Oxidative stress in the latissimus dorsi muscle of diabetic rats

The purpose of the present study was to investigate the effects of experimental diabetes on the oxidant and antioxidant status of latissimus dorsi (LD) muscles of male Wistar rats (220 ± 5 g, N = 11). Short-term (5 days) diabetes was induced by a single injection of streptozotocin (STZ, 50 mg/kg, iv; glycemia >300 mg/dl). LD muscle of STZ-diabetic rats presented higher levels of thiobarbituric acid reactive substances (TBARS) and chemiluminescence (0.36 ± 0.02 nmol/mg protein and 14706 ± 1581 cps/mg protein) than LD muscle of normal rats (0.23 ± 0.04 nmol/mg protein and 7389 ± 1355 cps/mg protein). Diabetes induced a 92% increase in catalase and a 27% increase in glutathione S-transferase activities in LD muscle. Glutathione peroxidase activity was reduced (58%) in STZ-diabetic rats and superoxide dismutase activity was similar in LD muscle of both groups. A positive correlation was obtained between catalase activity and the oxidative stress of LD, as evaluated in terms of TBARS (r = 0.78) and by chemiluminescence (r = 0.89). Catalase activity also correlated inversely with glutathione peroxidase activity (r = 0.79). These data suggest that an increased oxidative stress in LD muscle of diabetic rats may be related to skeletal muscle myopathy.

Redox dysregulation and oxidative stress in schizophrenia: genetic and functional anomalies of glutathione synthesis in patients and experimental models involving GABA interneurons and NMDA receptors

Objective: Converging evidence speak in favor of an abnormal susceptibility to oxidative stress in schizophrenia. A decreased level of glutathione (GSH), the principal non-protein antioxidant and redox regulator, was observed both in cerebrospinal-fluid and prefrontal cortex of schizophrenia patients (Do et al., 2000). Results: Schizophrenia patients have an abnormal GSH synthesis most likely of genetic origin: Two independent case-control studies showed a significant association between schizophrenia and a GAG trinucleotide repeat (TNR) polymorphism in the GSH key synthesizing enzyme glutamate-cysteine-ligase (GCL) catalytic subunit (GCLC) gene. The most common TNR genotype 7/7 was more frequent in controls, whereas the rarest TNR genotype 8/8 was three times more frequent in patients. The disease-associated genotypes correlated with a decrease in GCLC protein expression, GCL activity and GSH content. Such a redox dysregulation during development could underlie the structural and functional anomalies in connectivity: In experimental models, GSH deficit induced anomalies similar to those observed in patients. (a) morphology: In animal models with GSH deficit during the development we observed in prefrontal cortex a decreased dendritic spines density in pyramidal cells and an abnormal development of parvalbumine (but not of calretinine) immunoreactive GABA interneurones in anterior cingulate cortex. (b) physiology: GSH depletion in hippocampal slices induces NMDA receptors hypofunction and an impairment of long term potentiation. In addition, GSH deficit affected the modulation of dopamine on NMDA-induced Ca 2+ response in cultured cortical neurons. While dopamine enhanced NMDA responses in control neurons, it depressed NMDA responses in GSH-depleted neurons. Antagonist of D2-, but not D1-receptors, prevented this depression, a mechanism contributing to the efficacy of antipsychotics. The redox sensitive ryanodine receptors and L-type calcium channels underlie these observations. (c) cognition: Developing rats with low [GSH] and high dopamine lead deficit in olfactory integration and in object recognition which appears earlier in males that females, in analogy to the delay of the psychosis onset between man and woman. Conclusion: These clinical and experimental evidence, combined with the favorable outcome of a clinical trial with N-Acetyl Cysteine, a GSH precursor, on both the negative symptoms (Berk et al., submitted) and the mismatch negativity in an auditory oddball paradigm supported the proposal that a GSH synthesis impairment of genetic origin represent, among other factors, one major risk factor in schizophrenia.

Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene.

Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCLM) subunit, is strongly associated with schizophrenia in two case-control studies and in one family study. GCLM gene expression is decreased in patients' fibroblasts. Thus, GSH metabolism dysfunction is proposed as one of the vulnerability factors for schizophrenia.

Oxidative stress biomarkers and aggressive behavior in fish exposed to aquatic cadmium contamination

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Behavior and viability of spontaneous oxidative stress-resistant Lactococcus lactis mutants in experimental fermented milk processing

Previously, we isolated two strains of spontaneous oxidative (SpOx2 and SpOx3) stress mutants of Lactococcus lactis subsp cremoris. Herein, we compared these mutants to a parental wild- type strain (J60011) and a commercial starter in experimental fermented milk production. Total solid contents of milk and fermentation temperature both affected the acidification profile of the spontaneous oxidative stress- resistant L. lactis mutants during fermented milk production. Fermentation times to pH 4.7 ranged from 6.40 h (J60011) to 9.36 h (SpOx2); V(max) values were inversely proportional to fermentation time. Bacterial counts increased to above 8.50 log(10) cfu/mL. The counts of viable SpOx3 mutants were higher than those of the parental wild strain in all treatments. All fermented milk products showed post-fermentation acidification after 24 h of storage at 4 degrees C; they remained stable after one week of storage.

Protective effect of Calendula officinalis extract against UVB-induced oxidative stress in skin: Evaluation of reduced glutathione levels and matrix metalloproteinase secretion

Background and purpose: Calendula officinalis flowers have long been employed time in folk therapy, and more than 35 properties have been attributed to decoctions and tinctures from the flowers. The main uses are as remedies for burns (including sunburns), bruises and cutaneous and internal inflammatory diseases of several origins. The recommended doses are a function both of the type and severity of the condition to be treated and the individual condition of each patient. Therefore, the present study investigated the potential use of Calendula officinalis extract to prevent UV irradiation-induced oxidative stress in skin. Methods: Firstly, the physico-chemical composition of marigold extract(ME) (hydroalcoholic extract)was assessed and the in vitro antioxidant efficacy was determined using different methodologies. Secondly, the cytotoxicity was evaluated in L929 and HepG2 cells with the MTT assay. Finally, the in vivo protective effect of ME against UVB-induced oxidative stress in the skin of hairless mice was evaluated by determining reduced glutathione (GSH) levels and monitoring the secretion/activity of metalloproteinases. Results and conclusions: The polyphenol, flavonoid, rutin and narcissin contents found in ME were 28.6 mg/g, 18.8 mg/g, 1.6 mg/g and 12.2 mg/g, respectively and evaluation of the in vitro antioxidant activity demonstrated a dose-dependent effect of ME against different radicals. Cytoxicity experiments demonstrated that ME was not cytotoxic for L929 and HepG2 cells at concentrations less than or equal to of 15 mg/mL However, concentrations greater than or equal to 30 mg/mL, toxic effects were observed. Finally, oral treatment of hairless mice with 150 and 300 mg/kg of ME maintained GSH levels close to non-irradiated control mice. In addition, this extract affects the activity/secretion of matrix metalloproteinases 2 and 9 (MMP-2 and -9) stimulated by exposure to UVB irradiation. However, additional studies are required to have a complete understanding of the protective effects of ME for skin. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Glutathione levels in and total antioxidant capacity of Candida sp. cells exposed to oxidative stress caused by hydrogen peroxide

INTRODUCTION: The capacity to overcome the oxidative stress imposed by phagocytes seems to be critical for Candida species to cause invasive candidiasis. METHODS: To better characterize the oxidative stress response (OSR) of 8 clinically relevant Candida sp., glutathione, a vital component of the intracellular redox balance, was measured using the 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB)-glutathione disulfide (GSSG) reductase reconversion method; the total antioxidant capacity (TAC) was measured using a modified method based on the decolorization of the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic) acid radical cation (ABTS*+). Both methods were used with cellular Candida sp. extracts treated or not with hydrogen peroxide (0.5 mM). RESULTS: Oxidative stress induced by hydrogen peroxide clearly reduced intracellular glutathione levels. This depletion was stronger in Candida albicans and the levels of glutathione in untreated cells were also higher in this species. The TAC demonstrated intra-specific variation. CONCLUSIONS: Glutathione levels did not correlate with the measured TAC values, despite this being the most important non-enzymatic intracellular antioxidant molecule. The results indicate that the isolated measurement of TAC does not give a clear picture of the ability of a given Candida sp. to respond to oxidative stress.

Early-Life Insults Impair Parvalbumin Interneurons via Oxidative Stress: Reversal by N-Acetylcysteine.

BACKGROUND: A hallmark of the pathophysiology of schizophrenia is a dysfunction of parvalbumin-expressing fast-spiking interneurons, which are essential for the coordination of neuronal synchrony during sensory and cognitive processing. Oxidative stress as observed in schizophrenia affects parvalbumin interneurons. However, it is unknown whether the deleterious effect of oxidative stress is particularly prevalent during specific developmental time windows. METHODS: We used mice with impaired synthesis of glutathione (Gclm knockout [KO] mice) to investigate the effect of redox dysregulation and additional insults applied at various periods of postnatal development on maturation and long-term integrity of parvalbumin interneurons in the anterior cingulate cortex. RESULTS: A redox dysregulation, as in Gclm KO mice, renders parvalbumin interneurons but not calbindin or calretinin interneurons vulnerable and prone to exhibit oxidative stress. A glutathione deficit delays maturation of parvalbumin interneurons, including their perineuronal net. Moreover, an additional oxidative challenge in preweaning or pubertal but not in young adult Gclm KO mice reduces the number of parvalbumin-immunoreactive interneurons. This effect persists into adulthood and can be prevented with the antioxidant N-acetylcysteine. CONCLUSIONS: In Gclm KO mice, early-life insults inducing oxidative stress are detrimental to immature parvalbumin interneurons and have long-term consequences. In analogy, individuals carrying genetic risks to redox dysregulation would be potentially vulnerable to early-life environmental insults, during the maturation of parvalbumin interneurons. Our data support the need to develop novel therapeutic approaches based on antioxidant and redox regulator compounds such as N-acetylcysteine, which could be used preventively in young at-risk subjects.

Targeting Oxidative Stress and Aberrant Critical Period Plasticity in the Developmental Trajectory to Schizophrenia.

Schizophrenia is a neurodevelopmental disorder reflecting a convergence of genetic risk and early life stress. The slow progression to first psychotic episode represents both a window of vulnerability as well as opportunity for therapeutic intervention. Here, we consider recent neurobiological insight into the cellular and molecular components of developmental critical periods and their vulnerability to redox dysregulation. In particular, the consistent loss of parvalbumin-positive interneuron (PVI) function and their surrounding perineuronal nets (PNNs) as well as myelination in patient brains is consistent with a delayed or extended period of circuit instability. This linkage to critical period triggers (PVI) and brakes (PNN, myelin) implicates mistimed trajectories of brain development in mental illness. Strategically introduced antioxidant treatment or later reinforcement of molecular brakes may then offer a novel prophylactic psychiatry.

Relationship between oxidative stress, glutathione S-transferase polymorphisms and hydroxyurea treatment in sickle cell anemia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)