RESUMO
Hepatic fibrosis is an extracellular matrix deposition by hepatic stellate cells (HSC). Fibrosis can be caused by iron, which will lead to hydroxyl radical production and cell damage. Fructose-1,6-bisphosphate (FBP) has been shown to deliver therapeutic effects in many pathological situations. In this work, we aimed to test the effects of FBP in HSC cell line, GRX, exposed to an excess of iron (Fe). The Fe-treatment increased cell proliferation and FBP reversed this effect, which was not due to increased necrosis, apoptosis or changes in cell cycle. Oil Red-O staining showed that FBP successfully increased lipid content and lead GRX cells to present characteristics of quiescent HSC. Fe-treatment decreased PPAR-γ expression and increased Col-1 expression. Both effects were reversed by FBP which also decreased TGF-ß1 levels in comparison to both control and Fe groups. FBP, also, did not present scavenger activity in the DPPH assay. The treatment with FBP resulted in decreased proliferation rate, Col-1 expression and TGF-ß1 release by HSC cells. Furthermore, activated PPAR-γ and increased lipid droplets induce cells to become quiescent, which is a key event to reversion of hepatic fibrosis. FBP also chelates iron showing potential to improve Cell redox state.
Assuntos
Compostos Ferrosos/antagonistas & inibidores , Frutosedifosfatos/farmacologia , Células Estreladas do Fígado/efeitos dos fármacos , Quelantes de Ferro/farmacologia , Animais , Compostos de Bifenilo/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Compostos Ferrosos/farmacologia , Regulação da Expressão Gênica , Células Estreladas do Fígado/citologia , Células Estreladas do Fígado/metabolismo , Gotículas Lipídicas/efeitos dos fármacos , Gotículas Lipídicas/metabolismo , Camundongos , Oxirredução , PPAR gama/genética , PPAR gama/metabolismo , Picratos/química , Transdução de Sinais , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismoRESUMO
Kynurenic acid (KYNA) is an endogenous metabolite of the kynurenine pathway for tryptophan degradation and an antagonist of both N-methyl-D-aspartate (NMDA) and alpha-7 nicotinic acetylcholine (α7nACh) receptors. KYNA has also been shown to scavenge hydroxyl radicals (OH) under controlled conditions of free radical production. In this work we evaluated the ability of KYNA to scavenge superoxide anion (O(2)(-)) and peroxynitrite (ONOO(-)). The scavenging ability of KYNA (expressed as IC(50) values) was as follows: OH=O(2)(-)>ONOO(-). In parallel, the antiperoxidative and scavenging capacities of KYNA (0-150 µM) were tested in cerebellum and forebrain homogenates exposed to 5 µM FeSO(4) and 2.5 mM 3-nitropropionic acid (3-NPA). Both FeSO(4) and 3-NPA increased lipid peroxidation (LP) and ROS formation in a significant manner in these preparations, whereas KYNA significantly reduced these markers. Reactive oxygen species (ROS) formation were determined in the presence of FeSO(4) and/or KYNA (0-100 µM), both at intra and extracellular levels. An increase in ROS formation was induced by FeSO(4) in forebrain and cerebellum in a time-dependent manner, and KYNA reduced this effect in a concentration-dependent manner. To further know whether the effect of KYNA on oxidative stress is independent of NMDA and nicotinic receptors, we also tested KYNA (0-100 µM) in a biological preparation free of these receptors - defolliculated Xenopus laevis oocytes - incubated with FeSO(4) for 1 h. A 3-fold increase in LP and a 2-fold increase in ROS formation were seen after exposure to FeSO(4), whereas KYNA attenuated these effects in a concentration-dependent manner. In addition, the in vivo formation of OH evoked by an acute infusion of FeSO(4) (100 µM) in the rat striatum was estimated by microdialysis and challenged by a topic infusion of KYNA (1 µM). FeSO(4) increased the striatal OH production, while KYNA mitigated this effect. Altogether, these data strongly suggest that KYNA, in addition to be a well-known antagonist acting on nicotinic and NMDA receptors, can be considered as a potential endogenous antioxidant.
Assuntos
Antioxidantes/farmacologia , Sequestradores de Radicais Livres/farmacologia , Ácido Cinurênico/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/administração & dosagem , Células Cultivadas , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Relação Dose-Resposta a Droga , Compostos Ferrosos/antagonistas & inibidores , Compostos Ferrosos/farmacologia , Hidróxidos/metabolismo , Ácido Cinurênico/administração & dosagem , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Microinjeções , Nitrocompostos/antagonistas & inibidores , Nitrocompostos/farmacologia , Oócitos/metabolismo , Propionatos/antagonistas & inibidores , Propionatos/farmacologia , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/metabolismo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Xenopus laevisRESUMO
The antiperoxidative properties of alpha-mangostin, a xanthone isolated from mangosteen fruit, were tested for the first time in nerve tissue exposed to different toxic insults. Two reliable biological preparations (rat brain homogenates and synaptosomal P2 fractions) were exposed to the toxic actions of a free radical generator (ferrous sulfate), an excitotoxic agent (quinolinate), and a mitochondrial toxin (3-nitropropionate). alpha-Mangostin decreased the lipoperoxidative action of FeSO(4) in both preparations in a concentration-dependent manner, and completely abolished the peroxidative effects of quinolinate, 3-nitropropionate and FeSO(4) + quinolinate at all concentrations tested. Interestingly, when tested alone in brain homogenates, alpha-mangostin significantly decreased the lipoperoxidation even below basal levels. alpha-Mangostin also prevented the decreased reductant capacity of mitochondria in synaptosomal fractions. Our results suggest that alpha-mangostin exerts a robust antiperoxidative effect in brain tissue preparations probably through its properties as a free radical scavenger. In light of these findings, this antioxidant should be tested in other neurotoxic models involving oxidative stress.