Induction of oxidative stress and lipid peroxidation in rats chronically exposed to cypermethrin through dermal application

Cumulative dietary risk assessment of chronic acetylcholinesterase inhibition by residues of pesticides

A retrospective cumulative risk assessment of dietary exposure to pesticide residues was conducted for chronic inhibition of acetylcholinesterase. The pesticides considered in this assessment were identified and characterised in a previous scientific report on the establishment of cumulative assessment groups of pesticides for their effects on the nervous system. The exposure assessments used monitoring data collected by Member States under their official pesticide monitoring programmes in 2016, 2017 and 2018, and individual food consumption data from 10 populations of consumers from different countries and from different age groups. Exposure estimates were obtained by means of a two-dimensional probabilistic model, which was implemented in SAS ® software. The characterisation of cumulative risk was supported by an uncertainty analysis based on expert knowledge elicitation. For each of the 10 populations, it is concluded with varying degrees of certainty that cumulative exposure to pesticides contributing to the chronic inhibition of acetylcholinesterase does not exceed the threshold for regulatory consideration established by risk managers.

Maximum contaminant level of arsenic in drinking water potentiates quinalphos-induced renal damage on co-administration of both arsenic and quinalphos in Wistar rats

This study was designed to determine alterations in renal biomarkers, antioxidant profile, and histomorphology of renal tissue following subacute exposure to quinalphos alone or in conjunction with arsenic in rats. A total of 54 adult Wistar rats were randomly divided into nine groups of six rats each and were administered sub-lethal concentrations of quinalphos (1/100^th and 1/10^th of LD₅₀) orally daily and arsenic (50 and 100 ppb) in drinking water for 28 days. Significantly (p < 0.05) decreased levels of antioxidant biomarkers in renal tissue, viz., total thiols, catalase, superoxide dismutase, glutathione peroxidase, glutathione-s-transferase, and glutathione reductase along with increased (p < 0.05) thiobarbituric acid reacting substance (TBRAS) levels indicated that significant oxidative damage to renal tissue occurred following repeated administrations of quinalphos at either dose levels or arsenic at the concentration of 100 ppb when compared with the control rats. The alterations in the antioxidant parameters were observed to be more pronounced in co-administered groups as compared with either toxicant administered group. Similarly, activity of renal acetylcholinesterase was decreased after repeated exposure to quinalphos or arsenic, but inhibition was higher (up to 48%) in rat renal tissue co-exposed with quinalphos and arsenic at the higher concentration. These findings corroborated with the histopathological alterations in renal tissue of toxicant exposed rats. The altered plasma and tissue antioxidant biomarkers along with histopathological changes in the kidney at higher dose level of either toxicant indicate that renal tissue is significantly impacted by these toxicants, and these effects become more pronounced after their co-administration.

Protective effects of extracts of lichen Dirinaria consimilis (Stirton) D.D. Awasthi in bifenthrin- and diazinon-induced oxidative stress in rat erythrocytes in vitro

The intoxication of insecticides such as bifenthrin and diazinon has been reported to generate free radicals, and thereby alter the antioxidant defense system in erythrocytes. The present study is aimed to investigate the protective effects of acetone (DA) and methanolic (DM) extracts of lichen Dirinaria consimilis against bifenthrin and diazinon toxicity in rats' erythrocytes in vitro. Rats' erythrocytes were exposed to bifenthrin and diazinon, individually and also in combination with DA or DM at 1 ppm for 3 h at 37 ˚C. By using spectrophotometric methods, all the samples were estimated for changes in hemoglobin (Hb) concentration, malondialdehyde (MDA) levels, and enzyme [Superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferases (GST)] activities. The outcomes showed that both the insecticides were highly toxic to rats' erythrocytes. Among all groups, both the insecticides and DA exposed groups showed very low levels of MDA content, and GST activity in rats' erythrocytes, when compared to the control. Besides, DA groups pretreated with both insecticides showed significant improvement of total Hb concentration, SOD, and CAT activities, with respect to the control. Hence, the present results indicate that the extracts of D. consimilis act as an antioxidant agent that reduces oxidative stress burden in insecticides toxicity.

Evaluation of biomarkers of stress in chronic stress-exposed comorbid depression model Wistar rats

Background In recent years, increased stress in human life has a dual effect on brain and body physiology. Chronic stress takes a toll on physiology as well as on quality of life, ultimately leading to affective disorders. Rodent models are indispensable tools for studying the etiology and progress of depression. C-reactive protein has been proposed as a novel inflammatory marker. Methods Rats were divided into control and experimental stress groups (n = 6 each). The experimental group consisted of rats that were exposed to a set of chronic unpredictable stressors for 15 days. At the end of the 15th day, the animals were anesthetized, and blood samples were collected through cardiac puncture. Then the blood samples were analyzed for selected biochemical and oxidative stress parameters. Results Serum glutamic oxaloacetic transaminase (p < 0.0001), serum glutamic pyruvic transaminase (p < 0.001), serum malondialdehyde (p < 0.0001), total antioxidant level (p < 0.0001), and serum cortisol (p < 0.0001) were significantly increased in the stressed group when compared with the control group. C-reactive protein significantly (p < 0.0001) increased in the stressed group when compared with the control group. Conclusion Our results demonstrate that chronic unpredictable stress ameliorated depression-like behavior, which might have caused the dysregulation of the hypothalamic-pituitary-adrenal axis, causing the imbalance in the biochemical and oxidative parameters increasing the inflammatory markers. The inflammation-induced model of the chronic unpredictable stress model of comorbid depression might provide a variety of new targets for antidepressant therapies.

Ameliorative effect of resveratrol on testicular oxidative stress, spermatological parameters and DNA damage in glyphosate-based herbicide-exposed rats

In this study, the reproductive impacts of being exposed to glyphosate (GLF) and the protective impacts of resveratrol (RES) were assessed in 28 Wistar male rats, which were equally separated into four groups. Control group were fed normal diet without GLF or RES, group II received normal feed containing 20 mg kg-1 daily-1 RES, group III received normal feed containing 375 mg kg-1 daily-1 GLF, and group IV received normal feed containing 375 mg kg-1 daily-1 GLF+20 mg kg-1 daily-1 RES. GLF administration decreased sperm motility, sperm plasma membrane integrity, glutathione level and superoxide dismutase in the testicular tissue of rats. On the other hand, abnormal sperm rate, malondialdehyde level, and DNA damage were detected to be high in the group treated with GLF. The findings indicate that RES protects spermatological parameters and DNA damage, decreases GLF-induced lipid peroxidation, improves the antioxidant defence mechanism and regenerates tissue damage in the testis of rats.

Markers of genotoxicity and oxidative stress in farmers exposed to pesticides

The effects of chronic exposure to pesticides can lead to the development of several diseases, including different types of cancer, since the genotoxic and mutagenic capacity of these substances can be observed. The objective of this study is to investigate the relation between the occupational exposure to various pesticides and the presence of DNA damage and oxidative stress. Blood samples from 50 rural workers (41 men and 9 women) exposed to pesticides, 46 controls (20 men and 26 women) from the same city (Antônio Carlos, Santa Catarina state, Brazil) and 29 controls (15 men and 14 women) from another city (Florianópolis, Santa Catarina state, Brazil), were evaluated using the comet assay and the cytokinesis-block micronucleus (CBMN) technique for genetic damage, and the test of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity for the oxidative stress. Cholinesterase activities were also determined, but there was no statistical difference among exposed workers and controls. Significant differences were found in DNA damage among groups. The comet assay performed on peripheral blood lymphocytes of these individuals had a significantly higher DNA damage index in the exposed group comparing to controls (p < 0.0001). MNi (p < 0.001), NBUDs (p < 0.005) and NPBs (p < 0.0001) were also found to be significantly higher in the exposed group. The TBARS values were significantly higher comparing to the Florianopolis control group (p < 0.0001). Even though CAT values were higher than controls, there was no statistical difference. Thus, it is concluded that the exposed individuals, participants of this study, are more subject to suffer genetic damage and, consequently, more susceptible to diseases resulting from such damages.

Oxidative stress and genetic damage among workers exposed primarily to organophosphate and pyrethroid pesticides

The indiscriminate use of pesticides in agriculture and public health campaigns has been associated with an increase of oxidative stress and DNA damage, resulting in health outcomes. Some defense mechanisms against free radical-induced oxidative damage include the antioxidant enzyme systems. The aim of this study was to determine the levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and the relationship of antioxidant enzyme levels with DNA damage among sprayers (workers) occupationally exposed to pesticides. The determinations of MDA and antioxidant enzymes were performed spectrophotometrically. The genotoxic effects were evaluated using the comet assay. The results showed a marginally significant decrease in SOD and CAT activities in the high exposure group compared to the control group. For MDA, statistically significant differences were found among people working long term vs. those working temporarily (P = 0.02) as sprayers. In the moderate exposure group, a positive correlation was observed between MDA levels and GPx activity. In the high exposure group, a negative correlation was observed between GR and CAT activities, and between MDA levels and GPx activities. Furthermore, in the high exposure group, a positive correlation between DNA damage parameters and MDA levels was observed. The results suggest an important role of antioxidant enzymes for the protection of DNA damage caused by occupational exposure to pesticides.

Lycopene ameliorates atrazine-induced oxidative damage in adrenal cortex of male rats by activation of the Nrf2/HO-1 pathway

Atrazine (ATZ) is one of the most commonly used herbicides contaminating plants, soil and water resources. Several strategies have been used to counteract ATZ toxicity. Here, we tested the hypothesis that lycopene could ameliorate ATZ-induced toxicity in the adrenal cortex. For this purpose, 35 adult male albino rats were randomized into five equal groups: untreated control, vehicle control (received 0.5 mL corn oil/day), lycopene (treated with lycopene dissolved in 0.5 mL corn oil, 10 mg/kg b.w./day), ATZ (received ATZ dissolved in 0.5 mL corn oil 300 mg/kg b.w./day), and ATZ + lycopene (treated with ATZ and lycopene at the same previously mentioned doses). All treatments were given by oral gavage for 4 weeks. We found that ATZ exposure significantly increased relative adrenal weight, plasma ACTH levels, and adrenal oxidative stress as manifested by elevated malondialdehyde levels, decreased reduced glutathione content and depressed antioxidant enzyme activities in adrenal cortex tissues with respect to control groups. Furthermore, the transcription of adrenal cortex nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), nuclear factor kappa B, and caspase-3 genes was increased significantly compared with the control groups. This was accompanied with DNA fragmentation and structural and ultrastructural changes in zona glomerulosa and zona fasiculata of the adrenal cortex. Notably, all these changes were partially ameliorated in rats treated concomitantly with ATZ and lycopene. Our results showed that lycopene exerts protective effects against ATZ-induced toxicity in rat adrenal cortex. These effects may be attributed to the antioxidative property of lycopene and its ability to activate the Nrf2/HO-1 pathway.

Control of Tetranychus urticae Koch by extracts of three essential oils of chamomile, marjoram and Eucalyptus

OBJECTIVE

To evaluate the acaricidal activity of extracts of three essential oils of chamomile, marjoram and Eucalyptus against Tetranychus urticae (T. urticae) Koch.

METHODS

Extracts of three essential oils of chamomile, marjoram and Eucalyptus with different concentrations (0.5%, 1.0%, 2.0%, 3.0% and 4.0%) were used to control T. urticae Koch.

RESULTS

The results showed that chamomile (Chamomilla recutita) represented the most potent efficient acaricidal agent against Tetranychus followed by marjoram (Marjorana hortensis) and Eucalyptus. The LC50 values of chamomile, marjoram and Eucalyptus for adults were 0.65, 1.84 and 2.18, respectively and for eggs 1.17, 6.26 and 7.33, respectively. Activities of enzymes including glutathione-S-transferase, esterase (α-esterase and β-esterase) and alkaline phosphatase in susceptible mites were determined and activities of enzymes involved in the resistance of acaricides were proved. Protease enzyme was significantly decreased at LC50 of both chamomile and marjoram compared with positive control. Gas chromatography-mass spectrometer (GC-MS) proved that the major compositions of Chamomilla recutita are α-bisabolol oxide A (35.251%), and trans-β-farersene (7.758%), while the main components of Marjorana hortensis are terpinene-4-ol (23.860%), p-cymene (23.404%) and sabinene (10.904%).

CONCLUSIONS

It can be concluded that extracts of three essential oils of chamomile, marjoram and Eucalyptus possess acaricidal activity against T. urticae.

Dietary exposure to continuous small doses of α-cypermethrin in the presence or absence of dietary curcumin does not induce oxidative stress in male Wistar rats

•

α-Cypermethrin induces toxicity in rats when administered at single high doses.

•

In humans, exposure is primarily via contaminated food.

•

Continuous dietary exposure does not cause oxidative stress or hepatotoxicity in rats.

•

Single-dose gastric-intubation studies may have overestimated its toxicity in rats.

α-Cypermethrin is a widely used insecticide and, at high doses, induces oxidative stress in mammals. Curcumin is an antioxidant phytochemical commonly used for food coloring and flavoring. We aimed to investigate the effects of continuous dietary exposure to low doses of α-cypermethrin, as is the case in exposed humans, on oxidative stress and its potential prevention by dietary curcumin. Four groups of ten male Wistar rats were ad libitum-fed a control diet or identical diets fortified with α-cypermethrin (350 mg/kg diet), curcumin (1000 mg/kg diet), or α-cypermethrin and curcumin (350 and 1000 mg/kg diet, respectively) for 7 weeks. α-Cypermethrin accumulated in adipose tissues and was detectable in kidney, liver, and brains. Dietary α-cypermethrin did not alter concentrations of malondialdehyde, ascorbic and uric acid, retinol, liver damage markers, or the activities of CAT and SOD, but reduced vitamin E in blood. α-Cypermethrin did not affect malondialdehyde or reduced glutathione concentrations in any of the tissues, but significantly increased glutathione disulfide in kidney and subcutaneous adipose tissue. In conclusion, dietary exposure to small doses of α-cypermethrin did not induce oxidative stress in rats and may be less toxic than exposure to comparable quantities administered as single high doses by gastric intubation.

Increased levels of oxidative DNA damage in pesticide sprayers in Thessaly Region (Greece). Implications of pesticide exposure

The widespread use of pesticides substances nowadays largely guarantees the protection of crops and people from undesired pests. However, exposure to pesticides was related to a variety of human health effects. The present study was conducted in the region of Thessaly which is characterized by intensive agricultural activities and wide use of pesticides. The study aimed at estimating the oxidative damage to DNA in different subpopulations in Thessaly region (Greece) and investigating its correlation with exposure to pesticides and other potential risk factors. In total, the study involved 80 pesticide sprayers, 85 rural residents and 121 individuals, inhabitants of the city of Larissa. Demographic characteristics, habits, medical history and exposure history of the participants to pesticides were recorded by personal interviews. Blood and urine samples were collected from all participants. For the measurement of exposure to organophosphorus insecticides, dialkylphosphate (DAP) metabolites were quantified in urine, by gas chromatography-mass spectrometry. Genomic DNA was extracted from peripheral blood samples and the oxidation by-product 8-hydroxydeoxyguanosine (8-OHdG) was determined by Enzyme Immuno-Assay. Urinary metabolite concentrations were not associated with 8-OHdG levels but it was found that pesticide sprayers had significantly higher levels of 8-OHdG (p=0.007) in comparison to the control group. Last season's exposure to insecticides and fungicides, expressed as total area treated multiplied by the number of applications, showed a statistically significant association with the risk of having high 8-OHdG levels [RR: 2.19 (95%CI:1.09-4.38) and RR: 2.32 (95% CI:1.16-4.64) respectively]. Additionally, from the subgroups of pesticides examined, seasonal exposure to neonicotinoid insecticides [RR: 2.22 (95% CI:1.07-4.63)] and glufosinate ammonium [RR: 3.26 (95% CI:1.38-7.69)] was found to have the greater impact on 8-OHdG levels. This study produced findings that support the hypothesis that pesticide exposure is involved in the induction of oxidative damage to DNA and identified chemical groups of pesticides which should be given greater attention in future investigations.

Cypermethrin-induced reproductive toxicity in the rat is prevented by resveratrol

AIMS

The current study was to assess the protective role of resveratrol in cypermethrin-induced reproductive toxicity in male Wistar rats.

MATERIALS AND METHODS

Rats were exposed to cypermethrin (3.83 mg/kg bw) for 14 days. Pre- and post-treatment of resveratrol (20 mg/kg bw for 14 days) was given to cypermethrin exposed rats. At the end of the experiment, rats were sacrificed, testis and epididymis were removed, sperm characteristics, sex hormones, and various biochemical parameters were studied.

RESULTS

Cypermethrin exposure resulted in a significant decrease in weight of testis and epididymis, testicular sperm head counts, sperm motility and live sperm counts and increase in sperm abnormalities. Serum testosterone (T), follicle stimulating hormone (FSH), luteinizing hormone (LH), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and total protein (TP) content were decreased and lipid peroxidation (LPO) level was increased on cypermethrin exposure. Pre- and post-treatment of resveratrol increased sperm head counts, sperm motility, live sperm counts, T, FSH, LH, GSH, CAT, SOD, GST, GR, GPx and TP contents and decreased LPO. Treatment with resveratrol alone has improved sperm parameters and testicular antioxidant defence system.

CONCLUSION

The study concluded that resveratrol ameliorated cypermethrin-induced testicular damage by reducing oxidative stress and by enhancing the level of sex hormones.

Sub-acute deltamethrin and fluoride toxicity induced hepatic oxidative stress and biochemical alterations in rats

The current study investigated the effects of deltamethrin, fluoride (F(-)) and their combination on the hepatic oxidative stress and consequent alterations in blood biochemical markers of hepatic damage in rats. Significant hepatic oxidative stress and hepatic damage were observed in the toxicant exposed groups. These changes were higher in the deltamethrin-F(-) co-exposure treatment group, depicting a positive interaction between the two chemicals.