Etudes Compléments alimentaires

Comment la brûle déclenche l’anabolisme?

09/05/2019 | Etudes sur les hormones et Etudes Musculation et Etudes Compléments alimentaires

 

IL-6 release from muscles during exercise is stimulated by lactate-dependent protease activity
Pernille Hojman       08 MAY 2019 ajpendo

IL-6 is secreted from muscles to the circulation during high-intensity and long-duration exercise, where muscle-derived IL-6 works as an energy sensor to increase release of energy substrates from liver and adipose tissues. We investigated the mechanism involved in the exercise-mediated surge in IL-6 during exercise. Using interval-based cycling in healthy young men, swimming exercise in mice, and electrical stimulation of primary human muscle cells, we explored the role of lactate production in muscular IL-6 release during exercise. First, we observed a tight correlation between lactate production and IL-6 release during both strenuous bicycling and electrically stimulated muscle cell cultures. In mice, intramuscular injection of lactate mimicked the exercise-dependent release of IL-6, and pH buffering of lactate production during exercise attenuated IL-6 secretion. Next, we used in vivo bioimaging to demonstrate that intrinsic intramuscular proteases were activated in mice during swimming, and that blockade of protease activity blunted swimming-induced IL-6 release in mice. Last, intramuscular injection of the protease hyaluronidase resulted in dramatic increases in serum IL-6 in mice, and immunohistochemical analyses showed that intramuscular lactate and hyaluronidase injections led to release of IL-6-containing intramyocellular vesicles. We identified a pool of IL-6 located within vesicles of skeletal muscle fibers, which could be readily secreted upon protease activity. This protease-dependent release of IL-6 was initiated by lactate production, linking training intensity and lactate production to IL-6 release during strenuous exercise.

La caféine est aussi absorbée par la muqueuse buccale

22/04/2019 | Etudes Compléments alimentaires et Etudes Perte de poids

 

Caffeine release and absorption from caffeinated gums
Cecile Morris   Food & Function

The objectives of this study were to estimate the impact of chewing time on caffeine release from gum and to understand caffeine pharmacokinetics. Caffeine release increased with chewing time (2 min < 5 min

< 10 min). Furthermore, two plasma caffeine concentration peaks were observed suggesting that

caffeine absorption occurs both through the oral mucosa and gastrointestinal tract. This is of practical relevance to maximise caffeine doses and to synchronise effort with peak caffeine concentration.

Effets de la mélatonine sur la régénération nerveuse?

02/04/2019 | Etudes Compléments alimentaires

 

Effects of melatonin on neural reconstruction after acute spinal cord injury through regulation of endoplasmic reticulum stress response and autophagy
Yunho Jin     The FASEB Journal       1 Apr 2019Abstract Number:662.2

It has been reported that autophagy and endoplasmic reticulum (ER) stress response cause improved hindlimb motor function and reduced damage of axons in spinal cord injured animals, respectively. However, the effects of melatonin on neural reconstruction and motor recovery through regulation of ER stress response and autophagy have not been well described. Therefore, the purpose of this study is to elucidate the effects of melatonin treatment on neural reconstruction and motor recovery through regulation of ER stress response and autophagy.

To verify the effect of melatonin injection on post-SCI alterations regarding neural cells, autophagy, and ER stress response, we analyzed markers at protein level, and morphological changes. At day 3 after SCI, melatonin did not cause behavioral improvement (p<.05). At molecular levels, melatonin suppressed the loss of astrocytes after SCI (p<.05). Beclin-1 expression was decreased by melatonin treatment (p<.05). In other words, autophagy activation in SCI+MT was lower than that of SCI group, indicating melatonin-mediated suppression of autophagic cell death. In addition, GRP78 expression was preserved in SCI+MT group with no difference compared to non-injured groups. Namely, ER stress response was advanced by melatonin. In histological analysis, it was proved that dendritic branches were preserved by melatonin treatment.

In conclusion, exogenous treatment of melatonin may result in neural reconstruction after SCI through regulating autophagy and ER stress response at the injured spinal segments.

Rôles des polyamines dans l’action anabolique des androgènes?

02/04/2019 | Etudes sur les hormones et Etudes Compléments alimentaires

 

Expression of Genes that Comprise the Core Molecular Clock are Altered in the Atrophied Skeletal Muscle by Androgen Deprivation
Michael L Rossetti     The FASEB Journal       1 Apr 2019Abstract Number:579.1

Skeletal muscle atrophy increases the risk of morbidity and mortality during various pathological conditions. In males, a decrease in the production and/or bioavailability of androgens (termed hypogonadism) directly contributes to muscle atrophy during various pathological conditions. While it is known that androgens prevent muscle atrophy, the mechanism(s) by which androgens mediate this effect are largely undefined. Our laboratory previously showed that mitochondrial turnover is enhanced in the tibialis anterior (TA) muscle of mice by androgen deprivation induced by castration surgery, and the magnitude of turnover was related to the degree of muscle atrophy.

These data suggest that potentially dysfunctional mitochondria contribute to the muscle atrophy observed following androgen deprivation. To gain a better understanding of that factors that might contribute to changes in mitochondrial quality control during androgen deprived conditions, we subjected total RNA from the TA of sham and castrated mice to microarray analysis. This unbiased approach identified significant changes in expression of genes that comprise the core molecular clock. qRT-PCR confirmed that expression of Brain and Muscle Arntl 1 (Bmal1) was decreased, while expression of Period 1, Period 2, and Period 3 (Per1, 2, & 3) were increased in the TA of castrated mice. When measured across a diurnal cycle, the change in expression of Bmal1, Per1, and Per2 exhibited reduced amplitude under androgen-deprived conditions. Interestingly, strong relationships were observed between the castration-mediated changes of core clock components and the measures of mitochondrial turnover. Specifically, Bmal1 expression was directly related to BCL2/adenovirus E1B 19 kDA protein-interacting protein 3 (BNIP3) protein content (R2 = 0.88), and the expression of core clock components were also directly related to the content of various mitochondrial proteins.

Expression of core clock components were also related to the autophagy marker, p62, and the mass of the TA. Ex post facto analysis of the microarray also identified changes in genes regulating polyamine biosynthesis. As polyamines are known to alter core clock function, we determined whether androgen deprivation altered polyamine content. While castration did not alter Spermine content, there was a significant reduction in the content of Spermidine in the TA of castrated mice.

Overall, these data suggest that reduced Spermidine concentrations may contribute to alterations in the core molecular clock in the skeletal muscle under androgen-deprived conditions, which may in turn contribute to reduced mitochondrial quality control and subsequent muscle atrophy

Quelle efficacité du papier pH pour mesurer l’acidité du sang?

02/04/2019 | Etudes Compléments alimentaires

 

Accuracy of pH Measurements in Blood-Free Balanced Salt Solutions with and without Bovine Serum Albumin—with Four Devices (ABL80, i-STAT®, pH Paper, and pH Probe)
Josephine E. Hees       The FASEB Journal               1 Apr 2019Abstract Number:544.1

Introduction
Accurate and precise measurements are vital in research. Discrepancies between the actual values and values measured by a device can have serious implications on the design and results of an experiment. Thus, it is critical to know what devices provide reliable values. The aim of this study was to compare four different devices commonly used to measure pH in the absence and presence of Bovine Serum Albumin (BSA).

Methods
A balanced salt solution (NaCl 119 mM, NaHCO3 24 mM, Glucose 5.5 mM, CaCa2 1.6 mM, KCl 4.7 mM, MgSO4 1.17 mM, NaPO4 1.18 mM) with or without 4% BSA was bubbled with different CO2 percentages (2.5%, 3.8%, 5%, 7.5 %, 10%), 30% O2 and N2 as the balance gas using a gas mixer. After a steady state pH was reached, judged by the pH probe, four samples were taken simultaneously, and 3 replicate measurements with each of the four devices were made. The devices used in this study were the ABL 80 FLEX (RADIOMETER, blood gas analyzer), VetScan i-STAT® 1, pH paper (Macherey-Nagel, pH range 6.4 – 8.0) and a pH probe (OAKTON®, pH700). Measured pH values were plotted against the expected pH values for a given concentration of CO2 according to the Henderson–Hasselbalch equation (pH = pKa + log10 ([A−]/[HA]). Linear regression ± SEM was done for each device with and without BSA and the coefficient of determination and regression coefficients were calculated. The mean and difference of each measurement by device were then calculated and used to create Bland-Altman plots (right lower corner in each panel) to assess the agreement of the measuring device with the expected pH.

Results
Except for the pH paper, all devices showed a strong agreement with the expected pH for each CO2 percentage. The addition of BSA to the solution resulted in a trend to more acidic readings and to be even more in agreement with the expected pH for all four devices.

Conclusion
The blood gas analyzer, i-STAT®, and pH probe all proved to be suitable devices for use in measuring the pH of a balanced salt solution in the chosen pH range. The pH paper appeared to be unsuitable to measure the pH within physiological ranges. Additionally, throughout all measurements, the solutions with 4% BSA tended to provide even more accurate values than the solutions without BSA.

Actions santé de la mélatonine

11/01/2019 | Etudes sur les hormones et Echauffement et blessures et Etudes Compléments alimentaires et Etudes Anti-âge

 

The multiple protective roles and molecular mechanisms of melatonin and its precursor N-acetylserotonin in targeting brain injury and liver damage and in maintaining bone health
ChengliangLuoa       Free Radical Biology and Medicine Volume 130, January 2019, Pages 215-233

Highlights
• Melatonin and NAS are protective agents for brain injury, liver damage and bone health.
• Melatonin and NAS are anti-oxidative stress and anti-inflammation.
• Melatonin and NAS are against autophagy dysfunction and anti-apoptosis.
• MT1/MT2 are needed for brain and liver injuries and MT2 is important for bone health.
• Melatonin and NAS will be likely to show utility in clinical trials.

Melatonin is a neurohormone associated with sleep and wakefulness and is mainly produced by the pineal gland. Numerous physiological functions of melatonin have been demonstrated including anti-inflammation, suppressing neoplastic growth, circadian and endocrine rhythm regulation, and its potent antioxidant activity as well as its role in regeneration of various tissues including the nervous system, liver, bone, kidney, bladder, skin, and muscle, among others.

In this review, we summarize the recent advances related to the multiple protective roles of melatonin receptor agonists, melatonin and N-acetylserotonin (NAS), in brain injury, liver damage, and bone health. Brain injury, including traumatic brain injury, ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and newborn perinatal hypoxia-ischemia encephalopathy, is a major cause of mortality and disability. Liver disease causes serious public health problems and various factors including alcohol, chemical pollutants, and drugs induce hepatic damage. Osteoporosis is the most common bone disease in humans. Due in part to an aging population, both the cost of care of fracture patients and the annual fracture rate have increased steadily. Despite the discrepancy in the pathophysiological processes of these disorders, time frames and severity, they may share several common molecular mechanisms. Oxidative stress is considered to be a critical factor in these pathogeneses. We update the current state of knowledge related to the molecular processes, mainly including anti-oxidative stress, anti-apoptosis, autophagy dysfunction, and anti-inflammation as well as other properties of melatonin and NAS. Particularly, the abilities of melatonin and NAS to directly scavenge oxygen-centered radicals and toxic reactive oxygen species, and indirectly act through antioxidant enzymes are disscussed. In this review, we summarize the similarities and differences in the protection provided by melatonin and/or NAS in brain, liver and bone damage.

We analyze the involvement of melatonin receptor 1A (MT1), melatonin receptor 1B (MT2), and melatonin receptor 1C (MT3) in the protection of melatonin and/or NAS. Additionally, we evaluate their potential clinical applications. The multiple mechanisms of action and multiple organ-targeted properties of melatonin and NAS may contribute to development of promising therapies for clinical trials.

Combien de mélatonine pour la santé?

26/12/2018 | Etudes sur les hormones et Etudes Compléments alimentaires et Etudes Anti-âge

 

Melatonin as a chronobiotic/cytoprotector: its role in healthy aging
Daniel P. Cardinali         Biological Rhythm Research Volume 50, 2019 - Issue 1

Preservation of sleep, a proper nutrition and adequate physical exercise are key elements for healthy aging. Aging causes sleep alterations, and in turn, sleep disturbances lead to numerous pathophysiological changes that accelerates the aging process. In the central nervous system, sleep loss impairs the clearance of waste molecules like amyloid-β or tau peptides. Melatonin, a molecule of unusual phylogenetic conservation present in all known aerobic organisms, is effective both as a chronobiotic and a cytoprotective agent to maintain a healthy aging.

The late afternoon increase of melatonin “opens the sleep doors” every night and its therapeutic use to preserve slow wave sleep has been demonstrated. Melatonin reverses inflammaging via prevention of insulin resistance, suppression of inflammation and down regulation of proinflammatory cytokines. Melatonin increases the expression of α- and γ-secretase and decreases β-secretase expression. It also inhibits tau phosphorylation. Clinical data support the efficacy of melatonin to treat Alzheimer’s disease, particularly at the early stages of disease. From animal studies the cytoprotective effects of melatonin need high doses to become apparent (i.e. in the 40–100 mg/day range). The potentiality of melatonin as a nutraceutical is discussed.

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