heterocyclic pyrethroids DCA-O, DCA-01, and DCA-11 was low. However, regarding chronic toxicity, deltamethrin, permethrin and dihaloacetylated heterocyclic pyrethroids DCA-O, DCA-01, and DCA-11 induced anxiety-like behaviors, excitatory behaviors, Gln-Glu-GABA circulatory dysfunction in blood. Particularly, deltamethrin, though permethrin also had reproductive toxicity. © 2020 Society of Chemical Industry.

Co-exposure to deltamethrin and thiacloprid induces cytotoxicity and oxidative stress in human lung cells

Deltamethrin (DEL) and thiacloprid (THIA) are commonly used synthetic insecticides in agriculture either separately or in combination. There is limited information in human cells for the effects of the mixture of DEL + THIA on oxidative stress. Therefore, the present study was designed to examine the effects of the mixture on cell proliferation and oxidative stress in human lung fibroblast cells. Human telomerase reverse transcriptase (hTERT)-expressing human lung fibroblasts, WTHBF-6 cells, were treated with 2.5 + 37.5, 5 + 75, 12.5 + 187.5, and 25 +375 µM concentrations of DEL + THIA for the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and 5 + 75, 12.5 + 187.5, and 25 + 375 µM for lipid peroxidation and reduced glutathione (GSH) assays for 24, 48, and 72 h in the absence and presence of metabolizing fractions of the mammalian liver (S9 mixture). Both the mixture of DEL + THIA and their metabolites significantly reduced cell viability and induced cytotoxicity in WTHBF-6 cells, especially at higher concentrations. The mixture of DEL + THIA significantly decreased GSH levels at the highest concentration for all treatment times and at the highest two concentrations (12.5 + 187.5 and 25 + 375 µM) for 72 h in the presence of S9 mixture. The highest concentration of DEL + THIA mixture caused a significant increase in malondialdehyde (MDA) level at 72 h in the absence of S9 mixture. There were also significant increases in MDA levels at the highest concentration for 48-h and all concentrations of DEL + THIA for 72-h treatment in WTHBF-6 cell cultures with S9. These data showed that the mixture of DEL + THIA and their metabolites can induce cytotoxicity and oxidative stress in human lung fibroblasts.

Synthesis, insecticidal activity, resistance, photodegradation and toxicity of pyrethroids (A review)

Pyrethroids are a class of highly effective, broad-spectrum, less toxic, biodegradable synthetic pesticides. However, despite the extremely wide application of pyrethroids, there are many problems, such as insecticide resistance, lethal/sub-lethal toxicity to mammals, aquatic organisms or other beneficial organisms. The objectives of this review were to cover the main structures, synthesis, steroisomers, mechanisms of action, anti-mosquito activities, resistance, photodegradation and toxicities of pyrethroids. That was to provide a reference for synthesizing or screening novel pyrethroids with low insecticide resistance and low toxicity to beneficial organisms, evaluating the environmental pollution of pyrethroids and its metabolites. Besides, pyrethroids are mainly used for the control of vectors such as insects, and the non-target organisms are mammals, aquatic organisms etc. While maintaining the insecticidal activity is important, its toxic effects on non-target organisms should be also considered. Pyrethroid resistance is present not only in insect mosquitoes but also in environmental microorganisms, which results in anti-pyrethroids resistance (APR) strains. Besides, photodegradation product dibenzofurans is harmful to mammals and environment. Additionally, pyrethroid metabolites may have higher hormonal interference than the parents. Particularly, delivery of pyrethroids in nanoform can reduce the discharge of more toxic substances (such as organic solvents, etc.) to the environment.

Bioallethrin-induced generation of reactive species and oxidative damage in isolated human erythrocytes

Bioallethrin is an insecticide that is widely used to control mosquitoes, fleas and cockroaches. The widespread use of bioallethrin has resulted in both occupational and non-occupational human exposure. Bioallethrin enters blood, regardless of the route of exposure, where it can interact with erythrocytes. We have studied the effect of bioallethrin on isolated human erythrocytes under in vitro conditions. Erythrocytes were incubated with increasing concentrations of bioallethrin (10-200 μM) for 4 h at 37 °C. Several biochemical parameters were analyzed in bioallethrin treated and untreated (control) cells. Incubation of erythrocytes with bioallethrin increased protein oxidation, lipid peroxidation and depleted sulfhydryl group content. Membrane damage was evident from cell lysis, osmotic fragility, inhibition of bound enzymes and transmembrane electron transport system. Bioallethrin also increased hemoglobin oxidation, heme degradation and the release of free iron moiety. This will decrease the oxygen transporting ability of blood. Bioallethrin treatment altered the specific activities of antioxidant enzymes and diminished the antioxidant power of cells. Scanning electron microscopy showed that bioallethrin treatment also altered erythrocyte mophology. Almost all changes were in a bioallethrin concentration dependent manner. The cytotoxicity of bioallethrin is probably mediated by reactive oxygen and nitrogen species whose formation was significantly enhanced in treated erythrocytes. Thus bioallethrin enhances the generation of reactive species which cause oxidative damage of cell components in human erythrocytes.

Synthesis, insecticidal activities and resistance in Aedes albopictus and cytotoxicity of novel dihaloacetylated heterocyclic pyrethroids

BACKGROUND

The use of safe and effective insecticides against mosquito-borne stocks is still one of the most effective ways to rapidly interrupt the spread of diseases such as malaria, dengue etc., but many insects are resistant to most insecticides and most of the traditional pyrethroids (like permethrin, deltamethrin etc.) contain phenoxy groups so it is easy to form dibenzofuran, a pollutant, after photodegradation. It is therefore necessary to synthesize novel pyrethroids which have better mosquito-killing activity, poor resistance to mosquitoes, and no dibenzofuran formation during photodegradation.

RESULTS

A series of novel dihaloacetylated heterocyclic pyrethroids were synthesized to enhance antimosquito activity. Bioassays based on the guidelines of the Chinese Center for Disease Control and Prevention (CDC) indicate that the synthesized compounds DCA-O (LC₅₀  = 2.95 ± 0.05 μg L^-1 ), DCA-01 (LC₅₀  = 5.83 ± 0.36 μg L^-1 ) and DCA-11 (LC₅₀  = 5.79 ± 1.51 μg L^-1 ) exhibit high insecticidal activities and sensitivity against Aedes albopictus while deltamethrin and permethrin produced moderate levels of resistance. Moreover, the analysis of the photodegradation implies that the novel compounds synthesized by substituting a phenoxy group with a heterocyclic ring do not form dibenzofuran, a pollutant. Lastly, the cytotoxicity data of pyrethroids on human dopaminergic neuroblastoma SH-SY5Y cells confirm that the synthesized compounds have low toxicity for the cells.

CONCLUSION

Novel dihaloacetylated heterocyclic pyrethroids, made by simple synthesis steps, have better antimosquito activity, lower drug resistance, are less polluting to the environment and show low toxicity to human nerve cells. This also provides an effective idea for the synthesis of pyrethroids. Novel dihaloacetylated heterocyclic pyrethroids have better antimosquito activity, lower drug resistance, are less polluting to the environment, ahow low toxicity to human nerve cells and simple synthesis steps. © 2019 Society of Chemical Industry.

Oxidative stress and related gene expression effects of cyfluthrin in human neuroblastoma SH-SY5Y cells: Protective effect of melatonin

This study was designed to assess oxidative stress induction in human neuroblastoma SH-SY5Y cells in response to cyfluthrin exposure. Cell viability MTT assay was carried out to assess cyfluthrin cytotoxicity; IC₃₀ and IC₅₀ values for cyfluthrin were calculated to be 4.81 ± 0.92 μM and 19.39 ± 3.44 μM, respectively. Cyfluthrin induced a significant increase in ROS generation, lipid peroxides measured as malondialdehyde (MDA) and nitric oxide (NO) production and a significant decrease in NQO1 activity. The antioxidant activity of melatonin (MEL), Trolox, N-acetylcysteine (NAC) and Sylibin against cyfluthrin-induced oxidative stress was examined. Cyfluthrin increased significantly gene expressions of apoptosis, proinflammation and oxidative stress (Bax, Bcl-2, Casp-3, BNIP3, AKT1, p53, APAF1, NFκB1, TNFα and Nrf2) mediators. In the most genes, the mRNA levels induced by cyfluthrin were partially reduced by MEL (1 μM). Cyfluthrin effects on gene expression profiling of oxidative stress pathway by Real-Time PCR array analysis showed that of the 84 genes examined, (fold change > 1.5) changes in mRNA levels were detected in 31 genes: 13 upregulated and 18 down-regulated. A fold change >3.0 fold was observed on upregulated CYBB, DUOX1, DUOX2, AOX1, BNIP3, HSPA1A, NOS2, and NQO1 genes. The greater fold change reversion (2.5 fold) by MEL (1 μM) was observed on cyfluthrin-upregulated CYBB, AOX1, BNIP3 and NOS2 genes. These results demonstrated that oxidative stress is a key element in cyfluthrin induced neurotoxicity as well as MEL may play a role in reducing cyfluthrin-induced oxidative stress.

Insight Into Microbial Applications for the Biodegradation of Pyrethroid Insecticides

Pyrethroids are broad-spectrum insecticides and presence of chiral carbon differentiates among various forms of pyrethroids. Microbial approaches have emerged as a popular solution to counter pyrethroid toxicity to marine life and mammals. Bacterial and fungal strains can effectively degrade pyrethroids into non-toxic compounds. Different strains of bacteria and fungi such as Bacillus spp., Raoultella ornithinolytica, Psudomonas flourescens, Brevibacterium sp., Acinetobactor sp., Aspergillus sp., Candida sp., Trichoderma sp., and Candia spp., are used for the biodegradation of pyrethroids. Hydrolysis of ester bond by enzyme esterase/carboxyl esterase is the initial step in pyrethroid biodegradation. Esterase is found in bacteria, fungi, insect and mammalian liver microsome cells that indicates its hydrolysis ability in living cells. Biodegradation pattern and detected metabolites reveal microbial consumption of pyrethroids as carbon and nitrogen source. In this review, we aim to explore pyrethroid degrading strains, enzymes and metabolites produced by microbial strains. This review paper covers in-depth knowledge of pyrethroids and recommends possible solutions to minimize their environmental toxicity.

Pyrethroid exposure and neurotoxicity: a mechanistic approach

Pyrethroids are a class of synthetic insecticides that are used widely in and around households to control the pest. Concerns about exposure to this group of pesticides are now mainly related to their neurotoxicity and nigrostriatal dopaminergic neurodegeneration seen in Parkinson’s disease. The main neurotoxic mechanisms include oxidative stress, inflammation, neuronal cell loss, and mitochondrial dysfunction. The main neurodegeneration targets are ion channels. However, other receptors, enzymes, and several signalling pathways can also participate in disorders induced by pyrethroids. The aim of this review is to elucidate the main mechanisms involved in neurotoxicity caused by pyrethroids deltamethrin, permethrin, and cypermethrin. We also review common targets and pathways of Parkinson’s disease therapy, including Nrf2, Nurr1, and PPARγ, and how they are affected by exposure to pyrethroids. We conclude with possibilities to be addressed by future research of novel methods of protection against neurological disorders caused by pesticides that may also find their use in the management/treatment of Parkinson’s disease.

Influence of Nanomolar Deltamethrin on the Hallmarks of Primary Cultured Cortical Neuronal Network and the Role of Ryanodine Receptors

BACKGROUND

The pyrethroid deltamethrin (DM) is broadly used for insect control. Although DM hyperexcites neuronal networks by delaying inactivation of axonal voltage-dependent [Formula: see text] channels, this mechanism is unlikely to mediate neurotoxicity at lower exposure levels during critical perinatal periods in mammals.

OBJECTIVES

We aimed to identify mechanisms by which acute and subchronic DM altered axonal and dendritic growth, patterns of synchronous [Formula: see text] oscillations (SCOs), and electrical spike activity (ESA) functions critical to neuronal network formation.

METHODS

Measurements of SCOs using [Formula: see text] imaging, ESA using microelectrode array (MEA) technology, and dendritic complexity using Sholl analysis were performed in primary murine cortical neurons from wild-type (WT) and/or ryanodine receptor 1 ([Formula: see text]) mice between 5 and 14 d in vitro (DIV). [Formula: see text] binding analysis and a single-channel voltage clamp were utilized to measure engagement of RyRs as a direct target of DM.

RESULTS

Neuronal networks responded to DM ([Formula: see text]) as early as 5 DIV, reducing SCO amplitude and depressing ESA and burst frequencies by 60-70%. DM ([Formula: see text]) enhanced axonal growth in a nonmonotonic manner. [Formula: see text] enhanced dendritic complexity. DM stabilized channel open states of RyR1, RyR2, and cortical preparations expressing all three isoforms. DM ([Formula: see text]) altered gating kinetics of RyR1 channels, increasing mean open time, decreasing mean closed time, and thereby enhancing overall open probability. SCO patterns from cortical networks expressing [Formula: see text] were more responsive to DM than WT. [Formula: see text] neurons showed inherently longer axonal lengths than WT neurons and maintained less length-promoting responses to nanomolar DM.

CONCLUSIONS

Our findings suggested that RyRs were sensitive molecular targets of DM with functional consequences likely relevant for mediating abnormal neuronal network connectivity in vitro. https://doi.org/10.1289/EHP4583.

Deltamethrin toxicity: A review of oxidative stress and metabolism

Deltamethrin is widely used worldwide due to its valuable insecticidal activity against pests and parasites. Increasing evidence has shown that deltamethrin causes varying degrees of toxicity. Moreover, oxidative stress and metabolism are highly correlated with toxicity. For the first time, this review systematically summarizes the deltamethrin toxicity mechanism from the perspective of oxidative stress, including deltamethrin-mediated oxidative damage, antioxidant status, oxidative signaling pathways and modulatory effects of antagonists, synergists and placebos on oxidative stress. Further, deltamethrin metabolism, including metabolites, metabolic enzymes and pathways and deltamethrin metabolite toxicity are discussed. This review will shed new light on deltamethrin toxicity mechanisms and provide effective strategies to ensure pest control and prevention of human and animal poisoning.

Chiral pharmaceuticals: Environment sources, potential human health impacts, remediation technologies and future perspective

Chiral pharmaceuticals (CPs), including non-steroid anti-inflammatory drugs (NSAIDs), β-blockers and some herbicide and pesticides, are widely used in aquaculture, clinical treatment and many other fields. However, people are increasingly concerned about such ubiquitous pollutants, which can frequently be detected in contaminated soil and water. In large part, the significant sources of chiral pharmaceuticals stem from industrial processes, such as the direct discharge of untreated or incompletely treated wastewaters containing chiral pharmaceuticals, incorrect storage and use, animal wastes and biosolids. The main ways for human exposure to chiral pharmaceuticals are the disease treatment process and chiral pharmaceuticals contaminants. According to the results of a series of toxic studies, some diseases, even cancers, may be associated with exposure to certain chiral pharmaceuticals. Therefore, the treatment of chiral pharmaceuticals has become an important issue. The current advanced remediation techniques for chiral pharmaceuticals include the conventional method (sorption and sonolysis), biotransformation (an aerobic granular sludge-sequencing batch reactor and constructed wetland system) and advanced oxidation processes (ozonation and photocatalysis). Herein, in this review, we summarize the current status and sources of chiral pharmaceuticals, potential effects on human health, as well as the superiority, disadvantages and prospects of current advanced remediation technologies. Moreover, we also anticipate the prospect of the future research needed for chiral pharmaceuticals pollutant remediation.

Inflammatory and cytotoxic effects of bifenthrin in primary microglia and organotypic hippocampal slice cultures

BACKGROUND

Pyrethroids, such as bifenthrin (BF), are among the most widely used class of insecticides that pose serious risks to human and wildlife health. Pyrethroids are proposed to affect astrocytic functions and to cause neuron injury in the central nervous system (CNS). Microglia are key cells involved in innate immune responses in the CNS, and microglia activation has been linked to inflammation and neurotoxicity. However, little information is known about the effects of BF-induced toxicity in primary microglial cells as well as in organotypic hippocampal slice cultures (OHSCs).

METHODS

Oxidative stress and inflammatory responses induced by BF were evaluated in primary microglial cells and OHSCs incubated with different concentrations of BF (1-20 μM) for 4 and 24 h. mRNA and protein synthesis of cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), nuclear erythroid-2 like factor-2 (Nrf-2), and microsomal prostaglandin synthase-1 (mPGES-1) was also studied by qPCR and Western blot. Cell viability was analyzed by MTT-tetrazolio (MTT) and lactate dehydrogenase (LDH) assays. Neurotoxicity in OHSCs was analyzed by propidium iodide (PI) staining and confocal microscopy.

RESULTS

Exposure of microglial cells to BF for 24 h resulted in a dose-dependent reduction in the number of viable cells. At sub-cytotoxic concentrations, BF increased reactive oxygen species (ROS), TNF-alpha synthesis, and prostaglandin E2 (PGE2) production, at both 4- and 24-h time points, respectively. Furthermore, BF incubation decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and increased lipid peroxidation, protein oxidation, and H2O2 formation. In addition, BF significantly induced protein synthesis and mRNA expression of oxidative and inflammatory mediators after 4 and 24 h, including Nrf-2, COX-2, mPGES-1, and nuclear factor kappaB (NF-kappaB). A 24-h exposure of OHSCs to BF also increased neuronal death compared to untreated controls. Furthermore, depletion of microglia from OHSCs potently enhanced neuronal death induced by BF.

CONCLUSIONS

Overall, BF exhibited cytotoxic effects in primary microglial cells, accompanied by the induction of various inflammatory and oxidative stress markers including the Nrf-2/COX-2/mPGES-1/NF-kappaB pathways. Moreover, the study provided evidence that BF induced neuronal death in OHSCs and suggests that microglia exert a protective function against BF toxicity.

β-Cypermethrin and its metabolite 3-phenoxybenzoic acid exhibit immunotoxicity in murine macrophages

β-Cypermethrin (β-CYP), one of most important pyrethroids, is widely used to control insects, and has been detected in organisms, including human. Pyrethroids have been shown to pose neurotoxicity, hepatotoxicity, endocrine disruption and reproductive risks in mammals. However, research in immunotoxicity of pyrethroids, especially their metabolites, is limited. A common metabolite of pyrethroids is 3-phenoxybenzoic acid (3-PBA) in mammals. Thus, in this study, we evaluated the immunotoxicity of β-CYP and 3-PBA in mouse macrophages, RAW 264.7 cells. MTT assays showed that both β-CYP and 3-PBA reduced cell viability in a concentration- and time-dependent manner. Flow cytometry with Annexin-V/PI staining demonstrated that both β-CYP and 3-PBA induced RAW 264.7 cell apoptosis. Furthermore, our results also showed that N-acetylcysteine partially blocked β-CYP- and 3-PBA-induced cytotoxicity and apoptosis. Intrinsic apoptotic pathway was stimulated by both β-CYP and 3-PBA exposure. In addition, we found that β-CYP and 3-PBA inhibited mRNA levels of pro-inflammatory cytokines with or without LPS stimulation. Phagocytosis assay showed that both β-CYP and 3-PBA inhibited phagocytic ability of macrophages. Moreover, it was also found that both β-CYP and 3-PBA increased reactive oxygen species (ROS) levels in RAW 264.7 cells. Accordingly, both β-CYP and 3-PBA were found to regulate the mRNA levels of oxidative stress-related genes in RAW 264.7 cells. Taken together, the results obtained in this study demonstrated that β-CYP and 3-PBA may have immunotoxic effect on macrophages and that elevated ROS may underlie the mechanism. The present study will help to understand the health risks caused by β-CYP and other pyrethroids.

Relative toxicity for indoor semi volatile organic compounds based on neuronal death

BACKGROUND

Semi Volatile Organic Compounds (SVOCs) are contaminants commonly found in dwellings as a result of their use as plasticizers, flame retardants, or pesticides in building materials and consumer products. Many SVOCs are suspected of being neurotoxic, based on mammal experimentation (impairment of locomotor activity, spatial learning/memory or behavioral changes), raising the question of cumulative risk assessment. The aim of this work is to estimate the relative toxicity of such SVOCs, based on neuronal death.

METHOD

SVOCs fulfilling the following conditions were included: detection frequency >10% in dwellings, availability of data on effects or mechanism of action for neurotoxicity, and availability of dose-response relationships based on cell viability assays as a proxy of neuronal death. Benchmark concentration values (BMC) were estimated using a Hill model, and compared to assess relative toxicity.

RESULTS

Of the 58 SVOCs selected, 28 were suspected of being neurotoxic in mammals, and 21 have been documented as inducing a decrease in cell viability in vitro. 13 have at least one dose-response relationship that can be used to derive a BMC based on a 10% fall in neuronal viability. Based on this in vitro endpoint, PCB-153 appeared to be the most toxic compound, having the lowest BMC₁₀ (0.072μM) and diazinon the least toxic compound, having the highest BMC₁₀ (94.35μM). We showed that experimental designs (in particular choice of cell lines) had a significant influence on BMC calculation.

CONCLUSION

For the first time, the relative in vitro toxicity of 13 indoor contaminants belonging to different chemical families has been assessed on the basis of neuronal cell viability. Lack of comparable toxicity datasets limits the number of SVOCs that can be included. More standardized protocols in terms of cell lines, species and exposure duration should be developed with a view to cumulative risk assessment.

Effects of bifenthrin exposure in soil on whole-organism endpoints and biomarkers of earthworm Eisenia fetida

In this study, toxic effects of bifenthrin in soil on earthworms were evaluated by acute and chronic toxic endpoints combined with a set of biomarkers. Bifenthrin was moderately toxic in 72-h filter paper test and low toxic in 14-d soil test. The exposure of earthworms to bifenthrin-polluted soil for 8 weeks showed that cocoons were inhibited by high dose of bifenthrin, and larvae were stimulated by low dose but inhibited by high dose of bifenthrin. Furthermore, 28-d soil test on the responses of enzymes associated with antioxidation and detoxification in worms showed that peroxidase (POD) was stimulated by bifenthrin, superoxide dismutase (SOD) inhibited in the early period but stimulated in the later period, glutathione S- transferase (GST) inhibited in the later period, and ethoxyresorufin-O-deethylase (EROD) inhibited at day 3 but markedly stimulated at day 28 at high dose. The different responses of these indexes indicated that multi indexes should be jointly taken into account for comprehensive evaluation of the environmental risk of contaminants in soil.

Pyrethroid insecticide lambda-cyhalothrin and its metabolites induce liver injury through the activation of oxidative stress and proinflammatory gene expression in rats following acute and subchronic exposure

Lambda-cyhalothrin (LTC) [α-cyano-3-phenoxybenzyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclo-propanecarboxylate] is a synthetic type II pyrethroid insecticide commonly used in residential and agricultural areas. The potential hepatotoxicity of pyrethroids remains unclear and could easily be assessed by measuring common clinical indicators of liver disease. To understand more about the potential risks for humans associated with LTC exposure, male adult rats were orally exposed to 6.2 and 31.1 mg/kg bw of LTC for 7, 30, 45, and 60 days. Histopathological changes and alterations of main parameters related to oxidative stress and inflammatory responses in the liver were evaluated. Further, lambda-cyhalothrin metabolites [3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethyl-cyclopropane carboxylic acid (CFMP), 4-hydroxyphenoxybenzoic acid (4-OH-3-PBA), and 3-phenoxybenzoic acid (3-PBA)] in the liver tissues were identified and quantified by ultra-high-performance liquid chromatography coupled to quadripole time-of-flight mass spectrometry (UHPLC-MS-Q-ToF). Results revealed that LTC exposure significantly increased markers of hepatic oxidative stress in a time-dependent and dose-dependent manner, and this was associated with an accumulation of CFMP and 3-PBA in the liver tissues. In addition, the levels of tumor necrosis factor-α (TNF-α) and interleukin (IL-6 and IL-1β) gene expressions were significantly increased in the liver of exposed rats compared to controls. Correlation analyses revealed that CFMP and 3-PBA metabolite levels in the liver tissues were significantly correlated with the indexes of oxidative stress, redox status, and inflammatory markers in rats exposed to lambda-cyhalothin. Overall, this study provided novel evidence that hepatic damage is likely due to increased oxidative stress and inflammation under the condition of acute and subchronic exposure to lambda-cyhalothrin and that LTC metabolites (CFMP and 3-PBA) could be used as potential biomarker in human biomonitoring studies.

mTOR inhibition by rapamycin protects against deltamethrin-induced apoptosis in PC12 Cells

The autophagy pathway can be induced and upregulated in response to intracellular reactive oxygen species (ROS). In this study, we explored a novel pharmacotherapeutic approach involving the regulation of autophagy to prevent deltamethrin (DLM) neurotoxicity. We found that DLM-induced apoptosis in PC12 cells, as demonstrated by the activation of caspase-3 and -9 and by nuclear condensation. DLM treatment significantly decreased dopamine (DA) levels in PC12 cells. In addition, we observed that cells treated with DLM underwent autophagic cell death, by monitoring the expression of LC3-II, p62, and Beclin-1. Exposure of PC12 cells to DLM led to the production of ROS. Treatment with N-acetyl cysteine (NAC) effectively blocked both apoptosis and autophagy. In addition, mitogen-activated protein kinase (MAPK) inhibitors attenuated apoptosis as well as autophagic cell death. We also investigated the modulation of DLM-induced apoptosis in response to autophagy regulation. Pretreatment with the autophagy inducer, rapamycin, significantly enhanced the viability of DLM-exposed cells, and this enhancement of cell viability was partially due to alleviation of DLM-induced apoptosis via a decrease in levels of cleaved caspase-3. However, pretreatment of cells with the autophagy inhibitor, 3-methyladenine (3MA), significantly increased DLM toxicity in these cells. Our results suggest that DLM-induced cytotoxicity is modified by autophagy regulation and that rapamycin protects against DLM-induced apoptosis by enhancing autophagy. Pharmacologic induction of autophagy by rapamycin may be a useful treatment strategy in neurodegenerative disorders. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 109-121, 2017.

From the Cover: Vulnerability of C6 Astrocytoma Cells After Single-Compound and Joint Exposure to Type I and Type II Pyrethroid Insecticides

A primary mode-of-action of all pyrethroid insecticides (PYRs) is the disruption of the voltage-gated sodium channel electrophysiology in neurons of target pests and nontarget species. The neurological actions of PYRs on non-neuronal cells of the nervous system remain poorly investigated. In the present work, we used C6 astrocytoma cells to study PYR actions (0.1-50 μM) under the hypothesis that glial cells may be targeted by and vulnerable to PYRs. To this end, we characterized the effects of bifenthrin (BF), tefluthrin (TF), α-cypermethrin (α-CYP), and deltamethrin (DM) on the integrity of nuclear, mitochondrial, and lysosomal compartments. In general, 24- to 48-h exposures produced concentration-related impairment of cell viability. In single-compound, 24-h exposure experiments, effective concentration (EC)₁₅s 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT assay) were computed as follows (in μM): BF, 16.1; TF, 37.3; α-CYP, 7.8; DM, 5.0. We found concentration-related damage in several C6-cell subcellular compartments (mitochondria, nuclei, and lysosomes) at ≥ 10^-1 μM levels. Last, we examined a mixture of all PYRs (ie, Σ individual EC₁₅) using MTT assays and subcellular analyses. Our findings indicate that C6 cells are responsive to nM levels of PYRs, suggesting that astroglial susceptibility may contribute to the low-dose neurological effects caused by these insecticides. This research further suggests that C6 cells may provide relevant information as a screening platform for pesticide mixtures targeting nervous system cells by expected and unexpected toxicogenic pathways potentially contributing to clinical neurotoxicity.

Fipronil sulfone induced higher cytotoxicity than fipronil in SH-SY5Y cells: Protection by antioxidants

Fipronil is a broad spectrum insecticide from the phenyl pyrazole family, which targets GABA receptor. Limited information is available about the metabolite fipronil sulfone cytotoxic actions. This study examined in vitro neurotoxicity of fipronil and fipronil sulfone and evaluated Trolox (vitamin E analog) (0.3, 1μM), N-acetyl-cysteine (0.5, 1mM), melatonin (0.1, 1μM) and Tempol (superoxide dismutase analog) (0.3, 0.5mM) protective role in SH-SY5Y cells. MTT and LDH assays were carried out to assess the cytotoxicity of fipronil and fipronil sulfone at 3-100μM concentrations. Fipronil sulfone was more toxic than fipronil. Tempol showed the best neuroprotectant profile against fipronil (50 and 150μM) and fipronil sulfone (3 and 10μM) reaching control levels. Fipronil (100μM) and fipronil sulfone (3μM) treatments induced a 4.7- and 5-fold increases in lipid peroxides measured as malondialdehyde (MDA) and a 2.2- and 2.0-fold increases in the levels of nitric oxide (NO). These results suggest that oxidative stress observed may be one of the major mechanisms of fipronil-induced neurotoxicity and it may be attributed in part to fipronil disposition and metabolism. Our results led us postulate that metabolite fipronil sulfone might be responsible for the fipronil-induced toxicity rather than fipronil itself.

Effects of exposure to pyrethroid cyfluthrin on serotonin and dopamine levels in brain regions of male rats

The effects of cyfluthrin oral exposure (1, 5, 10 and 20mg/kg bw, 6 days) on brain region monoamine levels of male rats were examined. Cyfluthrin-treated rats (1, 5 and 10mg/kg bw, orally 6 days), had no visible injury, i.e., no clinical signs of dysfunction were observed. However, rats treated with cyfluthrin at the highest dose (20mg/kg bw, orally 6 days) showed skeletal muscle contraction in the hind limbs, slight movement incoordination without any signs of dyskinesia and tremor after 1-2h of treatment. These signs were reversible at 6h after dose. After last dose of cyfluthrin, dopamine (DA) and serotonin (5-HT) and its metabolites levels were determined in brain regions hypothalamus, midbrain, hippocampus, striatum and prefrontal cortex by HPLC. Cyfluthrin (1mg/kg bw, orally 6 days) did not affect the DA, 5-HT and metabolites levels in the brain regions studied. Cyfluthrin (5, 10 and 20mg/kg bw, orally 6 days) caused a statistically significant decrease in DA and its metabolites DOPAC and HVA levels and in 5-HT and its metabolite 5-HIAA levels in a brain region- and dose-related manner. Moreover, cyfluthrin (20mg/kg bw, orally 6 days) evoked a statistically significant increase in 5-HT turnover in striatum and midbrain, and in DA turnover in striatum and prefrontal cortex. These findings indicate that serotoninergic and dopaminergic neurotransmission is affected by exposure to cyfluthrin and may contribute to the overall spectrum of neurotoxicity caused by this pyrethroid.

Protective effects of l-glutamine against toxicity of deltamethrin in the cerebral tissue

BACKGROUND

Deltamethrin (DLM) is a broad-spectrum synthetic dibromo-pyrethroid pesticide that is widely used for agricultural and veterinary purposes. However, human exposure to the pesticide leads to neurotoxicity. Glutamine is one of the principal, free intracellular amino acids and may also be an antioxidant. This study was undertaken in order to examine the neuroprotective and antioxidant potential of l-glutamine against DLM toxicity in female Wistar albino rats.

MATERIALS AND METHODS

The rats were divided into the following groups (n=10): Group I: control (distilled water; 10 mL/kg, po one dose), Group II: l-glutamine (1.5 g/kg, po one dose), Group III: DLM (35 mg/kg, po one dose), and Group IV: DLM (35 mg/kg, po one dose) and l-glutamine (1.5 g/kg, po one dose after 4 hours). Total oxidant status (TOS), total antioxidant status (TAS), tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels and apoptosis were evaluated in brain tissue.

RESULTS

DLM-treated animals had a significant increase in brain biochemical parameters, as well as TOS and TAS. Furthermore, the histopathological examination showed neuronal cell degeneration in the cerebral tissue. l-Glutamine treatment decreased the elevated brain levels of TOS and neuronal cell degeneration. There was no difference in tumor necrosis factor-α, IL-1β, and IL-6 levels between the groups.

CONCLUSION

l-Glutamine may reduce the toxic effects of DLM in the cerebral tissue through antioxidant properties.

Long-term toxic effects of deltamethrin and fenvalerante in soil

In this study, the long-term toxic effects of pyrethroids on the earthworm Eisenia fetida were evaluated. Earthworms were exposed to moist filter paper and soil for 14 days to evaluate the survival, exposed to soil for 56 days to assess the reproductive success and for 28 days to identify the cytotoxicity. Results showed that the earthworm survival rate decreased with increasing the concentration of either deltamethrin or fenvalerate in both filter paper test and soil test. No worms survived at 602.15 μg cm(-2) of deltamethrin and 0.86 μg cm(-2) of fenvalerate in the filter paper test, however 100-125 mg kg(-1) of both chemicals resulted in the maximum mortality of 90% in the soil test. The CYP3A4 enzyme activity responded significantly to deltamethrin and fenvalerante in soil at low concentration levels, however, the toxicity response of worms under the long-term exposure conflicted with the degradation of deltamethrin and fenvalerate in soil, indicating the possible formation of more toxic pyrethroid metabolites. This study gave an insight into the toxicological effects profile of pyrethroids for a better risk assessment of pyrethroids deltamethrin and fenvalerante in soil.

In vitro neurotoxicity evaluation of piperazine designer drugs in differentiated human neuroblastoma SH-SY5Y cells

Abuse of synthetic drugs is widespread worldwide. Studies indicate that piperazine designer drugs act as substrates at dopaminergic and serotonergic receptors and/or transporters in the brain. This work aimed to investigate the cytotoxicity of N-benzylpiperazine, 1-(3-trifluoromethylphenyl)piperazine, 1-(4-methoxyphenyl)piperazine and 1-(3,4-methylenedioxybenzyl)piperazine in the differentiated human neuroblastoma SH-SY5Y cell line. Cytotoxicity was evaluated after 24 h incubations through the MTT reduction and neutral red uptake assays. Oxidative stress (reactive oxygen and nitrogen species production and glutathione content) and energetic (ATP content) parameters, as well as intracellular Ca(2+), mitochondrial membrane potential, DNA damage (comet assay) and cell death mode were also evaluated. Complete cytotoxicity curves were obtained after 24 h incubations with each drug. A significant decrease in intracellular total glutathione content was noted for all the tested drugs. All drugs caused a significant increase of intracellular free Ca(2+) levels, accompanied by mitochondrial hyperpolarization. However, ATP levels remained unchanged. The investigation of cell death mode revealed a predominance of early apoptotic cells. No genotoxicity was found in the comet assay. Among the tested drugs, 1-(3-trifluoromethylphenyl)piperazine was the most cytotoxic. Overall, piperazine designer drugs are potentially neurotoxic, supporting concerns on risks associated with the abuse of these drugs.

Evidence for dose-additive effects of a type II pyrethroid mixture. In vitro assessment

Despite the widespread use of pyrethroid insecticides that led to common exposure in the population, few studies have been conducted to quantitatively assess dose-additive effects of pyrethroids using a funcional measure involved in the common toxic mode of action. The aim of this study was to evaluate the potency and efficacy of 6 Type II pyretroids (α-cypermethrin, cyfluthrin, λ-cyhalothrin, deltamethrin, cyphenothrin and esfenvalerate) to evoke induction of both nitric oxide and lipid peroxides levels measured as malondialdehyde in three in vitro models (SH-SY5Y, HepG2 and Caco-2 human cells) as well as to test the hypothesis of dose additivity for mixtures of these same 6 pyrethroids. Concentration-responses for 6 pyrethroids were determined as well as the response to mixtures of all 6 pyrethroids. Additivity was tested assuming a dose-additive model. The human neuroblastoma SH-SY5Y cell line was the most sensitive in vitro model. The rank order of potency for cell SH-SY5Y viability MTT assay was deltamethrin>cyphenothrin>λ-cyhalothrin>cyfluthrin>esfenvalerate>α-cypermethrin. When 6 pyrethroids were present in the mixture at an equitoxic mixing ratio, the action on nitric oxide (NO) and lipid peroxides measured as malondialdehyde (MDA) production was consistent with a dose-additive model. The results of the present study are consistent with previous reports of additivity of pyrethroids in vivo e in vitro.