In vitro effect of N-acetyl-L-cysteine on glutathione and sulfhydryl levels in X-linked adrenoleukodystrophy patients

Introduction: Recent evidence shows that oxidative stress seems to be related with the pathophysiology of X-linked adrenoleukodystrophy (X-ALD), a neurodegenerative disorder. Methods: In the present study, the in vitro effect of N-acetyl-L-cysteine (NAC) on glutathione (GSH) and sulfhydryl levels in X-ALD patients was evaluated. Results: A significant reduction of GSH and sulfhydryl content was observed in X-ALD patients compared to the control group. Furthermore, 5 mM of NAC, in vitro, led to an increase in GSH content and sulfhydryl groups in these patients. Conclusion: These data probably indicate that an adjuvant therapy with the antioxidant NAC could improve the oxidative imbalance in X-ALD patients(AU)

Tumor necrosis factor-alpha [TNF-alpha] in glutathione[GSH]-depleted rats. a possible link to impaired glucose metabolism

reated with the glutathione depleting agent, allyl alcohol [A1A1] [1 mmol/kg] was found to induce a marked increase in serum TNF-alpha 45 minutes post treatment. This increase is suggested to play a critical role in the development of impaired glucose metabolism and glucose intolerance in A1A1-treated rats. Impaired glucose metabolism was evidenced by the significant increase in serum creatinine, urea and blood urea nitrogen accounting for accelerated glycolysis and breakdown of creatinine phosphate. These are the metabolic consequences of the activation of a back up system for the generation of ATP when the primary energy forming pathway is impaired. Meanwhile, the present data show a significant decrease in the serum levels of triglycerides and cholesterol in A1A1-treated rats that was accompanied with a concomitant increase in their liver levels indicating the development of fatty livers in these rats. Due to the strong link between TNF-alpha and the GSH status and to the well established role of TNF-alpha: in causing insulin resistance, which is potentiated by fat accumulation in different tissues, it is concluded that the combination of TNF-alpha overproduction, GSH depletion and lipid accumulation in the liver caused by A1A1 treatment, cooperate making cells more sensitive to A1A1 poisoning, therefore, imposing a potent negative impact on glucose metabolism. Added to the deleterious effects of TNF-alpha, enhanced lipid peroxidation observed in A1A1- treated rats suggests possible alterations in the rates of glucose transport and metabolism which may further contribute to AlAl-induced impairment in glucose metabolism. Finally, the selective effect of TNF-alpha in inhibiting insulin secretion give an additional support to its hypothesized role in initiating glucose intolerance in GSH-depleted rat

N-acetylcysteine potentially affects hepatic glutathione synthesis only under conditions of enhanced oxidative stress

N-acetylcysteine [NAC] has been widely investigated as a potentially useful protective and antioxidant agent in many pathological states. The present work was undertaken to further investigate the mechanisms of its protective effect in rats subjected to acute carbon tetrachloride [CCI4]-induced liver injury regarding its potential impact on hepatic glutathione stores. Four groups of rats have been employed; normal control, NAC-treated [40 mg/kg, i.p.], CCI4-intoxicated [0.5 ml/kg, i.p.] and NAC pretreated + CCI4-intoxicated group. Exposure to CCI4depleted reduced glutathione content and enhanced lipid peroxidation in liver tissue. However, total hepatic glutathione content was unchanged. This oxidative injury was accompanied by pronounced hepatolysis observed as an increase in serum alanine transaminase [ALT] and aspartate transaminase [AST] activities as well as total bilirubin level. Pretreatment with NAC reduced oxidative damage of liver cells as observed by decreased membrane lipid peroxidation and increased reduced glutathione content in both normal and CCI4-intoxicated groups. However, total glutathione content was only elevated in the CCI4-intoxicated group and was accompanied by a significant decrease of the elevated serum ALT and AST activities as well as bilirubin level. Thus, beside its potential direct radical-scavenging properties and reduced glutathione-sparing effect, parenterally administered NAC can replenish glutathione stores, an action that is observed only under conditions of oxidative stress

Alpha lipoic acid protects against acute hepatocellular damage induced by carbon tetrachloride in vitro: comparison with N-acetylcysteine

Alpha lipoic acid [ALA] has been widely investigated as a potentially useful protective and antioxidant agent in various pathological states. Oxidative stress is one of the mechanisms involved in acute carbon tetrachloride [CCI4]-induced hepatotoxicity. In previous in vivo work, ALA has shown a potentially protective effect in acute CCI4-induced hepatotoxicity. The current work was designed to investigate whether this effect could be also manifested in vitro using isolated rat hepatocytes in suspension. This was carried out in comparison with one of the standard hepatoprotective agents viz., N-acetylcysteine [NAC]. Suspended hepatocytes were preincubated with either ALA or NAC for 30 min before being exposed to the hepatotoxin for n further 30 min. The hepatotoxicity was assessed by estimating the leakage of lactate dehydrogenase [LDH], the enhanced formation of lipid peroxides and the depletion of intracellular reduced glutathione [GSH]. ALA showed a protective effect against the induced hepatocellular injury almost identical to NAC, as was evidenced by its inhibitory influence on LDH leakage, the enhanced lipid peroxide production, and depletion of GSH. These data show that the hepatoprotective effect of ALA is effective as NAC in vitro and seems to be mediated, at least in part, by its antioxidant properties

Enzimas de la biosíntesis del glutation reducido (GSH): valores normales y estudio de un paciente con dificiencia de GSH / Enzimes of the biosynthesis of reduced glutathione: normal values and study of a patient with GSH deficiency

Se estandarizaron las técnicas de actividad de g -glutamil cisteil sintetasa y glutatión sintetasa con el objetivo de estudiar los pacientes con deficiencia congénita de glutatión reducido. Los valores normales encontrados en nuestro laboratorio no presentaron diferencias significativas con los señalados por otros autores. Se estudiaron varios miembros de una familia con deficiencia de glutatión reducido. Los estudios bioquímicos excluyeron la posible deficiencia de glucosa-6-fosfato deshidrogenasa. En el propósito y un hermano (G.D.R.) se encontró deficiencia de glutatión sintetasa. Ambos presentan una anemia hemolítica congénita no esferocítica, con hemólisis crónica e íctero que se exacerba en el transcurso de procesos infecciosos y también litiasis vesicular. Ninguno presentó acidosis metabólica ni trastornos neurológicos progresivos, por lo que ambos son portadores de la forma benigna de la enfermedad. En el padre y otro hermano, los resultados del estudio hematológico y bioquímico indican que posiblemente son heterocigóticos para la deficiencia de esta enzima. Esta es la primera familia con deficiencia de glutatión sintetasa encontrada en nuestra población

Curso: Tópicos de Medicina Interna: Aula 1: Glutationa: o antioxidante: síntese, metabolismo e degradação / Course: Internal Medicine Topics: Class 1: Glutathione: the antioxidant: synthesis, metabolism and degradation

Existem várias evidências de que a glutationa reduzida (GSH)atua na destruição de intermediários reativos de oxigênio e de outros radicais livres que são constantemente formados sob condições normais ou após administração de certas drogas, raios X e oxigênio. O nível celular da GSH é regulado por processos que compreendem o sistema de captação de aminoácidos através da membrana, o grupo de enzimas intracelulares envolvidas na síntese e regulação por feedback e o processo de exportação do tripeptídeo. A regulação da GSH intracelular pode ocorrer pela glutationa oxidada (GSSG) indesejável. São de grande interesse terapêutico os estudos com agentes que, de alguma forma, aumentam ou diminuem o nível da GSH. Em geral, o aumento da GSH é prejudicial ao tratamento químio ou radioterápico do câncer e o tratamento com butionina sulfoximina (BSO), promovendo o decréscimo do nível celular da GSH, pode aumentar a sensibilidade tumoral a drogas anti-câncer e à radioterapia. Por outro lado, os estudos com agentes que aumentam o nível de GSH podem contribuir para o aumento da proteção contra o estresse oxidativo.

El HIV y el estres oxidativo / The HIV and the oxidative stress

Debido a la alarmante progresión del SIDA en todo el planeta, el virus que lo causa -HIV human immuno-deficiency virus- ha sido, hasta el presente, el más estudiado en la historia de la medicina, con lo cual puede decirse que existe un extenso conocimiento respecto de su estructura y reproducción. Mediante el microscopio electrónico de alta resolución, se determinó que el HIV posee una constitución casi esférica, y que su corteza externa, o cápsula, es semejante a la de cualquier membrana celular, vale decir que está constituida por una doble capa lipídica regularmente atravesada por moléculas proteicas que constituyen el sistema de histocompatibilidad. Otras moléculas de naturaleza virósica formadas por glucoproteínas, se proyectan fuera de la cápsula en forma de espículas y se denomina g120, la porción externa y gp41, la que se halla sumergida en la membrana. Debajo de la membrana existe una capa de matriz proteica llamada p17 que, a su vez, rodea el núcleo del virus. Este último es una proteína (p24), que dispuesta en forma de cono truncado, envuelve el material genético del HIV formado por dos cadenas de RNA de 9200 nucleótidos. La presencia del RNA (ácido ribonucleico) en lugar de DNA (ácido desoxiribonucleico), le confiere el carácter de retrovirus. Unido al RNA se encuentran numerosas enzimas denominadas transcriptasa reversa, proteasa y ribonucleasa (Fig. 1)