The role of mitochondria and biotransformation in abamectin-induced cytotoxicity in isolated rat hepatocytes

Abamectin (ABA), which belongs to the family of avermectins, is used as a parasiticide; however, ABA poisoning can impair liver function. In a previous study using isolated rat liver mitochondria, we observed that ABA inhibited the activity of adenine nucleotide translocator and FoF1-ATPase. The aim of this study was to characterize the mechanism of ABA toxicity in isolated rat hepatocytes and to evaluate whether this effect is dependent on its metabolism. The toxicity of ABA was assessed by monitoring oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, cell viability, intracellular Ca2+ homeostasis, release of cytochrome c, caspase 3 activity and necrotic cell death. ABA reduces cellular respiration in cells energized with glutamate and malate or succinate. The hepatocytes that were previously incubated with proadifen, a cytochrome P450 inhibitor, are more sensitive to the compound as observed by a rapid decrease in the mitochondrial membrane potential accompanied by reductions in ATP concentration and cell viability and a disruption of intracellular Ca2+ homeostasis followed by necrosis. Our results indicate that ABA biotransformation reduces its toxicity, and its toxic action is related to the inhibition of mitochondrial activity, which leads to decreased synthesis of ATP followed by cell death. © 2012 Elsevier Ltd.

Dynamics and Conformational Studies of TOAC Spin Labeled Analogues of Ctx(Ile21)-Ha Peptide from Hypsiboas albopunctatus

Antimicrobial peptides (AMPs) isolated from several organisms have been receiving much attention due to some specific features that allow them to interact with, bind to, and disrupt cell membranes. The aim of this paper was to study the interactions between a membrane mimetic and the cationic AMP Ctx(Ile21)-Ha as well as analogues containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) incorporated at residue positions n = 0, 2, and 13. Circular dichroism studies showed that the peptides, except for [TOAC13]Ctx(Ile21)-Ha, are unstructured in aqueous solution but acquire different amounts of α-helical secondary structure in the presence of trifluorethanol and lysophosphocholine micelles. Fluorescence experiments indicated that all peptides were able to interact with LPC micelles. In addition, Ctx(Ile21)-Ha and [TOAC13]Ctx(Ile21)-Ha peptides presented similar water accessibility for the Trp residue located near the N-terminal sequence. Electron spin resonance experiments showed two spectral components for [TOAC0]Ctx(Ile21)-Ha, which are most likely due to two membrane-bound peptide conformations. In contrast, TOAC2 and TOAC13 derivatives presented a single spectral component corresponding to a strong immobilization of the probe. Thus, our findings allowed the description of the peptide topology in the membrane mimetic, where the N-terminal region is in dynamic equilibrium between an ordered, membrane-bound conformation and a disordered, mobile conformation; position 2 is most likely situated in the lipid polar head group region, and residue 13 is fully inserted into the hydrophobic core of the membrane. © 2013 Vicente et al.

Ionotropic but not metabotropic glutamatergic receptors in the locus coeruleus modulate the hypercapnic ventilatory response in unanaesthetized rats

Aim: Central chemoreceptors are important to detect changes of CO2/H+, and the Locus coeruleus (LC) is one of the many putative central chemoreceptor sites. Here, we studied the contribution of LC glutamatergic receptors on ventilatory, cardiovascular and thermal responses to hypercapnia. Methods: To this end, we determined pulmonary ventilation (VE), body temperatures (Tb), mean arterial pressure (MAP) and heart rate (HR) of male Wistar rats before and after unilateral microinjection of kynurenic acid (KY, an ionotropic glutamate receptor antagonist, 10 nmol/0.1 μL) or α-methyl-4-carboxyphenylglycine (MCPG, a metabotropic glutamate receptor antagonist, 10 nmol/0.1 μL) into the LC, followed by 60 min of air breathing or hypercapnia exposure (7% CO2). Results: Ventilatory response to hypercapnia was higher in animals treated with KY intra-LC (1918.7 ± 275.4) compared with the control group (1057.8 ± 213.9, P < 0.01). However, the MCPG treatment within the LC had no effect on the hypercapnia-induced hyperpnea. The cardiovascular and thermal controls were not affected by hypercapnia or by the injection of KY and MCPG in the LC. Conclusion: These data suggest that glutamate acting on ionotropic, but not metabotropic, receptors in the LC exerts an inhibitory modulation of hypercapnia-induced hyperpnea. © 2013 Scandinavian Physiological Society.

Effects of β-glucan extracted from Agaricus blazei on the expression of ERCC5, CASP9, and CYP1A1 genes and metabolic profile in HepG2 cells

The polysaccharide β-glucan has biological properties that stimulate the immune system and can prevent chronic pathologies, including cancer. It has been shown to prevent damage to DNA caused by the chemical and physical agents to which humans are exposed. However, the mechanism of β-glucan remains poorly understood. The objective of the present study was to verify the protective effect of β-glucan on the expression of the genes ERCC5 (involved in excision repair of DNA damage), CASP9 (involved in apoptosis), and CYP1A1 (involved in the metabolism of xenobiotics) using real-time polymerase chain reaction and perform metabolic profile measurements on the HepG2 cells. Cells were exposed to only benzo[a]pyrene (B[a]P), β-glucan, or a combination of B[a]P with β-glucan. The results demonstrated that 50 μg/mL β-glucan significantly repressed the expression of the ERCC5 gene when compared with the untreated control cells in these conditions. No change was found in the CASP9 transcript level. However, the CYP1A1 gene expression was also induced by HepG2 cells exposed to B[a]P only or in association with β-glucan, showing its effective protector against damage caused by B[a]P, while HepG2 cells exposed to only β-glucan did not show CYP1A1 modulation. The metabolic profiles showed moderate bioenergetic metabolism with an increase in the metabolites involved in bioenergetic metabolism (alanine, glutamate, creatine and phosphocholine) in cells treated with β-glucan and to a lesser extent treated with B[a]P. Thus, these results demonstrate that the chemopreventive activity of β-glucan may modulate bioenergetic metabolism and gene expression. © 2013 The Author(s).

Síntese em fase sólida e estudos comformacionais de análogos contendo TOAC de um peptídeo de rã Hypsiboas albopunctatus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estímulo da solubilização de fosfato resultante da co-inoculação de Aspergillus niger e Burkholderia cepacia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da interação funcional entre as proteínas elF5A e Yptl em S. cerevisiae

Pós-graduação em Biotecnologia - IQ

Síntese e avaliação farmacológica de protótipos candidatos à fármacos para o tratamento dos sintomas da anemia falciforme

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Produção de pellets livres e imobilizados e mecanismo de solubilização de fosfatos inorgânicos por Aspergillus niger

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Glutamina mais ácido glutâmico e aditivos fitogênicos nas dietas de frangos de corte criados no sistema alternativo de produção

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Níveis de valina, isoleucina e arginina em dietas com baixo nível protéico para codornas japonesas em postura

Pós-graduação em Zootecnia - FMVZ

Desenvolvimento de eletrodos modificados com poli ácido glutâmico e sua aplicação na análise de compostos antioxidantes e farmacêuticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nucleotídeos e ácido glutâmico em dietas de leitões desmamados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)