Influence of dietary bitter orange peel powder on growth, body composition, blood parameters, gut morphometry, and thermal tolerance of Nile tilapia (Oreochromis niloticus).

The potential of bitter orange peel powder (BOPP) as a nutritional strategy for fish was investigated in Nile tilapia. A total of 120 juveniles with an average initial weight of 9.8 ± 0.7 g were divided into four groups, replicated three times, resulting in 12 experimental units (60 L each) at a stocking density of 1.63 g of fish per liter. Productive parameters, whole-body composition, blood biochemistry, erythroid morphometry, intestinal histology, and heat tolerance were assessed in the juveniles subjected to one of the following treatments: non-supplemented basal diet (control group); basal diet with BOPP at 10 g/kg (BOPP10 group); basal diet with BOPP at 20 g/kg (BOPP20 group); and basal diet with BOPP at 40 g/kg (BOPP40 group). The BOPP additive had a positive influence on Nile tilapia growth, as final weight and weight gain were greater in all BOPP-treated fish, despite the reduction in crude protein in BOPP10 and BOPP20 groups. Fish receiving BOPP40 had an increase in total lipids and showed the highest levels of triglycerides and total cholesterol. Villi development was greater in the tilapia given BOPP10. It may be concluded that BOPP presented the most promising results for Nile tilapia juveniles when used at 10 g/kg diet. Regarding the erythroid morphometry, there was a general increase in nuclear and cytoplasmic areas in BOPP-fed tilapia; this seems to be the first report on the direct impact of the inclusion of functional additives in fish diet upon such parameters. As concerns the thermal tolerance evaluated at the end of the feeding trial, no differences were registered among the experimental groups. Thus, BOPP represents a feasible alternative ingredient to be explored in fish nutrition, since orange peel is a natural low-cost source of essential nutrients and valuable bioactive compounds.

TRP14 is the rate-limiting enzyme for intracellular cystine reduction and regulates proteome cysteinylation.

It has remained unknown how cells reduce cystine taken up from the extracellular space, which is a required step for further utilization of cysteine in key processes such as protein or glutathione synthesis. Here, we show that the thioredoxin-related protein of 14 kDa (TRP14, encoded by TXNDC17) is the rate-limiting enzyme for intracellular cystine reduction. When TRP14 is genetically knocked out, cysteine synthesis through the transsulfuration pathway becomes the major source of cysteine in human cells, and knockout of both pathways becomes lethal in C. elegans subjected to proteotoxic stress. TRP14 can also reduce cysteinyl moieties on proteins, rescuing their activities as here shown with cysteinylated peroxiredoxin 2. Txndc17 knockout mice were, surprisingly, protected in an acute pancreatitis model, concomitant with activation of Nrf2-driven antioxidant pathways and upregulation of transsulfuration. We conclude that TRP14 is the evolutionarily conserved enzyme principally responsible for intracellular cystine reduction in C. elegans, mice, and humans.

Dietary Supplementation with R-(+)-Limonene Improves Growth, Metabolism, Stress, and Antioxidant Responses of Silver Catfish Uninfected and Infected with Aeromonas hydrophila.

R-(+)-limonene is a monoterpene from plants of the genus Citrus with diverse biological properties. This research evaluated the effects of dietary supplementation with R-(+)-limonene on growth, metabolic parameters in plasma and liver, and the antioxidant and stress responses in silver catfish, Rhamdia quelen, challenged or not with Aeromonas hydrophila. Fish were fed for 67 days with different doses of R-(+)-limonene in the diet (control 0.0, L0.5, L1.0, and L2.0 mL/kg of diet). On the 60th day, a challenge with A. hydrophila was performed. R-(+)-limonene in the diet potentiated the productive performance of the fish. The metabolic and antioxidant responses indicate that R-(+)-limonene did not harm the health of the animals and made them more resistant to the bacterial challenge. Histological findings showed the hepatoprotective effect of dietary R-(+)-limonene against A. hydrophila. Igf1 mRNA levels were upregulated in the liver of fish fed with an L2.0 diet but downregulated with bacterial challenge. The expression levels of crh mRNA were higher in the brains of fish fed with the L2.0 diet. However, the L2.0 diet downregulated crh and hspa12a mRNA expression in the brains of infected fish. In conclusion, the results indicated that R-(+)-limonene can be considered a good dietary supplement for silver catfish.

Long-Term Aspartame Administration Leads to Fibrosis, Inflammasome Activation, and Gluconeogenesis Impairment in the Liver of Mice.

BACKGROUND: Aspartame is an artificial sweetener used in foods and beverages worldwide. However, it is linked to oxidative stress, inflammation, and liver damage through mechanisms that are not fully elucidated yet. This work aimed to investigate the effects of long-term administration of aspartame on the oxidative and inflammatory mechanisms associated with liver fibrosis progression in mice. METHODS: Mice were divided into two groups with six animals each: control and aspartame. Aspartame (80 mg/kg, via oral) or vehicle was administrated for 12 weeks. RESULTS: Aspartame caused liver damage and elevated serum transaminase levels. Aspartame also generated liver fibrosis, as evidenced by histology analysis, and pro-fibrotic markers' upregulation, including transforming growth factor ß 1, collagen type I alpha 1, and alpha-smooth muscle actin. Furthermore, aspartame reduced nuclear factor erythroid 2-related factor 2 (Nrf2) activation and enzymatic antioxidant activity and increased lipid peroxidation, which triggered NOD-like receptor containing protein 3 (NLRP3) inflammasome activation and p53 induction. Furthermore, aspartame reduced peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) levels, possibly through p53 activation. This PGC-1α deficiency could be responsible for the changes in lipid profile in serum, total lipid accumulation, and gluconeogenesis impairment in liver, evidenced by the gluconeogenic enzymes' downregulation, thus causing hypoglycemia. CONCLUSIONS: This work provides new insights to understand the mechanisms related to the adverse effects of aspartame on liver tissue.

Rutin-added diet protects silver catfish liver against oxytetracycline-induced oxidative stress and apoptosis.

It is unknown whether the flavonoid rutin can protect the silver catfish liver in response to exposure to a known stressor, such as the prophylactic usage of the antimicrobial agent oxytetracycline. Thus, the current study aimed to assess the effect of rutin incorporation into the silver catfish diet formulation on oxytetracycline-induced liver oxidative stress and apoptosis. Fish were split into four groups as follows: control, rutin (1.5 g kg diet-1), oxytetracycline (0.1 g kg diet-1) and rutin+oxytetracycline (1.5 g kg diet-1 and 0.1 g kg diet-1, respectively). After two weeks of feeding with the different diets (standard, rutin-, oxytetracycline and rutin+oxytetracycline-added diets), fish were euthanized to collect the liver. Although the rutin-added diet was unable to recover glutathione peroxidase activity, ascorbic acid and reduced glutathione (GSH) levels, which were depleted due to oxytetracycline consumption, it markedly diminished the oxidized glutathione (GSSG) content, thus decreasing the GSSG to GSH ratio, an important index of oxidative stress. It also increased glutathione reductase and markedly augmented glucose-6-phosphate dehydrogenase activities, which were declined after oxytetracycline ingestion. Furthermore, the rutin-added diet reestablished superoxide dismutase and catalase activities and reduced lipid peroxidation, nitric oxide and superoxide anion levels as well, all changes resulting from oxytetracycline consumption. Finally, it also prevented oxytetracycline-induced apoptosis through increasing heat shock protein 70 and markedly decreasing high mobility group box 1 and, consequently, reducing cleaved caspase-3 protein levels. Therefore, in conclusion, the incorporation of this flavonoid to the silver catfish diet protected the liver against oxytetracycline-induced liver oxidative stress and apoptosis.

Dietary addition of rutin impairs inflammatory response and protects muscle of silver catfish (Rhamdia quelen) from apoptosis and oxidative stress in Aeromonas hydrophila-induced infection.

This research aimed to assess the influence of dietary addition of rutin on inflammation, apoptosis and antioxidative responses in muscle of silver catfish (Rhamdia quelen) challenged with Aeromonas hydrophila (A. hydrophila). Fish were split into four groups as follows: control, 0.15% rutin, A. hydrophila, 0.15% rutin + A. hydrophila. After 2 weeks of feeding with standard or rutin diets, fish were challenged or not with A. hydrophila for 1 week. Rutin-added diet abrogates A. hydrophila induced-hemorrhage and inflammatory infiltration. It decreases A. hydrophila induced-apoptosis through decreasing the ratio of Bax to Bcl-2 and increasing phospho-Akt to Akt ratio. It diminishes the A. hydrophila induced-rise in nitric oxide and superoxide anion levels and reestablishes superoxide dismutase activity as well. Although such diet is unable to recover the levels of reduced glutathione (GSH), cysteine and glutamate cysteine ligase, which are depleted as a result of A. hydrophila infection, it diminishes the oxidized glutathione (GSSG) content, thus decreasing GSSG to GSH ratio. It increases the levels of cysteine residues of proteins and diminishes those of thiol-protein mixed disulfides, which were changed after A. hydrophila challenge. Finally, it reduces A. hydrophila induced-lipid peroxidation, markedly elevates ascorbic acid and thus reestablishes total antioxidant capacity, whose levels were decreased after A. hydrophila challenge. In conclusion, the dietary addition of rutin at 0.15% impairs A. hydrophila-induced inflammatory response, inhibits A. hydrophila-induced apoptosis and promotes cell survival. It also reduces the A. hydrophila-induced oxidative stress and stimulates the antioxidative responses in muscle of A. hydrophila-infected silver catfish.

p38α deficiency restrains liver regeneration after partial hepatectomy triggering oxidative stress and liver injury.

p38α MAPK negatively regulates the G1/S and G2/M cell cycle transitions. However, liver-specific p38α deficiency impairs cytokinesis and reduces hepatocyte proliferation during cirrhosis and aging in mice. In this work, we have studied how p38α down-regulation affects hepatocyte proliferation after partial hepatectomy, focusing on mitotic progression, cytokinesis and oxidative stress. We found that p38α deficiency triggered up-regulation of cyclins A1, B1, B2, and D1 under basal conditions and after hepatectomy. Moreover, p38α-deficient hepatocytes showed enhanced binucleation and increased levels of phospho-histone H3 but impaired phosphorylation of MNK1 after hepatectomy. The recovery of liver mass was transiently delayed in mice with p38α-deficient hepatocytes vs wild type mice. We also found that p38α deficiency caused glutathione oxidation in the liver, increased plasma aminotransferases and lactate dehydrogenase activities, and decreased plasma protein levels after hepatectomy. Interestingly, p38α silencing in isolated hepatocytes markedly decreased phospho-MNK1 levels, and silencing of either p38α or Mnk1 enhanced binucleation of hepatocytes in culture. In conclusion, p38α deficiency impairs mitotic progression in hepatocytes and restrains the recovery of liver mass after partial hepatectomy. Our results also indicate that p38α regulates cytokinesis by activating MNK1 and redox modulation.

Role of obesity in the release of extracellular nucleosomes in acute pancreatitis: a clinical and experimental study.

BACKGROUND/OBJECTIVES: A high body mass index increases the risk of severe pancreatitis and associated mortality. Our aims were: (1) To determine whether obesity affects the release of extracellular nucleosomes in patients with pancreatitis; (2) To determine whether pancreatic ascites confers lipotoxicity and triggers the release of extracellular nucleosomes in lean and obese rats. METHODS: DNA and nucleosomes were determined in plasma from patients with mild or moderately severe acute pancreatitis either with normal or high body mass index (BMI). Lipids from pancreatic ascites from lean and obese rats were analyzed and the associated toxicity measured in vitro in RAW 264.7 macrophages. The inflammatory response, extracellular DNA and nucleosomes were determined in lean or obese rats with pancreatitis after peritoneal lavage. RESULTS: Nucleosome levels in plasma from obese patients with mild pancreatitis were higher than in normal BMI patients; these levels markedly increased in obese patients with moderately severe pancreatitis vs. those with normal BMI. Ascites from obese rats exhibited high levels of palmitic, oleic, stearic, and arachidonic acids. Necrosis and histone 4 citrullination-marker of extracellular traps-increased in macrophages incubated with ascites from obese rats but not with ascites from lean rats. Peritoneal lavage abrogated the increase in DNA and nucleosomes in plasma from lean or obese rats with pancreatitis. It prevented fat necrosis and induction of HIF-related genes in lung. CONCLUSIONS: Extracellular nucleosomes are intensely released in obese patients with acute pancreatitis. Pancreatitis-associated ascitic fluid triggers the release of extracellular nucleosomes in rats with severe pancreatitis.

Obesity causes PGC-1α deficiency in the pancreas leading to marked IL-6 upregulation via NF-κB in acute pancreatitis.

Obesity is associated with local and systemic complications in acute pancreatitis. PPARγ coactivator 1α (PGC-1α) is a transcriptional coactivator and master regulator of mitochondrial biogenesis that exhibits dysregulation in obese subjects. Our aims were: (1) to study PGC-1α levels in pancreas from lean or obese rats and mice with acute pancreatitis; and (2) to determine the role of PGC-1α in the inflammatory response during acute pancreatitis elucidating the signaling pathways regulated by PGC-1α. Lean and obese Zucker rats and lean and obese C57BL6 mice were used first; subsequently, wild-type and PGC-1α knockout (KO) mice with cerulein-induced pancreatitis were used to assess the inflammatory response and expression of target genes. Ppargc1a mRNA and protein levels were markedly downregulated in pancreas of obese rats and mice versus lean animals. PGC-1α protein levels increased in pancreas of lean mice with acute pancreatitis, but not in obese mice with pancreatitis. Interleukin-6 (Il6) mRNA levels were dramatically upregulated in pancreas of PGC-1α KO mice after cerulein-induced pancreatitis in comparison with wild-type mice with pancreatitis. Edema and the inflammatory infiltrate were more intense in pancreas from PGC-1α KO mice than in wild-type mice. The lack of PGC-1α markedly enhanced nuclear translocation of phospho-p65 and recruitment of p65 to Il6 promoter. PGC-1α bound phospho-p65 in pancreas during pancreatitis in wild-type mice. Glutathione depletion in cerulein-induced pancreatitis was more severe in KO mice than in wild-type mice. PGC-1α KO mice with pancreatitis, but not wild-type mice, exhibited increased myeloperoxidase activity in the lungs, together with alveolar wall thickening and collapse, which were abrogated by blockade of the IL-6 receptor glycoprotein 130 with LMT-28. In conclusion, obese rodents exhibit PGC-1α deficiency in the pancreas. PGC-1α acts as selective repressor of nuclear factor-κB (NF-κB) towards IL-6 in pancreas. PGC-1α deficiency markedly enhanced NF-κB-mediated upregulation of Il6 in pancreas in pancreatitis, leading to a severe inflammatory response. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Age-dependent regulation of antioxidant genes by p38α MAPK in the liver.

p38α is a redox sensitive MAPK activated by pro-inflammatory cytokines and environmental, genotoxic and endoplasmic reticulum stresses. The aim of this work was to assess whether p38α controls the antioxidant defense in the liver, and if so, to elucidate the mechanism(s) involved and the age-related changes. For this purpose, we used liver-specific p38α-deficient mice at two different ages: young-mice (4 months-old) and old-mice (24 months-old). The liver of young p38α knock-out mice exhibited a decrease in GSH levels and an increase in GSSG/GSH ratio and malondialdehyde levels. However, old mice deficient in p38α had higher hepatic GSH levels and lower GSSG/GSH ratio than young p38α knock-out mice. Liver-specific p38α deficiency triggered a dramatic down-regulation of the mRNAs of the key antioxidant enzymes glutamate cysteine ligase, superoxide dismutase 1, superoxide dismutase 2, and catalase in young mice, which seems mediated by the lack of p65 recruitment to their promoters. Nrf-2 nuclear levels did not change significantly in the liver of young mice upon p38α deficiency, but nuclear levels of phospho-p65 and PGC-1α decreased in these mice. p38α-dependent activation of NF-κB seems to occur through classical IκB Kinase and via ribosomal S6 kinase1 and AKT in young mice. However, unexpectedly the long-term deficiency in p38α triggers a compensatory up-regulation of antioxidant enzymes via NF-κB activation and recruitment of p65 to their promoters. In conclusion, p38α MAPK maintains the expression of antioxidant genes in liver of young animals via NF-κΒ under basal conditions, whereas its long-term deficiency triggers compensatory up-regulation of antioxidant enzymes through NF-κΒ.

Chronic aspartame intake causes changes in the trans-sulphuration pathway, glutathione depletion and liver damage in mice.

No-caloric sweeteners, such as aspartame, are widely used in various food and beverages to prevent the increasing rates of obesity and diabetes mellitus, acting as tools in helping control caloric intake. Aspartame is metabolized to phenylalanine, aspartic acid, and methanol. Our aim was to study the effect of chronic administration of aspartame on glutathione redox status and on the trans-sulphuration pathway in mouse liver. Mice were divided into three groups: control; treated daily with aspartame for 90 days; and treated with aspartame plus N-acetylcysteine (NAC). Chronic administration of aspartame increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase activities and caused liver injury as well as marked decreased hepatic levels of reduced glutathione (GSH), oxidized glutathione (GSSG), γ-glutamylcysteine ​​(γ-GC), and most metabolites of the trans-sulphuration pathway, such as cysteine, S-adenosylmethionine (SAM), and S-adenosylhomocysteine ​​(SAH). Aspartame also triggered a decrease in mRNA and protein levels of the catalytic subunit of glutamate cysteine ligase (GCLc) and cystathionine γ-lyase, and in protein levels of methionine adenosyltransferase 1A and 2A. N-acetylcysteine prevented the aspartame-induced liver injury and the increase in plasma ALT activity as well as the decrease in GSH, γ-GC, cysteine, SAM and SAH levels and GCLc protein levels. In conclusion, chronic administration of aspartame caused marked hepatic GSH depletion, which should be ascribed to GCLc down-regulation and decreased cysteine levels. Aspartame triggered blockade of the trans-sulphuration pathway at two steps, cystathionine γ-lyase and methionine adenosyltransferases. NAC restored glutathione levels as well as the impairment of the trans-sulphuration pathway.

Redox signaling in the gastrointestinal tract.

Redox signaling regulates physiological self-renewal, proliferation, migration and differentiation in gastrointestinal epithelium by modulating Wnt/ß-catenin and Notch signaling pathways mainly through NADPH oxidases (NOXs). In the intestine, intracellular and extracellular thiol redox status modulates the proliferative potential of epithelial cells. Furthermore, commensal bacteria contribute to intestine epithelial homeostasis through NOX1- and dual oxidase 2-derived reactive oxygen species (ROS). The loss of redox homeostasis is involved in the pathogenesis and development of a wide diversity of gastrointestinal disorders, such as Barrett's esophagus, esophageal adenocarcinoma, peptic ulcer, gastric cancer, ischemic intestinal injury, celiac disease, inflammatory bowel disease and colorectal cancer. The overproduction of superoxide anion together with inactivation of superoxide dismutase are involved in the pathogenesis of Barrett's esophagus and its transformation to adenocarcinoma. In Helicobacter pylori-induced peptic ulcer, oxidative stress derived from the leukocyte infiltrate and NOX1 aggravates mucosal damage, especially in HspB+ strains that downregulate Nrf2. In celiac disease, oxidative stress mediates most of the cytotoxic effects induced by gluten peptides and increases transglutaminase levels, whereas nitrosative stress contributes to the impairment of tight junctions. Progression of inflammatory bowel disease relies on the balance between pro-inflammatory redox-sensitive pathways, such as NLRP3 inflammasome and NF-κB, and the adaptive up-regulation of Mn superoxide dismutase and glutathione peroxidase 2. In colorectal cancer, redox signaling exhibits two Janus faces: On the one hand, NOX1 up-regulation and derived hydrogen peroxide enhance Wnt/ß-catenin and Notch proliferating pathways; on the other hand, ROS may disrupt tumor progression through different pro-apoptotic mechanisms. In conclusion, redox signaling plays a critical role in the physiology and pathophysiology of gastrointestinal tract.

Epigenetic Regulation of Early- and Late-Response Genes in Acute Pancreatitis.

Chromatin remodeling seems to regulate the patterns of proinflammatory genes. Our aim was to provide new insights into the epigenetic mechanisms that control transcriptional activation of early- and late-response genes in initiation and development of severe acute pancreatitis as a model of acute inflammation. Chromatin changes were studied by chromatin immunoprecipitation analysis, nucleosome positioning, and determination of histone modifications in promoters of proinflammatory genes in vivo in the course of taurocholate-induced necrotizing pancreatitis in rats and in vitro in rat pancreatic AR42J acinar cells stimulated with taurocholate or TNF-α. Here we show that the upregulation of early and late inflammatory genes rely on histone acetylation associated with recruitment of histone acetyltransferase CBP. Chromatin remodeling of early genes during the inflammatory response in vivo is characterized by a rapid and transient increase in H3K14ac, H3K27ac, and H4K5ac as well as by recruitment of chromatin-remodeling complex containing BRG-1. Chromatin remodeling in late genes is characterized by a late and marked increase in histone methylation, particularly in H3K4. JNK and p38 MAPK drive the recruitment of transcription factors and the subsequent upregulation of early and late inflammatory genes, which is associated with nuclear translocation of the early gene Egr-1 In conclusion, specific and strictly ordered epigenetic markers such as histone acetylation and methylation, as well as recruitment of BRG-1-containing remodeling complex are associated with the upregulation of both early and late proinflammatory genes in acute pancreatitis. Our findings highlight the importance of epigenetic regulatory mechanisms in the control of the inflammatory cascade.

Resveratrol prevents oxidative damage and loss of sperm motility induced by long-term treatment with valproic acid in Wistar rats.

Valproic acid (VPA) is a drug widely use for the treatment of epilepsy in both children and adults. Evidence suggests that long-term use of VPA may lead to an impairment in the male reproductive function. Oxidative stress is considered to play a major role in VPA associated toxicity. In the present work, we demonstrated that the natural antioxidant compound resveratrol (RSV) can be use to prevent VPA oxidative damage. Wistar rats treated with VPA (400mgkg(-1)) by gavage for 28days showed decrease in sperm motility accompanied by increase in oxidative damage to lipids and proteins. Additionally, VPA administration leaded to depletion of reduced glutathione and decrease in total antioxidant potential in testes and epididymides of Wistar rats. The co-administration of RSV (10mgkg(-1)) efficiently prevented VPA pro-oxidant effects. In summary, RSV was shown to protect the reproductive system from the damage induced by VPA. Altogether, our data strongly suggests that RSV administration might be a valuable strategy to minimize reproductive impairment in patients requiring long-term VPA treatment.

Effect of diets enriched with rutin on blood parameters, oxidative biomarkers and pituitary hormone expression in silver catfish (Rhamdia quelen).

The effects of adding rutin to the diet (0, 0.15 or 0.30%) of silver catfish for 21 days on blood parameters, oxidative stress biomarkers and pituitary hormones expression were investigated. Fish that received the diet containing 0.15% rutin exhibited reduced plasma cortisol levels. The levels of lipid peroxidation were lowered in the all tissues of animals receiving the diet containing rutin. Rutin increased the activity of the superoxide dismutase (SOD), catalase (CAT), nonprotein thiols (NPSH), ascorbic acid content (AA) and total reactive antioxidant potential (TRAP) in the brain; glutathione S-transferase (GST) activity and TRAP in the gills; SOD, CAT and GST activity, NPSH, AA levels and TRAP in the liver; CAT and GST activity and TRAP levels in the kidneys; and glutathione peroxidase activity, NPSH, AA levels and TRAP in the muscle. There were no changes regarding the expression of growth hormone, prolactin and somatolactin in fish fed with the diet containing rutin when compared with the control. The supplementation of rutin to the diet of fish is beneficial because it increases the antioxidant responses of tissues.

Disulfide stress and its targets in acute pancreatitis.

Under physiological conditions, the balance between ROS production and removal properly maintains the intracellular redox-sensitive signaling as well as the appropriate status of protein thiols and disulfides. However, inflammation among other factors can modify this balance causing a rapid increase in intracellular ROS levels and hence thiol oxidation, eventually leading to oxidative stress. In the case of acute pancreatitis, both redox signaling and oxidative stress seem to contribute to the progression of the severe form of the disease. In this review we will focus on the reversible oxidation of protein cysteines during the course of acute pancreatitis. We describe disulfide stress in an acute inflammatory process, which is characterized by thiol oxidation in proteins, particularly protein cysteinylation, without significant changes in the glutathione redox status.

The protective effect of N-acetylcysteine on oxidative stress in the brain caused by the long-term intake of aspartame by rats.

Long-term intake of aspartame at the acceptable daily dose causes oxidative stress in rodent brain mainly due to the dysregulation of glutathione (GSH) homeostasis. N-Acetylcysteine provides the cysteine that is required for the production of GSH, being effective in treating disorders associated with oxidative stress. We investigated the effects of N-acetylcysteine treatment (150 mg kg(-1), i.p.) on oxidative stress biomarkers in rat brain after chronic aspartame administration by gavage (40 mg kg(-1)). N-Acetylcysteine led to a reduction in the thiobarbituric acid reactive substances, lipid hydroperoxides, and carbonyl protein levels, which were increased due to aspartame administration. N-Acetylcysteine also resulted in an elevation of superoxide dismutase, glutathione peroxidase, glutathione reductase activities, as well as non-protein thiols, and total reactive antioxidant potential levels, which were decreased after aspartame exposure. However, N-acetylcysteine was unable to reduce serum glucose levels, which were increased as a result of aspartame administration. Furthermore, catalase and glutathione S-transferase, whose activities were reduced due to aspartame treatment, remained decreased even after N-acetylcysteine exposure. In conclusion, N-acetylcysteine treatment may exert a protective effect against the oxidative damage in the brain, which was caused by the long-term consumption of the acceptable daily dose of aspartame by rats.

Effect of N-acetylcysteine on the spinal-cord glutathione system and nitric-oxide metabolites in rats with neuropathic pain.

Since N-acetylcysteine (NAC) is a donor of cysteine, we studied the relationship between NAC and concentration of oxidized and reduced glutathione (GSH/GSSG ratio), and glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities in the lumbosacral spinal cord of rats with chronic constriction injury (CCI) of the sciatic nerve that received NAC (150mg/kg/day, i.p.) or 0.9% saline solution for 3 or 10 days. Hydrogen peroxide (H2O2) and nitric-oxide (NO) metabolites were also measured. Von Frey hair and hot-plate tests showed hyperalgesia at day 1 in CCI rats. Hyperalgesia persisted at all other times in saline-treated CCI rats, but returned to pre-injury values in NAC-treated CCI rats after 3 postoperative days. GST activity and the GSH/GSSG ratio increased in saline-treated CCI rats, while the NAC treatment increased GST and GPx activities at day 10, with no significant change in the GSH/GSSG ratio. NAC treatment did not affect H2O2 levels, but it reduced NO metabolites in CCI rats 3 days after the surgery. Thus, the anti-hyperalgesic effect of NAC appears not to involve its action as a cysteine precursor for GSH synthesis, but involves a decrease in NO.

Humic acid and moderate hypoxia alter oxidative and physiological parameters in different tissues of silver catfish (Rhamdia quelen).

Aquatic animals are naturally exposed simultaneously to environments with different concentrations of humic acid (HA) and seasonal or daily variations of dissolved oxygen (DO) levels. This study investigated the effects of simultaneous exposure to different HA and DO levels on plasma ion levels and some hematological and oxidative parameters in different tissues of silver catfish (Rhamdia quelen). The fish were exposed to 0, 2.5 or 5 mg L(-1) HA for 120 h. After this period, each group was divided into two groups: normoxia and hypoxia. Exposure to the different DO levels lasted 96 h, totaling 216 h of experimentation. At the end of the experimental period, blood sampling was performed, and the fish were euthanized prior to the excision of the gills and the brain to evaluate hematological and oxidative parameters. To verify the antioxidant capacity of HA, total phenolic compounds were measured. In general, all tissues of silver catfish exposed simultaneously to hypoxia and different HA concentrations showed a reduction in lipid peroxidation levels, as well as a modulation of the antioxidant system. These effects occurred in an HA concentration-dependent manner. Thus, HA is beneficial to silver catfish exposed to hypoxia. These beneficial effects can be attributed, most likely, to the action of the different HA constituents and functional groups, including phenolic compounds, which have antioxidant properties.

N-acetylcysteine protects the rat kidney against aspartame-induced oxidative stress.

Long-term intake of aspartame at the acceptable daily ingestion dose causes oxidative stress in the rat kidney through the dysregulation of glutathione homeostasis. N-acetylcysteine (NAC) provides the cystein required for the production of GSH, being effective in treating disorders associated with oxidative stress. The aim of this research was to investigate the effects of NAC on the aspartame-induced oxidative stress in the rat kidney. The animals received aspartame by gavage for six weeks (40mg/kg). From the 5th week, NAC (1mmol/kg, via intraperitoneal) was injected for two weeks. Then, they were anaesthetized for blood sample and euthanized for the kidney collection. The blood was centrifuged at 1800g for 15min and the serum was separated for creatinine measurement. The tissue was homogenized in 1.15% KCl buffer and centrifuged at 700g for 10min at 4°C. The supernatant fraction obtained was used to the measurements of oxidative stress biomarkers. The creatinine levels were enhanced in the serum of aspartame-treated rats. NAC caused a reduction in the thiobarbituric acid reactive substances, lipid hydroperoxides, carbonyl protein and hydrogen peroxide levels, which were increased in the kidney of aspartame-treated animals. Additionally, NAC caused an elevation in the glutathione peroxidase and glutathione reductase activities, total glutathione, ascorbic acid, and total reactive antioxidant potential levels, which were decreased in the kidney of aspartame-treated rats. In conclusion, NAC may be useful for the protection of the rat kidney against aspartame-induced oxidative stress.