Glutathione and glutathione-related enzymes in rats exposed to dimethoate and/or pyrantel

Occupational exposure to organophosphorus and carbamates in farmers in La Cienega, Jalisco, Mexico: oxidative stress and membrane fluidity markers

Background

The region of La Cienega in Jalisco Mexico, is an important agricultural reference for the production of corn, sorghum and wheat, among other grains, so the use of pesticides for pest control is high. However, in this rural area there are no toxicological studies that assess the occupational risk of pesticide use. Therefore, this study is the first to determine the oxidative stress levels markers (GSH, GSSG, carbonyl groups, nitric oxide metabolites and lipid peroxides) as well as alteration of the mitochondrial membrane fluidity caused by occupational exposure to organophosphorus and carbamates in farmers of this region. This occupational risk can increase cellular oxidation, which explains the high prevalence of neurodegenerative diseases and cancer in Cienega settlers to be analyzed in future studies.

Methods

Comparative cross-sectional study was performed using two groups: one not exposed group (n = 93) and another one with occupational exposure (n = 113). The latter group was sub-divided into 4 groups based on duration of use/exposure to pesticides. Oxidative stress levels and membrane fluidity were assessed using spectrophotometric methods. Statistical analyses were performed using SPSS software ver. 19.0 for windows.

Results

The most commonly used pesticides were organophosphorus, carbamates, herbicide-type glyphosate and paraquat, with an average occupational exposure time of 35.3 years. There were statistically significant differences in markers of oxidative stress between exposed farmers and not exposed group (p = 0.000). However, in most cases, no significant differences were found in markers of oxidative stress among the 4 exposure sub-groups (p > 0.05).

Conclusion

In the Cienega region, despite the indiscriminate use of organophosphorus and carbamates, there are no previous studies of levels oxidative stress. The results show increased levels of oxidative stress in occupationally exposed farmers, particularly membrane fluidity levels increased three times in contrast to not exposed group.

Tebuconazole induced oxidative stress and histopathological alterations in adult rat heart

TEB belongs to the family of triazole fungicides and it is used to protect agricultural crop plants from fungal pathogens. The information regarding its cardiotoxic effects through different pathways particularly by perturbing the oxidative balance and causing damage to the myocardium is still limited. In the present study, oxidative and histopathologic damages caused by TEB in the cardiac tissue of male adult rats, were evaluated. Rats were exposed orally to TEB at 0.9, 9, 27 and 45 mg/kg b.w. for 28 days. Results showed that following TEB treatment malondialdehyde (MDA), protein carbonyl (PC), advanced oxidation protein product (AOPP), antioxidant enzyme activities (GPx and GR) and GSSG levels increased, while GSH levels and thus the GSH/GSSG ratio decreased. Superoxide dismutase (SOD) and catalase (CAT) initially increased at the doses of 0.9, 9 and 27 mg/kg b.w. and then decreased at the dose of 45 mg/kg b.w. Moreover, western blot analysis showed that TEB increased SOD1, CAT and HSP70 protein levels after 24 h. Furthermore, TEB induced various histological changes in the myocardium, including leucocytic infiltration, hemorrhage congestion of cardiac blood vessels and cytoplasmic vacuolization. Therefore, our investigation revealed, that TEB exhibits cardiotoxic effects by changing oxidative balance and damaging the cardiac tissue.

The organophosphorus pesticide dimethoate decreases cell viability and induces changes in different biochemical parameters of rat pancreatic stellate cells

In the present study we employed cultured pancreatic stellate cells to study the effect of the organophosphorus insecticide dimethoate on pancreatic cell physiology. Esterase activity, cell viability, reactive oxygen species generation and Ca²⁺ mobilization were examined. Our results show that dimethoate (0.1, 1 and 10 μM) induced a concentration-dependent inhibition of cholinesterase enzymatic activity at all concentrations tested. A drop in carboxylesterase activity was noted in the presence of 10 μM dimethoate. In the presence of the pesticide a decrease in cell viability was detected. The clearer effect could be observed when the cells had been incubated during 96 h in the presence of dimethoate. The pesticide induced a slight but statistically significant increase in the production of reactive oxygen species in the mitochondria. Incubation of cells with dimethoate, in the presence of Ca²⁺ in the extracellular medium, led to a slow and progressive increase in [Ca²⁺]_c towards an elevated value over the prestimulation level. A similar behavior was observed in the absence of extracellular Ca²⁺, indicating that dimethoate releases Ca²⁺ from the intracellular stores. Our results suggest that dimethoate might alter intracellular pathways that are critical for pancreatic physiology, creating a situation potentially leading to dysfunction in the exocrine pancreas.

Concentration of hepatic vitamins A and E in rats exposed to chlorpyrifos and/or enrofloxacin

The aim of the study was to determine the level of antioxidant vitamins A and E in the liver of rats exposed to chlorpyrifos and/or enrofloxacin. Chlorpyrifos (Group I) was administered at a dose of 0.04 LD50 (6 mg/kg b.w.) for 28 days, and enrofloxacin (Group II) at a dose of 5 mg/kg b.w. for 5 consecutive days. The animals of group III were given both of the mentioned above compounds at the same manner as groups I and II, but enrofloxacin was applied to rats for the last 5 days of chlorpyrifos exposure (i.e. on day 24, 25, 26, 27 and 28). Chlorpyrifos and enrofloxacin were administered to rats intragastrically via a gastric tube. The quantitative determination of vitamins was made by the HPLC method. The results of this study indicated a reduction in the hepatic concentrations of vitamins A and E, compared to the control, which sustained for the entire period of the experiment. The four-week administration of chlorpyrifos to rats resulted in a significant decrease of vitamins in the initial period of the experiment, i.e. up to 24 hours after exposure. For vitamin A the maximum drop was observed after 24 hours (19.24%) and for vitamin E after 6 hours (23.19%). Enrofloxacin caused a slight (3-9%) reduction in the level of the analysed vitamins. In the chlorpyrifos-enrofloxacin co-exposure group reduced vitamins A and E levels were also noted, but changes in this group were less pronounced in comparison to the animals intoxicated with chlorpyrifos only. The decrease in the antioxidant vitamin levels, particularly noticeable in the chlorpyrifos- and the chlorpyrifos combined with enrofloxacin-treated groups, may result not only from the increase in the concentration of free radicals, but also from the intensification of the secondary stages of lipid peroxidation.

Effect of enrofloxacin and chlorpyrifos on the levels of vitamins A and E in Wistar rats

This study investigates the effects of enrofloxacin and chlorpyrifos, and their combination on vitamin A and E concentrations in the liver of rats. Results of this study indicated a reduction in the contents of vitamins A and E in the liver, which persisted for the entire period of the experiment. Vitamins A and E concentrations were slightly decreased (2-7%) in enrofloxacin-treated rats. In the group of rats intoxicated with chlorpyrifos, a significant decrease in the level of vitamin A was observed up to the 24th hour, and for vitamin E up to the 3rd day from the discontinuation of intoxication with the compounds under study. In the enrofloxacin-chlorpyrifos co-exposure group reduced vitamins A and E level was also noted. The greatest fall in vitamin A level was observed after 3h, while the contents of vitamin E decreased progressively up to the 3rd day. Changes in this group were less pronounced in comparison to the animals intoxicated with chlorpyrifos only.

Food safety in Thailand 1: it is safe to eat watermelon and durian in Thailand

OBJECTIVES

The wide use of pesticides raises serious concerns regarding food safety and environmental impacts. There is increasing public concern about the potential health risks linked with exposure to pesticides. Regulation of maximum residue limits (MRL) of pesticide residues in food commodities has been established in many developed countries. For developing countries, like Thailand, this regulation often exists in law, but is not completely enforced in practice. Thus, pesticide residue levels in vegetables and fruits have not been thoroughly monitored. The present study aimed to examine potential health risks associated with pesticide exposure by determining the pesticide residues in two commonly consumed fruits, watermelon and durian.

METHODS

The fruit samples were purchased from markets in central provinces of Thailand and assayed for the content of 28 pesticides. Analysis of pesticides was performed by multiresidue extraction and followed by GC-MS/MS detection.

RESULTS

Of 28 pesticides investigated, 5 were detected in 90.7% of the watermelon samples (n = 75) and 3 in 90% of durian samples (n = 30). Carbofuran, chlorpyrifos, diazinon, dimethoate and metalaxyl were found in watermelons, whereas dichlorvos, dimethoate and metalaxyl were detected in durians. However, their levels were much lower than the recommended MRL values.

CONCLUSIONS

These pesticide levels detected in the fruits are unlikely to harm the consumers; therefore it is safe to eat watermelon and durian in Thailand. While our results found negligible risk associated with pesticide exposure from consuming these common tropical fruits, special precautions should be considered to decrease total exposure to these harmful pesticides from various foods.