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International audience; Studies focusing on the interaction of dietary and acute emotional stress on oxidative stress in cortex frontal and in brain mitochondria are scarce. Dietary-induced insulin resistance, as observed in Western diets, has been associated with increased oxidative stress causing mitochondrial dysfunction. We hypothesized that acute emotional stress could be an aggravating factor by impacting redox status in cortex and brain mitochondria. Thus, the aim of the present study was to evaluate the combination of an insulin resistance inducing high-fat/high-fructose (HF/HFr) diet and acute emotional stress on brain oxidative stress in rats. We measured several oxidative stress parameters (carbonyls, FRAP, TBARS assays, GSH, GSSG, oxidized DNA, mRNA expression of redox proteins (Nrf2), and uric acid). The HF/HFr diet resulted in increased oxidative stress both in the brain mitochondria and in the frontal cortex and decreased expression of the Nrf2 gene. The emotional stress induced an oxidative response in plasma and in brain mitochondria of the control group. In the HF/HFr group it triggered an increase expression of the redox transcription factor Nrf2 and its downstream antioxidant genes. This suggests an improvement of the redox stress tolerance in response to an enhanced production of reactive oxygen species. Accordingly, a blunted oxidative effect on several markers was observed in plasma and brain of HF/HFr-stressed group. This was confirmed in a parallel study using lipopolysaccharide as a stress model. Beside the Nrf2 increase, the stress induced a stronger UA release in HF/HFr which could take a part in the redox stress.

There is substantial evidence that Reactive Oxygen Species (ROS) play a major part in cell functioning. Although their harmfulness through oxidative stress is well documented, their role in signaling and sensing as an oxidative signal still needs to be investigated. In most cells, the mitochondrial Electron Transport Chain (ETC) is the primary source of ROS. The production of ROS by reverse electron transfer through complex I has been demonstrated both in an experimental context but also in many pathophysiological situations. Therefore, understanding the mechanisms that regulate this ROS production is of great interest to control its harmful effects. We used nigericin, Pi and valinomycin as tools to modulate the pH gradient (∆pH) and the membrane potential (∆Ψ) of the protonmotive force (∆p) in liver and muscle mitochondria to accurately determine how these parameters control the ROS production. We show that a high ∆Ψ is the "sine qua none" condition for ROS production from the reverse electron transfer (RET) through the complex I. However, a high ∆Ψ is not the only condition governing ROS production. Indeed, using tools that modulate the mitochondrial NADH level, we also demonstrate that ROS production is directly related to the mitochondrial redox potential when the membrane potential is almost stable.

Key points Maternal training during gestation enhances offspring body composition and energy substrates handling in early adulthood. Offspring nutrition also plays a role as some beneficial effects of maternal training during gestation disappear after consumption of a high-fat diet. Abstract Maternal exercise during gestation has been reported to modify offspring metabolism and health. Whether these effects are exacerbated when offspring are receiving a high-fat diet remains unclear. Our purpose was to evaluate the effect of maternal exercise before and during gestation on the offspring fed a high-fat/high-sucrose diet (HF) by assessing its body composition, pancreatic function and energy substrates handling by two major glucose-utilizing tissues: liver and muscle. Fifteen-week-old nulliparous female Wistar rats exercised 4 weeks before as well as during gestation at a constant submaximal intensity (TR) or remained sedentary (CT). At weaning, pups from each group were fed either a standard diet (TRCD or CTCD) or a high-fat/high-sucrose diet (TRHF or CTHF) for 10 weeks. Offspring from TR dams gained less weight compared to those from CT dams. Selected fat depots were larger with the HF diet compared to control diet (CD) but significantly smaller in TRHF compared to CTHF. Surprisingly, the insulin secretion index was higher in islets from HF offspring compared to CD. TR offspring showed a higher muscle insulin sensitivity estimated by the ratio of phosphorylated protein kinase B to total protein kinase B compared with CT offspring (+48%, P

It is now well established that the intrauterine life environment is of major importance for health during later life. Endurance training during pregnancy is associated with positive metabolic adjustments and beneficial effects on the balance between pro and antioxidant (redox state) in the offspring. Our hypothesis is that these changes could rely on mitochondrial adaptations in the offspring due to modifications of the fetal environment induced by maternal endurance training. Therefore, we compared the liver and skeletal muscle mitochondrial function and the redox status of young rats whose mothers underwent moderate endurance training (treadmill running) before and during gestation (T) to those of young rats from untrained mothers (C). Our results show a significant reduction in the spontaneous H2O2 release by liver and muscle mitochondria in the T vs. C rats (p In plasma, GPX activity and protein oxidation are significantly higher in T rats compared to C rats (p We demonstrated for the first time, to our knowledge, that it is possible to act on the bioenergetic functionning including alterations of the mitochondrial function in the offspring by modifying maternal physical activity before and during pregnancy. These changes could be crucial for the future health of the offspring.

International audience; Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants present in dietary fats. Most studies evaluating PCB effects have been conducted with a single compound or a mixture of PCBs given as a single acute dose. The purpose of this study was to evaluate in vivo PCB toxicity in a realistic model of exposure: a low daily dose of PCBs (twice the tolerable daily intake (TDI)), chronically administered (8 weeks) to rats in contaminated goat milk. Liver and brain PCB toxicities were investigated by evaluating oxidative stress status and mitochondrial function. PCB toxicity in the liver was also estimated by transaminase enzymatic activity. This study shows that even at low doses, chronic PCB exposure resulted in a statistically significant reduction of mitochondrial function in liver and brain. In the liver, oxygen consumption in the condition of adenosine triphosphate (ATP) production (state 3) decreased by 22-29% (p < 0.01), according to the respiratory substrates. In the brain, respiratory chain complexes II and III were reduced by 24% and 39%, respectively (p < 0.005). The exposed rats presented higher lipid peroxidation status (+20%, p < 0.05) and transaminase activity (+30%, p < 0.05) in the blood. Thus, our study showed that exposure of rats to a daily realistic dose of PCBs (twice the TDI in a food complex mixture of environmental origin) resulted in multiple disruptions in the liver and brain.

By performing a controlled exposure of an amphibian model to endocrine disruptors (EDs) at concentrations within the range of safe drinking water, we provide evidence of the role played by these widespread contaminants in amphibian population decline through metabolic disruption. In frogs exposed throughout their life cycle, this disruption induces a metabolic syndrome characteristic of a prediabetes state. Exposed animals produce progeny that metamorphose later, are smaller and lighter at the adult stage, and have reduced reproductive success. These transgenerational effects of EDs may impact overwintering survival, recruitment for reproduction, and fitness, each representing possible triggers of population decline.

International audience; Despite numerous studies suggesting that amphibians are highly sensitive to endocrine disruptors (EDs), both their role in the decline of populations and the underlying mechanisms remain unclear. This study showed that frogs exposed throughout their life cycle to ED concentrations low enough to be considered safe for drinking water, developed a prediabetes phenotype and, more commonly, a metabolic syndrome. Female Xenopus tropicalis exposed from tadpole stage to benzo(a)pyrene or triclosan at concentrations of 50 ng⋅L-1 displayed glucose intolerance syndrome, liver steatosis, liver mitochondrial dysfunction, liver transcriptomic signature, and pancreatic insulin hypersecretion, all typical of a prediabetes state. This metabolic syndrome led to progeny whose metamorphosis was delayed and occurred while the individuals were both smaller and lighter, all factors that have been linked to reduced adult recruitment and likelihood of reproduction. We found that F1 animals did indeed have reduced reproductive success, demonstrating a lower fitness in ED-exposed Xenopus Moreover, after 1 year of depuration, Xenopus that had been exposed to benzo(a)pyrene still displayed hepatic disorders and a marked insulin secretory defect resulting in glucose intolerance. Our results demonstrate that amphibians are highly sensitive to EDs at concentrations well below the thresholds reported to induce stress in other vertebrates. This study introduces EDs as a possible key contributing factor to amphibian population decline through metabolism disruption. Overall, our results show that EDs cause metabolic disorders, which is in agreement with epidemiological studies suggesting that environmental EDs might be one of the principal causes of metabolic disease in humans.

Background The mechanisms by which hypertonic sodium lactate (HSL) solution act in injured brain are unclear. We investigated the effects of HSL on brain metabolism, oxygenation, and perfusion in a rodent model of diffuse traumatic brain injury (TBI). Methods Thirty minutes after trauma, anaesthetised adult rats were randomly assigned to receive a 3 h infusion of either a saline solution (TBI–saline group) or HSL (TBI–HSL group). The sham–saline and sham–HSL groups received no insult. Three series of experiments were conducted up to 4 h after TBI (or equivalent) to investigate: 1) brain oedema using diffusion-weighted magnetic resonance imaging and brain metabolism using localized 1 H-magnetic resonance spectroscopy ( n = 10 rats per group). The respiratory control ratio was then determined using oxygraphic analysis of extracted mitochondria, 2) brain oxygenation and perfusion using quantitative blood-oxygenation-level-dependent magnetic resonance approach ( n = 10 rats per group), and 3) mitochondrial ultrastructural changes ( n = 1 rat per group). Results Compared with the TBI–saline group, the TBI–HSL and the sham-operated groups had reduced brain oedema. Concomitantly, the TBI–HSL group had lower intracellular lactate/creatine ratio [0.049 (0.047–0.098) vs 0.097 (0.079–0.157); P vs 66% (55–73); P vs 38.4 (31.0–47.5) nm; P Conclusions These findings indicate that the hypertonic sodium lactate solution can reverse brain oxygenation and metabolism dysfunction after traumatic brain injury through vasodilatory, mitochondrial, and anti-oedema effects.

Since emotional stress elicits brain activation, mitochondria should be a key component of stressed brain response. However, few studies have focused on mitochondria functioning in these conditions. In this work, we aimed to determine the effects of an acute restraint stress on rat brain mitochondrial functions, with a focus on permeability transition pore (PTP) functioning. Rats were divided into two groups, submitted or not to an acute 30-min restraint stress (Stress, S-group, vs. Control, C-group). Brain was removed immediately after stress. Mitochondrial respiration and enzymatic activities (complex I, complex II, hexokinase) were measured. Changes in PTP opening were assessed by the Ca(2+) retention capacity. Cell signaling pathways relevant to the coupling between mitochondria and cell function (adenosine monophosphate-activated protein kinase, phosphatidylinositol 3-kinase, glycogen synthase kinase 3 beta, MAPK, and cGMP/NO) were measured. The effect of glucocorticoids was also assessed in vitro. Stress delayed (43%) the opening of PTP and resulted in a mild inhibition of complex I respiratory chain. This inhibition was associated with significant stress-induced changes in adenosine monophosphate-activated protein kinase signaling pathway without changes in brain cGMP level. In contrast, glucocorticoids did not modify PTP opening. These data suggest a rapid adaptive mechanism of brain mitochondria in stressed conditions, with a special focus on PTP regulation. In a rat model of acute restraint stress, we observed substantial changes in brain mitochondria functioning. Stress significantly (i) delays (43%) the opening of permeability transition pore (PTP) by the calcium (Ca(2+) ), its main inductor and (ii) results in an inhibition of complex I in electron transport chain associated with change in AMPK signaling pathway. These data suggest an adaptive mechanism of brain mitochondria in stressed condition, with a special focus on PTP regulation.

Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful tool for in vivo tract tracing or functional imag- ing of the central nervous system. However Mn 21 may be toxic at high levels. In this study, we addressed the impact of Mn 21 on mouse hippo- campal neurons (HN) and neuron-like N2a cells in culture, using several approaches. Both HN and N2a cells not exposed to exogenous MnCl2 were shown by synchrotron X-ray fluorescence to contain 5 mg/g Mn. Concentrations of Mn 21 leading to 50% lethality (LC50) after 24 h of incubation were much higher for N2a cells (863 mM) than for HN (90 mM). The distribution of Mn 21 in both cell types exposed to Mn 21 concentrations below LC50 was perinuclear whereas that in cells exposed to concentrations above LC50 was more diffuse, suggesting an overloading of cell storage/detoxification capacity. In addition, Mn 21 had a cell-type and dose-dependent impact on the total amount of intra- cellular P, Ca, Fe and Zn measured by synchrotron X-ray fluorescence. For HN neurons, immunofluorescence studies revealed that concentra- tions of Mn 21 below LC50 shortened neuritic length and decreased mitochondria velocity after 24 h of incubation. Similar concentrations of Mn 21 also facilitated the opening of the mitochondrial permeability transition pore in isolated mitochondria from rat brains. The sensitivity of primary HN to Mn 21 demonstrated here supports their use as a rele- vant model to study Mn 21 -induced neurotoxicity. V C 2014 Wiley

Inhibiting the opening of mitochondrial permeability transition pore (mPTP), thereby maintaining the mitochondrial membrane potential and calcium homeostasis, could reduce the induction of cell death. Although recombinant human erythropoietin (rhEpo) and carbamylated erythropoietin (Cepo) were shown to prevent apoptosis after traumatic brain injury (TBI), their impact on mPTP is yet unknown. Thirty minutes after diffuse TBI (impact-acceleration model), rats were intravenously administered a saline solution (TBI-saline), 5000 UI/kg rhEpo (TBI-rhEpo) or 50 μg/kg Cepo (TBI-Cepo). A fourth group received no TBI insult (sham-operated) (n = 11 rats per group). Post-traumatic brain edema was measured using magnetic resonance imaging. A first series of experiments was conducted 2 h after TBI (or equivalent) to investigate the mitochondrial function with the determination of thresholds for mPTP opening and ultrastructural mitochondrial changes. In addition, the intramitochondrial calcium content [Caim] was measured. In a second series of experiments, brain cell apoptosis was assessed at 24 h post-injury. TBI-rhEpo and TBI-Cepo groups had a reduced brain edema compared with TBI-saline. They had higher threshold for mPTP opening with succinate as substrate: 120 (120-150) (median, interquartiles) and 100 (100-120) versus 80 (60-90) nmol calcium/mg protein in TBI-saline, respectively (p 0.05). Similar findings were shown with glutamate-malate as substrate. TBI-rhEpo and Cepo groups had less morphological mitochondrial disruption in astrocytes. The elevation in [Caim] after TBI was not changed by rhEpo and Cepo treatment. Finally, rhEpo and Cepo reduced caspase-3 expression at 24 h post-injury. These results indicate that rhEpo and Cepo could modulate mitochondrial dysfunction after TBI. The mechanisms involved are discussed.

International audience; Gestational diabetes mellitus (GDM) is associated with increased insulin resistance and a heightened level of oxidative stress (OS). Additionally, high iron consumption could also increase insulin resistance and OS, which could aggravate GDM risk. The aim of this study is to evaluate a high fructose diet (F) as an alternative experimental model of GDM on rats. We also have evaluated the worst effect of a fructose iron-enriched diet (FI) on glucose tolerance and OS status during pregnancy. Anthropometric parameters, plasma glucose levels, insulin, and lipid profile were assessed after delivery in rats fed an F diet. The effects observed in mothers (hyperglycemia, and hyperlipidemia) and on pups (macrosomia and hypoglycemia) are similar to those observed in women with GDM. Therefore, the fructose diet could be proposed as an experimental model of GDM. In this way, we can compare the effect of an iron-enriched diet on the metabolic and redox status of mother rats and their pups. The mothers' glycemic was similar in the F and FI groups, whereas the glycemic was significantly different in the newborn. In rat pups born to mothers fed on an FI diet, the activities of the antioxidant enzyme glutathione peroxidase (GPx) and glutathione-S-transferase in livers and GPx in brains were altered and the gender analysis showed significant differences. Thus, alterations in the glycemic and redox status in newborns suggest that fetuses are more sensitive than their mothers to the effect of an iron-enriched diet in the case of GDM pregnancy. This study proposed a novel experimental model for GDM and provided insights on the effect of a moderate iron intake in adding to the risk of glucose disorder and oxidative damage on newborns.

Only a few studies have explored the effects of maternal exercise during gestation on adult offspring metabolism. We set out to test whether maternal controlled submaximal exercise maintained troughout all gestational periods induces persistant metabolic changes in the offspring. We used a model of 15-wk-old nulliparous female Wistar rats that exercised (trained group) before and during gestation at a submaximal intensity or remained sedentary (control group). At weaning, male offspring from trained dams showed reduced basal glycemia (119.7 ± 2.4 vs. 130.5 ± 4.1 mg/dl, P < 0.05), pancreas relative weight (3.96 ± 0.18 vs. 4.54 ± 0.14 g/kg body wt, P < 0.05), and islet mean area (22,822 ± 4,036 vs. 44,669 ± 6,761 μm2, P < 0.05) compared with pups from control dams. Additionally, they had better insulin secretory capacity when stimulated by 2.8 mM glucose + 20 mM arginine compared with offspring from control dams (+96%, P < 0.05). At 7 mo of age, offspring from trained mothers displayed altered glucose tolerance (AUC = 15,285 ± 527 vs. 11,898 ± 988 mg·dl−1·120 min, P < 0.05) and decreased muscle insulin sensitivity estimated by the phosphorylated PKB/total PKB ratio (−32%, P < 0.05) and tended to have a reduced islet insulin secretory capacity compared with rats from control dams. These results suggest that submaximal maternal exercise modifies short-term male offspring pancreatic function and appears to have rather negative long-term consequences on sedentary adult offspring glucose handling.

Insulin resistance (IR), which is a leading cause of the metabolic syndrome, results in early brain function alterations which may alter brain mitochondrial functioning. Previously, we demonstrated that rats fed a control diet and submitted to an acute restraint stress exhibited a delayed mitochondrial permeability transition pore (mPTP) opening. In this study, we evaluated the combined effects of dietary and emotional stressors as found in western way of life. We studied, in rats submitted or not to an acute stress, the effects of diet-induced IR on brain mitochondria, using a high fat/high fructose diet (HF(2)), as an IR inducer, with addition or not of cinnamon as an insulin sensitizer. We measured Ca(2+) retention capacity, respiration, ROS production, enzymatic activities and cell signaling activation. Under stress, HF(2) diet dramatically decreased the amount of Ca(2+) required to open the mPTP (13%) suggesting an adverse effect on mitochondrial survival. Cinnamon added to the diet corrected this negative effect and resulted in a partial recovery (30%). The effects related to cinnamon addition to the diet could be due to its antioxidant properties or to the observed modulation of PI3K-AKT-GSK3β and MAPK-P38 pathways or to a combination of both. These data suggest a protective effect of cinnamon on brain mitochondria against the negative impact of an HF(2) diet. Cinnamon could be beneficial to counteract deleterious dietary effects in stressed conditions.

International audience; The permeability transition pore (PTP) is a mitochondrial inner membrane channel involved in cell death. The inhibition of PTP opening has been proved to be an effective strategy to prevent cell death induced by oxidative stress. Several ubiquinone analogs are known to powerfully inhibit PTP opening with an effect depending on the studied cell line. Here, we have studied the effects of ubiquinone 0 (Ub(0)), ubiquinone 5 (Ub(5)) and ubiquinone 10 (Ub(10)) on PTP regulation, H(2)O(2) production and cell viability in U937 cells. We found that Ub(0) induced both PTP opening and H(2)O(2) production. Ub(5) did not regulate PTP opening yet induced H(2)O(2) production. Ub(10) potently inhibited PTP opening yet induced H(2)O(2) production. Both Ub(0) and Ub(5) induced cell death, whereas Ub(10) was not toxic. Moreover, Ub(10) prevented tert-butyl hydroperoxide-induced PTP opening and subsequent cell death. We conclude that PTP-inhibitor ubiquinone analogs are able to prevent PTP opening-induced cell death only if they are not toxic per se, which is the case when they have no or low pro-oxidant activity.

Introduction et but de l’etude L’impact de l’environnement maternel lors de la vie fœtale sur la sante future de la descendance est aujourd’hui reconnu. Nous avons precedemment montre que l’entrainement physique durant la gestation a d’importantes repercussions sur le fonctionnement pancreatique et sur la gestion des substrats energetiques de la descendance [1] . Le but de notre travail a ete d’etudier l’effet de l’exercice maternel avant et pendant la gestation sur le metabolisme de la descendance exposee ou non a un regime riche en gras et en sucre. Materiel et methodes Des femelles rats Wistar ont ete ou non entrainees sur tapis roulant avant et pendant la gestation (groupes entrainement [TR] et temoin [CT], respectivement). Au sevrage, les petits mâles ont ete soumis soit a un regime controle standard (A04), soit a un regime gras et sucre (HF). A trois mois, les petits des quatre groupes (CTA04, CTHF, TRA04, TRHF) ont ete soumis a des tests de tolerance au glucose et a l’insuline. Nous avons egalement evalue la capacite secretoire de leurs ilots pancreatiques et l’activation de la voie de signalisation de l’insuline dans le muscle et le foie (en cours). La fonction mitochondriale, en presence de pyruvate, palmitoyl carnitine (PC) et palmitoyl co-A (PCoA), a ete evaluee par oxygraphie sur les fibres musculaires isolees permeabilisees des muscles plantaires. Resultats Les resultats sont presentes dans le Tableau 1 . Dix semaines de regime gras et sucre alterent la tolerance au glucose et reduisent le poids du pancreas des rats soumis au regime HF, sans effet sur la sensibilite a l’insuline. Le regime HF augmente la prise de poids, la masse grasse ainsi que la glycemie et l’insulinemie basale. L’exercice maternel limite la prise de poids de la descendance soumise au regime A04 ou HF et diminue la masse grasse des rats HF. L’entrainement maternel diminue le Km pour le pyruvate et le PCoA chez la descendance soumise a un regime A04. Conclusion L’exercice maternel limite la prise de poids de la descendance, quel que soit le regime et diminue la masse grasse chez les rats soumis au regime HF. L’entrainement maternel ameliore egalement l’affinite du muscle aux hydrates de carbone et a certains lipides comme le PCoA chez la descendance soumise a un regime A04. Cette meilleure affinite disparait chez la descendance soumise au regime HF.

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Introduction et but de l’etude Il est aujourd’hui reconnu que l’environnement maternel lors de la gestation affecte non seulement le fœtus mais egalement la sante future de l’individu [1] . Cependant, tres peu d’etudes ont explore l’effet de l’exercice maternel pendant la gestation sur l’homeostasie du glucose de la descendance [2] . Le but de notre travail a donc ete d’etudier l’effet de l’entrainement maternel avant et pendant la gestation sur le metabolisme du glucose et la fonction pancreatique de la descendance a plus ou moins long terme. Materiel et methodes Des femelles rats Wistar ont ete ou non entrainees avant et pendant la gestation (groupes temoin CT et entrainement TR). A 3 semaines (au sevrage) ou a 7 mois, les petits mâles ont subi des tests de tolerance au glucose (ipGTT) et a l’insuline (ipITT). Nous avons egalement evalue la capacite secretoire de leurs ilots pancreatiques (en cours pour les 7 mois) et l’activation de la voie de signalisation de l’insuline dans le muscle et le foie. Resultats et analyse statistique Les resultats sont presentes dans le Tableau 1 . A 3 semaines, les petits des meres entrainees ont une glycemie basale plus faible et une insulinemie basale plus elevee que les ratons issus de meres sedentaires. Ils ont egalement une meilleure sensibilite a l’insuline, sans difference de tolerance au glucose avec le groupe CT. Le poids du pancreas est plus faible mais la capacite secretoire des ilots pancreatiques plus importante chez les ratons du groupe TR. A 7 mois, la tolerance au glucose est moins bonne chez les rats du groupe TR par rapport a ceux du groupe CT. Il n’y a pas de difference de sensibilite globale a l’insuline malgre une moins bonne insulino-sensibilite du muscle chez les rats du groupe TR. Aucune difference n’est observee concernant la glycemie basale, le poids du pancreas et le contenu en insuline du pancreas entre les deux groupes. Conclusion L’entrainement maternel semble avoir un effet positif sur la fonction pancreatique et l’insulino-sensibilite de la descendance a 3 semaines. A 7 mois, les effets obtenus sont differents, avec une deterioration de la tolerance au glucose et une moins bonne insulino-sensibilite dans le muscle chez les rats issus de meres entrainees. Les consequences de l’entrainement maternel sur l’homeostasie du glucose de la descendance apparaitraient donc comme plutot nefastes a plus long terme.

Introduction et but de l’etude Les PolyChloroBiphenyles (PCBs) designent une famille de 209 composes lipophiles qui sont presents aujourd’hui dans la plupart des composantes de l’alimentation humaine (et en particulier les produits laitiers, les poissons). A ce jour, la toxicite des PCBs a surtout ete exploree chez le rongeur en utilisant une ou quelques molecules generalement les plus toxiques et a fortes doses. L’objectif de cette etude a ete d’elaborer un modele realiste d’exposition a un melange de PCBs dans le but de tester une eventuelle protection de l’aleurone de ble (AB), une matrice alimentaire issue du son de ble, riche en composes bioactifs. Materiel et methodes Les rats ont ete traites durant 8 semaines avec du lait de chevres contaminees aux PCBs associe ou pas a l’AB. Les quantites de PCBs apportees aux rats correspondent a une dose realiste (2 fois la dose journaliere acceptable). La toxicite des PCBs au niveau du foie et du cerveau a ete etudiee en determinant : l’atteinte de la fonction mitochondriale, le stress oxydant, les transaminases et le metabolisme des acides gras. Resultats et Analyse statistique L’exposition aux PCBs augmente significativement la peroxydation lipidique (TBARs) dans le foie et le cerveau (~20 %) et les transaminases du plasma (de 30 a 50 %). De plus, le rapport n-6/n-3 est significativement augmente de 21 % dans le foie (Tableau 1). Enfin, les PCBs perturbent la fonction mitochondriale dans le foie et le cerveau. Ainsi, par exemple ils reduisent significativement (P De facon surprenante, la consommation de l’AB corrige : – Totalement les augmentations des TBARs, des transaminases et du rapport n-6/n-3 observees lors du l’exposition aux PCBs (Tableau 1). – Partiellement la fonction mitochondriale (tableau page suivante). Conclusion Nos resultats montrent qu’il est possible de prevenir ses atteintes induites par les PCBs par la consommation d’AB. L’utilisation de l’aleurone de cereales comme additif alimentaire pour prevenir la toxicite des polluants organiques persistants a fait l’objet d’un depot de brevet. Tableau 1 : Quelques exemple de l’effet d’une administration de lait contamine aux PCBs avec ou sans prise d’aleurone chez le rat - Communication P015. Controle PCBs PCBs + Aleurone Moyenne SD Moyenne SD Moyenne SD ASAT, UI/L (plasma) 146,4 ± 41,2 A 220,9 ± 32,2 B 154,7 ± 19,0 A TBARs, μmol/g proteine (cerveau) 0,45 ± 0,12 A 0,56 ± 0,09 B 0,48 ± 0,07 A Ratio n-6/n-3 (foie) 5,06 ± 0,59 B 6,11 ± 0,56 A 5,48 ± 0,62 B N =10 par groupe. a. b : les resultats annotes avec des lettres differentes sont significativement differents (p>0,05) one-way ANOVA (analyse de variance a un facteur).

Metyrapone is a cytochrome P 450 inhibitor that protects against ischemia- and excitotoxicity-induced brain damages in rodents. This study examines whether metyrapone would act on energy metabolism in a manner congruent with its neuroprotective effect. In a first investigation, the rats instrumented with telemetric devices measuring abdominal temperature, received i.p. injection of either metyrapone or saline. One hour after injection, their blood and hippocampus were sampled. Hippocampus metabolite concentrations were measured using 1 H high-resolution magic angle spinning-magnetic resonance spectroscopy ( 1 H HRMAS-MRS). The hippocampus levels in phosphorylated mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) were measured by Western Blot analysis and those of c-fos and HSP70-2 mRNA were quantified by RT-PCR. In a second investigation, the rats received the same treatment and were sacrificed 1 h after. The functioning of mitochondria was immediately studied on their whole brain. Metyrapone provoked a slight hypothermia which was correlated to the increase in blood glucose concentration. Metyrapone also increased blood lactate concentrations without modifying hippocampus lactate content. In the hippocampus, metyrapone decreased γ-aminobutyric acid (GABA) and glutamate levels but increased glutamine and N-acetyl-aspartate contents (NAA). Phosphorylated mTOR and AMPK and the c-fos and HSP70-2 mRNA levels were similar between treatment groups. Metyrapone did not modify blood corticosterone levels. Mitochondrial oxygen consumption was similar in both groups whatever the substrate used. These metabolic modifications, which take place without modifying blood glucocorticoid levels, are consistent with the neuroprotective properties of metyrapone as demonstrated in animal models.

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International audience; The objective of this study was to determine the effects of cinnamon on glycogen synthesis, related gene expression, and protein levels in the muscle and liver using an animal model of insulin resistance, the high-fat/high-fructose (HF/HFr) diet-fed rat. Four groups of 22 male Wistar rats were fed for 12 weeks with (1) HF/HFr diet to induce insulin resistance, (2) HF/HFr diet containing 20 g cinnamon per kilogram of diet, (3) control diet, and (4) control diet containing 20 g cinnamon per kilogram of diet. In the liver, cinnamon added to the HF/HFr diet led to highly significant increases of liver glycogen. There were no significant changes in animals consuming the control diet plus cinnamon. In the liver, cinnamon also counteracted the decreases of the gene expressions due to the consumption of the HF/HFr diet for the insulin receptor, insulin receptor substrates 1 and 2, glucose transporters 1 and 2, and glycogen synthase 1. In muscle, the decreased expressions of these genes by the HF/HFr diet and glucose transporter 4 were also reversed by cinnamon. In addition, the overexpression of glycogen synthase 3β messenger RNA levels and protein observed in the muscle of HF/HFr fed rats was decreased in animals consuming cinnamon. These data demonstrate that, in insulin-resistant rats, cinnamon improves insulin sensitivity and enhances liver glycogen via regulating insulin signaling and glycogen synthesis. Changes due to cinnamon in control animals with normal insulin sensitivity were not significant.

International audience; Polyphenols from cinnamon (CN) have been described recently as insulin sensitizers and antioxidants but their effects on the glucose/insulin system in vivo have not been totally investigated. The aim of this study was to determine the effects of CN on insulin resistance and body composition, using an animal model of the metabolic syndrome, the high fat/high fructose (HF/HF) fed rat. Four groups of 22 male Wistar rats were fed for 12 weeks with: (i) (HF/HF) diet to induce insulin resistance, (ii) HF/HF diet containing 20 g cinnamon/kg of diet (HF/HF + CN), (iii) Control diet (C) and (iv) Control diet containing 20 g cinnamon/kg of diet (C + CN). Data from hyperinsulinemic euglycemic clamps showed a significant decrease of the glucose infusion rates in rats fed the HF/HF diet. Addition of cinnamon to the HF/HF diet increased the glucose infusion rates to those of the control rats. The HF/HF diet induced a reduction in pancreas weight which was prevented in HF/HF+CN group (p

Background The A3243G mutation in the tRNALeu gene (UUR), is one of the most common pathogenic mitochondrial DNA (mtDNA) mutations in France, and is associated with highly variable and heterogeneous disease phenotypes. To define the relationships between the A3243G mutation and mtDNA backgrounds, we determined the haplogroup affiliation of 142 unrelated French patients – diagnosed as carriers of the A3243G mutation – by control-region sequencing and RFLP survey of their mtDNAs. Results The analysis revealed 111 different haplotypes encompassing all European haplogroups, indicating that the 3243 site might be a mutational hot spot. However, contrary to previous findings, we observed a statistically significant underepresentation of the A3243G mutation on haplogroup J in patients (p = 0.01, OR = 0.26, C.I. 95%: 0.08–0.83), suggesting that might be due to a strong negative selection at the embryo or germ line stages. Conclusion Thus, our study supports the existence of mutational hotspot on mtDNA and a "haplogroup J paradox," a haplogroup that may increase the expression of mtDNA pathogenic mutations, but also be beneficial in certain environmental contexts.

International audience; Mitochondrial reactive oxygen species (ROS) production was investigated in mitochondria extracted from liver of rats treated with or without metformin, a mild inhibitor of respiratory chain complex 1 used in type 2 diabetes. A high rate of ROS production, fully suppressed by rotenone, was evidenced in non-phosphorylating mitochondria in the presence of succinate as a single complex 2 substrate. This ROS production was substantially lowered by metformin pretreatment and by any decrease in membrane potential (Delta Phi(m)), redox potential (NADH/NAD), or phosphate potential, as induced by malonate, 2,4-dinitrophenol, or ATP synthesis, respectively. ROS production in the presence of glutamate-malate plus succinate was lower than in the presence of succinate alone, but higher than in the presence of glutamate-malate. Moreover, while rotenone both increased and decreased ROS production at complex 1 depending on forward (glutamate-malate) or reverse (succinate) electron flux, no ROS overproduction was evidenced in the forward direction with metformin. Therefore, we propose that reverse electron flux through complex 1 is an alternative pathway, which leads to a specific metformin-sensitive ROS production.

Introduction et but de l’etude L’impact de l’environnement maternel lors de la vie fœtale sur la sante future de la descendance est aujourd’hui reconnu. Nos premiers resultats nous on permis de constater que l’entrainement physique durant la gestation avait d’importantes repercussions sur le fonctionnement pancreatique et sur la gestion des substrats energetiques de la descendance. Malgre tout, il nous reste a determiner si ces modifications sont benefiques ou nefastes pour la sante du futur adulte surtout lorsque celui-ci est soumis a une nutrition desequilibree. Le but de notre travail a donc ete d’etudier l’effet de l’exercice maternel avant et pendant la gestation sur la sante metabolique de la descendance exposee ou non a un regime riche en gras et en sucre (high-fat/high-sucrose). Materiel et methodes Des femelles rats Wistar ont ete ou non entrainees avant et pendant la gestation (groupes entrainement TR et controle CT, respectivement). Au sevrage, les petits mâles ont ete soumis soit a un regime controle standard (A04) soit a un regime gras et sucre (HF). A trois mois, les petits des quatre groupes (CTA04, CTHF, TRA04, TRHF) ont ete soumis a des tests de tolerance au glucose (intraperitoneal Glucose Tolerance Test, ipGTT) et a l’insuline (intraperitoneal Insulin Tolerance Test, ipITT). La composition corporelle a egalement ete evaluee et des tissus ont ete collectes afin de realiser differents dosages. Resultats et Analyse statistique Groupe CTA04 TRA04 CTHF TRHF Poids corporel a 3 mois (g) 377,3 ± 12,9 ¤$ 345,4 ± 6,9 *$£ 439,7 ± 18,5 *¤£ 405,6 ± 5,8 ¤$ Masse grasse relative (g/100 g poids corporel) 3,3 ± 0,2 $£ 3,6 ± 0,2 $£ 7,4 ± 0,3 *¤ 6,6±0,3 *¤ Glycemie basale (mg/dl) 120,8 ± 4,3$£ 120,9 ± 4,1$£ 135,6 ± 2,4*¤ 141,4 ± 4,4 *¤ Aire sous la courbe ipGTT H 5293,1 ± 1433,3 3948,8 ± 1288,9 9035 ± 1074,3 8300 ± 433,6¤ Aire sous la courbe ipITT 4070 ± 1171,6 5141,1 ± 1144,2 7247,5 ± 571,8 * 7770 ± 775,4 Les resultats sont exprimes sous la forme de la moyenne ± SEM. n =8. Statistiques : ANOVA, tests de Kruskal-Wallis et de Holm-Sidak. * p L’entrainement physique des meres durant la gestation limite la prise de poids des petits des 9 semaines de regime, qu’ils soient soumis au regime A04 ou HF. Le regime HF entraine une augmentation du poids corporel des petits qui est essentiellement due a une prise de masse grasse. L’entrainement maternel a tendance a limiter cette prise de masse grasse chez les petits soumis au regime HF (-11 % de masse grasse relative). La tolerance au glucose est moins bonne et la glycemie basale augmentee chez les petits soumis au regime HF. De facon surprenante, dans le groupe CT, apres 10 semaines de regime, l’insulino-sensibilite est meilleure chez les petits soumis au regime HF par rapport au regime A04. Le contenu total en insuline du pancreas a tendance a etre plus faible chez les petits des meres entrainees, quel que soit le regime. Conclusion L’exercice maternel aurait un impact positif sur la prise de poids de la descendance et modifierait sa tolerance au glucose lorsqu’elle est soumise a un regime gras et sucre. Les effets sur le metabolisme restent a determiner (en cours).

International audience; Hyperglycemia-induced oxidative stress is detrimental for endothelial cells, contributing to the vascular complications of diabetes. The mitochondrial permeability transition pore (PTP) is an oxidative stress-sensitive channel involved in cell death; therefore, we have examined its potential role in endothelial cells exposed to oxidative stress or high glucose level. Metformin, an antihyperglycemic agent used in type 2 diabetes, was also investigated because it inhibits PTP opening in transformed cell lines. Cyclosporin A (CsA), the reference PTP inhibitor, and a therapeutic dose of metformin (100 micromol/l) led to PTP inhibition in permeabilized human microvascular endothelial cells (HMEC-1). Furthermore, exposure of intact HMEC-1 or primary endothelial cells from either human umbilical vein or bovine aorta to the oxidizing agent tert-butylhydroperoxide or to 30 mmol/l glucose triggered PTP opening, cytochrome c decompartmentalization, and cell death. CsA or metformin prevented all of these effects. The antioxidant N-acetyl-l-cysteine also prevented hyperglycemia-induced apoptosis. We conclude that 1) elevated glucose concentration leads to an oxidative stress that favors PTP opening and subsequent cell death in several endothelial cell types and 2) metformin prevents this PTP opening-related cell death. We propose that metformin improves diabetes-associated vascular disease both by lowering blood glucose and by its effect on PTP regulation.

International audience; Food restriction is the most effective modulator of oxidative stress and it is believed that a reduction in caloric intake per se is responsible for the reduced generation of reactive oxygen species (ROS) by mitochondria. Hydrogen peroxide (H(2)O(2)) generation and oxygen consumption (O(2)) by skeletal muscle mitochondria were determined in a peculiar strain of rats (Lou/C) characterized by a self-low-caloric intake and a dietary preference for fat. These rats were fed either with a standard high-carbohydrate (HC) or a high-fat (HF) diet and the results were compared to those measured in Wistar rats fed a HC diet. H(2)O(2) production was significantly reduced in Lou/C rats fed a HC diet; this effect was not due to a lower O(2) consumption but rather to a decrease in rotenone-sensitive NADH-ubiquinone oxidoreductase activity and increased expression of uncoupling proteins 2 and 3. The reduced H(2)O(2) generation displayed by Lou/C rats was accompanied by a significant inhibition of permeability transition pore (PTP) opening. H(2)O(2) production was restored and PTP inhibition was relieved when Lou/C rats were allowed to eat a HF diet, suggesting that the reduced oxidative stress provided by low caloric intake is lost when fat proportion in the diet is increased.

International audience; Metformin, a drug widely used in the treatment of Type II diabetes, has recently received attention owing to new findings regarding its mitochondrial and cellular effects. In the present study, the effects of metformin on respiration, complex 1 activity, mitochondrial permeability transition, cytochrome c release and cell death were investigated in cultured cells from a human carcinoma-derived cell line (KB cells). Metformin significantly decreased respiration both in intact cells and after permeabilization. This was due to a mild and specific inhibition of the respiratory chain complex 1. In addition, metformin prevented to a significant extent mitochondrial permeability transition both in permeabilized cells, as induced by calcium, and in intact cells, as induced by the glutathione-oxidizing agent t-butyl hydroperoxide. This effect was equivalent to that of cyclosporin A, the reference inhibitor. Finally, metformin impaired the t-butyl hydroperoxide-induced cell death, as judged by Trypan Blue exclusion, propidium iodide staining and cytochrome c release. We propose that metformin prevents the permeability transition-related commitment to cell death in relation to its mild inhibitory effect on complex 1, which is responsible for a decreased probability of mitochondrial permeability transition.

International audience

International audience; The generation of Reactive Oxygen Species (ROS) as by-products in mitochondria Electron Transport Chain (ETC) has long been admitted as the cost of aerobic energy metabolism with oxidative damages as consequence. The purpose of this methodological review is to present some of the most widespread methods of ROS generation and to underline the limitations as well as some problems, identified with some experiments as examples, in the interpretation of such results. There is now no doubt that besides their pejorative role, ROS are involved in a variety of cellular processes for the continuous adaptation of the cell to its environment. Because ROS metabolism is a complex area (low production, instability of species, efficient antioxidant defense system, several places of production...) bias, variances and limitations in ROS measurements must be recognized in order to avoid artefactual conclusions, and especially to improve our understanding of physiological and pathophysiological mechanisms of such phenomenon.

International audience; Several links relate mitochondrial metabolism and type 2 diabetes or chronic hyperglycaemia. Among them, ATP synthesis by oxidative phosphorylation and cellular energy metabolism (ATP/ADP ratio), redox status and reactive oxygen species (ROS) production, membrane potential and substrate transport across the mitochondrial membrane are involved at various steps of the very complex network of glucose metabolism. Recently, the following findings (1) mitochondrial ROS production is central in the signalling pathway of harmful effects of hyperglycaemia, (2) AMPK activation is a major regulator of both glucose and lipid metabolism connected with cellular energy status, (3) hyperglycaemia by inhibiting glucose-6-phosphate dehydrogenase (G6PDH) by a cAMP mechanism plays a crucial role in NADPH/NADP ratio and thus in the pro-oxidant/anti-oxidant cellular status, have deeply changed our view of diabetes and related complications. It has been reported that metformin has many different cellular effects according to the experimental models and/or conditions. However, recent important findings may explain its unique efficacy in the treatment of hyperglycaemia- or insulin-resistance related complications. Metformin is a mild inhibitor of respiratory chain complex 1; it activates AMPK in several models, apparently independently of changes in the AMP-to-ATP ratio; it activates G6PDH in a model of high-fat related insulin resistance; and it has antioxidant properties by a mechanism (s), which is (are) not completely elucidated as yet. Although it is clear that metformin has non-mitochondrial effects, since it affects erythrocyte metabolism, the mitochondrial effects of metformin are probably crucial in explaining the various properties of this drug.