RESUMO
BACKGROUND: Organophosphorus pesticides exert their toxic effects mainly by the inhibition of acetylcholinesterase (AChE), which is related to emotional disorders, such as depression. Atropine-oximes therapy is commonly used; however, the efficacy of oximes in the reactivation of AChE has been inconsistent. The objective of this study was to investigate the possible neuroprotective effect of (3Z)-5-Chloro-3-(hydroxyimino)indolin-2-one (Câ-HIN), a compound that combines the isatin and oxime functional groups, in rats exposed to malathion. The effect of Câ-HIN on the AChE activity and the BDNF-Trkß pathway in the prefrontal cortex of malathion-exposed rats were tested. METHODS: Wistar male rats were co-treated with Câ-HIN [50 mg/kg (p.o.) (3 mL/kg)] and/or malathion [250 mg/kg (i.p.) (5 mL/kg)] and performed behavioral tests twelve hours after these exposures. RESULTS: The Câ-HIN reversed the increased immobility time in the forced swimming test and the decreased grooming time in the splash test induced by malathion, but any significant difference was observed in locomotion analysis. These results demonstrate the antidepressant-like effect of Câ-HIN. The cortical AChE activity was reactivated by Câ-HIN in rats exposed to malathion. Malathion induced an increase in Trkß and a decrease in BDNF levels in the prefrontal cortex of rats, which were avoided by Câ-HIN. CONCLUSION: These findings support the hypothesis that Câ-HIN is an AChE reactivator with antidepressant-like properties, which is related to the improvement of BDNF-Trkß signaling after acute exposure to malathion in rats. Thus, the results allow suggesting the potential use of Câ-HIN as an oxime-based therapy against the neurotoxic effects of malathion.
Assuntos
Acetilcolinesterase/metabolismo , Antidepressivos/farmacologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Indóis/farmacologia , Malation/toxicidade , Oxindóis/farmacologia , Receptor trkB/metabolismo , Transdução de Sinais , Animais , Antidepressivos/administração & dosagem , Antidepressivos/química , Antidepressivos/uso terapêutico , Comportamento Animal/efeitos dos fármacos , Depressão/tratamento farmacológico , Indóis/administração & dosagem , Indóis/química , Indóis/uso terapêutico , Masculino , Atividade Motora/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Oxindóis/administração & dosagem , Oxindóis/química , Oxindóis/uso terapêutico , Ratos Wistar , Transdução de Sinais/efeitos dos fármacosRESUMO
Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg-Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg-Cys complex. The liver slices were pre-treated with Met (250 µM) 15 min before being exposed to MeHg (25 µM) or MeHg-Cys (25 µM each) for 30 min at 37 °C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg-Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg-Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg-Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg-Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg-Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg- and/or MeHg-Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the competition of Met with the complex formed between MeHg and endogenous cysteine. In summary, our results show that Met pre-treatment produces pronounced protection against the toxic effects induced by MeHg and/or the MeHg-Cys complex on mitochondrial function and cell viability. Consequently, this amino acid offers considerable promise as a potential agent for treating acute MeHg exposure.
Assuntos
Metionina/fisiologia , Compostos de Metilmercúrio/antagonistas & inibidores , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/fisiologia , Mimetismo Molecular/fisiologia , Animais , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Carcinógenos Ambientais/química , Carcinógenos Ambientais/metabolismo , Carcinógenos Ambientais/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Interações Medicamentosas/fisiologia , Fígado/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Metionina/química , Compostos de Metilmercúrio/química , Compostos de Metilmercúrio/toxicidade , Técnicas de Cultura de Órgãos , Consumo de Oxigênio/efeitos dos fármacos , Consumo de Oxigênio/fisiologia , Ratos , Ratos WistarRESUMO
Methylmercury (MeHg) can cause deleterious effects in vertebrate tissues, particularly in the central nervous system. MeHg interacts with sulfhydryl groups from low and high molecular weight thiols in the blood, which can facilitate MeHg uptake into different tissues. The purpose of this study was to examine the effect of MeHg-Cysteine (MeHg-Cys) complex administration on Hg-uptake in cerebral areas (cortex and cerebellum), liver and kidney of adult mice. Animals were divided into four groups: control (1 mL/kg distilled water), MeHg (2 mg/kg), Cys (2 mg/kg) and MeHg-Cys complex (0.8 molar ratio). Mice received one intraperitoneal injection per day for 60 consecutive days. Treatment with MeHg significantly increased mercury concentrations in all tissues analysed when compared with the control group. The accumulation of mercury in brain and in liver was further increased in animals that received MeHg-Cys complex when compared with the MeHg alone group. However, renal Hg decreased in MeHg-Cys treated mice, when compared with the group treated only with MeHg. In summary, the transport of MeHg-Cys complex was tissue-specific, and we observed an increase in its uptake by liver and brain as well as a decrease in kidney.