Energetic Substrates Research Articles

Anaplerotic Role of Glucose in the Oxidation of Endogenous Fatty Acids during Dengue Virus Infection.

Dengue virus (DENV) is among the most important human arboviruses and is clinically and experimentally associated with lipid metabolism disorders. Using high-resolution respirometry, we analyzed the metabolic switches induced by DENV in a human hepatic cell line. This experimental approach allowed us to determine the contribution of fatty acids, glutamine, glucose, and pyruvate to mitochondrial bioenergetics, shedding light on the mechanisms involved in DENV-induced metabolic alterations. We found that while infection strongly inhibits glutamine oxidation, it increases the cellular capacity of metabolizing glucose; remarkably, though, this substrate, instead being used as an energy source, performs an anaplerotic role in the oxidation of endogenous lipids. Fatty acids become the main energetic substrate in infected cell, and through the pharmacological modulation of β-oxidation we demonstrated that this pathway is essential for virus replication. Interestingly, infected cells were much less susceptible to the Crabtree effect, i.e., the glucose-mediated inhibition of mitochondrial oxygen consumption, suggesting that infection favors cellular respiration by increasing ADP availability. IMPORTANCE Dengue virus infection is a major cause of human arbovirosis, for which clinical and experimental evidence supports the idea that liver dysfunction and lipid metabolism disorders are characteristics of severe disease. Analyzing mitochondrial bioenergetics, here we show that infection of hepatic cells with dengue virus favors the cellular capacity of metabolizing glucose, impairing the normal metabolic flexibility that allows the oxidative machinery to switch among the main energetic substrates. However, instead of being used as an energy source, glucose performs an anaplerotic role in the oxidation of endogenous fatty acids, which become the main energetic substrate during infection. Taken together, the results shed light on metabolic mechanisms that may explain the profound alterations in lipid metabolism for severe dengue patients, contributing to the understanding of dengue physiopathology.

Influence of metformin and insulin on myocardial substrate oxidation under conditions encountered during cardiac surgery

BackgroundThe influence of diabetic therapies on myocardial substrate selection during cardiac surgery is unknown but may be important to ensure optimal surgical outcomes. We hypothesized that metformin and insulin alter myocardial substrate selection during cardiac surgery and may affect reperfusion cardiac function. MethodsRat hearts (n = 8 per group) were evaluated under 3 metabolic conditions: normokalemia, cardioplegia, or bypass. Groups were perfused with Krebs-Henseleit buffer in the presence of no additives, metformin, insulin, or both insulin and metformin. Perfusion buffer containing physiologic concentrations of energetic substrates with different carbon-13 (13C) labeling patterns were used to determine substrate oxidation preferences using 13C magnetic resonance spectroscopy and glutamate isotopomer analysis. Rate pressure product and oxygen consumption were measured. ResultsMyocardial function was not different between groups. For normokalemia, ketone oxidation was reduced in the presence of insulin and the combination of metformin and insulin reduced fatty acid oxidation. Metformin reduced fatty acid and ketone oxidation during cardioplegia. Fatty acid oxidation was increased in the bypass group compared with all other conditions. ConclusionMetformin and insulin affect substrate utilization and reduce fatty acid oxidation before reperfusion. These alterations in substrate oxidation did not affect myocardial function in otherwise normal hearts.

Rapid regulation of substrate use for oxidative phosphorylation during a single session of high intensity interval or aerobic exercises in different rat skeletal muscles.

Different exercise protocols lead to long-term adaptations that are related to increased mitochondrial content through the activation of mitochondrial biogenesis. However, immediate mitochondrial response to exercise and energetic substrate utilization is still unknown. We evaluate the mitochondrial physiology of two types rat skeletal muscle fibres immediately after a single session of high intensity interval exercise (HIIE) or aerobic exercise (AER). We found AER was able to reduce the ATP synthesis dependent oxygen flux in the tibialis (TA) when stimulated by complex I and II substrates. On the other hand, there was an increase of the maximum velocity (Vmax) for glycerol-phosphate oxidation and Vmax and affinity (KM) of palmitoyl-carnitine oxidation (PC). The exercise did not affect oxygen flux coupled to ATP synthesis in red gastrocnemius (RG) but, surprisingly, reduced its affinity for PC, decreasing the apparent catalytic efficiency (Vmax/KM) of oxidation for PC. Neither exercise protocol was able to change the electron transfer system capacity of the mitochondria or markers of mitochondrial content. The AER group had increased H2O2 production compared to the SED and HIIE groups, with the mechanism being predominantly the escape of electrons through reverse flux in complex I and other sites in TA, and only through other sites in RG. There were no changes in the activities of antioxidant enzymes. Our results show that mitochondria from different muscles submitted to distinct exercise protocols show alterations in the specific fluxes of substrate utilization and oxygen metabolism, indicating that the dynamics of mitochondria are linked to the metabolic flexibility.

Differential effects of AMP-activated protein kinase in isolated rat atria subjected to simulated ischemia-reperfusion depending on the energetic substrates available.

AMP-activated protein kinase (AMPK) is a serine-threonine kinase that functions primarily as a metabolic sensor to coordinate anabolic and catabolic processes in the cell, via phosphorylation of multiple proteins involved in metabolic pathways, aimed to re-establish energy homeostasis at a cell-autonomous level. Myocardial ischemia and reperfusion represents a metabolic stress situation for myocytes. Whether AMPK plays a critical role in the metabolic and functional responses involved in these conditions remains uncertain. In this study, in order to gain a deeper insight into the role of endogenous AMPK activation during myocardial ischemia and reperfusion, we explored the effects of the pharmacological inhibition of AMPK on contractile function rat, contractile reserve, tissue lactate production, tissue ATP content, and cellular viability. For this aim, isolated atria subjected to simulated 75min ischemia-75min reperfusion (Is-Rs) in the presence or absence of the pharmacological inhibitor of AMPK (compound C) were used. Since in most clinical situations of ischemia-reperfusion the heart is exposed to high levels of fatty acids, the influence of palmitate present in the incubation medium was also investigated. The present results suggest that AMPK activity significantly increases during Is, remaining activated during Rs. The results support that intrinsic activation of AMPK has functional protective effects in the reperfused atria when glucose is the only available energetic substrate whereas it is deleterious when palmitate is also available. Cellular viability was not affected by either of these conditions.

Role of brown adipose tissue in the pathogenesis of metabolic syndrome

Aim: Recent studies dealing with metabolic syndrome (MS) and related complications has been focused on brown adipose tissue (BAT), because depots of this tissue has been lately found in adult humans and because of its ability to degrade energetic substrates. However, the exact role of BAT in the pathogenesis of MS remains unclear. Here we study age-related changes of interscapular BAT (iBAT) activity of non-obese model of dyslipidemia and metabolic syndrome - hereditary hypertriglyceridemic rats (HHTg) in comparison with control rats Wistar. We further analyzed the effect iBAT extirpation on metabolic syndrome-related disorders.

Systemic effects of cAMP in chemotherapy for Heren’s carcinoma.

e14052 Background: Along with tumor itself, mechanisms of regulation of homeostasis are the target for tumor progression inhibition. The brain, various organs and tumor have different resources of energetic and metabolic substrates. Involvement of cyclic adenosine monophosphate (cAMP) into intimate mechanisms of proliferation, hormonal and energetic homeostasis indicates the possibility to use this factor in chemotherapy of tumors to improve the resistance of the organism. The purpose of the study was to analyze levels of endogenous cAMP in tumor and in organs as a criterium of systemic body response to chemotherapy with cAMP application. Methods: The study included 56 male Wistar rats with Heren’s carcinoma receiving peritumoral injections of cyclophosphan (CP) 50 mcg/kg (Baxter Oncology GmbH, Germany) alone and in combination with cAMP (Sigma-Aldrich, USA), P.O. at a concentration of 0.01%. cAMP levels in homogenates of organs and tumors were measured by immunoradiometric assay (Immunotech, Czech Republic) using Arian radiometer (Vitaco, Russia). Data were processed using Statistica 6. Results: cAMP levels in growing tumors in rats without treatment (the control) were maximal (7.03±1.5 nmol/L). CP injections alone during inhibition of carcinoma growth allowed the reduction of tumor cAMP level by 3.3 times. Combination of CP and cAMP resulted in tumor regression, and endogenous cAMP levels in tumor decreased by 10 times compared with the control. Similar dynamics of cAMP reductions was noted in the adrenal glands. The lungs, thymus, lymph nodes and especially the testes and the brain, on the contrary, showed accumulation of cAMP to the normal levels and higher. Conclusions: The range of cAMP levels in organs and tumors of rats receiving combination of CP and cAMP demonstrated the development of adaptive and regenerative processes in organs responsible for the neuroendocrine regulation, suppression of stimulation of stress-realizing systems and metabolic support of the processes of increasing non-specific antitumor resistance along with inhibited proliferative activity of tumors.

Metabolic Reprogramming in Glioma.

Many cancers have long been thought to primarily metabolize glucose for energy production—a phenomenon known as the Warburg Effect, after the classic studies of Otto Warburg in the early twentieth century. Yet cancer cells also utilize other substrates, such as amino acids and fatty acids, to produce raw materials for cellular maintenance and energetic currency to accomplish cellular tasks. The contribution of these substrates is increasingly appreciated in the context of glioma, the most common form of malignant brain tumor. Multiple catabolic pathways are used for energy production within glioma cells, and are linked in many ways to anabolic pathways supporting cellular function. For example: glycolysis both supports energy production and provides carbon skeletons for the synthesis of nucleic acids; meanwhile fatty acids are used both as energetic substrates and as raw materials for lipid membranes. Furthermore, bio-energetic pathways are connected to pro-oncogenic signaling within glioma cells. For example: AMPK signaling links catabolism with cell cycle progression; mTOR signaling contributes to metabolic flexibility and cancer cell survival; the electron transport chain produces ATP and reactive oxygen species (ROS) which act as signaling molecules; Hypoxia Inducible Factors (HIFs) mediate interactions with cells and vasculature within the tumor environment. Mutations in the tumor suppressor p53, and the tricarboxylic acid cycle enzymes Isocitrate Dehydrogenase 1 and 2 have been implicated in oncogenic signaling as well as establishing metabolic phenotypes in genetically-defined subsets of malignant glioma. These pathways critically contribute to tumor biology. The aim of this review is two-fold. Firstly, we present the current state of knowledge regarding the metabolic strategies employed by malignant glioma cells, including aerobic glycolysis; the pentose phosphate pathway; one-carbon metabolism; the tricarboxylic acid cycle, which is central to amino acid metabolism; oxidative phosphorylation; and fatty acid metabolism, which significantly contributes to energy production in glioma cells. Secondly, we highlight processes (including the Randle Effect, AMPK signaling, mTOR activation, etc.) which are understood to link bio-energetic pathways with oncogenic signals, thereby allowing the glioma cell to achieve a pro-malignant state.

Effects of Glutamate Receptor Activation on Local Oxygen Changes.

Glutamate is ubiquitous throughout the brain and serves as the primary excitatory neurotransmitter. Neurons require energy to fire, and energetic substrates (i.e., O2, glucose) are renewed via cerebral blood flow (CBF) to maintain metabolic homeostasis. Magnetic resonance brain functionality studies rely on the assumption that CBF and neuronal activity are coupled consistently throughout the brain; however, the origin of neuronal activity does not always coincide with signals indicative of energy consumption (e.g., O2 decreases) at high spatial resolutions. Therefore, relationships between excitatory neurotransmission and energy use must be evaluated at higher resolutions. In this study, we showed that both endogenously released and exogenously ejected glutamate decrease local tissue O2 concentrations, but whether hyperemic O2 restoration followed depended on the stimulus method. Electrically stimulating the glutamatergic corticostriatal pathway evoked biphasic O2 responses at striatal terminals: first O2 decreased, then concentrations increased above baseline. Using iontophoresis to locally eject ionotropic glutamate receptor antagonists revealed that these receptors only influenced the O2 decrease. We compared electrical stimulation to iontophoretic glutamate stimulation, and measured concurrent single-unit activity and O2 to limit both stimulation and recordings to <50 μm radius from our sensor. Similarly, iontophoretic glutamate delivery elicited monophasic O2 decreases without subsequent increases.

The desert gerbil Psammomys obesus as a model for metformin-sensitive nutritional type 2 diabetes to protect hepatocellular metabolic damage: Impact of mitochondrial redox state.

IntroductionWhile metformin (MET) is the most widely prescribed antidiabetic drug worldwide, its beneficial effects in Psammomys obesus (P. obesus), a rodent model that mimics most of the metabolic features of human diabetes, have not been explored thoroughly. Here, we sought to investigate whether MET might improve insulin sensitivity, glucose homeostasis, lipid profile as well as cellular redox and energy balance in P. obesus maintained on a high energy diet (HED).Materials and methodsP. obesus gerbils were randomly assigned to receive either a natural diet (ND) consisting of halophytic plants (control group) or a HED (diabetic group) for a period of 24 weeks. MET (50 mg/kg per os) was administered in both animal groups after 12 weeks of feeding, i.e., the time required for the manifestation of insulin resistance in P. obesus fed a HED. Parallel in vitro experiments were conducted on isolated hepatocytes that were shortly incubated (30 min) with MET and energetic substrates (lactate + pyruvate or alanine, in the presence of octanoate).ResultsIn vivo, MET lowered glycemia, glycosylated haemoglobin, circulating insulin and fatty acid levels in diabetic P. obesus. It also largely reversed HED-induced hepatic lipid alterations. In vitro, MET increased glycolysis but decreased both gluconeogenesis and ketogenesis in the presence of glucogenic precursors and medium-chain fatty acid. Importantly, these changes were associated with an increase in cytosolic and mitochondrial redox states along with a decline in respiration capacity.ConclusionsMET prevents the progression of insulin resistance in diabetes-prone P. obesus, possibly through a tight control of gluconeogenesis and fatty acid β-oxidation depending upon mitochondrial function. While the latter is increasingly becoming a therapeutic issue in diabetes, the gut microbiota is another promising target that would need to be considered as well.

Characterization of the Pro-Inflammatory Cytokine IL-1β on Butyrate Oxidation in Colorectal Cancer Cells.

Cancer, in part, is driven, by alterations in cellular metabolism that promote cell survival and cell proliferation. Identifying factors that influence this shift in cellular metabolism in cancer cells is important. Interleukin-1β (IL-1β) is a pro-inflammatory cytokine that has been reported to be elevated in colorectal cancer patients. While much is known toward the effect of dietary nutrients on regulating inflammation and the inflammatory response, which includes cytokines such as IL-1β, far less is understood how cytokines impact nutrient fate to alter cancer cell metabolism. Butyrate, a nutrient derived from the fermentation of dietary fiber in the colon, is the preferential exogenous energetic substrate used by non-cancerous colonocytes, but is used less efficiently by colorectal cancer cells. To test whether IL-1β alters colonocyte energy metabolism, we measured butyrate oxidation in HCT116 colorectal cancer cells with and without IL-1β. We hypothesize that IL-1β will push cancerous colonocytes away from the utilization and oxidation of butyrate. In this study, we demonstrate that pretreatment of colorectal cancer cells with IL-1β diminished butyrate oxidation and NADH levels. This effect was blocked with the interleukin receptor antagonist A (IL-1RA). Moreover, IL-1β suppressed basal mitochondrial respiration and lowered the mitochondrial spare capacity. By using inhibitors to block downstream targets of the interleukin-1 receptor pathway, we show that p38 is required for the IL-1β-mediated decrease in butyrate oxidation. These data provide insight into the metabolic effects induced by IL-1β in colorectal cancer, and identify relevant targets that may be exploited to block the effects of this cytokine. J. Cell. Biochem. 118: 1614-1621, 2017. © 2016 Wiley Periodicals, Inc.

Our hungry brain: Which role do glial cells play for the energy supply?

Abstract:Our brain, which accounts for about 2 % of our body weight, uses up to 20 % of our total energy requirements. The supply with sufficient energetic substrates to all brain cells, which are very densely packed, in particular in the human brain, is a huge logistic challenge. The most important energy substrate for our brain is glucose, which reaches the brain via the blood circulation. Glucose is not only utilized by nerve cells directly, but to a large extent also taken up by glial cells, which then either store glucose after conversion to glycogen as energy reserve, or transfer it as lactate to nerve cells. Lactate in nerve cells can then be converted to pyruvate, which is efficiently utilized together with oxygen for the formation of chemical energy in form of ATP. The intermediate metabolic product lactate hence plays an important role as energetic substrate, which is exchanged between cells both under aerobic and non-aerobic conditions. Transport of lactate across the cell membrane is carried out in co-transport with protons (H+), which are crucial regulators of various metabolic processes and membrane transporters. In addition, the lactate carriers form a functional network with carbonic anhydrases, enzymes, which not only catalyze the equilibrium between carbon dioxide, hydrogen carbonate (bicarbonate) and protons, but also facilitate lactate transport. In this article, we focus on physiological processes of the energy metabolism in glial cells as well as on the transfer of energetic substrates to nerve cells, processes, which themselves are critically modulated by pH and its regulation in glial cells.

Regulation of Pyruvate Dehydrogenase Kinase 4 in the Heart through Degradation by the Lon Protease in Response to Mitochondrial Substrate Availability

Cardiac metabolic inflexibility is driven by robust up-regulation of pyruvate dehydrogenase kinase 4 (PDK4) and phosphorylation-dependent inhibition of pyruvate dehydrogenase (PDH) within a single day of feeding mice a high fat diet. In the current study, we have discovered that PDK4 is a short lived protein (t½ ∼ 1 h) and is specifically degraded by the mitochondrial protease Lon. Lon does not rapidly degrade PDK1 and -2, indicating specificity toward the PDK isoform that is a potent modulator of metabolic flexibility. Moreover, PDK4 degradation appears regulated by dissociation from the PDH complex dependent on the respiratory state and energetic substrate availability of mouse heart mitochondria. Finally, we demonstrate that pharmacologic inhibition of PDK4 promotes PDK4 degradation in vitro and in vivo These findings reveal a novel strategy to manipulate PDH activity by selectively targeting PDK4 content through dissociation and proteolysis.

Cetoacidosis diabética en niños

La cetoacidosis diabética es la complicación aguda de la diabetes más frecuente, con una alta incidencia en la población pediátrica, múltiples desencadenantes y un alto costo al sistema de salud. El punto de partida fisiopatológico es el déficit absoluto o relativo de la insulina que lleva a un incremento de las hormonas contrarreguladoras para obtener el substrato energético a partir de la glucogenólisis, la gluconeogénesis, la lipólisis y la proteólisis. Lo anterior genera un aumento de los cuerpos cetónicos que produce acidosis metabólica con una importante deshidratación y trastorno electrolítico que en conjunto exacerban y perpetúan la disfunción metabólica. El tratamiento de esta entidad tiene como base la insulinoterapia por vía intravenosa o subcutánea, incluso cuando se han alcanzado niveles óptimos de glucemia, y una hidratación adecuada. La transición a insulina subcutánea al detener el goteo de insulina es importante para prevenir la recurrencia de la cetoacidosis diabética. Con este manuscrito se pretende brindar al lector una revisión actualizada de un tema de alta relevancia clínica, que sirva como herramienta al momento de ejercer un enfoque diagnóstico y terapéutico de la cetoacidosis diabética.

Seipin deficiency alters brown adipose tissue thermogenesis and insulin sensitivity in a non-cell autonomous mode.

Loss-of-function mutations in BSCL2 are responsible for Berardinelli-Seip congenital lipodystrophy, a rare disorder characterized by near absence of adipose tissue associated with insulin resistance. Seipin-deficient (Bscl2−/−) mice display an almost total loss of white adipose tissue (WAT) with residual brown adipose tissue (BAT). Previous cellular studies have shown that seipin deficiency alters white adipocyte differentiation. In this study, we aimed to decipher the consequences of seipin deficiency in BAT. Using a brown adipocyte cell-line, we show that seipin knockdown had very little effect on adipocyte differentiation without affecting insulin sensitivity and oxygen consumption. However, when submitted to cold acclimation or chronic β3 agonist treatment, Bscl2−/− mice displayed altered thermogenic capacity, despite several signs of BAT remodeling. Under cold activation, Bscl2−/− mice were able to maintain their body temperature when fed ad libitum, but not under short fasting. At control temperature (i.e. 21 °C), fasting worsened Bscl2−/− BAT properties. Finally, Bscl2−/− BAT displayed obvious signs of insulin resistance. Our results in these lipodystrophic mice strongly suggest that BAT activity relies on WAT as an energetic substrate provider and adipokine-producing organ. Therefore, the WAT/BAT dialogue is a key component of BAT integrity in guaranteeing its response to insulin and cold-activated adrenergic signals.

Oxidative status of the myocardium in response to different intensities of physical training.

The intensity of exercise determines the metabolic pathway and the energetic substrate that is spent. Our study sought to identify the effects of different intensities of swimming on myocardial oxidative status and the blood lipid profile. Eighty Wistar rats (male and female) submitted to different intensities of a swimming regimen (low, LS; moderate, MS; or high, HS) for 16 weeks. Samples of blood and myocardium from the left ventricle were collected to determine lipid profiles and oxidative status. Reactive oxygen species (ROS) and antioxidant capacity against peroxyl radicals (ACAP), lipid profiles and lipid peroxidation was analyzed. ROS levels and ACAP were higher in male rats than in female rats overall (p<0.05). However, ACAP in the myocardium was significantly elevated in LS female rats compared to the MS and HS female rats, which had a significantly lower ACAP compared to all other groups. LS and MS training in both sexes and HS training (in females) led to significant decreases in the heart's lipid peroxidation. Amelioration of the lipid profile and reduction in oxidative damage contributed to a physiological state that benefits cardiovascular function in exercised animals. The results show that low and moderate intensity exercise promotes beneficial adaptations.

Short fasting does not protect perfused ex vivo rat liver against ischemia-reperfusion. On the importance of a minimal cell energy charge

ObjectiveDietary restriction or reduced food intake was supported to protect against renal and hepatic ischemic injury. In this vein, short fasting was recently shown to protect in situ rat liver against ischemia-reperfusion. Here, perfused ex vivo instead of in situ livers were exposed to ischemia-reperfusion to study the impact of disconnecting liver from extrahepatic supply in energetic substrates on the protection given by short-term fasting. MethodsPerfused ex vivo livers using short (18 h) fasted compared with fed rats were submitted to ischemia-reperfusion and studied for release of cytolysis markers in the perfusate. Energetic stores are differently available in time and cell energetic charges (ratio of adenosine triphosphate plus half of the adenosine diphosphate concentrations to the sum of adenosine triphosphate + adenosine diphosphate + adenosine monophosphate concentrations), adenosine phosphates, and glycogen, which were further measured at different time points in livers. ResultsShort fasting versus feeding failed to protect perfused ex vivo rat livers against ischemia/reperfusion, increasing the release of cytolysis markers (potassium, cytochrome c, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) in the perfusate during reoxygenation phase. Toxicity of short fasting versus feeding was associated with lower glycogen and energetic charges in livers and lower lactate levels in the perfusate. ConclusionHigh energetic charge, intracellular content in glycogen, and glycolytic activity may protect liver against ischemia/reperfusion injury. This work does not question how much the protective role previously demonstrated in the literature for dietary restriction and short fasting. In fact, it suggests that exceeding the energy charge threshold value of 0.3 might trigger the effectiveness of this protective role.

Solute Carriers in the Blood-Brain Barier: Safety in Abundance.

Blood-brain barrier formed by brain capillary endothelial cells, being in contact with astrocytes endfeet and pericytes, separates extracellular fluid from plasma. Supply of necessary nutrients and removal of certain metabolites takes place due to the activity of transporting proteins from ABC (ATP binding cassette) and SLC (solute carrier) superfamilies. This review is focused on the SLC families involved in transport though the blood-brain barrier of energetic substrates (glucose, monocarboxylates, creatine), amino acids, neurotransmitters and their precursors, as well as organic ions. Members of SLC1, SLC2, SLC3/SLC7, SLC5, SLC6, SLC16, SLC22, SLC38, SLC44, SLC47 and SLCO (SLC21), whose presence in the blood-brain barriers has been demonstrated are characterized with a special emphasis put on polarity of transporters localization in a luminal (blood side) versus an abluminal (brain side) membrane.

Abstract 35: Breast cancer metabolism: Are ketone bodies energetic substrates

Abstract Cancer cell metabolism differs from non-transformed cells in that cancer cells do not employ oxidative phosphorylation for ATP-production from glucose even in the presence of adequate oxygen concentrations. This conjecture increases the cancer cell's reliance on glucose, potentially reducing the cancer cell's ability to utilize non-glucose substrates. The main alternative to glucose are high-energy breakdown products of hepatic lipid metabolism, collectively termed ketone bodies. Non-transformed cells are able to metabolize ketone bodies to form ATP, but the role of ketone bodies’ metabolism in human breast cancer cells is unclear, since it relies on metabolic functions downstream of glucose metabolism. Here we aimed to determine if human breast cancer cells will utilize ketone bodies (beta-hydroxybuterate) as energy substrate in the absence of glucose. Cell proliferation of MDA-MB-231 and MCF-7 human breast cancer cells was measured after 48 h or 72 h of treatment using an MTT-Assay. Treatment conditions were various glucose concentrations (4.5 g/l to 0 g/l) and 25 nM beta-hydroxybuterate (BHB) for all cells after overnight serum starvation. After 48 h, cell proliferation decreased to 47% (p&amp;lt;0.001) in no glucose medium compared to proliferation observed for cells in 4.5 g/l glucose for MDA-MB-231 cells. Cell proliferation at glucose concentrations as low as 0.125 g/l did not change cell proliferation in these cells. After 48 h, cell proliferation of MCF-7 cells decreased to 24% (p&amp;lt;0.001) for cells treated with 0 g/l glucose, to 83% (p = 0.0078) for cells treated with 0.125 g/l glucose and to 87% (p = 0.0108) for cells treated with 0.25 g/l glucose. After 72 h, cell proliferation decreased to 30.5% (p&amp;lt;0.001) after treatment with no glucose compared to proliferation observed for cells in 4.5 g/l glucose for MDA-MB-231 cells. Cell proliferation at glucose concentrations as low as 0.125 g/l did not significantly change cell proliferation in these cells. After 72 h, cell proliferation of MCF-7 cells decreased to 22% (p&amp;lt;0.001) for cells treated with 0 g/l glucose and to 74% (p = 0.0288) for cells treated with 0.125 g/l glucose compared to proliferation observed for cells in 4.5 g/l glucose. All conditions and time points had been supplemented with 25 nM BHB. These preliminary results indicate that human breast cancer cells are not able to use ketone bodies as energy substrates in the absence of glucose. An additional finding was also that more aggressive, triple-negative breast cancer cells are able to survive with very low glucose conditions. Pending further investigation, this may provide a rationale for dietary carbohydrate restriction as neoadjuvant therapy for breast cancer patients, but may necessitate further glucose restrictions than what can be achieved through diet alone. Citation Format: Alyssa M. Dixon, Michael Weichhaus. Breast cancer metabolism: Are ketone bodies energetic substrates. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 35.

Short-term ubiquinol supplementation reduces oxidative stress associated with strenuous exercise in healthy adults: A randomized trial.

Studies about Coenzyme Q10 (CoQ10 ) supplementation on strenuous exercise are scarce, especially those related with oxidative stress associated with physical activity and virtually nonexistent with the reduced form, Ubiquinol. The objective of this study was to determine, for the first time, whether a short-term supplementation with Ubiquinol can prevent oxidative stress associated to strenuous exercise. The participants (n = 100 healthy and well trained, but not on an elite level) were classified in two groups: Ubiquinol (experimental group), and placebo group (control). The protocol consisted of conducting two identical strenuous exercise tests with a rest period between tests of 24 h. Blood and urine samples were collected from the participants before supplementation (basal value) (T1), after supplementation (2 weeks) (T2), after first physical exercise test (T3), after 24 h of rest (T4), and after second physical exercise test (T5).The increase observed in the lactate, isoprostanes, DNA damage, and hydroperoxide levels reveals the severity of the oxidative damage induced by the exercise. There was a reduction in the isoprostanes, 8-OHdG, oxidized LDL, and hydroperoxydes in the supplemented Ubiquinol group, an increase in total antioxidant status, fat soluble antioxidant (both plasma and membrane), and CAT activity. Also, NO in the Ubiquinol-supplemented group was maintained within a narrow range. Oxidative stress induced by strenuous exercise is accumulative and increases transiently in subsequent sessions of physical activity. A short-term supplementation (2 weeks) with Ubiquinol (200 mg/day) before strenuous exercise, decreases oxidative stress and increases plasma NO, fact that could improve endothelial function, energetic substrate supply, and muscle recovery after strenuous exercise. © 2016 BioFactors, 42(6):612-622, 2016.

Robust Brain Hyperglycemia during General Anesthesia: Relationships with Metabolic Brain Inhibition and Vasodilation.

Glucose is the main energetic substrate for the metabolic activity of brain cells and its proper delivery into the extracellular space is essential for maintaining normal neural functions. Under physiological conditions, glucose continuously enters the extracellular space from arterial blood via gradient-dependent facilitated diffusion governed by the GLUT-1 transporters. Due to this gradient-dependent mechanism, glucose levels rise in the brain after consumption of glucose-containing foods and drinks. Glucose entry is also accelerated due to local neuronal activation and neuro-vascular coupling, resulting in transient hyperglycemia to prevent any metabolic deficit. Here, we explored another mechanism that is activated during general anesthesia and results in significant brain hyperglycemia. By using enzyme-based glucose biosensors we demonstrate that glucose levels in the nucleus accumbens (NAc) strongly increase after iv injection of Equthesin, a mixture of chloral hydrate and sodium pentobarbital, which is often used for general anesthesia in rats. By combining electrochemical recordings with brain, muscle, and skin temperature monitoring, we show that the gradual increase in brain glucose occurring during the development of general anesthesia tightly correlate with decreases in brain-muscle temperature differentials, suggesting that this rise in glucose is related to metabolic inhibition. While the decreased consumption of glucose by brain cells could contribute to the development of hyperglycemia, an exceptionally strong positive correlation (r = 0.99) between glucose rise and increases in skin-muscle temperature differentials was also found, suggesting the strong vasodilation of cerebral vessels as the primary mechanism for accelerated entry of glucose into brain tissue. Our present data could explain drastic differences in basal glucose levels found in awake and anesthetized animal preparations. They also suggest that glucose entry into brain tissue could be strongly modulated by pharmacological drugs via drug-induced changes in metabolic activity and the tone of cerebral vessels.