Etudes Perte de poids

α‐Cedrene pour plus de muscle?

19/06/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

α‐Cedrene, a Newly Identified Ligand of MOR23, Increases Skeletal Muscle Mass and Strength
Tao Tong Molecular Nutrition &  Food Research 14 June 2018

Scope
Skeletal muscle atrophy is a common and debilitating condition that lacks an effective therapy. In this study, we tested the effects of α‐cedrene, a natural ligand of mouse olfactory receptor 23 (MOR23) whose ectopic function regulating myogenesis was reported recently, on skeletal muscle growth.

Methods and results
α‐Cedrene, not only stimulated hypertrophy but also attenuated free fatty acid–induced atrophy of cultured skeletal myotubes, as evidenced by an increased myotube diameter, fusion index, and total cellular protein content. These hypertrophic and antiatrophic properties of α‐cedrene in cultured myotubes were confirmed in corresponding mouse models. The skeletal muscle mass, total muscle protein content, average cross‐sectional area of myofibers, and muscle strength were significantly greater in α‐cedrene–treated mice compared with untreated animals during either a regular chow diet or high‐fat diet. Receptor knockdown experiments using RNA interference in cultured skeletal myotubes revealed that the hypertrophic and antiatrophic properties of α‐cedrene may be mediated by MOR23. Furthermore, α‐cedrene induced the expression of MOR23 and enhanced its downstream cAMP–PKA–CREB signaling in the skeletal muscle of mice fed chow or high‐fat diet.

Conclusions
α‐Cedrene is a promising agent that may be applied to enhance the mass and strength of skeletal muscle.

Pourquoi le diabète augmente le niveau de BCAA sanguins?

10/06/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

Fasting serum amino acids concentration is associated with insulin resistance and pro-inflammatory cytokines
Diabetes Research and Clinical Practice Volume 140, June 2018, Pages 107-117               Sang-GukLee
Highlights
• Serum branched chain amino acids (BCAAs) were increased in type 2 diabetes mellitus.
• Serum non-BCAAs were also elevated in patients with type 2 diabetes.
• HOMA-IR and pro-inflammatory cytokines were independent predictors of amino acid.
• Insulin resistance or inflammatory cytokines could induce skeletal muscle proteolysis.
• Elevated serum amino acids are an early manifestation of impaired insulin action.

Aims
We evaluated specific alterations in amino acids (AAs) profile in patients with type 2 diabetes mellitus (T2DM) and impaired fasting glucose (IFG) compared with healthy controls. In addition, we tried to find the mechanisms behind these AA alterations.

Methods
Twenty AAs, TNF-α, and IL-6 were analyzed in fasting serum samples from a total of 198 individuals (56 drug-naïve patients with T2DM, 69 patients IFG, and 73 healthy controls). The C2C12 mouse myoblast cell lines were used to examine the changes of MAFbx and MuRF1 expressions, which are muscle specific E3 ligases acting as major mediators of skeletal muscle proteolysis, after development of insulin resistance induced by palmitate treatment.

Results
In addition to branched chain amino acids BCAAs, fasting serum AAs such as glutamic acid, lysine, phenylalanine, arginine, alanine, tyrosine, aspartic acid, were higher in patients with T2DM and intermediately elevated in patients with IFG compared with normoglycemic controls. These serum AA concentrations positively correlated with fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), and pro-inflammatory cytokines. In addition, HOMA-IR and pro-inflammatory cytokines were two important independent predictors of serum AA levels. In vitro experiments showed that palmitate treatment in C2C12 myotubes induced insulin resistance, increased pro-inflammatory cytokine gene expression, and increased MAFbx gene and protein expression.

Conclusions
The increase in fasting serum AAs can be an early manifestation of insulin resistance. Increased muscle proteolysis induced by insulin resistance and inflammatory cytokines can be a possible mechanism for the rise in serum AA levels.

Comment une alimentation acide agresse les reins?

25/05/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

Kidney Response to the Spectrum of Diet-Induced Acid Stress
Nimrit Goraya                     Nutrients 2018, 10(5), 596;


Chronic ingestion of the acid (H+)-producing diets that are typical of developed societies appears to pose a long-term threat to kidney health. Mechanisms employed by kidneys to excrete this high dietary H+ load appear to cause long-term kidney injury when deployed over many years. In addition, cumulative urine H+ excretion is less than the cumulative increment in dietary H+, consistent with H+ retention. This H+ retention associated with the described high dietary H+ worsens as the glomerular filtration rate (GFR) declines which further exacerbates kidney injury. Modest H+ retention does not measurably change plasma acid–base parameters but, nevertheless, causes kidney injury and might contribute to progressive nephropathy. Current clinical methods do not detect H+ retention in its early stages but the condition manifests as metabolic acidosis as it worsens, with progressive decline of the glomerular filtration rate.

We discuss this spectrum of H+ injury, which we characterize as “H+ stress”, and the emerging evidence that high dietary H+ constitutes a threat to long-term kidney health.

Influence de la sérine sur la sécrétion de GH et cortisol?

28/03/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

Effects of L-serine supplementation on the daily rhythms of growth hormone and corticosterone concentrations in mice
Li Wu,      Biological Rhythm Research       22 Mar 2018    

The impact of L-serine on the daily rhythms of growth hormone (GH) and corticosterone remains unknown. We explored whether the daily rhythms of these hormones were affected by L-serine supplementation as well as the supplementation time.

The results showed that plasma GH concentration at Zeitgeber time (ZT) 4 and 8 were significantly increased by L-serine supplementation at ZT22, while the diurnal rhythms peaks of plasma corticosterone at ZT12 were suppressed by L-serine supplementation at ZT10. After the supplementation was stopped, the effects of L-serine on the diurnal rhythms of plasma GH and corticosterone lasted for 2 days then they were fading on day 4. L-serine concentrations in plasma and hypothalamus after supplementation at ZT22 was lower than those after supplementation at ZT10.

In conclusion, L-serine modulates the daily rhythms of GH and corticosterone depending on its supplementation time. The modulation effect might be association with the daily rhythms of L-serine metabolism.

Irisine: le lien entre la muscu et le renforcement osseux?

14/03/2018 | Etudes sur les hormones et Etudes Perte de poids et Etudes Anti-âge

 

Myokine—Irisin—and Its Effects Linking Bone and Muscle Function
Graziana Colaianni           Clinical Reviews in Bone and Mineral Metabolism March 2018, Volume 16, Issue 1, pp 16–21

Irisin is a myokine secreted by the skeletal muscle during physical activity both in mice and humans. Its first identified role was to activate the browning response in white adipocytes, subsequently triggering non-shivering thermogenesis; therefore, Irisin has raised great expectations as a potential target in the treatment of obesity. In 2015, we demonstrated that Irisin plays a central role in the control of bone mass, driving positive effects on cortical mineral density and bone mechanical properties. This effect on the bone was triggered using an Irisin dosage 70 times lower than the one needed to induce the browning response, suggesting that the skeleton is the primary target organ of this myokine. Moreover, our studies also highlighted the autocrine effect of Irisin on the skeletal muscle, overall suggesting that Irisin plays a fundamental role in the physiology of the musculoskeletal system. More recently, we demonstrated the efficacy of Irisin in preventing and restoring bone and muscle losses in a mouse model affected by disuse-induced osteoporosis and muscular atrophy. Hopefully, if future investigations will be confirmed in humans, it may lead to develop an Irisin-based therapy for physically disable or bedridden patients and it might also represent a countermeasure for astronauts subjected to microgravity.

Du propionate de sodium pour perdre du gras?

13/03/2018 | Etudes Compléments alimentaires et Etudes Perte de poids

 

Acute oral sodium propionate supplementation raises resting energy expenditure and lipid oxidation in fasted humans
Edward S. Chambers   Diabetes, Obesity and Metabolism Content Alert: 20, 4 (April 2018)

Short-chain fatty acids (SCFAs), produced from fermentation of dietary fibre by the gut microbiota, have been suggested to modulate energy metabolism.

Previous work using rodent models has demonstrated that oral supplementation of the SCFA propionate raises resting energy expenditure (REE) by promoting lipid oxidation. The objective of the present study was to investigate the effects of oral sodium propionate on REE and substrate metabolism in humans. Eighteen healthy volunteers (9 women and 9 men; age 25 ± 1 years; body mass index 24.1 ± 1.2 kg/m2) completed 2 study visits following an overnight fast.

Tablets containing a total of 6845 mg sodium propionate or 4164 mg sodium chloride were provided over the 180-minute study period in random order. REE and substrate oxidation were assessed by indirect calorimetry. Oral sodium propionate administration increased REE (0.045 ± 0.020 kcal/min; P = .036); this was accompanied by elevated rates of whole-body lipid oxidation (0.012 ± 0.006 g/min; P = .048) and was independent of changes in glucose and insulin concentrations. Future studies are warranted to determine whether the acute effects of oral sodium propionate on REE translate into positive improvements in long-term energy balance in humans.

Effet d’une supplémentation en corps cétoniques sur la glycémie?

17/02/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

Prior ingestion of exogenous ketone monoester attenuates the glycemic response to an oral glucose tolerance test in healthy young individuals
Etienne Myette-Côté              The Journal of Physiology               15 February 2018  

The main objectives of this study were threefold: (1) To determine whether acute ingestion of Kme; (R)-3-hydroxybutyl (R)-3-hydroxybutyrate impacts plasma glucose levels during a standardized oral glucose tolerance test (OGTT). (2) To compare changes in insulin concentrations and estimates of insulin sensitivity after acute Kme supplementation. Twenty healthy participants (n = 10 males/females) aged between 18–35 years took part in a randomized crossover study. After an overnight fast, participants consumed a Kme supplement (ΔG®; 0.45 ml kg−1 body weight) or placebo (water) 30 min before completing a 75-gram OGTT. Blood samples were collected every 15–30 min over a period of 2.5 h. Participants and study personnel performing laboratory analyses were blinded to condition. Kme acutely raised blood D-beta-hydroxybutyrate (β-OHB) to 3.2±0.6 mm within 30 min with levels remaining elevated throughout the entire OGTT. Compared to placebo, Kme significantly decreased glucose area under the curve (AUC; −16%, P = 0.001), non-esterified fatty acid (NEFA) AUC (-44%, P

< 0.001) and C-peptide incremental AUC (P = 0.005), while improving oral glucose insulin sensitivity index by ∼11% (P = 0.001).

In conclusion, a

Kme supplement that acutely increased β-OHB levels up to ∼3 mm attenuated the glycemic response to an OGTT in healthy humans. The reduction in glycemic response did not appear to be driven by an increase in insulin secretion, but was accompanied by improved markers of insulin sensitivity. These results suggest that ketone monoester supplements could have therapeutic potential in the management and prevention of metabolic disease.

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