Neuregulin 1 affects leptin levels, food intake and weight gain in normal-weight, but not obese, db/db mice

Aim. - Studies in vitro have highlighted the potential involvement of neuregulin 1 (NRG1) in the regulation of energy metabolism. This effect has also been suggested in vivo, as intracerebroventricular injection of NRG1 reduces food intakes and weight gain in rodents. Thus, it was hypothesised that NRG1 might affect serum leptin levels in mice. Methods. - Weight, food intakes, energy expenditure, spontaneous physical activity and serum leptin levels were evaluated in normal-weight C57BL/6JRJ mice following intraperitoneal administration of NRG1 (50 mu g/kg, three times/week) or saline for 8 weeks. Based on the results of this first experiment, leptin-resistant obese db/db mice were then given NRG1 for 8 weeks. Results. - Leptin serum concentrations were six times higher in C57BL/6JRJ mice treated with NRG1 than in the animals given saline. NRG1 treatment also reduced weight gain by 10% and food intakes by 15% compared with saline treatment, while energy expenditure remained unchanged. In db/db mice, serum leptin concentrations, weight gain, food intakes, energy expenditure and spontaneous physical activity were not altered by NRG1 treatment. Conclusion. - The decrease in food intakes and weight gain associated with NRG1 treatment in C57BL/6JRJ mice may be partly explained by increased leptin levels, whereas db/db mice were not affected by the treatment, suggesting resistance to NRG1 in this pathological state

4E-BP1 and 4E-BP2 double knockout mice are protected from aging-associated sarcopenia

Epub ahead of printBACKGROUND: Sarcopenia is the loss of muscle mass/function that occurs during the aging process. The links between mechanistic target of rapamycin (mTOR) activity and muscle development are largely documented, but the role of its downstream targets in the development of sarcopenia is poorly understood. Eukaryotic initiation factor 4E-binding proteins (4E-BPs) are targets of mTOR that repress mRNA translation initiation and are involved in the control of several physiological processes. However, their role in skeletal muscle is still poorly understood. The goal of this study was to assess how loss of 4E-BP1 and 4E-BP2 expression impacts skeletal muscle function and homeostasis in aged mice and to characterize the associated metabolic changes by metabolomic and lipidomic profiling. METHODS: Twenty-four-month-old wild-type and whole body 4E-BP1/4E-BP2 double knockout (DKO) mice were used to measure muscle mass and function. Protein homeostasis was measured ex vivo in extensor digitorum longus by incorporation of l-[U-(14) C]phenylalanine, and metabolomic and lipidomic profiling of skeletal muscle was performed by Metabolon, Inc. RESULTS: The 4E-BP1/2 DKO mice exhibited an increase in muscle mass that was associated with increased grip strength (P < 0.05). Protein synthesis was higher under both basal (+102%, P < 0.05) and stimulated conditions (+65%, P < 0.05) in DKO skeletal muscle. Metabolomic and complex lipid analysis of skeletal muscle revealed robust differences pertaining to amino acid homeostasis, carbohydrate abundance, and certain aspects of lipid metabolism. In particular, levels of most free amino acids were lower within the 4E-BP1/2 DKO muscle. Interestingly, although glucose levels were unchanged, differences were observed in the isobaric compound maltitol/lactitol (33-fold increase, P < 0.01) and in several additional carbohydrate compounds. 4E-BP1/2 depletion also resulted in accumulation of medium-chain acylcarnitines and a 20% lower C2/C0 acylcarnitine ratio (P < 0.01) indicative of reduced beta-oxidation. CONCLUSIONS: Taken together, these findings demonstrate that deletion of 4E-BPs is associated with perturbed energy metabolism in skeletal muscle and could have beneficial effects on skeletal muscle mass and function in aging mice. They also identify 4E-BPs as potential targets for the treatment of sarcopenia

The 24-h Energy Intake of Obese Adolescents Is Spontaneously Reduced after Intensive Exercise: A Randomized Controlled Trial in Calorimetric Chambers

Background: Physical exercise can modify subsequent energy intake and appetite and may thus be of particular interest in terms of obesity treatment. However, it is still unclear whether an intensive bout of exercise can affect the energy consumption of obese children and adolescents. [br/] Objective: To compare the impact of high vs. moderate intensity exercises on subsequent 24-h energy intake, macronutrient preferences, appetite sensations, energy expenditure and balance in obese adolescent. [br/] Design: This randomized cross-over trial involves 15 obese adolescent boys who were asked to randomly complete three 24-h sessions in a metabolic chamber, each separated by at least 7 days: (1) sedentary (SED); (2) Low-Intensity Exercise (LIE) (40% maximal oxygen uptake, VO(2)max); (3) High-Intensity Exercise (HIE) (75% VO(2)max). Results: Despite unchanged appetite sensations, 24-h total energy intake following HIE was 6-11% lower compared to LIE and SED (p<0.05), whereas no differences appeared between SED and LIE. Energy intake at lunch was 9.4% and 8.4% lower after HIE compared to SED and LIE, respectively (p<0.05). At dinner time, it was 20.5% and 19.7% lower after HIE compared to SED and LIE, respectively (p<0.01). 24-h energy expenditure was not significantly altered. Thus, the 24-h energy balance was significantly reduced during HIE compared to SED and LIE (p<0.01), whereas those of SED and LIE did not differ. [br/] Conclusions: In obese adolescent boys, HIE has a beneficial impact on 24-h energy balance, mainly due to the spontaneous decrease in energy intake during lunch and dinner following the exercise bout. Prescribing high-intensity exercises to promote weight loss may therefore provide effective results without affecting appetite sensations and, as a result, food frustrations

L'analyse de gaz et les chambres calorimétriques pour l'homme

L'analyse de gaz et les chambres calorimétriques pour l'homme. Ecole des techniques : Analyses des ga

L'analyse de gaz et les Chambres Calorimétriques pour l'homme.

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Dérives des analyseurs d'O2 et de CO2 dues aux variations de la pression atmosphérique : conséquences et corrections pour la détermination des dépenses énergétiques de l'homme

Dérives des analyseurs d'O2 et de CO2 dues aux variations de la pression atmosphérique : conséquences et corrections pour la détermination des dépenses énergétiques de l'homme. Journées de la Mesure et de la Métrologie (J2M

Chambres calorimétriques pour l’homme et analyse de gaz

Les chambres calorimétriques du plateau technique “Calorimétrie Indirecte” de Clermont ‑ Ferrand permettent d’évaluer, avec précision, la dépense énergétique et l’utilisation des substrats énergétiques (protéines, lipides, glucides) d’un individu vivant dans des conditions qui autorisent un contrôle précis de son activité physique et de son alimentation. Elles fonctionnent sur le principe de la calorimétrie indirecte en circuit ouvert (mesure des échanges gazeux respiratoires : consommation d’oxygène et production de CO2). Leur confort et leurs équipements permettent d’effectuer des mesures de dépense énergétique, de fréquence cardiaque et d’actimétrie, sur une durée allant de 24 h à plusieurs jours.Ces équipements rares ont permis de mettre en évidence des résultats inédits concernant les dépenses énergétiques lors du sommeil grâce à la participation de personnes volontaires. Leur mise en œuvre et leur utilisation requièrent des compétences dans les domaines de l’instrumentation, des capteurs, de l’informatique et de la physique des gaz. Lors de la phase de conception, il faut tenir compte de contraintes parfois contradictoires entre elles, afin de faire des choix judicieux quant aux appareils et à l’instrumentation à utiliser. C’est notamment le cas du volume de la chambre, qui doit être suffisant pour le confort des volontaires, mais limité pour éviter une trop grande dilution des échanges respiratoires imposant une contrainte trop importante quant au choix des analyseurs d’O2 et de CO2. La validation de l’ensemble de l’installation et le temps de réponse sont des éléments à prendre en compte lors du calcul des volumes des échanges respiratoire

Méthodes de mesure ou d'évaluation des dépenses énergétiques chez l'homme

International audienc

L'analyse de gaz et les chambres calorimétriques pour l'homme

L'analyse de gaz et les chambres calorimétriques pour l'homme. Ecole technique Analyse des ga