Role of mitochondrial antioxidant defense systems in fatty acid β-oxidation defects

Mitochondrial fatty acid oxidation (FAO) plays a pivotal role in energy homeostasis, namely during periods of fasting or metabolic stress. FAO defects are a group of inherited metabolic disorders that encompass at least twelve distinct enzyme or transporter deficiencies, and can present with a wide range of clinical symptoms with various degrees of severity. Besides recent advances, many doubts still remain on the degree and characteristics of mitochondrial dysfunction on FAOD and its contribution to the clinical phenotype.

Cannabinoids impact on pregnancy: effects in trophoblast cells

Cannabinoids (CBs) can be classified as: phytocannabinoids, the constituents of the Cannabis sativa plant; synthetic cannabinoids lab-synthesized and the endocannabinoids that are endogenous lipid mediators. Cannabinoid compounds activate cannabinoid receptors – CB1 and CB2. The most prevalent psychoactive phytocannabinoid is Δ9tetrahydrocannabinol (THC), but more than 60 different CBs were already identified in the plant. The best characterized endocannabinoids (eCBs) are anandamide (AEA) and 2arachidonoylglycerol (2-AG), that are involved in several physiological processes including synaptic plasticity, pain modulation, energy homeostasis and reproduction. On the other hand, some synthetic cannabinoids that were initially designed for medical research, are now used as drugs of abuse. During the period of placental development, highly dynamic processes of remodeling occur, involving proliferation, apoptosis, differentiation and invasion of trophoblasts. It is known that a tight control of eCBs levels is required for normal pregnancy progression and that eCBs are involved in trophoblast cells turnover. Therefore, by sharing activation of the same receptors, exposure to exocannabinoids either by recreational or medicinal use may lead to alterations in the eCBs levels and in the endocannabinoid system homeostasis In this work, it was studied the impact of CBs in BeWo trophoblastic cells and in primary cultures of human cytotrophoblasts. Cells were treated for 24 hours with different concentrations of THC, the synthetic cannabinoid WIN‐55,212 (WIN) and 2-AG. Treatment with THC did not affect BeWo cells viability while WIN and 2-AG caused a dose-dependent viability loss. Morphological studies together with biochemical markers indicate that 2-AG is able to induce apoptosis in cytotrophoblasts. On the other hand, morphological studies after acridine orange staining suggest that autophagy may take part in WIN-induced loss of cell viability. All cannabinoids caused a decrease in mitochondrial membrane potential (Δψm) but only 2-AG led to ROS/RNS generation, though no changes in glutathione levels were observed. In addition, ER-stress may be involved in the 2-AG induced-oxidative stress, as preliminary results point to an increase in CCAAT-enhancer-binding protein homologous protein (CHOP) expression. Besides the decrease in cell viability, alterations in cell cycle progression were observed. WIN treatment induced a cell cycle arrest in G0/G1 phase, whereas 2-AG induced a cell cycle arrest in G2/M phase. Here it is reinforced the relevance of cannabinoid signaling in fundamental processes of cell proliferation and cell death in trophoblast cells. Since cannabis-based drugs are the most consumed illicit drugs worldwide and some of the most consumed recreational drugs by pregnant women, this study may contribute to the understanding of the impact of such substances in human reproduction.

Le rôle des acides gras oméga-3 sur la balance énergétique, la régulation de l’appétit, l’état émotionnel et l’implication du récepteur GPR120

L’obésité est un facteur de risque lié à des problèmes physiques, émotionnels et comportementaux. Aujourd’hui, l’alimentation est composée d’un régime typiquement occidental «Western diet» qui est riche en acides gras saturés (AGS) et pauvre en acides gras polyinsaturés (AGPI) tel que les oméga-3 (N-3) et occasionnant un déséquilibre du ratio alimentaire N-6/N-3. Ce déséquilibre est une des causes de la prévalence des maladies mentales y compris celles des troubles de l'humeur et de l’anxiété. L’acide docosahexaénoïque (ADH, 22: 6 n-3) est l’acide gras (AG) le plus abondant dans le cerveau et son accumulation est particulièrement élevée pendant la période périnatale. Il joue un rôle important dans le développement neuronal et d'autres fonctions du cerveau tel l'apprentissage et la mémoire. Des perturbations de l’environnement périnatal peuvent influencer à très long terme l’avenir de la descendance en la rendant plus susceptible de développer des problèmes d’obésité dans un contexte nutritionnel riche. On ignore cependant si le déficit alimentaire chez la mère et particulièrement en ADH aura un impact sur la motivation alimentaire de la progéniture. L’objectif principal de cette thèse est d’étudier le rôle potentiel des N-3 sur la balance énergétique, la motivation alimentaire, la dépression et le niveau d’anxiété des descendants de souris mâles adultes assujetties à une alimentation riche en gras. Nos données ont démontré qu‘un régime maternel déficitaire en ADH durant la période périnatale incitait la descendance à fournir plus d’effort afin d’obtenir un aliment palatable. Ceci entraînerait un dérèglement de l’homéostasie énergétique en augmentant le gain de poids et en diminuant l’activité locomotrice tout en exacerbant le comportement de type anxieux dès que les souris sont exposées à un milieu obésogène. Les acides gras libres (AGL) sont des nutriments essentiels fonctionnant comme des molécules de signalisation dans le cerveau en ayant des récepteurs qui jouent un rôle important dans le contrôle du métabolisme énergétique. Parmi eux, on distingue un récepteur couplé à la protéine G (GPCR), le GPR120. Ce récepteur activé par les AGPI ω-3 intervient dans les mécanismes anti-inflammatoires et insulino-résistants via les N-3. Une mutation dans le gène GPR120 occasionnée par une réduction de l’activité de signalisation du gène est liée à l’obésité humaine. L'objectif premier de cette deuxième étude était d’évaluer l'impact de la stimulation pharmacologique de GPR120 dans le système nerveux central (SNC) sur l'alimentation, les dépenses d'énergie, le comportement de type anxieux et la récompense alimentaire. Nos résultats démontrent qu’une injection centrale aiguë d'agoniste GPR120 III réduit la prise alimentaire ad libitum et la motivation alimentaire pour un aliment riche en gras et en sucre; ainsi que les comportements de type anxieux. L’injection centrale chronique (21 jours) de ce même agoniste GPR120 III transmis par une pompe osmotique a démontré que les souris placées sous diète hypercalorique (HFD n’ont présenté aucune modification lors de la prise alimentaire ni de gain de poids mais qu’il y avait comparativement au groupe de véhicule, une réduction du comportement de type anxieux, que ce soit dans le labyrinthe en croix surélevé (LCS) ou dans le test à champ ouvert (OFT). L’ADH est reconnu pour ses propriétés anorexigènes au niveau central. De plus, la stimulation des récepteurs de GPR120 au niveau du cerveau avec un agoniste synthétique peut produire un effet intense intervenir sur le comportement lié à l'alimentation des rongeurs. Trouver une approche visant à contrôler à la fois la neuroinflammation, la récompense alimentaire et les troubles émotionnels aiderait assurément au traitement de l'obésité et du diabète de type 2.

Fibroblast growth factors:new insights, new targets in the management of diabetes

The fibroblast growth factor (FGF) family consists of 22 evolutionarily and structurally related proteins (FGF1 to FGF23; with FGF15 being the rodent ortholog of human FGF19). Based on their mechanism of action, FGFs can be categorized into intracrine, autocrine/paracrine and endocrine subgroups. Both autocrine/paracrine and endocrine FGFs are secreted from their cells of origin and exert their effects on target cells by binding to and activating specific single-pass transmembrane tyrosine kinase receptors (FGFRs). Moreover, FGF binding to FGFRs requires specific cofactors, namely heparin/heparan sulfate proteoglycans or Klothos for autocrine/paracrine and endocrine FGF signaling, respectively. FGFs are vital for embryonic development and mediate a broad spectrum of biological functions, ranging from cellular excitability to angiogenesis and tissue regeneration. Over the past decade certain FGFs (e.g. FGF1, FGF10, FGF15/FGF19 and FGF21) have been further recognized as regulators of energy homeostasis, metabolism and adipogenesis, constituting novel therapeutic targets for obesity and obesity-related cardiometabolic disease. Until recently, translational research has been mainly focused on FGF21, due to the pleiotropic, beneficial metabolic actions and the relatively benign safety profile of its engineered variants. However, increasing evidence regarding the role of additional FGFs in the regulation of metabolic homeostasis and recent developments regarding novel, engineered FGF variants have revitalized the research interest into the therapeutic potential of certain additional FGFs (e.g. FGF1 and FGF15/FGF19). This review presents a brief overview of the FGF family, describing the mode of action of the different FGFs subgroups, and focuses on FGF1 and FGF15/FGF19, which appear to also represent promising new targets for the treatment of obesity and type 2 diabetes.

Leptin modifies the prosecretory and prokinetic effects of the inflammatory cytokine interleukin-6 on colonic function in Sprague–Dawley rats

Leptin ameliorates the prosecretory and prokinetic effects of the pro-inflammatory cytokine interleukin-6 on rat colon. Leptin also suppresses the neurostimulatory effects of irritable bowel syndrome plasma, which has elevated concentrations of interleukin-6, on enteric neurons. This may indicate a regulatory role for leptin in immune-mediated bowel dysfunction. In addition to its role in regulating energy homeostasis, the adipokine leptin modifies gastrointestinal (GI) function. Indeed, leptin-resistant obese humans and leptin-deficient obese mice exhibit altered GI motility. In the functional GI disorder irritable bowel syndrome (IBS), circulating leptin concentrations are reported to differ from those of healthy control subjects. Additionally, IBS patients display altered cytokine profiles, including elevated circulating concentrations of the pro-inflammatory cytokine interleukin-6 (IL-6), which bears structural homology and similarities in intracellular signalling to leptin. This study aimed to investigate interactions between leptin and IL-6 in colonic neurons and their possible contribution to IBS pathophysiology. The functional effects of leptin and IL-6 on colonic contractility and absorptosecretory function were assessed in organ baths and Ussing chambers in Sprague–Dawley rat colon. Calcium imaging and immunohistochemical techniques were used to investigate the neural regulation of GI function by these signalling molecules. Our findings provide a neuromodulatory role for leptin in submucosal neurons, where it inhibited the stimulatory effects of IL-6. Functionally, this translated to suppression of IL-6-evoked potentiation of veratridine-induced secretory currents. Leptin also attenuated IL-6-induced colonic contractions, although it had little direct effect on myenteric neurons. Calcium responses evoked by IBS plasma in both myenteric and submucosal neurons were also suppressed by leptin, possibly through interactions with IL-6, which is elevated in IBS plasma. As leptin has the capacity to ameliorate the neurostimulatory effects of soluble mediators in IBS plasma and modulated IL-6-evoked changes in bowel function, leptin may have a role in immune-mediated bowel dysfunction in IBS patients.

Regulation of prostate cancer cell function by activators of AMP-activated protein kinase

AMP-activated protein kinase (AMPK) is a key regulator of cell energy homeostasis. More recently, it has become apparent that AMPK regulates cell proliferation, migration and inflammation. Previous evidence has suggested that AMPK may influence proliferation and invasion by regulating the pro-proliferative mitogen-activated protein kinases (MAPKs). However, the mechanisms underlying this crosstalk between AMPK and MAPK signalling are not fully understood. As AMPK activation has been reported to have anti-proliferative effects, there has been increasing interest in AMPK activation as a therapeutic target for tumourigenesis. The aim of this study was to investigate whether AMPK activation influenced prostate cancer (PC) cell line proliferation, migration and signalling. Therefore, different PC cell lines were incubated with two structurally-unrelated molecules that activate AMPK by different mechanisms, AICAR and A769662. Both chemicals activated AMPK in a concentration- and time-dependent manner in PC3, DU145 and LNCaP cell lines. AMPK activity as assessed by AMPK activating phosphorylation as well as phosphorylation of the AMPK substrate ACC increased along with tumour severity in PC biopsies. Furthermore, both activators of AMPK decreased cell proliferation and migration in the androgen-independent PC cell lines PC3 and DU145. Inhibition of proliferation by A769662 was attenuated in AMPK α1-/- AMPK α2-/- knockout (KO) mouse embryonic fibroblasts (MEFs) compared to wild type (WT) MEFs, and the inhibitory effect on migration of AICAR lost significance in PC3 cells infected with adenoviruses expressing a dominant negative AMPK α mutant, indicating these effects are partially mediated by AMPK. Furthermore, long-term activation of AMPK was associated with inhibition of both the phosphatidylinositol 3’-kinase/protein kinase B (PI3K/Akt) signalling pathway in addition to the extracellular signal-regulated kinase 1/2 (ERK1/2) signalling pathway. Indeed, the actions of AMPK activators on PC cell line viability were mimicked by selective inhibitors of Akt and ERK1/2 pathways. In contrast to the effects of prolonged incubation with AMPK activators, short-term incubation with AMPK activators had no effect on epidermal growth factor (EGF)-stimulated ERK1/2 phosphorylation in PC cell lines. In addition, AMPK activation did not influence phosphorylation of the other MAPK family members p38 and JNK. Interestingly, both AICAR and A769662 decreased EGF-stimulated ERK5 phosphorylation in PC3, DU145 and LNCaP cells as assessed with an anti-phospho-ERK5 antibody. Further characterisation of this effect indicated that prior stimulation with the AMPK activators had no effect on ERK5 phosphorylation stimulated by transient transfection with a constitutively active ERK5 kinase (MEK5DD), which represents the only known canonical kinase for ERK5. Intriguingly, the pattern of EGF-stimulated ERK5 phosphorylation was distinct from that mediated by MEK5DD activation of ERK5. This finding indicates that AMPK activation inhibits EGF-stimulated ERK5 phosphorylation at a point at or above the level of MEK5, although why EGF and constitutively active MEK5 stimulate markedly different immunoreactive species recognised by the anti-phospho-ERK5 antibody requires further study. A769662 had a tendency to reduce EGF-stimulated ERK5 phosphorylation in WT MEFs, yet was without effect in MEFs lacking AMPK. These data indicate that AMPK may underlie the effect of A769662 to reduce EGF-stimulated ERK5 phosphorylation. Prolonged stimulation of PC cell lines with AICAR or A769662 inhibited EGF-stimulated Akt Ser473 phosphorylation, whereas only incubation with A769662 rapidly inhibited Akt phosphorylation. This difference in the actions of the different AMPK activators may suggest an AMPK-independent effect of A769662. Furthermore, AICAR increased phosphorylation of Akt in WT MEFs, an effect that was absent in MEFs lacking AMPK, indicating that this effect of AICAR may be AMPK-dependent. Taken together, the data presented in this study suggest that AMPK activators markedly inhibit proliferation and migration of PC cell lines, reduce EGF-stimulated ERK1/2 and Akt phosphorylation after prolonged incubation and rapidly inhibit ERK5 phosphorylation. Both AMPK activators exhibit a number of effects that are likely to be independent of AMPK in PC cell lines, although inhibition of ERK1/2, ERK5 and Akt may underlie the effects of AMPK activators on proliferation, viability and migration. Further studies are required to understand the crosstalk between those signalling pathways and their underlying significance in PC progression.

Cellular Mechanisms of Sleep Homeostasis : Studies on Brain Energy Metabolism and Aging

Sleep is governed by a homeostatic process in which the duration and quality of previous wake regulate the subsequent sleep. Active wakefulness is characterized with high frequency cortical oscillations and depends on stimulating influence of the arousal systems, such as the cholinergic basal forebrain (BF), while cessation of the activity in the arousal systems is required for slow wave sleep (SWS) to occur. The site-specific accumulation of adenosine (a by-product of ATP breakdown) in the BF during prolonged waking /sleep deprivation (SD) is known to induce sleep, thus coupling energy demand to sleep promotion. The adenosine release in the BF is accompanied with increases in extracellular lactate and nitric oxide (NO) levels. This thesis was aimed at further understanding the cellular processes by which the BF is involved in sleep-wake regulation and how these processes are affected by aging. The BF function was studied simultaneously at three levels of organization: 1) locally at a cellular level by measuring energy metabolites 2) globally at a cortical level (the out-put area of the BF) by measuring EEG oscillations and 3) at a behavioral level by studying changes in vigilance states. Study I showed that wake-promoting BF activation, particularly with glutamate receptor agonist N-methyl-D-aspatate (NMDA), increased extracellular adenosine and lactate levels and led to a homeostatic increase in the subsequent sleep. Blocking NMDA activation during SD reduced the high frequency (HF) EEG theta (7-9 Hz) power and attenuated the subsequent sleep. In aging, activation of the BF during SD or experimentally with NMDA (studies III, IV), did not induce lactate or adenosine release and the increases in the HF EEG theta power during SD and SWS during the subsequent sleep were attenuated as compared to the young. These findings implicate that increased or continuous BF activity is important for active wake maintenance during SD as well as for the generation of homeostatic sleep pressure, and that in aging these mechanisms are impaired. Study II found that induction of the inducible NO synthase (iNOS) during SD is accompanied with activation of the AMP-activated protein kinase (AMPK) in the BF. Because decreased cellular energy charge is the most common cause for AMPK activation, this finding implicates that the BF is selectively sensitive to the metabolic demands of SD as increases were not found in the cortex. In aging (study III), iNOS expression and extracellular levels of NO and adenosine were not significantly increased during SD in the BF. Furthermore, infusion of NO donor into the BF did not lead to sleep promotion as it did in the young. These findings indicated that the NO (and adenosine) mediated sleep induction is impaired in aging and that it could at least partly be due to the reduced sensitivity of the BF to sleep-inducing factors. Taken together, these findings show that reduced sleep promotion by the BF contributes to the attenuated homeostatic sleep response in aging.

On the Dynamics of the Adenylate Energy System: Homeorhesis vs Homeostasis

Biochemical energy is the fundamental element that maintains both the adequate turnover of the biomolecular structures and the functional metabolic viability of unicellular organisms. The levels of ATP, ADP and AMP reflect roughly the energetic status of the cell, and a precise ratio relating them was proposed by Atkinson as the adenylate energy charge (AEC). Under growth-phase conditions, cells maintain the AEC within narrow physiological values, despite extremely large fluctuations in the adenine nucleotides concentration. Intensive experimental studies have shown that these AEC values are preserved in a wide variety of organisms, both eukaryotes and prokaryotes. Here, to understand some of the functional elements involved in the cellular energy status, we present a computational model conformed by some key essential parts of the adenylate energy system. Specifically, we have considered (I) the main synthesis process of ATP from ADP, (II) the main catalyzed phosphotransfer reaction for interconversion of ATP, ADP and AMP, (III) the enzymatic hydrolysis of ATP yielding ADP, and (IV) the enzymatic hydrolysis of ATP providing AMP. This leads to a dynamic metabolic model (with the form of a delayed differential system) in which the enzymatic rate equations and all the physiological kinetic parameters have been explicitly considered and experimentally tested in vitro. Our central hypothesis is that cells are characterized by changing energy dynamics (homeorhesis). The results show that the AEC presents stable transitions between steady states and periodic oscillations and, in agreement with experimental data these oscillations range within the narrow AEC window. Furthermore, the model shows sustained oscillations in the Gibbs free energy and in the total nucleotide pool. The present study provides a step forward towards the understanding of the fundamental principles and quantitative laws governing the adenylate energy system, which is a fundamental element for unveiling the dynamics of cellular life.

Nutritional homeostasis in carnivorous southern catfish (Silurus meridionalis): is there a mechanism for increased energy expenditure during carbohydrate overfeeding?

In previous growth experiments with carnivorous southern catfish (Silurus meridionalis), the non-fecal energy lose was positively related to dietary. carbohydrate level. To test whether metabolic energy expenditure accounts for such energy loss, an experiment was performed with southern catfish juveniles (33.2-71.9 g) to study the effect of dietary carbohydrate level on fasting metabolic rate and specific dynamic action (SDA) at 27.5 degreesC. The fasting metabolic rate in this catfish was increased with dietary carbohydrate level, and the specific dynamic action (SDA) coefficient (energy expended on SDA as percent of assimilated energy) was not affected by dietary carbohydrate level. The results suggest that in southern catfish, carbohydrate overfeeding increases metabolic rate to oxidize unwanted assimilated carbohydrate. A discussion on the poor capacity of intermediate metabolism for adapting dietary carbohydrate in carnivorous fish and its possible relationship with facultative component of SDA was also documented in this paper. (C) 2004 Elsevier Inc. All rights reserved.

Carnosine:can understanding its actions on energy metabolism and protein homeostasis inform its therapeutic potential?

The dipeptide carnosine (β-alanyl-L-histidine) has contrasting but beneficial effects on cellular activity. It delays cellular senescence and rejuvenates cultured senescent mammalian cells. However, it also inhibits the growth of cultured tumour cells. Based on studies in several organisms, we speculate that carnosine exerts these apparently opposing actions by affecting energy metabolism and/or protein homeostasis (proteostasis). Specific effects on energy metabolism include the dipeptide's influence on cellular ATP concentrations. Carnosine's ability to reduce the formation of altered proteins (typically adducts of methylglyoxal) and enhance proteolysis of aberrant polypeptides is indicative of its influence on proteostasis. Furthermore these dual actions might provide a rationale for the use of carnosine in the treatment or prevention of diverse age-related conditions where energy metabolism or proteostasis are compromised. These include cancer, Alzheimer's disease, Parkinson's disease and the complications of type-2 diabetes (nephropathy, cataracts, stroke and pain), which might all benefit from knowledge of carnosine's mode of action on human cells. © 2013 Hipkiss et al.; licensee Chemistry Central Ltd.

A family with erythrocytosis establishes a role for prolyl hydroxylase domain protein 2 in oxygen homeostasis

The number of red blood cells is normally tightly regulated by a classic homeostatic mechanism based on oxygen sensing in the kidney. Decreased oxygen delivery resulting from anemia induces the production of erythropoietin, which increases red cell production and hence oxygen delivery. Investigations of erythropoietin regulation identified the transcription factor hypoxia-inducible factor (HIF). HIF is now recognized as being a key regulator of genes that function in a comprehensive range of processes besides erythropoiesis, including energy metabolism and angiogenesis. HIF itself is regulated through the -subunit, which is hydroxylated in the presence of oxygen by a family of three prolyl hydroxylase domain proteins (PHDs)/HIF prolyl hydroxylases/egg-laying-defective nine enzymes. Hydroxylation allows capture by the von Hippel–Lindau tumor suppressor gene product, ubiquitination, and destruction by the proteasome. Here we describe an inherited mutation in a mammalian PHD enzyme. We show that this mutation in PHD2 results in a marked decrease in enzyme activity and is associated with familial erythrocytosis, identifying a previously unrecognized cause of this condition. Our findings indicate that PHD2 is critical for normal regulation of HIF in humans.

Global iron-dependent gene regulation in Escherichia coli - A new mechanism for iron homeostasis

Organisms generally respond to iron deficiency by increasing their capacity to take up iron and by consuming intracellular iron stores. Escherichia coli, in which iron metabolism is particularly well understood, contains at least 7 iron-acquisition systems encoded by 35 iron-repressed genes. This Fe-dependent repression is mediated by a transcriptional repressor, Fur ( ferric uptake regulation), which also controls genes involved in other processes such as iron storage, the Tricarboxylic Acid Cycle, pathogenicity, and redox-stress resistance. Our macroarray-based global analysis of iron- and Fur-dependent gene expression in E. coli has revealed several novel Fur-repressed genes likely to specify at least three additional iron- transport pathways. Interestingly, a large group of energy metabolism genes was found to be iron and Fur induced. Many of these genes encode iron- rich respiratory complexes. This iron- and Fur-dependent regulation appears to represent a novel iron-homeostatic mechanism whereby the synthesis of many iron- containing proteins is repressed under iron- restricted conditions. This mechanism thus accounts for the low iron contents of fur mutants and explains how E. coli can modulate its iron requirements. Analysis of Fe-55-labeled E. coli proteins revealed a marked decrease in iron- protein composition for the fur mutant, and visible and EPR spectroscopy showed major reductions in cytochrome b and d levels, and in iron- sulfur cluster contents for the chelator-treated wild-type and/or fur mutant, correlating well with the array and quantitative RT-PCR data. In combination, the results provide compelling evidence for the regulation of intracellular iron consumption by the Fe2+-Fur complex.

Synbiotic approach restores intestinal homeostasis and prolongs survival in leukaemia mice with cachexia

Cancer cachexia is a multifactorial syndrome that includes muscle wasting and inflammation. As gut microbes influence host immunity and metabolism, we investigated the role of the gut microbiota in the therapeutic management of cancer and associated cachexia. A community-wide analysis of the caecal microbiome in two mouse models of cancer cachexia (acute leukaemia or subcutaneous transplantation of colon cancer cells) identified common microbial signatures, including decreased Lactobacillus spp. and increased Enterobacteriaceae and Parabacteroides goldsteinii/ASF 519. Building on this information, we administered a synbiotic containing inulin-type fructans and live Lactobacillus reuteri 100-23 to leukaemic mice. This treatment restored the Lactobacillus population and reduced the Enterobacteriaceae levels. It also reduced hepatic cancer cell proliferation, muscle wasting and morbidity, and prolonged survival. Administration of the synbiotic was associated with restoration of the expression of antimicrobial proteins controlling intestinal barrier function and gut immunity markers, but did not impact the portal metabolomics imprinting of energy demand. In summary, this study provided evidence that the development of cancer outside the gut can impact intestinal homeostasis and the gut microbial ecosystem and that a synbiotic intervention, by targeting some alterations of the gut microbiota, confers benefits to the host, prolonging survival and reducing cancer proliferation and cachexia.

Dose and latency effects of leucine supplementation in modulating glucose homeostasis: opposite effects in healthy and glucocorticoid-induced insulin-resistance states

Dexamethasone (DEXA) is a potent immunosupressant and anti-inflammatory agent whose main side effects are muscle atrophy and insulin resistance in skeletal muscles. In this context, leucine supplementation may represent a way to limit the DEXA side effects. In this study, we have investigated the effects of a low and a high dose of leucine supplementation (via a bolus) on glucose homeostasis, muscle mass and muscle strength in energy-restricted and DEXA-treated rats. Since the leucine response may also be linked to the administration of this amino acid, we performed a second set of experiments with leucine given in bolus (via gavage) versus leucine given via drinking water. Leucine supplementation was found to produce positive effects (e. g., reduced insulin levels) only when administrated in low dosage, both via the bolus or via drinking water. However, under DEXA treatment, leucine administration was found to significantly influence this response, since leucine supplementation via drinking water clearly induced a diabetic state, whereas the same effect was not observed when supplied via the gavage.

Effects of acute creatine supplementation on iron homeostasis and uric acid-based antioxidant capacity of plasma after wingate test

Background: Dietary creatine has been largely used as an ergogenic aid to improve strength and athletic performance, especially in short-term and high energy-demanding anaerobic exercise. Recent findings have also suggested a possible antioxidant role for creatine in muscle tissues during exercise. Here we evaluate the effects of a 1-week regimen of 20 g/day creatine supplementation on the plasma antioxidant capacity, free and heme iron content, and uric acid and lipid peroxidation levels of young subjects (23.1 +/- 5.8 years old) immediately before and 5 and 60 min after the exhaustive Wingate test. Results: Maximum anaerobic power was improved by acute creatine supplementation (10.5 %), but it was accompanied by a 2.4-fold increase in pro-oxidant free iron ions in the plasma. However, potential iron-driven oxidative insult was adequately counterbalanced by proportional increases in antioxidant ferric-reducing activity in plasma (FRAP), leading to unaltered lipid peroxidation levels. Interestingly, the FRAP index, found to be highly dependent on uric acid levels in the placebo group, also had an additional contribution from other circulating metabolites in creatine-fed subjects. Conclusions: Our data suggest that acute creatine supplementation improved the anaerobic performance of athletes and limited short-term oxidative insults, since creatine-induced iron overload was efficiently circumvented by acquired FRAP capacity attributed to: overproduction of uric acid in energy-depleted muscles (as an end-product of purine metabolism and a powerful iron chelating agent) and inherent antioxidant activity of creatine.