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Nathan Goodyear

The Role of Post-Exercise Nutrient Administration on Muscle Protein Synthesis and Glyco... - 0 views

www.ncbi.nlm.nih.gov/...PMC3761704

exercise athlete athletes recovery exercise recovery training protein carbohydrates glycogen muscle

shared by Nathan Goodyear on 10 Feb 16 - No Cached
  • Whey protein was superior to that of casein in upregulating protein synthesis
  • ability to digest more rapidly than casein protein
  • Free form amino acid ingestion acts similarly to whey by displaying a rapid and strong increase in aminoacidemia
  • ...11 more annotations...
  • it appears that protein synthesis rapidly increases for up to two hours after amino acid administration
  • The intervention of dietary protein or amino acid supplementation in conjunction with resistance training has proven to effectively increase protein synthesis rates
  • 291% increase in protein synthesis following the exercise bout, while protein degradation remained unchanged from baseline quantities
  • it has been established that post-exercise EAA supplementation stimulates protein synthesis, in conjunction with a positive protein balance, comparable to that of intravenous infusion of amino acids
  • Casein and whey protein ingestion yielded similar values of net positive protein balance, and thus an overall increase in protein synthesis
  • A later analysis revealed that soy protein increased protein synthesis in rats similar to that of whey after a treadmill exercise protocol
  • A human trial, however, concluded that milk proteins (caseins and whey) in comparison to soy promoted greater muscle protein accretion when they were ingested after regular resistance training
  • Whey hydrolysate ingested after a resistance exercise bout acutely stimulated mixed muscle protein synthesis 31% greater than soy
  • adequate amount of protein (20 g) is ingested (Tipton et al., 2009) immediately before or after a resistance exercise bout
  • The rapid phase lasts approximately 30-60 minutes and does not require the presence of insulin
  • slow phase, which can last up to several hours if carbohydrate availability is high and insulin levels remain elevated
  • Nathan Goodyear on 10 Feb 16
     
    Good review of recovery supplement strategy.
Nathan Goodyear

Branched Chain Amino Acid Supplementation for Patients with Cirrhosis | Clinical Correl... - 0 views

www.clinicalcorrelations.org/?p=3544

BCCA branched chain amino acids liver cirrhosis hepatitis amino acids

shared by Nathan Goodyear on 05 Oct 15 - No Cached
  • low level of BCAAs in patients with cirrhosis is hypothesized to be one of multiple factors responsible for development of hepatic encephalopathy
  • supplementation of BCAAs is thought to facilitate ammonia detoxification by supporting synthesis of glutamine, one of the non-branched chain amino acids, in skeletal muscle and in the brain as well as diminishing the influx of AAAs across the blood-brain barrier
  • oral BCAA supplementation is more useful in chronic encephalopathic patients than is parenteral BCAA supplementation in patients with acute encephalopathy
  • ...35 more annotations...
  • malnutrition progressing to cachexia is another common manifestation of cirrhosis
  • Malnutrition can be mitigated with BCAA supplementation
  • Studies show that administration of amino acid formulas enriched with BCAAs can reduce protein loss, support protein synthesis, and improve nutritional status of patients with chronic liver disease
  • Leucine has been shown to be the most effective of the BCAAs because it acts via multiple pathways to stimulate protein synthesis
  • BCAAs metabolites inhibit proteolysis
  • Patients with cirrhosis have both insulin deficiency and insulin resistance
  • BCAAs (particularly leucine) help to reverse the catabolic, hyperglucagonemic state of cirrhosis both by stimulating insulin release from the pancreatic β cells and by decreasing insulin resistance allowing for better glucose utilization
  • Coadministration of BCAAs and glucose has been found to be particularly useful
  • BCAA supplementation improves protein-energy malnutrition by improving utilization of glucose, thereby diminishing the drive for proteolysis, inhibiting protein breakdown, and stimulating protein synthesis
  • Cirrhotic patients have impaired immune defense, characterized by defective phagocytic activity and impaired intracellular killing activity
  • another effect of BCAA supplementation is improvement of phagocytic function of neutrophils and possibly improvement in natural killer T (NKT) cell lymphocyte activity
  • BCAA supplementation may reduce the risk of infection in patients with advanced cirrhosis not only through improvement in protein-energy malnutrition but also by directly improving the function of the immune cells themselves
  • BCAA administration has also been shown to have a positive effect on liver regeneration
  • A proposed mechanism for improved liver regeneration is the stimulatory effect of BCAAs (particularly leucine) on the secretion of hepatocyte growth factor by hepatic stellate cells
  • BCAAs activate rapamycin signaling pathways which promotes albumin synthesis in the liver as well as protein and glycogen synthesis in muscle tissue
  • Chemical improvement with BCAA treatment is demonstrated by recovery of serum albumin and lowering of serum bilirubin levels
  • long-term oral BCAA supplementation was useful in staving off malnutrition and improving survival by preventing end-stage fatal complications of cirrhosis such as hepatic failure and gastrointestinal bleeding
  • The incidence of death by any cause, development of liver cancer, rupture of esophageal varices, or progression to hepatic failure was decreased in the group that received BCAA supplementation
  • Patients receiving BCAA supplementation also have a lower average hospital admission rate, better nutritional status, and better liver function tests
  • patients taking BCAA supplementation report improved quality of life
  • BCAAs have been shown to mitigate hepatic encephalopathy, cachexia, and infection rates, complications associated with the progression of hepatic cirrhosis
  • BCAAs make up 20-25% of the protein content of most foods
  • Highest levels are found in casein whey protein of dairy products and vegetables, such as corn and mushrooms. Other sources include egg albumin, beans, peanuts and brown rice bran
  • In addition to BCAAs from diet, oral supplements of BCAAs can be used
  • Oral supplementation tends to provide a better hepatic supply of BCAAs for patients able to tolerate PO nutrition as compared with IV supplementation, especially when treating symptoms of hepatic encephalopathy
  • Coadministration of BCAAs with carnitine and zinc has also been shown to increase ammonia metabolism further reducing the encephalopathic symptoms
  • Cirrhotic patients benefit from eating frequent, small meals that prevent long fasts which place the patient in a catabolic state
  • the best time for BCAA supplementation is at bedtime to improve the catabolic state during starvation in early morning fasting
  • A late night nutritional snack reduces symptoms of weakness and fatigability, lowers postprandial hyperglycemia, increases skeletal muscle mass,[25] improves nitrogen balance, and increases serum albumin levels.[26] Nocturnal BCAAs even improve serum albumin in cirrhotic patients who show no improvement with daytime BCAAs
  • Protein-energy malnutrition (PEM), with low serum albumin and low muscle mass, occurs in 65-90% of cases of advanced cirrhosis
  • hyperglucagonemia results in a catabolic state eventually producing anorexia and cachexia
  • BCAAs are further depleted from the circulation due to increased uptake by skeletal muscles that use the BCAAs in the synthesis of glutamine, which is produced in order to clear the ammonia that is not cleared by the failing liver
  • patients with chronic liver disease, particularly cirrhosis, routinely have decreased BCAAs and increased aromatic amino acids (AAAs) in their circulation
  • Maintaining a higher serum albumin in patients with cirrhosis is associated with decreased mortality and improved quality of life
  • the serum BCAA concentration is strongly correlated with the serum albumin level
  • Nathan Goodyear on 05 Oct 15
     
    great review of cirrhosis and BCCA supplementation.
Nathan Goodyear

JISSN | Full text | International Society of Sports Nutrition position stand: creatine ... - 0 views

www.jissn.com/6

creatine sports nutrition exercise

shared by Nathan Goodyear on 27 Jan 14 - No Cached
  • the energy supplied to rephosphorylate adenosine diphosphate (ADP) to adenosine triphosphate (ATP) during and following intense exercise is largely dependent on the amount of phosphocreatine (PCr) stored in the muscle
  • Creatine is chemically known as a non-protein nitrogen
  • It is synthesized in the liver and pancreas from the amino acids arginine, glycine, and methionine
  • ...26 more annotations...
  • Approximately 95% of the body's creatine is stored in skeletal muscle
  • About two thirds of the creatine found in skeletal muscle is stored as phosphocreatine (PCr) while the remaining amount of creatine is stored as free creatine
  • The body breaks down about 1 – 2% of the creatine pool per day (about 1–2 grams/day) into creatinine in the skeletal muscle
  • The magnitude of the increase in skeletal muscle creatine content is important because studies have reported performance changes to be correlated to this increase
  • "loading" protocol. This protocol is characterized by ingesting approximately 0.3 grams/kg/day of CM for 5 – 7 days (e.g., ≃5 grams taken four times per day) and 3–5 grams/day thereafter [18,22]. Research has shown a 10–40% increase in muscle creatine and PCr stores using this protocol
  • Additional research has reported that the loading protocol may only need to be 2–3 days in length to be beneficial, particularly if the ingestion coincides with protein and/or carbohydrate
  • A few studies have reported protocols with no loading period to be sufficient for increasing muscle creatine (3 g/d for 28 days)
  • Cycling protocols involve the consumption of "loading" doses for 3–5 days every 3 to 4 weeks
  • Most of these forms of creatine have been reported to be no better than traditional CM in terms of increasing strength or performance
  • Recent studies do suggest, however, that adding β-alanine to CM may produce greater effects than CM alone
  • These investigations indicate that the combination may have greater effects on strength, lean mass, and body fat percentage; in addition to delaying neuromuscular fatigue
  • creatine phosphate has been reported to be as effective as CM at improving LBM and strength
  • Green et al. [24] reported that adding 93 g of carbohydrate to 5 g of CM increased total muscle creatine by 60%
  • Steenge et al. [23] reported that adding 47 g of carbohydrate and 50 g of protein to CM was as effective at promoting muscle retention of creatine as adding 96 g of carbohydrate.
  • It appears that combining CM with carbohydrate or carbohydrate and protein produces optimal results
  • Studies suggest that increasing skeletal muscle creatine uptake may enhance the benefits of training
  • Nearly 70% of these studies have reported a significant improvement in exercise capacity,
  • Long-term CM supplementation appears to enhance the overall quality of training, leading to 5 to 15% greater gains in strength and performance
  • Nearly all studies indicate that "proper" CM supplementation increases body mass by about 1 to 2 kg in the first week of loading
  • short-term adaptations reported from CM supplementation include increased cycling power, total work performed on the bench press and jump squat, as well as improved sport performance in sprinting, swimming, and soccer
  • Long-term adaptations when combining CM supplementation with training include increased muscle creatine and PCr content, lean body mass, strength, sprint performance, power, rate of force development, and muscle diameter
  • subjects taking CM typically gain about twice as much body mass and/or fat free mass (i.e., an extra 2 to 4 pounds of muscle mass during 4 to 12 weeks of training) than subjects taking a placebo
  • The gains in muscle mass appear to be a result of an improved ability to perform high-intensity exercise via increased PCr availability and enhanced ATP synthesis, thereby enabling an athlete to train harder
  • there is no evidence to support the notion that normal creatine intakes (< 25 g/d) in healthy adults cause renal dysfunction
  • no long-term side effects have been observed in athletes (up to 5 years),
  • One cohort of patients taking 1.5 – 3 grams/day of CM has been monitored since 1981 with no significant side effects
  • Nathan Goodyear on 27 Jan 14
     
    Nice review of the data, up to the publication date, on creatine.
Nathan Goodyear

Relationship between Low Free Testosterone Levels and Loss of Muscle Mass : Scientific ... - 0 views

www.nature.com/...srep01818.html

muscle men male hormone Testosterone free Testosterone low T low Testosterone

shared by Nathan Goodyear on 05 Mar 15 - No Cached
  • Our data confirm that a low FT level is a significant predictor of a risk for loss of appendicular muscle
  • Total lean mass is associated with bioavailable T in postmenopausal women
  • Further studies are needed to determine the role of androgens in preserving muscle mass in women
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  • Approximately 1% to 2% of T in the blood exists as FT
  • appendicular muscle loss was significantly associated with low levels of FT
  • These results suggest that a threshold level of FT exists for muscle loss, rather than a dose-response relationship
  • In the previous cross-sectional and longitudinal studies of French and American men, no dose-response relationships were reported between T and muscle mass
  • A minimal serum level of FT may be needed to preserve muscle mass in men, regardless of race/ethnicity.
  • Our result is in line with previous studies that reported a relationship between low FT and low muscle mass in men
  • T stimulates protein synthesis and inhibits protein degradation in muscle cells
  • T also increases satellite cell replication and activation in older men
  • In this study, no significant association between TT levels and muscle loss were observed
  • Although a progressive decrease in TT levels with ageing is observed in middle-aged and elderly American men16, 17, the TT levels do not change during ageing in Japanese men
  • FT levels may be a good marker for the loss of muscle mas
  • Nathan Goodyear on 05 Mar 15
     
    study of Japanese men finds that low free Testosterone was a predictor of decrease in muscle mass.
Nathan Goodyear

Effects of testosterone replacement on muscle mass and muscle protein synthesis in hypo... - 0 views

press.endocrine.org/...jcem.81.10.8855787

Testosterone low T low Testosterone hypogonadism muscle mass protein muscle metabolism men male hormone hormones

shared by Nathan Goodyear on 06 Mar 15 - No Cached
  • Nathan Goodyear on 06 Mar 15
     
    Testosterone therapy in men with low T is associated with an increase in protein synthesis and thus an increase in muscle mass.
Nathan Goodyear

Effect of testosterone on muscle mass and muscle protein synthesis | Journal of Applied... - 0 views

jap.physiology.org/...498

testosterone muscle mass protein muscle hormone hormones

shared by Nathan Goodyear on 06 Mar 15 - No Cached
  • Nathan Goodyear on 06 Mar 15
     
    Testosterone promotes muscle mass increase through increased protein synthesis.
Nathan Goodyear

Leucine-enriched essential amino acid supplementation during moderate steady state exer... - 0 views

www.ajcn.org/...809.abstract

Leucine BCAA branch chain amino acids muscle athlete athletics post exercise protein synthesis

shared by Nathan Goodyear on 10 Oct 11 - No Cached
  • Nathan Goodyear on 10 Oct 11
     
    leucine shown to increase muscle protein synthesis post exercise
Nathan Goodyear

Nutritional regulation of muscle protein synthesis with resistance exercise: strategies... - 0 views

www.nutritionandmetabolism.com/...1743-7075-9-40.pdf

exercise athletic training protein proteins whey muscle muscle protein synthesis MPS

shared by Nathan Goodyear on 20 Jul 12 - No Cached
  • Nathan Goodyear on 20 Jul 12
     
    This study proposes that immediate post-resistance training protein helps to stimulate muscle growth. Recovery from training is just as important as the training itself.
Nathan Goodyear

Testosterone administration to elderly men increases skeletal muscle strength and prote... - 0 views

ajpendo.physiology.org/...E820.short

Testosterone men male hormone hormones muscle muscle mass protein strength metabolism

shared by Nathan Goodyear on 06 Mar 15 - No Cached
  • Nathan Goodyear on 06 Mar 15
     
    small study finds that Testosterone therapy in elderly men increased protein synthesis, muscle mass, and increase in strength.
Nathan Goodyear

Frontiers | Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein ... - 1 views

journal.frontiersin.org/...full

BCAA amino acids resistance training exercise recovery exercise muscle

shared by Nathan Goodyear on 18 Jul 17 - No Cached
  • BCAAs exhibit the capacity to stimulate myofibrillar-MPS, however a full complement of EAA could be necessary to stimulate a maximal response of myofibrillar-MPS following resistance exercise
  • This information potentially has important nutritional implications for selecting amino acid supplements to facilitate skeletal muscle hypertrophy in response to resistance exercise training and the maintenance of muscle mass during aging, unloading, or disease
  • results from the present study suggest that ingesting BCAAs alone, without the other EAA, provides limited substrate for protein synthesis in exercised muscles
  • ...3 more annotations...
  • the overall response of MPS is not maximized. Instead, the limited availability of EAA likely explains the qualitative difference in magnitude of the MPS response to ingestion of BCAAs alone and ingestion of similar amounts of BCAAs as part of intact whey protein
  • decreased EAA concentrations following leucine ingestion
  • these data support the notion that EAA availability is the rate-limiting factor for stimulating a maximal MPS response to resistance exercise with BCAA ingestion
  • Nathan Goodyear on 18 Jul 17
     
    Complete amino acid supplementation exceeds muscle building capacity (myofibrillar-MPS) over BCAA alone.
Nathan Goodyear

A high proportion of leucine is required for optimal stimulation of the rate of muscle ... - 0 views

ajpendo.physiology.org/...E381.full

leucine muscle

shared by Nathan Goodyear on 08 Mar 11 - No Cached
  • Nathan Goodyear on 08 Mar 11
     
    amino acid leucine promotes muscle protein synthesis
Nathan Goodyear

Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after ... - 0 views

jn.nutrition.org/...533S.short

Leucine BCAA branch chain amino acids exercise athletes athletics

shared by Nathan Goodyear on 10 Oct 11 - No Cached
  • Nathan Goodyear on 10 Oct 11
     
    Leucine, a branch chain amino acid, important in promoting protein synthesis and thus muscle growth.  Very important post-exercise and in athletes
Nathan Goodyear

Testosterone physiology in resistance exercise an... [Sports Med. 2010] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...21058750

resistance exercise physiology testosterone men male hormone hormones

shared by Nathan Goodyear on 29 Jul 14 - No Cached
  • testosterone stimulates protein synthesis
  • promotion of muscle hypertrophy by testosterone
  • intracellular androgen receptor (AR)
  • ...8 more annotations...
  • In general, testosterone concentration is elevated directly following heavy resistance exercise in men
  • Findings on the testosterone response in women are equivocal with both increases and no changes observed in response to a bout of heavy resistance exercise
  • Age also significantly affects circulating testosterone concentrations.
  • Aging beyond 35-40 years is associated with a 1-3% decline per year in circulating testosterone concentration in men
  • aging results in a reduced acute testosterone response to resistance exercise in men.
  • In women, circulating testosterone concentration also gradually declines until menopause, after which a drastic reduction is found.
  • acute increases in testosterone can be induced by resistance exercise
  • testosterone is an important modulator of muscle mass in both men and women
  • Nathan Goodyear on 29 Jul 14
     
    Resistance training to increase endogenous Testosterone production: more specific, the exercise must be high rep or as the authors call it--high volume.  To do this, the weight needs to be light.
Nathan Goodyear

Nutrition and muscle protein synthesis: a descriptive review - 0 views

www.ncbi.nlm.nih.gov/...PMC2732256

protein muscle nutrition

shared by Nathan Goodyear on 01 Feb 13 - No Cached
  • Nathan Goodyear on 01 Feb 13
     
    review of literature on protein intake to maximize muscle growth
Nathan Goodyear

Aging, exercise, and muscle protein metabolism - 0 views

jap.physiology.org/...2040.abstract

aging exercise muscle protein metabolism

shared by Nathan Goodyear on 10 Oct 11 - No Cached
  • Nathan Goodyear on 10 Oct 11
     
    how exercise and protein synthesis effect the health of the elderly
Nathan Goodyear

Frontiers | Sarcopenia and Androgens: A Link between Pathology and Treatment | Endocrin... - 0 views

journal.frontiersin.org/...full

sarcopenia muscle loss

shared by Nathan Goodyear on 16 Apr 15 - No Cached
  • sarcopenia induces a change in the proportion of skeletal muscle fibers, inducing a shift from type II (fast) to type I (slow) fibers as well as preferential loss of type II fibers
  • testosterone stimulates protein synthesis by both a short-term mechanism-rapid activation of pre-existing components of the translational apparatus- and a long-term mechanism-increase in cell or tissue capacity at the protein synthesis level leading to increase in ribosome quantity
  • testosterone induces an increase in cross-sectional area (CSA) in type I and II muscle fibers and in myonuclear quantity, indicating that testosterone exerts more of a hypertrophic than a hyperplasic effect on skeletal muscle
  • Nathan Goodyear on 16 Apr 15
     
    good discussion of sarcopenia.
Nathan Goodyear

Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthes... - 0 views

www.ajcn.org/...402.abstract

omega-3

shared by Nathan Goodyear on 25 Mar 11 - No Cached
  • Omega-3 fatty acids stimulate muscle protein synthesis in older adults
  • Nathan Goodyear on 25 Mar 11
     
    Omega-3 shown to increase muscle growth
Nathan Goodyear

Cambridge Journals Online - British Journal of Nutrition - Abstract - Post-exercise whe... - 0 views

journals.cambridge.org/...displayAbstract

Whey protein exercise recovery amino acids muscle nutrition

shared by Nathan Goodyear on 17 Sep 13 - No Cached
  • Nathan Goodyear on 17 Sep 13
     
    Whey protein hydrolysate shown to be superior to amino acids in recovery phase of exercise.  
Nathan Goodyear

Regulation of muscle glycogen repletion, muscle, protein synthesis and repair following... - 0 views

www.jssm.org/...v3n3-3pdf.pdf

exercise training exercise recovery recovery glycogen muscle protein amino acids carbohydrates

shared by Nathan Goodyear on 30 Apr 13 - No Cached
  • Nathan Goodyear on 30 Apr 13
     
    Nice study and review of other studies that looked at post-exercise recovery strategies. This authors conclusion, and I concur, is that a mixture of carb 0.8 g/kg and protein 0.2 g/kg mixture immediately and 2 hours post is the best to restore glycogen stores and promote an anabolic state
Nathan Goodyear

Inflammatory cause of metabolic syndrome via brain stress and NF-κB - 0 views

www.ncbi.nlm.nih.gov/...PMC3314172

metabolic syndrome TLR cytokines hypothalamus brain neurology metabolic syndrome NF-kappaB DIO diet induced obesity over nutrition nutrition inflammation

shared by Nathan Goodyear on 09 Jul 13 - No Cached
  • Mechanistic studies further showed that such metabolic inflammation is related to the induction of various intracellular stresses such as mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, and autophagy defect under prolonged nutritional excess
  • intracellular stress-inflammation process for metabolic syndrome has been established in the central nervous system (CNS) and particularly in the hypothalamus
  • the CNS and the comprised hypothalamus are known to govern various metabolic activities of the body including appetite control, energy expenditure, carbohydrate and lipid metabolism, and blood pressure homeostasis
  • ...56 more annotations...
  • Reactive oxygen species (ROS) refer to a class of radical or non-radical oxygen-containing molecules that have high oxidative reactivity with lipids, proteins, and nucleic acids
  • a large measure of intracellular ROS comes from the leakage of mitochondrial electron transport chain (ETC)
  • Another major source of intracellular ROS is the intentional generation of superoxides by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase
  • there are other ROS-producing enzymes such as cyclooxygenases, lipoxygenases, xanthine oxidase, and cytochrome p450 enzymes, which are involved with specific metabolic processes
  • To counteract the toxic effects of molecular oxidation by ROS, cells are equipped with a battery of antioxidant enzymes such as superoxide dismutases, catalase, peroxiredoxins, sulfiredoxin, and aldehyde dehydrogenases
  • intracellular oxidative stress has been indicated to contribute to metabolic syndrome and related diseases, including T2D [72; 73], CVDs [74-76], neurodegenerative diseases [69; 77-80], and cancers
  • intracellular oxidative stress is highly associated with the development of neurodegenerative diseases [69] and brain aging
  • dietary obesity was found to induce NADPH oxidase-associated oxidative stress in rat brain
  • mitochondrial dysfunction in hypothalamic proopiomelanocortin (POMC) neurons causes central glucose sensing impairment
  • Endoplasmic reticulum (ER) is the cellular organelle responsible for protein synthesis, maturation, and trafficking to secretory pathways
  • unfolded protein response (UPR) machinery
  • ER stress has been associated to obesity, insulin resistance, T2D, CVDs, cancers, and neurodegenerative diseases
  • brain ER stress underlies neurodegenerative diseases
  • under environmental stress such as nutrient deprivation or hypoxia, autophagy is strongly induced to breakdown macromolecules into reusable amino acids and fatty acids for survival
  • intact autophagy function is required for the hypothalamus to properly control metabolic and energy homeostasis, while hypothalamic autophagy defect leads to the development of metabolic syndrome such as obesity and insulin resistance
  • prolonged oxidative stress or ER stress has been shown to impair autophagy function in disease milieu of cancer or aging
  • TLRs are an important class of membrane-bound pattern recognition receptors in classical innate immune defense
  • Most hypothalamic cell types including neurons and glia cells express TLRs
  • overnutrition constitutes an environmental stimulus that can activate TLR pathways to mediate the development of metabolic syndrome related disorders such as obesity, insulin resistance, T2D, and atherosclerotic CVDs
  • Isoforms TLR1, 2, 4, and 6 may be particularly pertinent to pathogenic signaling induced by lipid overnutrition
  • hypothalamic TLR4 and downstream inflammatory signaling are activated in response to central lipid excess via direct intra-brain lipid administration or HFD-feeding
  • overnutrition-induced metabolic derangements such as central leptin resistance, systemic insulin resistance, and weight gain
  • these evidences based on brain TLR signaling further support the notion that CNS is the primary site for overnutrition to cause the development of metabolic syndrome.
  • circulating cytokines can limitedly travel to the hypothalamus through the leaky blood-brain barrier around the mediobasal hypothalamus to activate hypothalamic cytokine receptors
  • significant evidences have been recently documented demonstrating the role of cytokine receptor pathways in the development of metabolic syndrome components
  • entral administration of TNF-α at low doses faithfully replicated the effects of central metabolic inflammation in enhancing eating, decreasing energy expenditure [158;159], and causing obesity-related hypertension
  • Resistin, an adipocyte-derived proinflammatory cytokine, has been found to promote hepatic insulin resistance through its central actions
  • both TLR pathways and cytokine receptor pathways are involved in central inflammatory mechanism of metabolic syndrome and related diseases.
  • In quiescent state, NF-κB resides in the cytoplasm in an inactive form due to inhibitory binding by IκBα protein
  • IKKβ activation via receptor-mediated pathway, leading to IκBα phosphorylation and degradation and subsequent release of NF-κB activity
  • Research in the past decade has found that activation of IKKβ/NF-κB proinflammatory pathway in metabolic tissues is a prominent feature of various metabolic disorders related to overnutrition
  • it happens in metabolic tissues, it is mainly associated with overnutrition-induced metabolic derangements, and most importantly, it is relatively low-grade and chronic
  • this paradigm of IKKβ/NF-κB-mediated metabolic inflammation has been identified in the CNS – particularly the comprised hypothalamus, which primarily accounts for to the development of overnutrition-induced metabolic syndrome and related disorders such as obesity, insulin resistance, T2D, and obesity-related hypertension
  • evidences have pointed to intracellular oxidative stress and mitochondrial dysfunction as upstream events that mediate hypothalamic NF-κB activation in a receptor-independent manner under overnutrition
  • In the context of metabolic syndrome, oxidative stress-related NF-κB activation in metabolic tissues or vascular systems has been implicated in a broad range of metabolic syndrome-related diseases, such as diabetes, atherosclerosis, cardiac infarct, stroke, cancer, and aging
  • intracellular oxidative stress seems to be a likely pathogenic link that bridges overnutrition with NF-κB activation leading to central metabolic dysregulation
  • overnutrition is an environmental inducer for intracellular oxidative stress regardless of tissues involved
  • excessive nutrients, when transported into cells, directly increase mitochondrial oxidative workload, which causes increased production of ROS by mitochondrial ETC
  • oxidative stress has been shown to activate NF-κB pathway in neurons or glial cells in several types of metabolic syndrome-related neural diseases, such as stroke [185], neurodegenerative diseases [186-188], and brain aging
  • central nutrient excess (e.g., glucose or lipids) has been shown to activate NF-κB in the hypothalamus [34-37] to account for overnutrition-induced central metabolic dysregulations
  • overnutrition can present the cell with a metabolic overload that exceeds the physiological adaptive range of UPR, resulting in the development of ER stress and systemic metabolic disorders
  • chronic ER stress in peripheral metabolic tissues such as adipocytes, liver, muscle, and pancreatic cells is a salient feature of overnutrition-related diseases
  • recent literature supports a model that brain ER stress and NF-κB activation reciprocally promote each other in the development of central metabolic dysregulations
  • when intracellular stresses remain unresolved, prolonged autophagy upregulation progresses into autophagy defect
  • autophagy defect can induce NF-κB-mediated inflammation in association with the development of cancer or inflammatory diseases (e.g., Crohn's disease)
  • The connection between autophagy defect and proinflammatory activation of NF-κB pathway can also be inferred in metabolic syndrome, since both autophagy defect [126-133;200] and NF-κB activation [20-33] are implicated in the development of overnutrition-related metabolic diseases
  • Both TLR pathway and cytokine receptor pathways are closely related to IKKβ/NF-κB signaling in the central pathogenesis of metabolic syndrome
  • Overnutrition, especially in the form of HFD feeding, was shown to activate TLR4 signaling and downstream IKKβ/NF-κB pathway
  • TLR4 activation leads to MyD88-dependent NF-κB activation in early phase and MyD88-indepdnent MAPK/JNK pathway in late phase
  • these studies point to NF-κB as an immediate signaling effector for TLR4 activation in central inflammatory response
  • TLR4 activation has been shown to induce intracellular ER stress to indirectly cause metabolic inflammation in the hypothalamus
  • central TLR4-NF-κB pathway may represent one of the early receptor-mediated events in overnutrition-induced central inflammation.
  • cytokines and their receptors are both upstream activating components and downstream transcriptional targets of NF-κB activation
  • central administration of TNF-α at low dose can mimic the effect of obesity-related inflammatory milieu to activate IKKβ/NF-κB proinflammatory pathways, furthering the development of overeating, energy expenditure decrease, and weight gain
  • the physiological effects of IKKβ/NF-κB activation seem to be cell type-dependent, i.e., IKKβ/NF-κB activation in hypothalamic agouti-related protein (AGRP) neurons primarily leads to the development of energy imbalance and obesity [34]; while in hypothalamic POMC neurons, it primarily results in the development of hypertension and glucose intolerance
  • the hypothalamus, is the central regulator of energy and body weight balance [
  • Nathan Goodyear on 09 Jul 13
     
    Great article chronicles the biochemistry of "over nutrition" and inflammation through NF-kappaB activation and its impact on the brain.
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