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Les oméga 6 sont-ils pro- ou anti-inflammatoires?

14/12/2017 | Etudes Anti-âge

 

The associations of serum n-6 polyunsaturated fatty acids with serum C-reactive protein in men: the Kuopio Ischaemic Heart Disease Risk Factor Study
Jyrki K. Virtanen               European Journal of Clinical Nutrition (2017)


There are concerns that high intake of n-6 polyunsaturated fatty acids (PUFA) may promote inflammation, because the end-product of n-6 PUFA metabolism, arachidonic acid, is a precursor for pro-inflammatory eicosanoids. Our aim was to investigate cross-sectional associations of the serum n-6 PUFAs, objective biomarkers for exposure, with serum high-sensitivity C-reactive protein (CRP), a key inflammation marker.

Subjects/methods
The study included 1287 generally healthy men aged 42–60 years from the population-based Kuopio Ischaemic Heart Disease Risk Factor Study, examined in 1984–1989. ANCOVA and logistic regression were used for analyses.

Results
In the multivariable-adjusted analyses, both serum total n-6 PUFA and linoleic acid, the predominant n-6 PUFA, were associated with lower CRP. The mean CRP concentrations in quartiles of linoleic acid were 1.86, 1.51, 1.53, and 1.37 mg/L (P-trend = 0.001). The odds ratio for elevated CRP (>3 mg/L) in the highest vs. the lowest quartile was 0.47 (95% confidence interval (CI) 0.25–0.87, P-trend = 0.01). Arachidonic acid or the mainly endogenously produced n-6 PUFAs, gamma-linolenic acid and dihomo-gamma-linolenic acid, were not associated with higher CRP, either. Age, body mass index, or serum long-chain n-3 PUFA concentration did not modify the associations (P-interactions > 0.14).

Conclusions
Serum n-6 PUFAs were not associated with increased inflammation in men. In contrast, the main n-6 PUFA linoleic acid had a strong inverse association with the key inflammation marker, CRP.

Les boosters de NO pour maigrir sur le long terme?

14/12/2017 | Etudes Perte de poids et Etudes Anti-âge et Etudes sur les boosters sexuels et la sexualité

 

Ca fait quand même un peu beaucoup…

Sildenafil induces browning of subcutaneous white adipose tissue in overweight adults
Metabolism Volume 78, January 2018, Pages 106-117

To investigate that short-term treatment of sildenafil can induce browning of subcutaneous white adipose tissue (sWAT) in human adults.

Design
A randomized, double-blinded, placebo-controlled, parallel group trial.

Methods
Sixteen eligibility overweight male subjects were recruited, comparing 100 mg/day sildenafil versus an identical placebo therapy for 7 days. sWAT samples were collected from subjects before and after 7-day sildenafil or placebo interventions.

Results
The results showed that multilocular UCP1-positive adipocytes existed in sWAT samples from subjects after sildenafil treatment. Compared to before treatment in both group as well as after treatment in placebo, sildenafil significantly decreased adipocyte size, increased the expressions of UCP1 protein and mRNA, mitochondrial density, and leak respiratory capacity in sWAT (p < 0.05). Sildenafil also increased plasma cyclic guanosine-3′,5′-monophosphate (cGMP) and catecholamine concentrations (p < 0.05), and consequently activated the expressions of vasodilator-stimulated phosphoprotein (VASP) and p70 ribosomal S6 kinase 1 (S6 K1) (p < 0.05). Sildenafil did not activate typical brown fat.

Conclusions
The current findings demonstrate that sildenafil can induce browning of sWAT in human, and this action may be through cGMP-dependent protein kinase I and mechanistic/mammalian target of rapamycin (mTOR) signaling pathways. Sldenafil may be a promising treatment for metabolic disease.

Chaleur ou froid pour optimiser l’anabolisme?

22/11/2017 | Echauffement et blessures et Etudes Musculation

 

Plus d’anabolisme, moins de catabolisme avec…

Impact of local heating and cooling on skeletal muscle transcriptional response related to myogenesis and proteolysis
Roksana B. Zak European Journal of Applied Physiology October 2017

Purpose

To determine the impact of local muscle heating and cooling on myogenic and proteolytic gene responses following resistance exercise.

Methods

Recreationally trained males (n = 12), age 25.3 ± 1.5, % body fat 13.6 ± 1.92, completed four sets of 8–12 repetitions of unilateral leg press and leg extension while heating one leg, and cooling the other. Muscle biopsies were taken from the vastus lateralis of each leg pre and 4 h post exercise.

Results

MyoD, FOXO1, and MuRF1 mRNA increased with exercise regardless of temperature (p < 0.05). Myostatin, MYF5, and atrogin-1 mRNA decreased with exercise regardless of temperature (p < 0.05). Myogenin, MRF4, and CASP3 mRNA were higher in the hot condition, compared to the cold (p < 0.05). PAX7 mRNA was lower in the hot compared to cold condition (p = 0.041). FOXO3 mRNA was higher in the cold compared to hot condition (p = 0.037). AKT1 and AKT2 were unaffected by either exercise or temperature. Femoral artery blood flow volume was higher in the hot (375.2 ± 41.2 ml min− 1), compared to the cold condition (263.5 ± 23.9 ml min− 1), p = 0.01. Tissue oxygen saturation was higher in the hot (71.7 ± 4.8%) than cold condition (55.3 ± 5.0%).

Conclusion

These results suggest an impaired muscle growth response with local cold application compared to local heat application.

Les protéines laitières rapides ont un impact à court et à long terme sur la glycémie

05/11/2017 | Etudes sur les hormones et Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

Cela explique que l’on peut ne pas le sentir au début puis y devenir sensible

Comparison between pre–exercise casein peptide and intact casein supplementation on glucose tolerance in high–fat diet–fed mice

Yutaka Matsunaga         Applied Physiology, Nutrition, and Metabolism, 2017

We hypothesized that along with exercise, casein peptide supplementation would have a higher impact on improving glucose tolerance than intact casein. Male six–week–old ICR mice were provided a high–fat diet to induce obesity and glucose intolerance. The mice were randomly divided into four treatment groups: control (Con), endurance training (Tr), endurance training with intact casein supplementation (Cas+Tr), and endurance training with casein peptide supplementation (CP+Tr). The mice in each group were orally administrated water, intact casein, or casein peptide (1.0 mg/g BW, everyday), and then subjected to endurance training (15–25 m/min, 60 min, 5 times/week for 4 weeks) on a motor–driven treadmill 30 min after ingestion. Our results revealed that total intra–abdominal fat was significantly lower in CP+Tr than in Con (p<0.05). Following an oral glucose tolerance test, the blood glucose area under the curve (AUC) was found to be significantly smaller for CP+Tr than for Con (p<0.05). Moreover, in the soleus muscle, GLUT4 protein levels were significantly higher in CP+Tr than in Con (p<0.01). However, intra–abdominal fat, blood glucose AUC, and GLUT4 protein content in the soleus muscle did not alter in Tr and Cas+Tr when compared with Con. These observations suggest that pre–exercise casein peptide supplementation has a higher effect on improving glucose tolerance than intact casein does in high–fat diet–fed mice.

L’acide férulique fait un comeback pour la prise de muscle

04/11/2017 | Etudes Compléments alimentaires et Etudes Anti-âge

 

Ferulic Acid Promotes Hypertrophic Growth of Fast Skeletal Muscle in Zebrafish Model
Ya We     Nutrients 2017, 9(10), 1066

As a widely distributed and natural existing antioxidant, ferulic acid and its functions have been extensively studied in recent decades. In the present study, hypertrophic growth of fast skeletal myofibers was observed in adult zebrafish after ferulic acid administration for 30 days, being reflected in increased body weight, body mass index (BMI), and muscle mass, along with an enlarged cross-sectional area of myofibers. qRT-PCR analyses demonstrated the up-regulation of relative mRNA expression levels of myogenic transcriptional factors (MyoD, myogenin and serum response factor (SRF)) and their target genes encoding sarcomeric unit proteins involved in muscular hypertrophy (skeletal alpha-actin, myosin heavy chain, tropomyosin, and troponin I). Western blot analyses detected a higher phosphorylated level of zTOR (zebrafish target of rapamycin), p70S6K, and 4E-BP1, which suggests an enhanced translation efficiency and protein synthesis capacity of fast skeletal muscle myofibers. These changes in transcription and translation finally converge and lead to higher protein contents in myofibers, as confirmed by elevated levels of myosin heavy chain (MyHC), and an increased muscle mass.

To the best of our knowledge, these findings have been reported for the first time in vivo and suggest potential applications of ferulic acid as functional food additives and dietary supplements owing to its ability to promote muscle growth.

Retour de la théorie de l’hyperplasie comme mode de croissance

18/08/2017 | Etudes Musculation

 

Differential requirement for satellite cells during overload-induced muscle hypertrophy in growing versus mature mice
Kevin A. Murach   Skelet Muscle. 2017; 7: 14.

Pax7+ satellite cells are required for skeletal muscle fiber growth during post-natal development in mice. Satellite cell-mediated myonuclear accretion also appears to persist into early adulthood. Given the important role of satellite cells during muscle development, we hypothesized that the necessity of satellite cells for adaptation to an imposed hypertrophic stimulus depends on maturational age.

Methods

Pax7CreER-R26RDTA mice were treated for 5 days with vehicle (satellite cell-replete, SC+) or tamoxifen (satellite cell-depleted, SC-) at 2 months (young) and 4 months (mature) of age. Following a 2-week washout, mice were subjected to sham surgery or 10 day synergist ablation overload of the plantaris (n = 6–9 per group). The surgical approach minimized regeneration, de novo fiber formation, and fiber splitting while promoting muscle fiber growth. Satellite cell density (Pax7+ cells/fiber), embryonic myosin heavy chain expression (eMyHC), and muscle fiber cross sectional area (CSA) were evaluated via immunohistochemistry. Myonuclei (myonuclei/100 mm) were counted on isolated single muscle fibers.

Results

Tamoxifen treatment depleted satellite cells by ≥90% and prevented myonuclear accretion with overload in young and mature mice (p < 0.05). Satellite cells did not recover in SC- mice after overload. Average muscle fiber CSA increased ~20% in young SC+ (p = 0.07), mature SC+ (p < 0.05), and mature SC- mice (p < 0.05). In contrast, muscle fiber hypertrophy was prevented in young SC- mice. Muscle fiber number increased only in mature mice after overload (p < 0.05), and eMyHC expression was variable, specifically in mature SC+ mice.

Conclusions

Reliance on satellite cells for overload-induced hypertrophy is dependent on maturational age, and global responses to overload differ in young versus mature mice.

Une supplémentation en corps cétoniques booste la récupération énergétique

17/08/2017 | Etudes cardio et Etudes Compléments alimentaires et Etudes Perte de poids

 

A Ketone Ester Drink Increases Postexercise Muscle Glycogen Synthesis in Humans
HOLDSWORTH, DAVID A         Medicine & Science in Sports & Exercise: September 2017 - Volume 49 - Issue 9 - p 1789–1795

Introduction: Physical endurance can be limited by muscle glycogen stores, in that glycogen depletion markedly reduces external work. During carbohydrate restriction, the liver synthesizes the ketone bodies, D-β-hydroxybutyrate, and acetoacetate from fatty acids. In animals and in the presence of glucose, D-β-hydroxybutyrate promotes insulin secretion and increases glycogen synthesis. Here we determined whether a dietary ketone ester, combined with plentiful glucose, can increase postexercise glycogen synthesis in human skeletal muscle.

Methods: After an interval-based glycogen depletion exercise protocol, 12 well-trained male athletes completed a randomized, three-arm, blinded crossover recovery study that consisted of consumption of either a taste-matched, zero-calorie control or a ketone monoester drink, followed by a 10-mM glucose clamp or saline infusion for 2 h. The three postexercise conditions were control drink then saline infusion, control drink then hyperglycemic clamp, or ketone ester drink then hyperglycemic clamp. Skeletal muscle glycogen content was determined in muscle biopsies of vastus lateralis taken before and after the 2-h clamps.

Results: The ketone ester drink increased blood D-β-hydroxybutyrate concentrations to a maximum of 5.3 versus 0.7 mM for the control drink (P < 0.0001). During the 2-h glucose clamps, insulin levels were twofold higher (31 vs 16 mU·L−1, P < 0.01) and glucose uptake 32% faster (1.66 vs 1.26 g·kg−1, P < 0.001). The ketone drink increased by 61 g, the total glucose infused for 2 h, from 197 to 258 g, and muscle glycogen was 50% higher (246 vs 164 mmol glycosyl units per kilogram dry weight, P < 0.05) than after the control drink.

Conclusion: In the presence of constant high glucose concentrations, a ketone ester drink increased endogenous insulin levels, glucose uptake, and muscle glycogen synthesis.

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