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Reductions in mitochondrial function have been proposed to cause insulin resistance, however the possibility that impairments in insulin signaling negatively affects mitochondrial bioenergetics has received little attention. Therefore, we tested the hypothesis that insulin could rapidly improve mitochondrial ADP sensitivity, a key process linked to oxidative phosphorylation and redox balance, and if this phenomenon would be lost following high-fat diet (HFD)-induced insulin resistance. Insulin acutely (60 min post I.P.) increased submaximal (100–1000 µM ADP) mitochondrial respiration ∼2-fold without altering maximal (>1000 µM ADP) respiration, suggesting insulin rapidly improves mitochondrial bioenergetics. The consumption of HFD impaired submaximal ADP-supported respiration ∼50%, however, despite the induction of insulin resistance, the ability of acute insulin to stimulate ADP sensitivity and increase submaximal respiration persisted. While these data suggest that insulin mitigates HFD-induced impairments in mitochondrial bioenergetics, the presence of a high intracellular lipid environment reflective of an HFD (i.e. presence of palmitoyl-CoA) completely prevented the beneficial effects of insulin. Altogether, these data show that while insulin rapidly stimulates mitochondrial bioenergetics through an improvement in ADP sensitivity, this phenomenon is possibly lost following HFD due to the presence of intracellular lipids.

Obesity and insulin resistance (IR) are associated with endoplasmic reticulum (ER) stress and mitochondrial dysfunction in several tissues. Although for many years mitochondrial and ER function were studied separately, these organelles also connect to produce interdependent functions. Communication occurs at mitochondria-associated ER membranes (MAMs) and regulates lipid and calcium homeostasis, apoptosis, and the exchange of adenine nucleotides, among other things. Recent evidence suggests that MAMs contribute to organelle, cellular, and systemic metabolism. In obesity and IR models, metabolic tissues such as the liver, skeletal muscle, pancreas, and adipose tissue present alterations in MAM structure or function. The purpose of this mini review is to highlight the MAM disruptions that occur in each tissue during obesity and IR and its relationship with glucose homeostasis and IR. We also discuss the current controversy that surrounds MAMs’ role in the development of IR.

Key pointsKetone bodies are proposed to represent an alternative fuel source driving energy production, particularly during exercise. Biologically, the extent to which mitochondria utilize ketone bodies compared to other substrates remains unknown. We demonstratein vitrothat maximal mitochondrial respiration supported by ketone bodies is low when compared to carbohydrate-derived substrates in the left ventricle and red gastrocnemius muscle from rodents, and in human skeletal muscle. When considering intramuscular concentrations of ketone bodies and the presence of other carbohydrate and lipid substrates, biological rates of mitochondrial respiration supported by ketone bodies are predicted to be minimal. At the mitochondrial level, it is therefore unlikely that ketone bodies are an important source for energy production in cardiac and skeletal muscle, particularly when other substrates are readily available. Ketone bodies (KB) have recently gained popularity as an alternative fuel source to support mitochondrial oxidative phosphorylation and enhance exercise performance. However, given the low activity of ketolytic enzymes and potential inhibition from carbohydrate oxidation, it remains unknown if KBs can contribute to energy production. We therefore determined the ability of KBs (sodiumdl-beta-hydroxybutyrate, beta-HB; lithium acetoacetate, AcAc) to stimulatein vitromitochondrial respiration in the left ventricle (LV) and red gastrocnemius (RG) of rats, and in human vastus lateralis. Compared to pyruvate, the ability of KBs to maximally drive respiration was low in isolated mitochondria and permeabilized fibres (PmFb) from the LV (similar to 30-35% of pyruvate), RG (similar to 10-30%), and human vastus lateralis (similar to 2-10%). In PmFb, the concentration of KBs required to half-maximally drive respiration (LV: 889 mu m beta-HB, 801 mu mAcAc; RG: 782 mu m beta-HB, 267 mu mAcAc) were greater than KB content representative of the muscle microenvironment (similar to 100 mu m). This would predict low rates (similar to 1-4% of pyruvate) of biological KB-supported respiration in the LV (8-14 pmol s(-1) mg(-1)) and RG (3-6 pmol s(-1) mg(-1)) at rest and following exercise. Moreover, KBs did not increase respiration in the presence of saturating pyruvate, submaximal pyruvate (100 mu m) reduced the ability of physiological beta-HB to drive respiration, and addition of other intracellular substrates (succinate + palmitoylcarnitine) decreased maximal KB-supported respiration. As a result, product inhibition is likely to limit KB oxidation. Altogether, the ability of KBs to drive mitochondrial respiration is minimal and they are likely to be outcompeted by other substrates, compromising their use as an important energy source.

Recent evidence suggests that young rodents submitted to high fructose (FRU) diet develop metabolic, and cognitive dysfunctions. However, it remains unclear whether these detrimental effects of FRU intake can also be observed in middle-aged mice. Nine months-old C57BL/6 female mice were fed with water (Control) or 10% FRU in drinking water during 12 weeks. After that, metabolic, and neurochemical alterations were evaluated, focusing on neurotransmitters, and antioxidant defenses. Behavioral parameters related to motor activity, memory, anxiety, and depression were also evaluated. Mice consuming FRU diet displayed increased water, and caloric intake, resulting in weight gain, which was partially compensated due to decreased food pellet intake. FRU fed animals displayed increased plasma glucose, and cholesterol levels, which was not observed in overnight-fasted animals. Superoxide dismutase (SOD), and catalase (CAT) activities were markedly decreased in the prefrontal cortex of animals receiving FRU diet, while glutathione peroxidase (GPx) slightly increased. Liver (lower GPx), striatum (higher SOD and lower CAT), and hippocampus (no changes) were less impacted. No changes were observed in glutathione reductase, and thioredoxin reductase activities, two ancillary enzymes for peroxide detoxification. FRU intake did not alter serotonin, dopamine, and norepinephrine levels in the hippocampus, prefrontal cortex, and striatum. No significant alterations were observed in working, and short-term spatial memory; and in anxiety- and depressive-like behaviors in animals treated with FRU. Increased locomotor activity was observed in FRU-fed middle-aged mice, as evaluated in the open field, elevated plus-maze, Y maze, and object location tasks. Overall, these results demonstrate that high FRU consumption can disturb antioxidant defenses, and increase locomotor activity in middle-aged mice, open the opportunity for further studies to address the underlying mechanisms related to these findings.

White adipose tissue (WAT) dysfunction in obesity is implicated in the onset of whole body insulin resistance. Alterations in mitochondrial bioenergetics, namely impaired mitochondrial respiration and increased mitochondrial reactive oxygen species (mtROS) production, have been suggested to contribute to this metabolic dysregulation. However, techniques investigating mitochondrial function are classically normalized to tissue weight, which may be confounding when considering obesity-related adipocyte hypertrophy. Furthermore, the effect of long-term high-fat diet (HFD) on mtROS in WAT has yet to be elucidated. Therefore, we sought to determine the HFD-mediated temporal changes in mitochondrial respiration and mtROS emission in WAT. C57BL/6N mice received low-fat diet or HFD for 1 or 8 wk and changes in inguinal WAT (iWAT) and epididymal WAT (eWAT) were assessed. While tissue weight-normalized mitochondrial respiration was reduced in iWAT following 8-wk HFD-feeding, this effect was mitigated when adipocyte cell size and/or number were considered. These data suggest HFD does not impair mitochondrial respiratory capacity per adipocyte within WAT. In support of this assertion, within eWAT compensatory increases in lipid-supported and maximal succinate-supported respiration occurred at 8 wk despite cell hypertrophy and increases in WAT inflammation. Although these data suggest impairments in mitochondrial respiration do not contribute to HFD-mediated WAT phenotype, lipid-supported mtROS emission increased following 1-wk HFD in eWAT, while both lipid and carbohydrate-supported mtROS were increased at 8 wk in both depots. Combined, these data establish that while HFD does not impair adipocyte mitochondrial respiratory capacity, increased mtROS is an enduring physiological occurrence within WAT in HFD-induced obesity.

Unusual eccentric exercise (EE) may affect muscle ability to produce rapid force. Previous study suggested that short-term mate tea (MT) consumption may enhance muscle strength recovery from EE, but MT benefits on the rate of torque development (RTD) are unknown. This study investigated the effect of MT on RTD and muscle damage and antioxidant defence biomarkers following EE. In a randomised, crossover design, 12 men drank either MT or water (control; CON) for 11 days. On the 8th day, 3 sets of 20 maximal isokinetic eccentric for elbow flexors with one arm were performed. RTD of the elbow flexor muscles at 0–50, 0–100, 50–100, 0–200, and 100–200 ms were assessed before and at 0, 24, 48, and 72 h after exercise. Blood samples were obtained before and at 24, 48, and 72 h after exercise and analysed for creatine kinase (CK), aldolase (ALD), total phenols, and reduced:oxidized glutathione (GSH:GSSG) ratio. RTD0–50 deficit after EE was independent of treatment. Compared with CON, MT improved RTD0–100 at 48 h (21%, P = 0.015) and 72 h (24%, P = 0.022); RTD0–200 at 48 h (18%, P = 0.034) and 72 h (21%, P = 0.029); RTD50–100 at 48 h (25%, P = 0.001) and 72 h (19%, P = 0.011); and RTD100–200 at 72 h (28%, P = 0.038). CK peaked (P = 0.012) in both trials at 72 h, and ALD was higher in MT than in CON before and at 24 h (P = 0.005 and P 50 ms by 2–3 days after EE. Furthermore, MT ameliorated circulating levels of muscle damage and antioxidant biomarkers irrespectively of exercise.

KEY POINTS Dietary nitrate is a prominent therapeutic strategy to mitigate some metabolic deleterious effects related to obesity. Mitochondrial dysfunction is causally linked to adipose tissue inflammation and insulin resistance. Whole-body glucose tolerance is prevented by nitrate independent of body weight and energy expenditure. Dietary nitrate reduces epididymal adipose tissue inflammation and mitochondrial reactive oxygen species emission while preserving insulin signalling. Metabolic beneficial effects of nitrate consumption are associated with improvements in mitochondrial redox balance in hypertrophic adipose tissue. ABSTRACT Evidence has accumulated to indicate that dietary nitrate alters energy expenditure and the metabolic derangements associated with a high fat diet (HFD), but the mechanism(s) of action remain incompletely elucidated. Therefore, we aimed to determine if dietary nitrate (4 mm sodium nitrate via drinking water) could prevent HFD-mediated glucose intolerance in association with improved mitochondrial bioenergetics within both white (WAT) and brown (BAT) adipose tissue in mice. HFD feeding caused glucose intolerance (P

Background: Klotho is an anti-aging protein with several therapeutic roles in the pathophysiology of different organs, such as the skeletal muscle and kidneys. Available evidence suggests that exercise increases Klotho levels, regardless of the condition or intervention, shedding some light on this anti-aging protein as an emergent and promising exerkine. Objective: Development of a systematic review and meta-analysis in order to verify the role of different exercise training protocols on the levels of circulating soluble Klotho (S-Klotho) protein. Data sources: A systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE through PubMed, EMBASE, CINAHL, CT.gov, and PEDro. Eligibility criteria: Randomized and quasi-randomized controlled trials that investigated effects of exercise training on S-Klotho levels. Results: We included 12 reports in the analysis, comprising 621 participants with age ranging from 30 to 65 years old. Klotho concentration increased significantly after chronic exercise training (minimum of 12 weeks) (Hedge’ g [95%CI] 1.3 [0.69 – 1.90]; P < 0.0001). Moreover, exercise training increases S-Klotho values regardless of the health condition of the individual or the exercise intervention, with the exception of combined aerobic + resistance training. Furthermore, protocol duration and volume seem to influence S-Klotho concentration, since the effect of the meta-analysis changes when subgrouping these variables. Conclusion: Altogether, circulating S-Klotho protein is altered after chronic exercise training and it might be considered an exerkine. However, this effect may be influenced by different training configurations, including protocol duration, volume, and intensity.

The liver is particularly susceptible to the detrimental effects of a high-fat diet (HFD), rapidly developing lipid accumulation and impaired cellular homeostasis. Recently, dietary nitrate has been shown to attenuate HFD-induced whole body glucose intolerance and liver steatosis, however, the underlying mechanism(s) remain poorly defined. In the current study, we investigated the ability of dietary nitrate to minimize possible impairments in liver mitochondrial bioenergetics following 8 wk of HFD (60% fat) in male C57BL/6J mice. Consumption of a HFD caused whole body glucose intolerance (P < 0.0001), and within the liver, increased lipid accumulation (P < 0.0001), mitochondrial-specific reactive oxygen species emission (P = 0.007), and markers of oxidative stress. Remarkably, dietary nitrate attenuated almost all of these pathological responses. Despite the reduction in lipid accumulation and redox stress (reduced TBARS and nitrotyrosine), nitrate did not improve insulin signaling within the liver or whole body pyruvate tolerance (P = 0.313 HFD vs. HFD + nitrate). Moreover, the beneficial effects of nitrate were independent of changes in weight gain, 5' AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) signaling, mitochondrial content, mitochondrial respiratory capacity and ADP sensitivity or antioxidant protein content. Combined, these data suggest nitrate supplementation represents a potential therapeutic strategy to attenuate hepatic lipid accumulation and decrease mitochondrial ROS emission following HFD, processes linked to improvements in whole body glucose tolerance. However, the beneficial effects of nitrate within the liver do not appear to be a result of increased oxidative capacity or mitochondrial substrate sensitivity.NEW & NOTEWORTHY The mechanism(s) for how dietary nitrate prevents high-fat diet (HFD)-induced glucose intolerance remain poorly defined. We show that dietary nitrate attenuates HFD-induced increases in lipid accumulation, mitochondrial-specific reactive oxygen species (ROS) emission, and markers of oxidative stress within the liver. The beneficial effects of nitrate were independent of changes 5' AMP-activated protein kinase signaling, mitochondrial content/respiratory capacity, or lipid-supported respiratory sensitivity. Combined, these data provide potential mechanisms underlying the therapeutic potential of dietary nitrate.

Sarcopenia, which is characterized by reduction in muscle mass and strength, contributes to several age-related conditions, including insulin resistance and frailty. Despite the importance of maintaining muscle mass for healthy aging, the mechanisms contributing to sarcopenia are not fully elucidated. Nevertheless, mitochondria appear to play a key role in the underlying condition, and importantly, respond robustly to exercise interventions. Mitochondria are intracellular organelles largely attributed to maintaining ATP concentrations, however, the importance of this organelle in overall cellular homeostasis has been expanded in the last decades to include redox signaling, calcium homeostasis, inflammation, and apoptosis. Several lines of evidence suggest that mitochondrial bioenergetics are altered in aged skeletal muscle, resulting in an increase in reactive oxygen species (ROS) production, while conversely genetic/pharmacological approaches that attenuate mitochondrial ROS promote healthy aging and maintenance of muscle mass. These observations suggest that increased free radicals are one of the bases of the aging process and related sarcopenia. Here, we reviewed the current knowledge regarding mitochondrial function and redox balance in aged human skeletal muscle, highlighting the implications of redox unbalance on skeletal muscle mass maintenance and muscle health. Additionally, we describe the benefits of exercise and nutrition interventions in the context of improving mitochondrial bioenergetics and functional outcomes regarding skeletal muscle mass and function.

Summary Background and aims Due to its high peroxidizable characteristics, n-3 fatty acids, present in fish oil, could increase tumor cells sensitivity to conventional cancer treatment while non-neoplastic cells remain unaffected, this may lead to an increase in cancer treatment response with no increase on adverse effects. The aim of this study was to evaluate anti-cancer treatment response, performance status and adverse events in gastrointestinal cancer patients supplemented with fish oil. Oxidative stress parameters were investigated in blood non-neoplastic cells as an indicator of cytotoxicity. Methods: This is a randomized, triple-blind, placebo-controlled clinical trial. Fish oil group (FOG) received two capsules of fish oil containing 1.55 g of EPA + DHA a day for nine weeks, placebo group (PG) received two capsules containing olive oil. Baseline was set right before the administration of the first chemotherapy, oxidative stress parameters, adverse events presence and grading and performance status were assessed at baseline and after nine weeks of supplementation. Tumor markers, response to treatment and survival were evaluated at baseline and after one year of study inclusion. Results: 76 patients were considered eligible, 56 were randomized, and 51 remained for analysis. After nine weeks, although there were no differences between groups for treatment response and presence of adverse events, PG patients were graded with more severe diarrhea than FOG patients (p = 0.03) and with higher (worse) performance status score (p = 0.02). No differences in lipid peroxidation and activity of antioxidant enzymes were observed between groups. Conclusions: Fish oil may lead to a better performance status for gastrointestinal cancer patients undergoing chemotherapy while does not seem to increase treatment-related toxicity. Registered under ClinicalTrials.gov Identifier no. NCT02699047 , www.clinicaltrials.gov .

New findings What is the central question of this study? What are the temporal responses of mitochondrial respiration and mitochondrial responsivity to insulin in soleus muscle fibres from mice during the development of obesity and insulin resistance? What is the main finding and its importance? Short- and long-term feeding with a high-fat diet markedly reduced soleus mitochondrial respiration and mitochondrial responsivity to insulin before any change in glycogen synthesis. Muscle glycogen synthesis and whole-body insulin resistance were present after 14 and 28 days, respectively. Our findings highlight the plasticity of mitochondria during the development of obesity and insulin resistance. Abstract Recently, significant attention has been given to the role of muscle mitochondrial function in the development of insulin resistance associated with obesity. Our aim was to investigate temporal alterations in mitochondrial respiration, H2 O2 emission and mitochondrial responsivity to insulin in permeabilized skeletal muscle fibres during the development of obesity in mice. Male Swiss mice (5-6 weeks old) were fed with a high-fat diet (60% calories from fat) or standard diet for 7, 14 or 28 days to induce obesity and insulin resistance. Diet-induced obese (DIO) mice presented with reduced glucose tolerance and hyperinsulinaemia after 7 days of high-fat diet. After 14 days, the expected increase in muscle glycogen content after systemic injection of glucose and insulin was not observed in DIO mice. At 28 days, blood glucose decay after insulin injection was significantly impaired. Complex I (pyruvate + malate) and II (succinate)-linked respiration and oxidative phosphorylation (ADP) were decreased after 7 days of high-fat diet and remained low in DIO mice after 14 and 28 days of treatment. Moreover, mitochondria from DIO mice were incapable of increasing respiratory coupling and ADP responsivity after insulin stimulation in all observed periods. Markers of mitochondrial content were reduced only after 28 days of treatment. The mitochondrial H2 O2 emission profile varied during the time course of DIO, with a reduction of H2 O2 emission in the early stages of DIO and an increased emission after 28 days of treatment. Our data demonstrate that DIO promotes transitory alterations in mitochondrial physiology during the early and late stages of insulin resistance related to obesity.

Made available in DSpace on 2021-06-25T11:10:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 We investigated whether combined long-term fructose and prednisolone intake would be more detrimental to the glucose homeostasis than if ingested separately. We also evaluated whether fish oil administration or interruption of treatments has any positive impact. For this, male adult Wistar rats ingested fructose (20%) (F) or prednisolone (12.5 µg/mL) (P) or both (FP) through drinking water for 12 weeks. A separate group of fructose and prednisolone-treated rats received fish oil treatment (1 g/kg) in the last 6 weeks. In another group, the treatment with fructose and prednisolone was interrupted after 12 weeks, and the animals were followed for more 12 weeks. Control groups ran in parallel (C). The F group had higher plasma TG (+42%) and visceral adiposity (+63%), whereas the P group had lower insulin sensitivity (−33%) and higher insulinemia (+200%). Only the the FP group developed these alterations combined with higher circulating uric acid (+126%), hepatic triacylglycerol content (+16.2-fold), lipid peroxidation (+173%) and lower catalase activity (−32%) that were associated with lower protein kinase B content and AMP-activated protein kinase (AMPK) phosphorylation in the liver, lower AMPK phosphorylation in the adipose tissue and higher beta-cell mass. Fish oil ingestion attenuated the elevation in circulating triacylglycerol and uric acid values, while the interruption of sugar and glucocorticoid intake reverted almost all modified parameters. In conclusion, long-term intake of fructose and prednisolone by male rats are more detrimental to glucose and lipid homeostasis than if ingested separately and the benefits of treatment interruption are broader than fish oil treatment. Laboratory of Investigation in Chronic Diseases - LIDoC Department of Physiological Sciences Centre of Biological Sciences Federal University of Santa Catarina - UFSC Multicentre Graduate Program in Physiological Sciences Centre of Biological Sciences Federal University of Santa Catarina - UFSC Graduate Program in Nutrition Centre of Health Sciences Federal University of Santa Catarina - UFSC Department of Physiology and Pathology School of Dentistry São Paulo State University - UNESP Department of Physiology and Pathology School of Dentistry São Paulo State University - UNESP

Obesity is associated with adipose tissue hypertrophy, systemic inflammation, mitochondrial dysfunction, and intestinal dysbiosis. Rodent models of high-fat diet (HFD)-feeding or genetic deletion of multifunctional proteins involved in immunity and metabolism are often used to probe the etiology of obesity; however, these models make it difficult to divorce the effects of obesity, diet composition, or immunity on endocrine regulation of blood glucose. We, therefore, investigated the importance of adipose inflammation, mitochondrial dysfunction, and gut dysbiosis for obesity-induced insulin resistance using a spontaneously obese mouse model. We examined metabolic changes in skeletal muscle, adipose tissue, liver, the intestinal microbiome, and whole-body glucose control in spontaneously hyperphagic C57Bl/6J mice compared to lean littermates. A separate subset of lean and obese mice was subject to 8 weeks of obesogenic HFD feeding, or to pair feeding of a standard rodent diet. Hyperphagia, obesity, adipose inflammation, and insulin resistance were present in obese mice despite consuming a standard rodent diet, and these effects were blunted with caloric restriction. However, hyperphagic obese mice had normal mitochondrial respiratory function in all tissues tested and no discernable intestinal dysbiosis relative to lean littermates. In contrast, feeding mice an obesogenic HFD altered the composition of the gut microbiome, impaired skeletal muscle mitochondrial bioenergetics, and promoted poor glucose control. These data show that adipose inflammation and redox stress occurred in all models of obesity, but gut dysbiosis and mitochondrial respiratory dysfunction are not always required for obesity-induced insulin resistance. Rather, changes in the intestinal microbiome and mitochondrial bioenergetics may reflect physiological consequences of HFD feeding.

Introduction: Causality of the association between impairments in mitochondrial function and insulin resistance remains debatable. We have previously demonstrated that mitochondrial ADP sensitivity is impaired in high-fat diet (HFD)-induced insulin resistance, which contributes to bioenergetic imbalance and higher reactive oxygen species (ROS) production. However, insulin regulates several metabolic processes within skeletal muscle, and we tested the hypothesis that insulin could rapidly improve mitochondrial ADP sensitivity, a phenomenon possibly lost in HFD-induced insulin resistance. Methods: Male and female C57Bl/6 mice were fed a control diet (10% fat) or HFD (60% fat) for 8 weeks. At the end of treatment, insulin was injected intraperitoneally (3 U/kg) twice (0 and 30 minutes). At 60 minutes red gastrocnemius muscle was excised to evaluate mitochondrial bioenergetics, ADP sensitivity, and ROS production. Results: In control mice, insulin increased respiration by ∼2-fold in the presence of submaximal (100-1000 μM ADP) but not maximal ADP-supported respiration. As a result, insulin decreased the apparent ADP Km from 700 to 380 μM ADP. Despite these respiratory changes, insulin had no effect on mitochondrial maximal succinate-supported ROS emission or the ability of ADP to suppress ROS emission. HFD consumption impaired whole-body glucose intolerance, skeletal muscle insulin resistance (decreased insulin-stimulated Akt Thr-308 and Ser-473 phosphorylation) and impaired mitochondrial submaximal ADP-supported respiration by ∼50% (ADP Km ∼1100 μM). However, despite the reduction in insulin signaling following HFD, insulin increased submaximal ADP-supported respiration by ∼2-fold, decreased the apparent ADP Km to ∼400 μM and improved the ability of ADP to suppress mitochondrial ROS emission. Conclusion: Insulin rapidly improves mitochondrial ADP sensitivity, mitigating the apparent HFD-induced mitochondrial dysfunction. Disclosure H. Brunetta: None. H.L. Petrick: None. E.A. Nunes: None. G. Holloway: None. Funding Natural Sciences and Engineering Research Council of Canada (400360); Coordination for the Improvement of Higher Education Personnel

Introduction: The liver is particularly susceptible to the detrimental effects of a high fat diet (HFD), and rapidly develops insulin resistance. While the underlying mechanisms associated with hepatic insulin resistance are not fully understood, mitochondria play a crucial role in regulating lipid metabolism and redox balance. Recently, dietary nitrate was shown to attenuate HFD-induced glucose intolerance, however the mechanism(s) remains unknown. Therefore, in the present study we examined the possibility that dietary nitrate increased mitochondrial lipid-supported respiration and/or attenuated reactive oxygen species (ROS) emission. Methods: Male C57Bl/6J mice (n = 22) were randomly assigned to consume a control diet (10% fat), HFD (60% fat), or HFD with 4mM sodium nitrate in drinking water for 8 weeks. Whole body glucose tolerance and energy expenditure (indirect calorimetry) were determined, and mitochondrial respiration and reactive oxygen species (ROS) emission were assessed in liver samples. Results: Compared to control animals, the consumption of HFD increased whole body fat oxidation and body mass, and induced glucose intolerance. The consumption of dietary nitrate did not affect HFD-mediated changes in energy expenditure, rates of fat oxidation or body mass, but nevertheless attenuated the induction of glucose intolerance. Within the liver, HFD-feeding in the presence or absence of dietary nitrate, did not alter pyruvate or lipid (palmitoyl-CoA) supported respiration, or the sensitivity to malonyl-CoA-mediated inhibition of lipid-supported respiration. In contrast, while HFD increased the endogenous ROS production, nitrate prevented this response. Conclusion: These data demonstrate that nitrate supplementation attenuated the HFD-mediated induction of whole-body glucose intolerance in association with a reduction in ROS emission within the liver. Future research needs to determine causality between these observations. Disclosure G. DesOrmeaux: None. H.L. Petrick: None. H. Brunetta: None. G. Holloway: None. Funding Natural Sciences and Engineering Research Council of Canada (400362)

Cardiometabolic diseases are multifactorial conditions involving dysfunction within the left ventricle (LV), adipose tissue (AT), and gut microbiome. Nitrate supplementation has been shown to influence cardiac contractility, mitochondrial function, and microbial populations, effects which require commensal gut bacteria to metabolize nitrate. Therefore, we examined if dietary nitrate and fecal microbial transplant (FMT) from nitrate-fed mice were capable of preventing high fat diet (HFD) induced cardiac abnormalities. Male C57Bl/6N mice were fed a control diet, or HFD (60% fat) in the absence or presence of 4mM sodium nitrate in drinking water for 8 weeks. A further subset of HFD-fed mice were gavaged with feces from HFD+nitrate donors or HFD donors for 3 days at the beginning of week 7, and followed until week 8. Compared to controls, HFD mice presented with ∼25% reduction in end diastolic volume, stroke volume, and cardiac output, in association with an increase in cardiac fibrosis, AT inflammation, and serum lipids. In contrast, dietary nitrate prevented these detrimental effects. The improvement in cardiac function following dietary nitrate was not attributed to changes in LV mitochondrial respiration, however, nitrate prevented the increase in LV mitochondrial reactive oxygen species (ROS) emission associated with HFD. While FMT from HFD+nitrate donors did not influence AT inflammation or cardiac fibrosis, HFD+nitrate FMT decreased serum lipids, LV ROS, and improved cardiac function compared to FMT from HFD-fed donors, without increasing serum nitrate concentrations. Altogether, dietary nitrate prevents the detriments of HFD on cardiac function and LV mitochondrial ROS emission, effects which may not be directly dependent on increasing serum nitrate. Rather, the beneficial effects of nitrate may be linked to changes in the gut microbiome, as FMT from nitrate-fed donors improved LV function. Disclosure H.L. Petrick: None. H. Brunetta: None. A. Kirsh: None. P. Barbeau: None. L.M. Ogilvie: None. J. Simpson: None. J.D. Schertzer: None. G. Holloway: None. Funding Natural Sciences and Engineering Research Council of Canada (400362)

Introduction: The angiotensin-converting enzyme I-D (ACE) polymorphism gene is one of the most widely investigated genetic variations in sports science. Apparently, allele I is related to endurance sports, while allele D is related to power-strength activities. Nevertheless, studies have presented controversial results when it comes as to its occurrence in a variety of sports. Objective: This study aims to evaluate the frequency of gene ACE polymorphism I-D in professional athletes of collective or individual sports. Methods: Five mL blood were collected from 189 subjects divided into two groups: athletes (AG, n=127, wrestling, taekwondo, soccer, futsal and handball) and non-athletes (NAG, n=62). The athletes group was subdivided by group modalities, into: collective and individual. Both groups were further subdivided into male and female. Thus, we have the groups FAC= collective female, FAI= individual female, MAC= collective male, and MAI= individual male. The statistical analysis was carried out by frequency test, and the Hardy- Weinberg equilibrium by the x² test. Results: The results for the AG group indicated the following frequencies: DD=7%, ID=44% and II=49%. Allele frequency: D=29% and I=71%. For the NAG, the results were: DD=6.5%, ID=45.2% and II=48%. Allele frequency: D=29% and I=71%. The AG genotypic and allele frequencies did not differ statistically from those of the NAG (p= 0.982 and p= 0.984, respectively). However, we noticed that the genotypes II and ID frequencies were significantly higher than those of the DD. Conclusion: It can be concluded that the genotypic and allelic I-D frequencies of the ACE gene do not seem to influence performance in either group or individual sports. ACTN3 genotype frequencies did not vary significantly between male and female control subjects, and overall, there was no significant deviation from Hardy-Weinberg (H-W) equilibrium. Level of evidence I; Diagnostic studies–Investigating diagnostic test.

Increased superoxide production by phagocytic NADPH oxidase has been associated with inflammatory conditions. Growing evidences suggest that dietary polyphenols may modulate the expression of NADPH oxidase subunits. Herein, we examined whether soluble mate tea (SMT) consumption – a polyphenol-rich beverage – affects the expression of the leukocyte NADPH oxidase protein p47phox and/or circulating biomarkers of inflammation and antioxidant biomarkers in humans. In a two-phase study, nine men were requested to drink water (control) for 8 d and then follow a second 8-d period drinking SMT. Blood samples were analysed for p47phox protein in CD16+/CD14− cells, interleukin (IL)-1β (IL-1β), tumour necrosis factor-alpha (TNF-α), IL-6, total phenols, and reduced and oxidised glutathione (GSH and GSSG, respectively) after each study phase. After SMT intake, CD16+/CD14− cells' p47phox protein and serum TNF-α and IL-6 levels were significantly attenuated (P P phox expression and inflammatory cytokine and antioxidants levels in peripheral blood, which may help decrease oxidative stress and low-grade inflammation.

Branched-chain keto acids (BCKA) metabolism involves several well-regulated steps within mitochondria, requires cofactors, and is modulated according to the metabolic status of the cells. This regulation has made it challenging to utilize in vitro approaches to determine the contribution of branched-chain amino acid oxidation to energy production. These methodological issues were elegantly addressed in a recent publication within the Biochemical Journal. In this issue, Goldberg et al. [Biochem. J. (2019) 476, 1521–1537] demonstrated in a well-designed system the dependence of ATP and bicarbonate for BCKA full oxidation. In addition, the utilized system allowed the authors to characterize specific biochemical routes within mitochondria for each BCKA. Among them, a quantitative analysis of the participation of BCKA on mitochondrial flux was estimated between tissues. These findings are milestones with meaningful impact in several fields of metabolism.

Aims To explore the impact of GC administration periconceptionally on the glucose metabolism of adult offspring (male and female) and whether this periconception exposure might influence the metabolic outcomes when the offspring are also treated with dexamethasone in adult life. Materials and methods Rats received a daily injection of dexamethasone (1 mg/kg, body mass) or saline solution (1 mL/kg body mass) for 7 consecutive days prior became pregnant. Male and female offspring had glucose homeostasis assessed at 3- and 6-month-old and after dexamethasone treatment (1 mg/kg, body mass) or vehicle for 5 consecutive days. Then, murinometric, functional, biochemical, and histomorphometric analyses were performed. Key findings Male and female offspring born from rats treated with GC prior to becoming pregnant had none of the murinometric and metabolic outcomes (i.e., body mass, food intake, blood glucose, plasma triacylglycerol, and glucose tolerance) changed up to 6-month-old. None of the expected diabetogenic effects caused by dexamethasone treatment at 6-month of age (i.e., elevation in fasting blood glucose, plasma insulin, triacylglycerol, and albumin, glucose intolerance, insulin insensitivity, augmentation in hepatic glycogen content, and increase in pancreatic islet mass) was observed in offspring born from rats treated with dexamethasone in the prepregnancy period. However, periconceptional exposure to GC predisposed the offspring of both sexes to a higher prevalence of augmented fed blood glucose values. Significance These results give validity for the use of GC as anti-inflammatory purposes in this critical periconceptional period, but highlight the importance to consider all parental habits when interpreting adult outcomes.

Regular ingestion of fructose and continuous glucocorticoid (GC) treatment, separately, may result in metabolic adverse effects (1,2), but their combined impact is not yet understood. Thus, we aimed to evaluate the impact of a combination of fructose and prednisolone ingestion on glucose and lipid metabolism as well as the effect of the interruption of this combined treatment. Male Wistar rats were divided into five groups as follows: control (C) group, fructose (F) group (20% fructose in the drinking water), prednisolone (P) group (12.5 μg/mL prednisolone in the drinking water), fructose plus prednisolone (FP) group (a combination of fructose and prednisolone in the drinking water as for F and P groups) for 90 consecutive days. Half of the rats (group R) from the FP group were maintained for 90 more days with a discontinuation of fructose and prednisolone to monitor the parameters. The combination of fructose and GC intake led to an increase in the circulating triacylglycerol from the fourth week of treatment until the end of treatment (P

Made available in DSpace on 2020-12-12T01:28:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Chronic stress is a risk factor for cardiovascular diseases (CVD) and anxiety disorders (AD). Obesity also increases the risk of CVD and AD. The modern lifestyle commonly includes high-fat diet (HFD) intake and daily exposure to stressful events. However, it is not completely understood whether chronic stress exacerbates HFD-induced behavioral and physiological changes. Thus, this study aimed to evaluate the effects of the exposure to chronic variable stress (CVS) on behavioral, cardiovascular, and endocrine parameters in rats fed an HFD. Male Wistar rats were divided into four groups: control-standard chow diet (control-SD), control-HFD, CVS-SD, and CVS-HFD. The control-HFD and CVS-HFD groups were fed with HFD for six weeks. The CVS-HFD and CVS-SD groups were exposed to a CVS protocol in the last ten days of the six weeks. The behavioral analysis revealed that CVS decreased the open-arm exploration time during the elevated plus-maze test (p < 0.05). HFD promoted metabolic disorders and increased angiotensin II and leptin blood levels (p < 0.05). CVS or HFD increased blood pressure and the sympathetic nervous system (SNS) modulation of the heart and vessels and decreased baroreflex activity (p < 0.05). Combining CVS and HFD exacerbated the cardiac SNS response and increased basal heart rate (HR) (p < 0.05). CVS or HFD did not affect vascular function and aorta nitrate (p > 0.05). Taken together, these data indicate a synergism between HFD and CVS on the HR and cardiac SNS responses, suggesting an increased cardiovascular risk. Besides, neuroendocrine and anxiogenic disturbers may contribute to the cardiovascular changes induced by HFD and CVS, respectively. Department of Physiological Sciences Biological Sciences Centre Federal University of Santa Catarina (UFSC) Postgraduate Program in Neuroscience Biological Sciences Centre Federal University of Santa Catarina (UFSC) Laboratory of Pharmacology São Paulo State University (UNESP) School of Pharmaceutical Sciences Laboratory of Pharmacology São Paulo State University (UNESP) School of Pharmaceutical Sciences

Context Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid and eicosapentaenoic acid, demonstrate possible beneficial effects as adjuvants in cancer treatment. One mechanism seems to be related to alterations in the redox status of cancer cells. Such alterations are thought to act in synergy with conventional anticancer agents. Objective This review examines published data on the effects of cotreatment with anticancer agents and n-3 PUFAS on oxidative stress parameters to determine whether any patterns of oxidative stress alterations can be identified. Data sources A systematic search of MEDLINE (via PubMed) was conducted to identify articles published in English, Spanish, or Portuguese until November 2017. Study selection The following inclusion criteria were applied: (1) individuals or animals with cancer or malignant cell lines supplemented with some source of n-3 PUFAs; (2) concomitant use of anticancer treatment; and (3) evaluation of oxidative stress-related variables. Data extraction A standardized outline was used to extract the following data: study type, supplement used, type of cells, tumor or patient characteristics, study design, anticancer treatment used, and oxidative stress-related outcomes. Results After the literature search and screening of 1563 citations, 28 studies were included for data extraction and evaluation: 16 in vitro studies (2 of which also used in vivo studies), 8 animal studies, and 4 human studies (3 clinical trials and 1 case series). In most in vitro and animal studies, intervention groups receiving cotreatment with n-3 PUFAs showed enhanced lipid peroxidation and cytotoxicity compared with groups receiving anticancer treatment alone. Eleven of the 12 studies that investigated the effect of vitamin E on the sensitivity of cancer cells to the oxidative stress caused by n-3 PUFAs showed that vitamin E abolished the positive effects of cotreatment. Conclusions Alterations in oxidative stress caused by cotreatment with anticancer agents and n-3 PUFAs can exert positive effects on the efficacy of conventional treatment. This seems to occur in most cells and tumors tested thus far, but not all. Identifying tumors that are sensitive to these oxidative effects may provide support for the rational use of n-3 PUFAs as an adjuvant treatment in specific types of cancer.

Increased superoxide production by phagocytic NADPH oxidase has been associated with inflammatory conditions. Growing evidences suggest that dietary polyphenols may modulate the expression of NADPH oxidase subunits. Herein, we examined whether soluble mate tea (SMT) consumption - a polyphenol-rich beverage - affects the expression of the leukocyte NADPH oxidase protein p47

l-Leucine has been used to improve metabolic outcomes in glucose-intolerant rodent models. However, because studies have used different experimental models and conditions it is difficult to establish the best approach for new clinical trials evaluating the potential effects of l-leucine on glucose homeostasis. We performed a systematic review to report the effect of l-leucine supplementation on glucose homeostasis in rodents with glucose intolerance. The search engines MEDLINE and ScienceDirect were applied using MeSH terms. Thirty-four studies were included in this systematic review. Based on the current data, ingestion of 90–140 mg day−1 of isolated l-leucine in diet-induced obesity (DIO) models shows improvement in metabolic markers if offered during the development of the metabolic disorder in almost all the studies, but not after. Branched-chain amino acid supplementation was effective in streptozotocin-induced β-cells death but not in DIO models. l-Leucine supplementation seems to have an optimal dose and timing for supplementation to improve glucose homeostasis in DIO.

Dietary phytochemical supplementation may improve muscle recovery from exercise. In this study, we investigated the effect of mate tea (MT) consumption – a phenol-rich beverage – on muscle strength and oxidative stress biomarkers after eccentric exercise. In a randomised, cross-over design, twelve men were assigned to drink either MT or water (control; CON) for 11 d. On the 8th day, subjects performed three sets of twenty maximal eccentric elbow flexion exercises. Maximal isometric elbow flexion force was measured before and at 0, 24, 48 and 72 h after exercise. Blood samples were obtained before and at 24, 48 and 72 h after exercise and analysed for total phenolics, GSH, GSSG, GSH:GSSG ratio and lipid hydroperoxides (LOOH). After eccentric exercise, muscle strength was significantly reduced over time, regardless of treatments. However, MT improved the rate of strength recovery by 8·6 % on the 1st day after exercise (PPPP