Doses Of Fipronil Research Articles

Pulmonary expression of Pla2g5 during lung damage in mice induced by fipronil and lipopolysaccharide interaction

With Indian pesticide industry touching new heights each year in terms of production and sale, its ill effects on health cannot just be ignored. Humans, as well as animals, are under the constant threat of being exposed to environmental pollutants like endotoxins and pesticides which are present ubiquitously in our surroundings. Phenylpyrazoles like fipronil were introduced into the Indian market with an aim to oversee the menace of insecticide resistance and public health hazards experienced with more commonly used pesticide but its adverse effects on the pulmonary system are now being reported globally. We reported first data that the Planar cell Polarity (PCP) pathway was the top dysregulated pathway during fipronil induced lung damage. In order to further elucidate the underlying molecular mechanisms, we analysed the data generated by gene expression profiling in lung tissues using biocomputational approaches. We found Eicosanoid signalling as one of the top enriched pathways dysregulated during fipronil and or endotoxin-induced lung inflammation. Global view of genes showed Pla2g5 as top differentially expressed gene with 1.6, 3.9, 1.2, 3.1 and 4.3-folds expression in lipopolysaccharide (LPS), high dose of fipronil (9.5mg/kg) alone or in combination with LPS and low dose of fipronil (4.75 mg/kg) alone or in combination with LPS, respectively which was validated using qPCR and immunohistochemistry. The data suggest a role Pla2g5 to activate eicosanoid signalling in fipronil and or LPS induced lung inflammation in mice.

Transcriptome analysis reveals the role of the PCP pathway in fipronil and endotoxin-induced lung damage

BackgroundPesticide residues in food and environment along with airborne contaminants like endotoxins pose a tangible threat to living beings. Fipronil, a broad-spectrum insecticide at acute doses in combination with endotoxin has been linked to airway inflammation. Wnt/PCP pathway plays important role in the pathogenesis of chronic inflammatory conditions by contributing to the release of downstream cytokines. However, there is no data on the PCP signaling pathway during fipronil-induced lung damage. This study aims to understand the molecular mechanisms underlying the pulmonary toxicity induced by fipronil alone or in combination with endotoxin.MethodsWe used a microarray approach to obtain a global view of the transcriptional responses of the lungs exposed to fipronil and endotoxin in a mice model. Lung tissues were harvested from male Swiss albino mice (n=42) following long term oral exposure to high and low doses of fipronil alone or in combination with endotoxin. The differentially expressed genes were analyzed by Ingenuity pathway analysis software to predict the top canonical pathways. The microarray data for selected genes was validated using quantitative PCR and immunohistochemistry.ResultsBoth BAL fluid and histopathology analysis suggested lung damage and altered transcriptomic profile of lung following exposure to high and low dose of fipronil with or without endotoxin. PCP pathway was among the top upregulated canonical pathways following exposure to both doses of fipronil individually or with LPS. Low dose of fipronil increased the expression of WNT-6, MAPK-8, IL-4 and IL-17C while higher dose decreased the expression of MAPK-8 and IL-17C. The expression data verified by realtime PCR was in concordance with microarray data.ConclusionLong-term exposure to low (4.75 mg kg-1) and high (9.50 mg kg-1) dose of fipronil alone or in combination with endotoxins alters the histoarchitecture and transcriptome profile of lungs with the involvement of the PCP pathway. PCP pathway showed higher enrichment in low dose group of fipronil alone or in combination with LPS. The data from the study provides the insights of the potential damage on lungs caused by fipronil and endotoxin interaction and helps to better understand the mechanism of this complex relation.

Non-detection of honeybee hive contamination following Vespula wasp baiting with protein containing fipronil.

Introduced wasps (Vespula germanica and V. vulgaris) are costly invertebrate pests in New Zealand, with large impacts on the local ecology and economy. Wasps eat honeybees (Apis mellifera), which has potentially devastating effects on hive health, as well as agricultural and horticultural industries. Vespex bait, which contains fipronil in a proteinaceous carrier, has recently been introduced for wasp control. In over a decade of reported trials, honeybees have never been observed foraging on Vespex, likely because the bait contains no sugars to serve as a bee food source. However, the potential for the control agent fipronil to enter beehives has not been tested. Therefore, here, we investigated this using a liquid chromatography–mass spectrometry assay of fipronil and two of its environmental breakdown and metabolic derivatives, fipronil desulfinyl and fipronil sulfone. We did not detect fipronil in any of the worker bee, bee larva, honey or pollen samples (n = 120 per product) collected from 30 hives over a 2-year period. Furthermore, although we detected fipronil desulfinyl in one honeybee sample, this is thought to have originated from a single individual, representing a rare occurrence of intoxication, and there was no evidence that Vespex was the toxicant source. There was also no evidence of trophallactic transfer of fipronil or its derivatives in any of the hives sampled. Previous studies have reported the impairment of individual bee performance at fipronil doses similar to the detection limit of our study. However, our results provide confidence that if undetectable intoxication was occurring, it would involve an acute exposure for those few individuals affected, with minimal impairment to colonies. Therefore, we conclude that the use of Vespex in the vicinity of honeybees does not result in significant hive uptake while effectively reducing wasp pressure on honeybee colonies.

Ecotoxicological effects of fipronil, neem cake and neem extract in edaphic organisms from tropical soil

Veterinary medicines are widely applied for the treatment and prevention of animal diseases. Consequently, animal manure contains significant amounts of environmental pollutants that are potential sources of environmental pollution when inappropriately applied in soils. This work aimed to evaluate ecotoxicological effects of doses of commercial fipronil, neem cake and neem extract in the survival and reproduction of earthworms (Eisenia andrei), enchytraeidae (Enchytraeus crypticus) and springtails (Folsomia candida) in Oxisol and tropical artificial soil (TAS). Applications of fipronil, neem cake and extract in soil were carried out according to standardized ISO methodologies by using a random experimental design with five replicates. Toxic effects of fipronil for springtails in Oxisol and TAS were observed with LC50 of 0.26 mg kg−1 (0.18–0.35 mg kg−1) and 0.29 mg kg−1 (0.22–0.37 mg kg−1), respectively. It was not observed significant toxic effects of fipronil for earthworms and enchytraeidae in both soils. However, significant amounts of juvenile earthworm and adult enchytraeidae decreased in fipronil doses higher than 10 mg kg−1. Neem cake and extract were not toxic for earthworms and enchytraeidae but, significant amounts of juvenile springtails decreased in neem cake doses from 500 to 1000 mg kg−1. It can be concluded that the use of veterinary medicines containing synthetic compounds for preventing diseases in animals needs to be controlled to avoid environmental pollution after applying manure in soil. Veterinary medicines containing natural compounds as neem cake and extract are eco-friendly and could be efficiently applied in soil in a sustainable way.

Ecotoxicological effect of fipronil and its metabolites on Folsomia candida in tropical soils

The aim of this study is to evaluate the toxicity of the fipronil and its metabolites, fipronil sulfone and fipronil desulfinyl on Folsomia candida. Three types of soils were used to perform the ecotoxicological tests, two natural soils (Oxisol and Entisol), and an artificial substrate (Tropical Artificial Soil). The treatments consisted of increasing doses of a veterinary medicinal product with active ingredient based on fipronil, and of its two main metabolites, fipronil sulfone and fipronil desulfinyl. The doses of fipronil were 0.00, 0.02, 0.04, 0.08, 0.15, 0.30, 0.60, and 1.00 mg kg−1 of the active ingredient. For fipronil sulfone and fipronil desulfinyl the doses tested were: 0.00, 0.01, 0.02, 0.04, 0.06, 0.08, 0.15, 0.30, 0.60, 1.00, and 5.00 mg kg−1. The effects of toxicity on F. candida were evaluated by survival and reproduction tests, based on the methods described by ISO 11267. There was a completely randomized design, with six replicates for the fipronil tests and eight for the metabolites. We show that fipronil and its metabolites, even at very low concentrations, are toxic to F. candida. Reduction of reproduction can be observed at concentrations of 0.15 mg kg−1. There was little difference in toxicity (LC50 and EC50) between fipronil and its metabolites. Rather, differences were related more to soil type, where the artificial soil was more sensitive than the two natural soils (Oxisol and Entisol). We conclude that it is important to perform ecotoxicological tests in natural soils, in order to generate more realistic representations of veterinary drug toxicity on the environment.

Toxicity and motor changes in Africanized honey bees (Apis mellifera L.) exposed to fipronil and imidacloprid.

This study evaluated the in vitro toxicity and motor activity changes in African-derived adult honey bees (Apis mellifera L.) exposed to lethal or sublethal doses of the insecticides fipronil and imidacloprid. Mortality of bees was assessed to determine the ingestion and contact lethal dose for 24 h using probit analysis. Motor activities in bees exposed to lethal (LD50) and sublethal doses (1/500th of the lethal dose) of both insecticides were evaluated in a behavioral observation box at 1 and 4 h. Ingestion and contact lethal doses of fipronil were 0.2316 ? 0.0626 and 0.0080 ? 0.0021 μg/bee, respectively. Ingestion and contact lethal doses of imidacloprid were 0.1079 ? 0.0375 and 0.0308 ? 0.0218 μg/bee, respectively. Motor function of bees exposed to lethal doses of fipronil and imidacloprid was impaired; exposure to sublethal doses of fipronil but not imidacloprid impaired motor function. The insecticides evaluated in this study were highly toxic to African-derived A. mellifera and caused impaired motor function in these pollinators.

Vitamin C attenuates biochemical and genotoxic damage in common carp (Cyprinus carpio) upon joint exposure to combined toxic doses of fipronil and buprofezin insecticides

In the present study, potential protective role of Vitamin C (l-ascorbic acid) was investigated in aquaria acclimated common carp (Cyprinus carpio) following exposure for 96 h to combined toxic doses of fipronil (FP) and buprofezin (BPFN) insecticides in combination (FP: 200 μg/L; 4.57 × 10−7 mol/L and BPFN: 50 mg/L; 1.64 × 10−4 mol/L). At end of 96 h exposure, fish were supplemented with low (25 mg/L) and high (50 mg/L) doses of Vitamin C, added once daily to aquaria water for continuous three weeks. Appropriate control groups were run in parallel. Fish behavior was monitored throughout for signs of toxicity. At completion of experiments, liver, kidney, brain and gills were excised for toxicity assessment and possible remediation by the Vitamin C through biochemical determination of reactive oxygen species (ROS), thiobarbituric acid reactive substances or TBARS, reduced glutathione (GSH) and total protein content, levels of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and the Comet assay. Hepatosomatic index (HSI), condition factor (CF), survival rate (SR), and combination index (CI) were also determined. Data were compared statistically at p < 0.05. Results showed significant behavioral and biochemical alterations, and DNA damage in the fish group exposed to FP and BPFN in combination. In fish groups supplemented with Vitamin C following FP and BPFN treatment, significant alleviation in tissue damage and toxic effects was represented by substantial decreases in ROS and TBARS production (p < 0.001), along with a concomitant significant increase in the survival rate, GSH and total protein content, HSI, CF, and activities of SOD, CAT and POD enzymes (p < 0.001). Mean tail length of comet and percent tail DNA decreased significantly (p < 0.001), which indicated amelioration of DNA damage. The study concludes that Vitamin C is an effective remedial treatment against FP and BPFN-induced damage in exposed fish.

CYP1A gene expression as a basic factor for fipronil toxicity in Caspian kutum fish.

The aim of this study was to assess the effects of fipronil insecticide on the Caspian kutum fish at different levels of biological organizations and to find possible relationship between these biomarkers. Different doses of fipronil (65, 130 and 200 mg/kg) were intraperitoneally administered to the fish for 2 weeks. After 7 and 14 days of exposure, alterations in organ-somatic index, tissue and DNA structure, oxidative stress and CYP1A gene expression in gill, liver, brain and kidney were studied. Determination of these parameters in the liver showed that the degree of tissue change (DTC), comet tail, superoxide dismutase (SOD) and relative CYP1A mRNA expression increased mostly in a time dependent manner whereas in the kidney increased mostly in a dose dependent manner. These parameters in the gill increased more in time and dose dependent manner. Apart from the changes in CYP1A expression and oxidative stress, no alterations was observed in the brain. Multiple regression analysis showed that the CYP1A had the most correlation with the organ-somatic index (R2 = 0.76) and comet tail (R2 = 0.89) in the liver, and with DTC (R2 = 0.93) and oxidative stress (R2 = 0.87) in the kidney. Generally, this study showed that CYP1A gene expression can be considered as one basic factor for fipronil toxicity in this fish. However, other possible factors also should be considered for future research.

Evaluation of Motor Changes and Toxicity of Insecticides Fipronil and Imidacloprid in Africanized Honey Bees (Hymenoptera: Apidae)

Honey bees are important pollinators and are essential in beekeeping. Honey bees get exposed to systemic pesticides while foraging in contaminated fields, and it is important to know the toxicity (LD50) and evaluate the impacts of bees’ exposure to these molecules. Fipronil and imidacloprid are systemic pesticides widely used in Brazil and other countries. The objective of this study was to determine the LD50 (24 hours) and evaluate motor changes in Africanized honey bee foragers exposed to lethal and sublethal doses of fipronil and imidacloprid. To determine the LD50, foraging honey bees were exposed by ingestion and contact to five doses of fipronil (Regent 800WG®) and imidacloprid (Appalus 200SC®) insecticides. After 24 hours of exposure, the number of dead bees was counted, and the results were subjected to probit analysis. The motor activity of bees exposed by ingestion or contact to LD50 and sublethal doses (1/500th of the LD50) of both pesticides was assessed 4 hours after exposure using a behavioral observation box. The ingestion and contact with LD50 of fipronil were 0.0528±0.0090 and 0.0054±0.0041 μg/bee, respectively; the ingestion and contact with LD50 of imidacloprid were 0.0809±0.0135 and 0.0626±0.0080 μg/bee, respectively. Bees exposed to lethal and sublethal doses of both insecticides experienced significant motor alterations compared to the control, except for exposure to sublethal doses of fipronil by contact. Fipronil and imidacloprid are highly toxic and promote motor changes in bees. Thus, it is important to establish management methods to reduce pollinators’ exposure to these pesticides.

Exposure to sub-acute doses of fipronil and buprofezin in combination or alone induces biochemical, hematological, histopathological and genotoxic damage in common carp (Cyprinus carpio L.)

Use of pesticides or insecticides can be highly toxic to aquatic life forms due to leaching and agricultural runoff, rains or flood. Fipronil (FP) is a GABA receptor inhibitor, while buprofezin (BPFN) is an insect growth regulator. Presently, we exposed groups of aquaria acclimated carp fish (Cyprinus carpio) for 96h to sub-lethal concentrations of fipronil (400μgL−1; 9.15×10−7molL−1) and buprofezin (BPFN, 100mgL−1; 1.072×10−6molL−1) singly or in combination. The extent of damage was assessed at biochemical, hematological, molecular biological and histopathological level. Results obtained in treated fish were compared statistically with those of control non-treated fish and also among treatment groups. Significance level was p<0.05. Compared to control, serum total protein and globulin concentrations decreased significantly (p<0.0001) in fish treated with FP; while albumin concentration remained unaltered with all treatments. Glucose concentration decreased significantly (p<0.002) in fish treated with FP. In contrast, combined FP+BPFN treatment and BPFN treatment caused insignificant elevation of glucose concentration. Hematological assessment demonstrated significant decrease in red blood cell and thrombocyte counts, hemoglobin concentration and hematocrit percent; while white blood cell count showed an increase in all treatment groups (p<0.0001). Blood smears from pesticide treated fish revealed aberrant erythrocyte morphologies which included necrosis, micronuclear formation and hyperchromatosis. DNA laddering assay carried out on whole blood demonstrated excessive smear formation in combined FP+BPFN and BPFN treatment groups but no smear formation was noticeable in FP treated fish. Compared to control, whole blood DNA content increased significantly in the combined FP+BPFN and BPFN treatment groups (p<0.001 and p<0.009). With all treatments histopathological changes observed in the gills were: epithelial uplifting and necrosis of lamellae, lamellar atrophy, disruption of cartilaginous core, fusion and disorganization of lamellae and telangiectasia. In liver these were: karyorrhexis, hepatocellular hypertrophy, nuclear hypertrophy, melanomacrophage aggregates and central vein contraction, while in the kidney: deterioration of glomerulus and dilatation of Bowman’s space, dilatation of renal tubules, thyroidisation, altered tubular lumen, nuclear hypertrophy, cellular atrophy, and cellular necrosis were the outcome. Our study revealed that FP and BPFN produce highly toxic effects on fish when given in combination or singly. To our knowledge, this is the first report on toxicity caused by FP and BPFN in single and combined state.

Fipronil-induced genotoxicity and DNA damage in vivo: Protective effect of vitamin E.

Fipronil, an insecticide of the phenylpyrazole class has been classified as a carcinogen by United States Environmental Protection Agency, yet very limited information is available about its genotoxic effects. Adult male and female animals were gavaged with various doses of fipronil (2.5, 12.5, and 25 mg/kg body weight (bw)) to evaluate micronucleus test (mice), chromosome aberration (CA), and comet assay (rats), respectively. Cyclophosphamide (40 mg/kg bw; intraperitoneal) was used as positive control. Another group of animals were pretreated with vitamin E orally (400 mg/kg bw) for 5 days prior to administration of fipronil (12.5 mg/kg). Fipronil exposure in both male and female mice caused significant increase in the frequency of micronuclei (MN) in polychromatic erythrocytes. Similarly, structural CAs in bone marrow cells and DNA damage in the lymphocytes was found to be significantly higher in the male and female rats exposed to fipronil as compared to their respective controls. The average degree of protection (male and female animals combined together) shown by pretreatment of vitamin E against fipronil-induced genotoxicity was 63.28%: CAs; 47.91%: MN formation; and 74.70%: DNA damage. Findings of this study demonstrate genotoxic nature of fipronil regardless of gender effect and documents protective role of vitamin E.

Memory impairment due to fipronil pesticide exposure occurs at the GABAA receptor level, in rats

Fipronil (F) a pesticide considered of second generation cause various toxic effects in target and non-target organisms including humans in which provoke neurotoxicity, having the antagonism of gamma-amino butyric acid (GABA) as their main mechanism for toxic action. GABAergic system has been involved in processes related to the memory formation and consolidation. The present work studied the importance of GABA to the mechanisms involved in the very early development of fipronil-induced memory impairment in rats. Memory behavior was assessed using new object recognition task (ORT) and eight radial arm maze task (8-RAM) to study effects on cognitive and spatial memory. Locomotor behavior was assessed using open field task (OF). The dose of fipronil utilized was studied through a pilot experiment. The GABA antagonist picrotoxin (P) was used to enhance fipronil effects on GABAergic system. Fipronil or picrotoxin decrease memory studied in ORT and 8-RAM tasks. Additionally, F and P co-exposure enhanced effects on memory compared to controls, F, and P, suggesting strongly a GABAergic effect. Weight gain modulation and fipronil in blood were utilized as animal's intoxication indicators. In conclusion, here we report that second-generation pesticides, such as fipronil, can have toxic interactions with the CNS of mammals and lead to memory impairment by modulating the GABAergic system.

Synergism of entomopathogenic fungus, Metarhizium anisopliae incorporated with fipronil against oil palm pest subterranean termite, Coptotermes curvignathus

The compatibility and synergy in efficacy of the termiticide fipronil with a biocontrol agent Metarhizium anisopliae, alone or in combination, against the subterranean termite, Coptotermes curvignathus were investigated. Sublethal doses of fipronil were found relatively less detrimental to fungal growth of M. anisopliae local isolates in a compatibility test. The fungus-insecticide bait formulation showed the greatest synergistic effect that increased termite mortality as well as reduced the lethal time at a sublethal dose of 0.05 mg a.i./l fipronil with conidia concentrations of 107 conidia/g bait (χ2 = 48.80) at LT50 value of 6.46 days, followed by 108 conidia/gbait (χ2 = 5.09) at LT50 value of 4.89 days compared to the use of these control agents alone. The insecticidal stress caused by sublethal fipronil in the formulated bait may weaken the termites and reduce their defence mechanism, which facilitates fungus infection on termites. The observed synergism treatments show the potential for integrated fungus-insecticide control method and need to be further investigated on termite infested oil palm trees.

In utero and lactational exposure to fipronil in female rats: Pregnancy outcomes and sexual development

ABSTRACTFipronil, a phenylpyrazole insecticide, is used in agriculture, veterinary medicine, and public health. Because this insecticide is considered a potential endocrine disruptor, the aim of this study was to examine the influence of perinatal exposure to fipronil on neonatal female reproductive system development. Pregnant rats were exposed (via gavage) daily to fipronil (0.03, 0.3, or 3 mg/kg) from gestational day 15 to day 7 after birth, and effects on the reproductive functions assessed on postnatal day (PND) 22. No signs of maternal toxicity were observed during daily treatment with fipronil. Perinatal exposure to the highest dose of fipronil (3 mg/kg) delayed the age of vaginal opening (VO) and first estrus without markedly affecting the anogenital distance (AGD). Further, exposure to 0.3 mg/kg fipronil produced a significantly shorter estrus cycle and reduced number of cycles during the period of evaluation. However, the other reproductive parameters analyzed, including fertility, hormone levels, sexual behavior, and histology of ovaries and uterus, displayed no marked alterations. In this experimental model, fipronil interfered with development of neonatal female reproductive system as evidenced by delay in VO and estrus cycle alterations without apparent significant effects on fertility. Further studies are needed to identify the mechanisms of action associated with the observed female reproductive system changes.

Sublethal doses of fipronil intensify synapsin immunostaining in Atta sexdens rubropilosa (Hymenoptera: Formicidae) brains.

Although ants are common insects in agricultural ecosystems, few studies have considered how xenobiotics might induce physiological and morphological alterations in these insects. This study aimed to verify the neurotoxic action of sublethal doses of fipronil on the mushroom bodies of brains from the leaf-cutting ant Atta sexdens rubropilosa through immunocytochemistry analysis for the protein synapsin. The LD50 value was established as 1.42 ng ant(-1), and the sublethal doses used were LD50/10 and LD50/100. Synapsin labelling was more evident in the brains extracted from ants exposed to the insecticide, specifically in the regions of glia in the mushroom bodies, compared with the control group. It was possible to measure the intensity of emitted fluorescence in the areas of the mushroom bodies, and a statistical test showed differences between the control group and the treatment group. Thus, it is concluded that sublethal doses of the insecticide fipronil intensified synapsin immunostaining, suggesting an increased release of neurotransmitters, which may be linked to neurotoxicity and overexcitation. These sublethal doses may have two different effects: compromising the operation and maintenance of the colony and leading to the establishment of resistance in insects.

Fipronil promotes motor and behavioral changes in honey bees (Apis mellifera) and affects the development of colonies exposed to sublethal doses.

Bees play a crucial role in pollination and generate honey and other hive products; therefore, their worldwide decline is cause for concern. New broad-spectrum systemic insecticides such as fipronil can harm bees and their use has been discussed as a potential threat to bees' survival. In the present study, the authors evaluate the in vitro toxicity of fipronil and note behavioral and motor activity changes in Africanized adult Apis mellifera that ingest or come into contact with lethal or sublethal doses of fipronil. The effects of sublethal doses on brood viability, population growth, behavior, and the expression of the defensin 1 gene in adult bees were studied in colonies fed with contaminated sugar syrup (8 µg fipronil L(-1) ). Fipronil is highly toxic to bees triggering agitation, seizures, tremors, and paralysis. Bees that are exposed to a lethal or sublethal doses showed reduced motor activity. The number of eggs that hatched, the area occupied by worker eggs, and the number of larvae and pupae that developed were reduced, adult bees showed lethargy, and colonies were abandoned when they were exposed to sublethal doses of fipronil. No change was seen in the bees' expression of defensin 1. The authors conclude that fipronil is highly toxic to honey bees and even sublethal doses may negatively affect the development and maintenance of colonies.

Fipronil induced oxidative stress involves alterations in SOD1 and catalase gene expression in male mice liver: Protection by vitamins E and C.

In the present investigation, hepatic oxidative stress induced by fipronil was evaluated in male mice. We also investigated whether pretreatment with antioxidant vitamins E and C could protect mice against these effects. Several studies conducted in cell lines have shown fipronil as a potent oxidant; however, no information is available regarding its oxidative stress inducing potential in an animal model. Out of 8 mice groups, fipronil was administered to three groups at low, medium, and high dose based on its oral LD50 (2.5, 5, and 10 mg/kg). All three doses of fipronil caused a significant increase in the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) level with concomitant increase in the absolute and relative weight of liver. High dose of fipronil caused significant down-regulation in the hepatic mRNA expression of superoxide dismutase 1 (SOD1) and catalase (0.412 ± 0.01 and 0.376 ± 0.05-fold, respectively) as well as an increase in the lipid peroxidation (LPO). Also, decrease in the activity of antioxidant enzymes; SOD, catalase, and glutathione-S-transferase (GST) and the content of nonantioxidant enzymes; glutathione and total thiol were recorded. Histopathological examination of liver revealed dose dependant changes such as severe fatty degeneration and vacuolation leading to hepatocellular necrosis. Prior administration of vitamin E or vitamin C against fipronil high dose caused decrease in lipid peroxidation and increased activity of antioxidant enzymes. Severe reduction observed in functional activities of antioxidant enzymes was aptly substantiated by down-regulation seen in their relative mRNA expression. Thus results of the present study imply that liver is an important target organ for fipronil and similar to in vitro reports, it induces oxidative stress in the mice liver, which in turn could be responsible for its hepatotoxic nature. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1147-1158, 2016.

Potential role of ATP-binding cassette transporters against acaricides in the brown dog tick Rhipicephalus sanguineus sensu lato.

ATP-binding cassette (ABC) transporters have been shown to be involved in pesticide detoxification in arthropod vectors and are thought to contribute to the development of drug resistance. Little is currently known about the role they play in ticks, which are among the more important vectors of human and animal pathogens. Here, the role of ABC transporters in the transport of fipronil and ivermectin acaricides in the tick Rhipicephalus sanguineus (Ixodida: Ixodidae) was investigated. Larvae were treated with acaricide alone and acaricide in combination with a sub-lethal dose of the ABC transporter inhibitor cyclosporine A. The LC50 doses and 95% confidence intervals (CIs) estimated by mortality data using probit analysis were 67.930 p.p.m. (95% CI 53.780-90.861) for fipronil and 3741 p.p.m. (95% CI 2857-4647) for ivermectin. The pre-exposure of larvae to a sub-lethal dose of cyclosporine A reduced the LC50 dose of fipronil to 4.808 p.p.m. (95% CI 0.715-9.527) and that of ivermectin to 167 p.p.m. (95% CI 15-449), which increased toxicity by about 14- and 22-fold, respectively. The comparison of mortality data for each separate acaricide concentration showed the synergic effect of cyclosporine A to be reduced at higher concentrations of acaricide. These results show for the first time a strong association between ABC transporters and acaricide detoxification in R.sanguineus s.l.

Assessment of serum biomarkers in rats after exposure to pesticides of different chemical classes

There is increasing emphasis on the use of biomarkers of adverse outcomes in safety assessment and translational research. We evaluated serum biomarkers and targeted metabolite profiles after exposure to pesticides (permethrin, deltamethrin, imidacloprid, carbaryl, triadimefon, fipronil) with different neurotoxic actions. Adult male Long–Evans rats were evaluated after single exposure to vehicle or one of two doses of each pesticide at the time of peak effect. The doses were selected to produce similar magnitude of behavioral effects across chemicals. Serum or plasma was analyzed using commercial cytokine/protein panels and targeted metabolomics. Additional studies of fipronil used lower doses (lacking behavioral effects), singly or for 14days, and included additional markers of exposure and biological activity. Biomarker profiles varied in the number of altered analytes and patterns of change across pesticide classes, and discriminant analysis could separate treatment groups from control. Low doses of fipronil produced greater effects when given for 14days compared to a single dose. Changes in thyroid hormones and relative amounts of fipronil and its sulfone metabolite also differed between the dosing regimens. Most cytokine changes reflected alterations in inflammatory responses, hormone levels, and products of phospholipid, fatty acid, and amino acid metabolism. These findings demonstrate distinct blood-based analyte profiles across pesticide classes, dose levels, and exposure duration. These results show promise for detailed analyses of these biomarkers and their linkages to biological pathways.

Fipronil induced oxidative stress in kidney and brain of mice: Protective effect of vitamin E and vitamin C

Fipronil is a relatively new insecticide of the phenpyrazole group. Fipronil-induced effects on antioxidant system and oxidative stress biomarkers are yet to be studied in vivo. The present study was undertaken to evaluate fipronil-induced alterations in the blood biochemical markers and tissue antioxidant enzymes after oral exposure in mice and to explore possible protective effect of pre-treatment of antioxidant vitamins against these alterations. Mice were divided into eight groups containing control, test and amelioration groups. Mice in the test groups were exposed to different doses of fipronil, i.e., 2.5, 5 and 10 mg/kg bw, respectively for 28 days. Mice in the amelioration groups were treated with vitamin E or vitamin C (each at 100 mg/kg) 2 h prior to high dose (10 mg/kg) of fipronil. Fipronil exposure at three doses caused significant increase in the blood biochemical markers, lipid peroxidation and prominent histopathological alterations; while level of antioxidant enzymes was severely decreased both in kidney and brain tissues. Prior administration of vitamin E or vitamin C in the fipronil exposed mice led to decrease in lipid peroxidation and significant increase in activities of antioxidants, viz., glutathione, total thiol, superoxide dismutase and catalase. Vitamin E and vitamin C administration in fipronil exposed mice also improved histological architecture of the kidney and brain when compared with fipronil alone treated groups. Thus, results of the present study demonstrated that in vivo fipronil exposure induces oxidative stress and pre-treatment with vitamin E or C can protect mice against this oxidative insult.