Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis.

Supplementation with Citrulline (Cit) has been shown to have a positive impact on aerobic exercise performance and related outcomes such as lactate, oxygen uptake (VO2) kinetics, and the rate of perceived exertion (RPE), probably due to its relationship to endogenous nitric oxide production. However, current research has shown this to be controversial. The main objective of this systematic review and meta-analysis was to analyze and assess the effects of Cit supplementation on aerobic exercise performance and related outcomes, as well as to show the most suitable doses and timing of ingestion. A structured literature search was carried out by the PRISMA® (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and PICOS guidelines in the following databases: Pubmed/Medline, Scopus, and Web of Science (WOS). A total of 10 studies were included in the analysis, all of which exclusively compared the effects of Cit supplementation with those of a placebo group on aerobic performance, lactate, VO2, and the RPE. Those articles that used other supplements and measured other outcomes were excluded. The meta-analysis was carried out using Hedges' g random effects model and pooled standardized mean differences (SMD). The results showed no positive effects of Cit supplementation on aerobic performance (pooled SMD = 0.15; 95% CI (-0.02 to 0.32); I2, 0%; p = 0.08), the RPE (pooled SMD = -0.03; 95% CI (-0.43 to 0.38); I2, 49%; p = 0.9), VO2 kinetics (pooled SMD = 0.01; 95% CI (-0.16 to 0.17); I2, 0%; p = 0.94), and lactate (pooled SMD = 0.25; 95% CI (-0.10 to 0.59); I2, 0%; p = 0.16). In conclusion, Cit supplementation did not prove to have any benefits for aerobic exercise performance and related outcomes. Where chronic protocols seemed to show a positive tendency, more studies in the field are needed to better understand the effects.

Body Composition, Dietary Intake and the Risk of Low Energy Availability in Elite-Level Competitive Rhythmic Gymnasts.

The aim of this study was to analyze dietary intake and body composition in a group of elite-level competitive rhythmic gymnasts from Spain. We undertook body composition and nutritional analysis of 30 elite gymnasts, divided into two groups by age: pre-teen (9-12 years) (n = 17) and teen (13-18 years) (n = 13). Measures of height, weight, and bioimpedance were used to calculate body mass index and percent body fat. Energy and nutrient intakes were assessed based on 7-day food records. The two groups had similar percentages of total body fat (pre-teen: 13.99 ± 3.83% vs. teen: 14.33 ± 5.57%; p > 0.05). The energy availability values for pre-teens were above the recommended values (>40 kcal/FFM/day) 69.38 ± 14.47 kcal/FFM/day, while those for the teens were much lower (34.7 ± 7.5 kcal/FFM/day). The distribution of the daily energy intake across the macronutrients indicates that both groups ingested less than the recommended level of carbohydrates and more than the recommended level of fat. Very low intakes of calcium and vitamin D among other micronutrients were also noted. The main finding is that teenage gymnasts do not consume as much energy as they need each day, which explains their weight and development. Moreover, they are at a high risk of developing low energy availability that could negatively impact their performance and future health.

Fractional Contribution of Wildland Firefighters' Personal Protective Equipment on Physiological Strain.

Activities performed by wildland firefighters are carried out wearing a personal protective equipment (PPE). Although the PPE protects workers from a wide variety of hazards, it may increase their physiological response and limit their performance. The aim of this study was to analyze the effect of the protective clothing (PPC) and the rest of the PPE elements (i.e., helmet, neck shroud, gloves, goggles, and mid-calf leather boots) on the wildland firefighters' thermophysiological response during a moderate-intense exercise. Six male wildland firefighters performed, in a counterbalanced order, a 120 min graded exercise test wearing three different clothing configurations: (i) a traditional short sports gear (SG), (ii) a PPC, and (iii) a complete firefighters' PPE. Trials were conducted on separate days at the same time of the day (12:00-15:00 h) and under climate-controlled conditions (∼30°C and ∼30% relative humidity). Heart rate, respiratory gas exchange, gastrointestinal and skin temperature, blood lactate concentration were recorded throughout the tests. Additionally, parameters of heat balance were estimated. Exercise time was shorter (p < 0.001) wearing the PPE (62.4 ± 13.3 min) than with the PPC (115.5 ± 5.0 min) and SG (118.2 ± 20.7 min). The increment of gastrointestinal temperature with the PPE (1.8 ± 0.3°C) was greater (p < 0.05) than the observed in PPC (1.2 ± 0.6°C) and SG (1.0 ± 0.2°C). The use of PPC increased (p < 0.05) subjects' metabolic demand and skin temperature versus SG during the last 20 min of the test. The sweat retention in the PPE (1,045.7 ± 214.7 g) and PPC (978.3 ± 330.6 g) was significantly higher than that obtained in the SG (510.0 ± 210.0 g). Sweat efficiency decreased (p < 0.05) in the following order: PPE (45.6 ± 18.3%), PPC (64.3 ± 7.8%), and SG (79.3 ± 7.0%). These results highlight the importance of the PPE elements in the subjects' thermal strain. The reduction in the sweat evaporation produced by the PPE, together with the ensemble mass caused a substantial increase in the subjects' thermophysiological response. As a consequence the performance was reduced by ∼50%.

Whole-body vibration improves the anti-inflammatory status in elderly subjects through toll-like receptor 2 and 4 signaling pathways.

Regular physical exercise has anti-inflammatory effects in elderly subjects. Yet, the inflammatory responses after whole body vibration (WBV) training, a popular exercise paradigm for the elderly, remain to be elucidated. This study assessed the effects of WBV training on the inflammatory response associated with toll-like receptors (TLRs) signaling pathways. Twenty-eight subjects were randomized to a training group (TG) or a control group (CG). TG followed an 8-week WBV training program. Blood samples were obtained before and after the training period in both groups. Peripheral blood mononuclear cells were isolated, and mRNA and protein levels of makers involved in the TLR2/TLR4 myeloid differentiation primary response gen 88 (MyD88) and TIR domain-containing adaptor inducing interferon (TRIF)-dependent pathways were analyzed. Plasma TNFα and C-reactive protein levels were also assessed. The WBV program reduced protein expression of TLR2, TLR4, MyD88, p65, TRIF and heat shock protein (HSP) 60, while HSP70 content increased. IL-10 mRNA level and protein concentration were upregulated, and TNFα protein content decreased, after WBV training. Plasma concentration of C-reactive protein and TNFα decreased in the TG. The current data suggest WBV may improve the anti-inflammatory status of elderly subjects through an attenuation of MyD88- and TRIF-dependent TLRs signaling pathways.

An assessment of the nutritional intake of soccer referees.

OBJECTIVE: The present study aims to analyze the eating habits and attitudes of a group of soccer referees and linesmen. METHOD: A nutritional study was undertaken of thirty-five soccer referees (aged between 18 and 50) refereeing at different levels, from the Spanish national third division down to the provincial second division. Through the use of a 3-day food diary and 24-hour recall, this study analyzed the intake and distribution of macro- and micro-nutrients and of dietary fiber consumed on different types of day (normal, training, and match days). RESULTS: There were no significant differences in calorie intake related to the three types of day (normal, training, and match days). This was true both of overall amounts (2371.1 kcal, 2479.7 kcal, and 2368.4 kcal, respectively) and amounts per unit of body weight (32.4 kcal/kg, 33.9 kcal/kg, and 32.4 kcal/kg, respectively). In respect of macro-nutrient intake, more specifically carbohydrates, the subjects consumed a diet with an insufficient amount of carbohydrates: 279 g, as against the 371 g (REC1) or 540 g (REC2) recommended according to physical activity levels. Slight increases were observed on game days, but were not statistically significant. Consideration of micro-nutrients showed that the quantities of three vitamins (B6, B12, and C) consumed were above the recommended amounts. However, this was not an issue, since the figures related to water-soluble vitamins. Finally, the amounts of minerals (Ca, Mg, and Fe) and fiber consumed were close to recommended values, regardless of the type of day being considered. CONCLUSIONS: This study found that the group of referees investigated consumed a diet that did not have sufficient calories from carbohydrates, in view of their occupation. This poor nutritional status might interfere with the development of their sporting performance and ultimately increase the risk of injury. This implies a need to design and implement a diet and to introduce educational programs on nutrition for these sportspeople.

Aging's effects on marathon performance insights from the New York City race.

Most studies on aging and marathon have analyzed elite marathoners, yet the latter only represent a very small fraction of all marathon participants. In addition, analysis of variance or unpaired Student t tests are frequently used to compare mean performance times across age groups. In this report the authors propose an alternative methodology to determine the impact of aging on marathon performance in both nonelite and elite marathoners participating in the New York City Marathon. In all, 471,453 data points corresponding to 370,741 different runners over 13 race editions (1999-2011) were retrieved. Results showed that the effect of aging on marathon performance was overall comparable in both sexes, the effect of aging differed between the fastest and slowest runners in both sexes, and the magnitude of the sex differences was higher in the slowest runners than in the fastest ones. Current data suggest that the biological differences between sexes allow men to have better marathon performance across most of the human life span.

Whole-body vibration training increases physical fitness measures without alteration of inflammatory markers in older adults.

This study investigated in older adults whether whole-body vibration (WBV) training results in significant increases of physical fitness measures without alterations in markers of inflammation. Sixteen volunteers completed a WBV programme 3 d.wk(-1) during 9 weeks. The programme consisted of lower and upper-body unloaded static and dynamic exercises. Training improved significantly several tests which evaluate physical fitness, such as 30-s chair stand, arm curl or chair sit and reach test. There was a significant increase in maximal voluntary isometric contraction (MVIC) between pre- and post-training conditions. Muscle power values, reached at 20, 40 and 60% MVIC, were also significantly greater after training. However, mRNA or protein levels for C-reactive protein, interleukin-6, interleukin-1ß, tumour necrosis factor-α and interleukin-10 did not significantly differ from basal values. Our data confirm the usefulness of WBV training for counteracting the loss of muscle strength associated with sarcopenia in older adults and show that WBV training could be a safe training method which induces no inflammatory effects.

Changes induced by diet and nutritional intake in the lipid profile of female professional volleyball players after 11 weeks of training.

BACKGROUND: The relationship between cardiovascular disease and lipid profile is well known. Apart from a heart-healthy diet, exercise is the primary factor that can modify this lipid-associated cardiovascular risk. The aim of the study was to evaluate potential changes in the levels of triglycerides, total cholesterol (TC), low-density lipoprotein-cholesterol (LDLc), and high-density lipoprotein-cholesterol (HDLc), as well as atherogenic indices (TC/HDLc and LDLc/HDLc), and also to analyse the diet over 11 weeks of training in female professional volleyball players. METHODS: The lipid profile of 22 female professional volleyball players was analysed on Day T0 (pre-preseason) and Day T11 (after 11 weeks of training). The consumption of fats by the players was estimated using a food frequency questionnaire, confirmed by seven days of full dietary records. RESULTS: By the end of the study, the LDLc levels and both atherogenic indices of the players had decreased (p < 0.05) compared to the values obtained at baseline. In addition, the diet of the players contained 35.5 ± 3.2% of fats (saturated fatty acid: 11.1 ± 1.2%, monounsaturated fatty acid: 14.3 ± 1.9%, and polyunsaturated fatty acid: 7.0 ± 1.1%) and 465 ± 57 mg of dietary cholesterol. Their score for the (monounsaturated + polyunsaturated fatty acid)/saturated fatty acid ratio was 1.9 ± 0.4, less than the recommended ≥ 2. CONCLUSION: These data indicate that the activity of the female professional volleyball players during the first 11 weeks of training in the season was heart healthy, because their lipid profile improved, despite an inadequate intake of fats.

Whole-body vibration training as complement to programs aimed at weight loss.

INTRODUCTION: Whole-body vibration training (WBVT) has been shown to be an extremely useful tool for increasing muscle mass, bone tissue, muscle power, flexibility, and strength, among others. However, to date, there are few studies on the effects of WBVT on energy metabolism and whether this tool could be able to enhance weight loss in addition to a nutritional plan and/or exercise. OBJECTIVE: The aim of this review is to analyse the most recent studies on vibration training in order to determine whether this method constitutes a reliable complement to programs aimed at weight loss. METHODS: An updated literature search was conducted using PubMed, SciELO and SPORTDiscus. In addition, a detailed search was also performed from references given in selected studies. RESULTS: WBVT appears to be associated with three pathways involved in weight loss: inhibition of adipogenesis and reduction of fat mass, increased energy expenditure, and increase in muscle mass. After analysing the literature, none of the results for the proposed pathways are consistent, and indeed are often contradictory. CONCLUSION: Further in-depth research is required on this subject. However, WBVT would appear to be a safe method, and may possibly yield benefits, mainly as regards muscle mass, which in turn might promote weight loss when combined with a nutritional plan and a traditional exercise program.

Introducción: El entrenamiento de vibraciones de cuerpo completo (EVCC) ha demostrado ser de gran utilidad para aumentar la masa muscular, el tejido óseo, la potencia muscular, la flexibilidad, y la fuerza, entre otros. No obstante, hasta la fecha es escasa la literatura respecto a sus efectos sobre el metabolismo energético y si esta herramienta podría ser capaz de potenciar la pérdida de peso como complemento a un programa nutricional y/o de ejercicio físico. Objetivo: El objetivo de la presente revisión es analizar los últimos estudios sobre el EVCC con la finalidad de determinar si puede ser un método fiable para complementar los programas orientados a la reducción del peso corporal. Métodos: Se realizó una búsqueda bibliográfica en Pubmed, Scielo y SPORTDiscus, así como una búsqueda manual entre las referencias de los estudios seleccionados. Resultados: El EVCC parece estar vinculado a tres vías relacionadas con la reducción del peso corporal: inhibición de la adipogénesis y reducción de la masa grasa, aumento del gasto energético y aumento de la masa muscular. Tras analizar la literatura, ninguna de las vías propuestas es consistente, y en muchas ocasiones los resultados son contradictorios. Conclusión: Se concluye que es necesario profundizar sobre esta línea de investigación. No obstante, el EVCC parece ser un método seguro y posiblemente tendría beneficios, principalmente sobre la masa muscular, lo que podría promover la pérdida de peso si se combina con un plan nutricional y un programa de ejercicio tradicional.

Whole-body vibration training as complement to programs aimed at weight loss / Entrenamiento de vibraciones de cuerpo completo como complemento a los programas orientados a la pérdida de peso

INTRODUCTION: Whole-body vibration training (WBVT) has been shown to be an extremely useful tool for increasing muscle mass, bone tissue, muscle power, flexibility, and strength, among others. However, to date, there are few studies on the effects of WBVT on energy metabolism and whether this tool could be able to enhance weight loss in addition to a nutritional plan and/or exercise. OBJECTIVE: The aim of this review is to analyse the most recent studies on vibration training in order to determine whether this method constitutes a reliable complement to programs aimed at weight loss. METHODS: An updated literature search was conducted using PubMed, SciELO and SPORTDiscus. In addition, a detailed search was also performed from references given in selected studies. RESULTS: WBVT appears to be associated with three pathways involved in weight loss: inhibition of adipogenesis and reduction of fat mass, increased energy expenditure, and increase in muscle mass. After analysing the literature, none of the results for the proposed pathways are consistent, and indeed are often contradictory. CONCLUSION: Further in-depth research is required on this subject. However, WBVT would appear to be a safe method, and may possibly yield benefits, mainly as regards muscle mass, which in turn might promote weight loss when combined with a nutritional plan and a traditional exercise program (AU)

Introducción: El entrenamiento de vibraciones de cuerpo completo (EVCC) ha demostrado ser de gran utilidad para aumentar la masa muscular, el tejido óseo, la potencia muscular, la flexibilidad, y la fuerza, entre otros. No obstante, hasta la fecha es escasa la literatura respecto a sus efectos sobre el metabolismo energético y si esta herramienta podría ser capaz de potenciar la pérdida de peso como complemento a un programa nutricional y/o de ejercicio físico. Objetivo: El objetivo de la presente revisión es analizar los últimos estudios sobre el EVCC con la finalidad de determinar si puede ser un método fiable para complementar los programas orientados a la reducción del peso corporal. Métodos: Se realizó una búsqueda bibliográfica en Pubmed, Scielo y SPORTDiscus, así como una búsqueda manual entre las referencias de los estudios seleccionados. Resultados: El EVCC parece estar vinculado a tres vías relacionadas con la reducción del peso corporal: inhibición de la adipogénesis y reducción de la masa grasa, aumento del gasto energético y aumento de la masa muscular. Tras analizar la literatura, ninguna de las vías propuestas es consistente, y en muchas ocasiones los resultados son contradictorios. Conclusión: Se concluye que es necesario profundizar sobre esta línea de investigación. No obstante, el EVCC parece ser un método seguro y posiblemente tendría beneficios, principalmente sobre la masa muscular, lo que podría promover la pérdida de peso si se combina con un plan nutricional y un programa de ejercicio tradicional (AU)

A review of the molecular aspects of melatonin's anti-inflammatory actions: recent insights and new perspectives.

Melatonin is a highly evolutionary conserved endogenous molecule that is mainly produced by the pineal gland, but also by other nonendocrine organs, of most mammals including man. In the recent years, a variety of anti-inflammatory and antioxidant effects have been observed when melatonin is applied exogenously under both in vivo and in vitro conditions. A number of studies suggest that this indole may exert its anti-inflammatory effects through the regulation of different molecular pathways. It has been documented that melatonin inhibits the expression of the isoforms of inducible nitric oxide synthase and cyclooxygenase and limits the production of excessive amounts of nitric oxide, prostanoids, and leukotrienes, as well as other mediators of the inflammatory process such as cytokines, chemokines, and adhesion molecules. Melatonin's anti-inflammatory effects are related to the modulation of a number of transcription factors such as nuclear factor kappa B, hypoxia-inducible factor, nuclear factor erythroid 2-related factor 2, and others. Melatonin's effects on the DNA-binding capacity of transcription factors may be regulated through the inhibition of protein kinases involved in signal transduction, such as mitogen-activated protein kinases. This review summarizes recent research data focusing on the modulation of the expression of different inflammatory mediators by melatonin and the effects on cell signaling pathways responsible for the indole's anti-inflammatory activity. Although there are a numerous published reports that have analyzed melatonin's anti-inflammatory properties, further studies are necessary to elucidate its complex regulatory mechanisms in different cellular types and tissues.

Sulforaphane treatment protects skeletal muscle against damage induced by exhaustive exercise in rats.

Sulforaphane (SF), one of the most important isothiocyanates in the human diet, present in cruciferous vegetables, is known to have chemopreventive activities in different tissues. No data are available on its effects in the prevention of skeletal muscle damage. In this study, we investigated the potential protective effects of SF treatment on muscle damage and oxidative stress induced by an acute bout of exhaustive exercise in rats. Male Wistar rats were treated with SF (25 mg/kg body wt ip) for 3 days before undergoing an acute exhaustive exercise protocol in a treadmill (+7% slope and 24 m/min). Acute exercise resulted in a significant increase in plasma lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activities. It also resulted in a significant increase in thiobarbituric acid-reactive substances, in a significant decrease in tissue total antioxidant capacity, and in a significant decrease in NAD(P)H:quinone oxidoreductase 1 (NQO1) expression and activity in vastus lateralis muscle. SF treatment significantly increased muscle NQO1, glutathione-S-transferase, and glutathione reductase expression and activity, with no effect on glutathione peroxidase and thioredoxin reductase. The observed SF-induced upregulation of phase II enzymes was accompanied by a significant increase in nuclear erythroid 2 p45-related factor 2 expression and correlated with a significant increase in total antioxidant capacity and a decrease in plasma LDH and CPK activities. Our data demonstrate that SF acts as an indirect antioxidant in skeletal muscle and could play a critical role in the modulation of the muscle redox environment, leading to the prevention of exhaustive exercise-induced muscle damage.

Melatonin reduces cardiac inflammatory injury induced by acute exercise.

Cardiac muscle tissue, when stimulated by acute exercise, presents increased signs of cell damage. This study was designed to investigate whether overexpression of inflammatory mediators induced in the heart by acute exercise could be prevented by melatonin and whether the protective effect of melatonin was related with inhibition of nuclear factor kappa B (NF-kappaB) activation. Male Wistar rats received melatonin i.p. at a dose of 1.0 mg/kg body weight 3 min before being exercised for 60 min on a treadmill at a speed of 25 m/min and a 10% slope. Exercise was associated with a significant increase in myeloperoxidase activity and in TNF-alpha, IL-1 and IL-6 mRNA levels. Both mRNA level and protein concentrations of intercellular adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2 were also significantly elevated. A significant activation of nuclear factor kappa B (NF-kappaB) was observed in exercised rats. These effects were totally or partially prevented by melatonin administration. Data obtained indicate that melatonin protects against heart damage caused by acute exercise. Impaired production of noxious mediators involved in the inflammatory process and down-regulation of the NF-kappaB signal transduction pathway appear to contribute to the beneficial effects of melatonin.

The anti-inflammatory flavones quercetin and kaempferol cause inhibition of inducible nitric oxide synthase, cyclooxygenase-2 and reactive C-protein, and down-regulation of the nuclear factor kappaB pathway in Chang Liver cells.

We examined the ability of the flavonoids quercetin and kaempferol to modulate inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and reactive C-protein (CRP) expression, and to induce changes in the nuclear factor kappa B (NF-kappaB) pathway in the human hepatocyte-derived cell line Chang Liver. Cells were incubated with a cytokine mixture supplemented with quercetin or kaempferol (5 to 200 micromol/l). Kaempferol produced a significant concentration-dependent decrease of iNOS, COX-2 and CRP protein level at all concentrations, but the percentage of inhibition induced by quercetin was reduced at high concentrations. Both flavonoids significantly inhibited mRNA level of iNOS, COX-2, and CRP. Inhibitory effects by quercetin and kaempferol were also observed on NF-kappaB activation and on protein concentration of the phosphorylated form of the inhibitor IkappaB alpha and of IKK (IkappaB kinase)alpha. The present study suggests that the modulation of iNOS, COX-2 and CRP by quercetin or kaempferol may contribute to the anti-inflammatory effects of these two structurally similar flavonoids in Chang Liver cells, via mechanisms likely to involve blockade of NF-kappaB activation and the resultant up-regulation of the pro-inflammatory genes. Our data also indicate that the minor structural differences between both compounds determine differences in their inhibitory capacity.

Melatonin inhibits the expression of the inducible isoform of nitric oxide synthase and nuclear factor kappa B activation in rat skeletal muscle.

This study investigated whether the induction of inducible nitric oxide synthase (iNOS) produced by acute exercise in rat skeletal muscle could be prevented by melatonin and whether iNOS down-regulation was related to inhibition of nuclear factor kappaB (NF-kappaB) activation. Male Wistar rats received melatonin i.p. at a dose of 1.0 mg/kg body weight 30 min before being exercised for 60 min on a treadmill at a speed of 25 m/min and a 10% slope. Exercise caused a significant induction of iNOS protein levels and a marked activation of NF-kappaB that were significantly prevented in rats treated with melatonin. Exercise also resulted in increased IkappaB kinasealpha (IKKalpha) and phosphorylated IkappaBalpha protein levels, whereas IkappaBalpha content decreased. These effects were blocked by melatonin administration. The increase in the muscle concentration of thiobarbituric acid reactive substances and in the oxidized/reduced glutathione ratio induced by exercise was partially prevented by melatonin. Our data indicate that melatonin has potent protective effects against damage caused by acute exercise in rat muscle, preventing oxidative stress, NF-kappaB activation and iNOS over-expression. These findings support the view that melatonin treatment, by abolishing the IKK/NF-kappaB signal transduction pathway, might block the production of noxious mediators involved in the inflammatory process.

Quercetin decreases oxidative stress, NF-kappaB activation, and iNOS overexpression in liver of streptozotocin-induced diabetic rats.

Increasing evidence in both experimental and clinical studies suggests that oxidative stress is involved in the pathogenesis and progression of diabetic tissue damage. This study investigated the protective effects of quercetin treatment on oxidative stress, nuclear factor (NF)-kappaB activation and expression of inducible nitric oxide synthase (iNOS) in streptozotocin-induced diabetic rats. Male Wistar rats were divided into 4 groups: control rats, control rats treated daily with quercetin (150 micromol/kg, i.p.), untreated diabetic rats, and diabetic rats treated with quercetin. Diabetes was induced by a single i.p. injection of streptozotocin (70 mg/kg). Eight weeks later we measured TBARS and hydroperoxide-initiated chemiluminescence (QL) in liver as markers of oxidative stress, and activities of the antioxidant enzymes catalase, superoxide dismutase (SOD), and glutathione peroxidase, NF-kappaB activation by an electrophoretic mobility shift assay and expression of IkappaB kinases (IKKalpha and IKKbeta), the inhibitor IkappaB (IkappaBalpha and IkappaBbeta), and iNOS by Western blot. The plasma glucose concentration was significantly increased in diabetic rats and was not changed by quercetin. Streptozotocin administration induced significant increases in hepatic TBARS concentration, QL, and SOD and catalase activities that were prevented by quercetin. Activation of NF-kappaB, induction of IKKalpha and iNOS protein levels, and increased degradation of IkappaBalpha were also observed in streptozotocin-treated rats. All of those effects were abolished by quercetin. These findings suggest that quercetin treatment, by abolishing the IKK/NF-kappaB signal transduction pathway, may block the production of noxious mediators involved in the development of early diabetes tissue injury and in the evolution of late complications.

Quercetin prevents oxidative stress and NF-kappaB activation in gastric mucosa of portal hypertensive rats.

The present study was designed to investigate the effects of quercetin on oxidative stress and activation of nuclear factor kappa B (NF-kappaB) in an experimental model of portal hypertensive gastropathy induced by partial portal vein ligation (PPVL). Portal pressure was significantly elevated in PPVL rats. Transaminase and alkaline phosphatase activities were not significantly modified, indicating absence of liver injury. Histological analysis of gastric sections showed a lost of normal architecture, with edema and vasodilatation. The cytosolic concentration of thiobarbituric acid reactive substances and the lipoperoxidation measurement by chemiluminiscence were significantly increased. Superoxide dismutase activity in gastric mucosa was significantly reduced. Portal hypertensive gastropathy induced a marked activation of NF-kappaB, accompanied by a decrease in IkappaB protein levels and a significant induction of nitric oxide synthase (iNOS) protein. Administration of quercetin markedly alleviated histological abnormalities and inhibited oxidative stress and NF-kappaB activation. IkappaB decrease and induction of iNOS protein were partially prevented by quercetin. Quercetin treatment, by abolishing the NF-kappaB signal transduction pathway, may block the production of noxious mediators involved in the pathogenesis of portal hypertensive gastropathy.