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Nathan Goodyear

Neuronal membrane cholesterol loss enhances amyloid peptide generation - 0 views

jcb.rupress.org/953

cholesterol neurodegeneration neurodegenerative disease brain neurology Beta-amyloid protein Alzheimer's disease

shared by Nathan Goodyear on 14 Jun 12 - No Cached
  • Nathan Goodyear on 14 Jun 12
     
    low neuronal cholesterol increases risk of neurodegeneration.  Low Cholesterol in neurons increases B-amyloid protein formation.  Are we increasing Alzheimer's incidence by lowering cholesterol too much?  After all, the brain needs cholesterol!
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.
Nathan Goodyear

Chronic exposure to Low dose bacterial lipopolysaccharide inhibits leptin signaling in ... - 0 views

www.ncbi.nlm.nih.gov/...PMC4523075

LPS lipopolysaccharides leptin CCK cholecystokinin metabolism weight appetite diet nutrition inflammation

shared by Nathan Goodyear on 04 Oct 17 - No Cached
  • Obesity and models of obesity induced by ingestion of HF-diet in rodents are associated with chronically elevated circulating levels of LPS
  • chronic low-dose administration of LPS induces leptin-resistance in vagal afferent neurons and abolition of CCK-induced inhibition of food intake
  • HF fat feeding has been shown to enhance gastrointestinal permeability promoting the translocation of LPS to the circulation
  • ...9 more annotations...
  • LPS leads to an increase in SOCS3 expression [20]. SOCS3 is a negative regulator of leptin signaling
  • We observed a significant increase in energy intake in the LPS-treated rats
  • the data provides a mechanism linking changes in gut microbiota induced by ingestion of HF diets to dysregulation of food intake and body weight
  • SOCS3 is an important mechanism by which leptin resistance develops in vagal afferent neurons and coincides with the onset of hyperphagia
  • Chronic low-dose LPS treatment induced TLR4 activation and MyD88 signaling in vagal afferent neurons, associated with increased SOCS3 expression and reduced leptin-signaling, characterized by the absence of leptin-induced pSTAT3.
  • We demonstrate that this chronic low dose LPS is sufficient to induce leptin–resistance in vagal afferent neurons, reduced sensitivity to the satiating effects of CCK, and loss of vagal afferent plasticity
  • it suggests that the increase in food intake and body weight we observed at week 6 in the LPS treated rats may be caused by LPS-induced leptin resistance.
  • chronic LPS treatment of mice for four weeks increased body weight
  • chronic LPS treatment of mice for four weeks increased subcutaneous fat
  • Nathan Goodyear on 04 Oct 17
     
    Very interesting study.  High fat diet in rats induced gut flora change that resulted in LPS which induced appetite through leptin resistance and reduced cholecystokinin signaling.
Nathan Goodyear

Diet-induced obesity and low testosterone increase neuroinflammation and impair neural ... - 0 views

www.ncbi.nlm.nih.gov/...PMC4190446

Testosterone neuroinflammation glia insulin resistance obesity diabetes brain CNS PNS inflammation low T low Testosterone TNF-alpha IL-1beta

shared by Nathan Goodyear on 28 Apr 15 - No Cached
  • both obesity and low testosterone are also risk factors for neural dysfunction, including cognitive impairment [58–61] and development of AD
  • Levels of obesity and testosterone are often inversely correlated
  • diet-induced obesity causes significant metabolic disturbances and impairs central and peripheral nervous systems.
  • ...23 more annotations...
  • both obesity and low testosterone are linked with promotion of inflammatory pathways [70–72] and exert harmful actions on the central [73–75] and peripheral [29,76] nervous systems
  • In general, obesity-related changes were worsened by low testosterone and improved by testosterone treatment; however, this relationship was not statistically significant in several instances. Further, our data suggest that a common pathway that may contribute to obesity and testosterone effects is regulation of inflammation
  • fasting blood glucose levels were independently and additively increased by GDX-induced testosterone depletion and high-fat diet
  • testosterone treatment significantly reduced fasting glucose under both the normal and high-fat diets, demonstrating potential therapeutic efficacy of testosterone supplementation
  • fasting insulin, insulin resistance (HOMA index), and glucose tolerance, low testosterone tended to exacerbate and or testosterone treatment improved outcomes.
  • testosterone status did not significantly affect body weight
  • testosterone’s effects likely do not indicate an indirect result on adiposity but rather regulatory action(s) on other aspects of metabolic homeostasis
  • Prior work in rodents has shown diet-induced obesity induces insulin resistance in rat brain [63] and that testosterone replacement improves insulin sensitivity in obese rats [64]. Our findings are consistent with the human literature, which indicates that (i) testosterone levels are inversely correlated to insulin resistance and T2D in healthy [30,65] as well as obese men [66], and (ii) androgen therapy can improve some metabolic measures in overweight men with low testosterone
  • it has been shown that TNFα has inhibitory effects on neuron survival, differentiation, and neurite outgrowth
  • Our data demonstrate that low testosterone and obesity independently increased cerebrocortical mRNA levels of both TNFα and IL-1β
  • Testosterone status also affected metabolic and neural measures
  • many beneficial effects of testosterone, including inhibition of proinflammatory cytokine expression
  • neuroprotection [80,81], are dependent upon androgen receptors, the observed effects of testosterone in this study may involve androgen receptor activation
  • testosterone can be converted by the enzyme aromatase into estradiol, which is also known to exert anti-inflammatory [82] and neuroprotective [83] actions
  • glia are the primary sources of proinflammatory molecules in the CNS
  • poorer survival of neurons grown on glia from mice maintained on high-fat diet
  • Since testosterone can affect glial function [86] and improve neuronal growth and survival [87–89], it was unexpected that testosterone status exhibited rather modest effects on neural health indices with the only significant response being an increase in survival in the testosterone-treated, high-fat diet group
  • significantly increased expression of TNFα and IL-1β in glia cultures derived from obese mice
  • testosterone treatment significantly lowered TNFα and IL-1β expression to near basal levels even in obese mice, indicating a protective benefit of testosterone across diet conditions
  • IL-1β treatment has been shown to induce synapse loss and inhibit differentiation of neurons
  • Testosterone status and diet-induced obesity were associated with significant regulation of macrophage infiltration
  • testosterone prevented and/or restored thermal nociception in both diet groups
  • a possible mechanism by which obesity and testosterone levels may affect the health of both CNS and PNS
  • Nathan Goodyear on 28 Apr 15
     
    Study points to obesity and low Testosterone contribution of neuroinflammation.  No effect of body weight was seen with TRT.  This animal model found similar positive effects of TRT in insulin sensitivity.  Obesity and low T increase inflammatory cytokine production: this study found an increase in TNF-alpha and IL-1beta and TRT reduced TNF-alpha and IL-1beta to near base-line.  Testosterone is neuroprotective and this study reviewed the small volume of evaded that pointed to benefit from estradiol.  Testosterone's effect on glial survival was positive but not significant.  Obesity and low T were found to be associated with increased macrophage infiltration in the PNS with increased TNF-alpha and IL-1beta.   Testosterone therapy improved peripheral neuropathy via its positive effects on nocicieption.
Nathan Goodyear

Hyperbaric Oxygen Therapy Can Improve Post Concussion Syndrome Years after Mild Traumat... - 0 views

www.ncbi.nlm.nih.gov/...PMC3829860

hbot hyperbaric therapy hyperbaric brain concussion post concussion syndrome TBI traumatic brain injury

shared by Nathan Goodyear on 17 May 17 - No Cached
  • The changes in SPECT images after treatment indicate that HBOT led to reactivation of neuronal activity in stunned areas that seemed normal under CT and MRI imaging. While SPECT imaging has a limited spatial resolution (compared, for example, to fMRI), the changes in activity were sufficiently robust to be clearly detected by the SPECT images.
  • HBOT might initiate a cellular and vascular repair mechanism and improve cerebral vascular flow
  • HBOT induces regeneration of axonal white matter [61], [62], [63], [64], has positive effect upon the myelinization and maturation of injured neural fibers [65], and can stimulate axonal growth and increase the ability of neurons to function and communicate with each other
  • ...6 more annotations...
  • HBOT was found to have a role in initiation and/or facilitation of angiogenesis and cell proliferation processes needed for axonal regeneration [67].
  • The observed reactivation of neuronal activity in the stunned areas found here, along with similar results in post-stroke patients
  • At the cellular level, HBOT can improve cellular metabolism, reduce apoptosis, alleviate oxidative stress and increase levels of neurotrophins and nitric oxide through enhancement of mitochondrial function (in both neurons and glial cells)
  • HBOT may promote the neurogenesis of endogenous neural stem cells
  • With regard to secondary injury mechanisms in mTBI, HBOT can initiate vascular repair mechanism and improve cerebral vascular flow [58], [59], [68], [69], promote blood brain barrier integrity and reduce inflammatory reactions [28] as well as brain edema
  • It might be possible that HBOT enables the metabolic change simply by supplying the missing energy/oxygen needed for those regeneration processes.
  • Nathan Goodyear on 17 May 17
     
    Hbot therapy, according to study, induces neuroplasticity and improves brain function in post concussion syndrome and those with mTBI.  The important point about this study was that the study was done years after the injury; what if the therapy was employed immediately after...
Nathan Goodyear

ScienceDirect.com - Cell Metabolism - Estrogen Receptors and the Metabolic Network - 0 views

www.sciencedirect.com/...S1550413111003123

ER-alpha ER-beta estrogen receptor receptors metabolic syndrome MetS hormone hormones

shared by Nathan Goodyear on 11 Oct 12 - No Cached
  • The pro-opiomelanocortin (POMC) neurons have an anorexigenic action and, when activated, reduce food intake through the release of two peptides, α-melanocyte-stimulating hormone (α-MSH) and cocaine-and-amphetamine-regulated transcripts (CART). The neuropeptide Y (NPY) neurons, on the other hand, release NPY hormone and agouti gene-related protein (AgRP), which prevent the binding of α-MSH to MC3R and MC4R, increasing food intake
  • This suggests that the central anorexic effects of E2 may occur via ERβ
  • The main hypothalamic areas involved in food intake and satiety are the arcuate nucleus (ARC), the lateral hypothalamus (LH), the paraventricular nucleus (PVN), the ventromedial hypothalamus (VMH), and the dorsomedial hypothalamus (DMH)
  • ...22 more annotations...
  • Leptin is a potent anorexigenic and catabolic hormone secreted by adipose cells that reduces food intake and increases energy expenditure
  • E2 not only modulates leptin receptor mRNA in the ARC and VMH, but also increases hypothalamic sensitivity to leptin, altering peripheral fat distribution
  • ghrelin. It acts on growth hormone secretagogue receptors (GHSR1a) located in the ARC and is a potent stimulator of food intake
  • It thus appears that of the two ERs, ERα plays a predominant role in the CNS regulation of lipid and carbohydrate homeostasis.
  • Both ERs have been identified in the ARC
  • Stimulation of MCH neurons increases food intake and fat accumulation while its inhibition leads to decreased food intake and reduced fat accumulation.
  • Both ERs have been identified in the LH
  • both ERs have been identified in this nucleus
  • The PVN is the region of the hypothalamus with the highest expression of ERβ and is reported to be weakly ERα positive
  • The VMH is ERα regulated
  • Skeletal muscle is responsible for 75% of the insulin-induced glucose uptake in the body
  • GLUT4 is highly expressed in muscle and represents a rate-limiting step in the insulin-induced glucose uptake
  • data suggest that in the physiological range, E2 is beneficial for insulin sensitivity, whereas hypo- or hyperestrogenism is related to insulin resistance
  • In aging female rats, E2 treatment improves glucose homeostasis mainly through its ability to increase muscle GLUT4 content on the cell membrane
  • It is evident that ERα and ERβ have distinct actions and that much more research is needed to clearly identify the function of each receptor in muscle.
  • E2 prevents accumulation of visceral fat, increases central sensitivity to leptin, increases the expression of insulin receptors in adipocytes, and decreases the lipogenic activity of lipoprotein lipase in adipose tissue
  • In rats, ovariectomy increases body weight, intra-abdominal fat, fasting glucose and insulin levels, and insulin resistance followed by decreased phosphorylation of AMPK and its substrate acetyl-CoA carboxylase in adipose tissue
  • decreased adiponectin, PPARγ coactivator-1α (PGC-1α), and uncoupling protein 2 (UCP2) and increased resistin
  • Men with aromatase deficiency have truncal obesity, elevated blood lipids, and severe insulin resistance
  • Although not all studies are in agreement, polymorphisms of ERα in humans have been associated with risk factors for CVDs
  • Human subcutaneous and visceral adipose tissues express both ERα and ERβ, whereas only ERα mRNA has been identified in brown adipose tissue
  • suggesting that ERα is the main regulator of GLUT4 expression in adipose tissue
  • Nathan Goodyear on 11 Oct 12
     
    very nice article that looks at the balance of ER-alpha/ER-beta and their role in metabolic syndrome.  This article discusses the balance of  these receptors are tissue dependent in their effect.  I like their conclusion: "...but these mechanisms will never be completely understood if they are not considered in the context of a whole system.
Nathan Goodyear

Minireview: Inflammation and Obesity Pathogenesis: The Hypothalamus Heats Up - 0 views

endo.endojournals.org/...4109.full

inflammation obesity overweight hypothalamus HPA

shared by Nathan Goodyear on 04 Oct 12 - No Cached
  • Leptin, secreted by adipocytes in proportion to body fat mass
  • The saturated fatty acid palmitate (16:0) induces NF-κB signaling through a TLR4-dependent mechanism
  • 18:0 (stearic) and longer saturated fatty acids as well as linolenic acid (18:3) increased proinflammatory cytokines, ER stress markers, and TLR4 activation
  • ...6 more annotations...
  • (SOCS)-3. A member of a protein family originally characterized as negative feedback regulators of inflammation (13, 37), SOCS3 inhibits insulin and leptin signaling
  • IKKβ signaling in discrete neuronal subsets appears to be required for both hypothalamic inflammation and excess weight gain to occur during HF feeding
  • the paradoxical observation that hyperphagia and weight gain occur when hypothalamic inflammation is induced by HF feeding, yet when it occurs in response to systemic or local inflammatory processes (e.g. administration of endotoxin), anorexia and weight loss are the rule
  • , serves as a circulating signal of energy stores in part by providing feedback inhibition of hypothalamic orexigenic pathways [e.g. neurons that express neuropeptide Y and agouti-related peptide (AgRP)]
  • and stimulating anorexigenic neurons
  • signals from Toll-like receptors (TLRs), evolutionarily conserved pattern recognition molecules critical for detecting pathogens, amplified through signaling intermediates such as MyD88 activate the inhibitor of κB-kinase-β (IKKβ)/nuclear factor-κB (NF-κB), c-Jun N-terminal kinase (Jnk) and other intracellular inflammatory signals in response to stimulation by circulating saturated fatty acids
  • Nathan Goodyear on 04 Oct 12
     
    great read on the current understanding of how obesity and resultant inflammation disrupts hypothalamic function.
Nathan Goodyear

PLOS ONE: N-Acetyl Cysteine May Support Dopamine Neurons in Parkinson's Disease: Prelim... - 0 views

journals.plos.org/...article

Parkinsons Parkinson's disease NAC N-acetylcysteine brain

shared by Nathan Goodyear on 17 Jun 16 - No Cached
  • Nathan Goodyear on 17 Jun 16
     
    pilot study finds that NAC protects the dopaminergic neurons in the brains in cell line stud.  Clinical found increased dopamine binding in the brain compared to placebo in individuals with Parkinson's disease.
Nathan Goodyear

Neuron - Activation of Central Orexin/Hypocretin Neurons by Dietary Amino Acids - 0 views

www.cell.com/...S0896627311007823

amino acids fatigue afternoon sugar orexin_hpocretin cells

shared by Nathan Goodyear on 01 Dec 11 - No Cached
  • Nathan Goodyear on 01 Dec 11
     
    non-essential amino acids are beneficial in preventing those afternoon energy slumps.  Sugar with its resultant insulin spike would make this worse.
Nathan Goodyear

The Androgen 5α-Dihydrotestosterone and Its Metabolite 5α-Androstan-3β, 17β-D... - 0 views

www.jneurosci.org/...1448.full

DHT 3 beta androstanediol androgens Hypothalamus HPA hormones stress

shared by Nathan Goodyear on 15 Jul 15 - No Cached
  • Sex steroid hormones are primarily responsible for sex difference in adult HPA function; androgens inhibit whereas estrogens enhance HPA axis activation after a stressor
  • the PVN contains relatively high levels of AR (Bingaman et al., 1994; Zhou et al., 1994) and ERβ (Alves et al., 1998; Hrabovszky et al., 1998; Somponpun and Sladek, 2003) but is essentially devoid of ERα
  • the nonaromatizable androgen DHT and the nonselective ER ligand E2 influence HPA reactivity by acting on neurons within or surrounding the PVN
  • ...9 more annotations...
  • inhibitory action of DHT is detectable at both the level of hormone secretion as well as PVN c-fos mRNA expression
  • the inhibition can be mimicked by the DHT metabolite 3β-diol and by the subtype selective ERβ agonist DPN
  • E2 acts to enhance HPA reactivity
  • the ability of the ER antagonist tamoxifen, but not the AR antagonist flutamide, to block the inhibitory actions of DHT, speaks to the intracellular mechanism by which this inhibitory signal might be transduced.
    • Nathan Goodyear
      Nathan Goodyear on 15 Jul 15
       
      that is because the interaction with the DHT metabolite is not with the AR, but with the ER-beta.
  • the DHT metabolite 3β-diol and the ERβ-subtype-selective agonist DPN suppressed ACTH, corticosterone, and c-fos mRNA responses to restraint stress in a manner similar to DHT
  • metabolism of DHT to 3β-diol and subsequent binding to ERβ can be inhibitory to HPA reactivity, and this is one possible mechanism for the action of DHT.
  • Our data also suggest that E2 enhances the reactivity of the HPA axis to stress by acting on or near neurons of the PVN
  • the actions of E2 appear to be through an ERα-dependent mechanism
  • these studies suggest that ERβ, within the male hypothalamus, acts to inhibit the HPA axis and that the inhibitory effects of DHT may be, at least in part, via its intracellular conversion to 3β-diol and subsequent binding to ERβ
  • Nathan Goodyear on 15 Jul 15
     
    DHT metabolites: particularly 3beta-androstanediol inhibit HPA axis through ER-beta.
Nathan Goodyear

How Mercury Produces Brain Damage - Video - 0 views

www.metacafe.com/..._mercury_produces_brain_damage

mercury brain damage neuron

shared by Nathan Goodyear on 22 Aug 11 - No Cached
  • Nathan Goodyear on 22 Aug 11
     
    Watch Mercury destroy brain neuron
Nathan Goodyear

Histidine suppresses food intake through its conversion into neuronal histamine. - PubM... - 0 views

www.ncbi.nlm.nih.gov/...11788786

histidine histamine leptin metabolism

shared by Nathan Goodyear on 13 Jan 16 - No Cached
  • Nathan Goodyear on 13 Jan 16
     
    neuronal histidine to histamine conversion suppresses appetite via leptin feedback signaling.  
Nathan Goodyear

Testosterone: a metabolic hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R25.full

male hormone hormones testosterone hypogonadal-obesity-adipocytokine hypothesis

shared by Nathan Goodyear on 08 May 13 - No Cached
  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
  • ...39 more annotations...
  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
  • Nathan Goodyear on 08 May 13
     
    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
Nathan Goodyear

Gender and sex hormones in multiple sclerosis pathology and therapy - 0 views

www.ncbi.nlm.nih.gov/...PMC2689399

hormones MS multiple Sclerosis Estriol progesterone

shared by Nathan Goodyear on 11 Jan 17 - No Cached
  • It is now well recognized that the disease manifestation is reduced in pregnant women with relapsing-remitting MS
  • This occurs particularly during the third trimester when levels of estrogens (estradiol and estriol) and progesterone (see Table 2) are elevated up to about 20 times
  • This seems well correlated with a decrease in active white matter lesions detected by MRI
  • ...12 more annotations...
  • This clinical improvement is however followed by temporary rebound exacerbations at post-partum, when the hormone levels decline
  • a shift from Th1 to Th2 immune response, expansion of suppressive regulatory T lymphocytes and decrease in the number of circulating CD16+ natural killer (NK)-cells
  • Th1 lymphocytes secrete proinflammatory cytokines (e.g. IL-2, IFNgamma, lymphotoxin) while Th2 cells secrete anti-inflammatory cytokines (e.g. IL-4, IL-5, IL-10), which favor humoral-mediated responses
  • Th2 cytokines are associated with down-regulation of Th1 cytokines and this Th2 shift is believed to provide protection from allograft rejection during pregnancy as well as from Th1-mediated autoimmune disease
  • it is worth noting that the levels of other hormones with anti-inflammatory activity (1,25-dihydroxy-vitamin D3, norepinephrine, cortisol) also increase by 2 to 4 times during late pregnancy
  • 1,25-dihydroxy vitamin D3 induces regulatory T-cell function important for development of self-tolerance
  • breast-feeding does not alter the relapse rate in women with MS
  • Leptin is a pleiotropic hormone produced primarily by adipocytes but also by T lymphocytes and neurons
  • Several lines of evidence indicate that leptin contributes to EAE/MS pathogenesis, influencing its onset and clinical severity, by acting as a proinflammatory cytokine which promotes regulatory T cell (Treg) anergy and hyporesponsiveness, resulting in increased Th1 (TNFalpha, INFgamma) and reduced Th2 (IL-4) cytokine production
  • circulating leptin levels are increased in relapsing-remitting MS patients (men and women analyzed together) while the CD4+CD25+Treg population decreases
  • As the leptin plasma concentrations are proportional to the amount of fat tissue, obese/overweight individuals produce higher levels of leptin
  • Nielsen et al found that estradiol and progesterone exert neuroprotection against glutamate neurotoxicity, while MPA antagonizes the neuroprotective effect of estradiol and exacerbated neuron death induced by glutamate excitotoxicity
  • Nathan Goodyear on 11 Jan 17
     
    very good review of the differences in MS and hormones between the sexes.
Nathan Goodyear

Annals of Internal Medicine | Gene-Diet Interactions in Brain Aging and Neurodegenerati... - 0 views

annals.org/article.aspx

diet calorie neurodegenerative disease brain neurology parkinson's disease Alzheimer's disease aging

shared by Nathan Goodyear on 25 Jun 12 - No Cached
  • it appears that dietary restriction promotes neuronal survival, plasticity, and even neurogenesis by inducing a mild cellular stress response that involves activation of genes that encode proteins designed to promote neuronal growth and surviva
  • Studies of animal models of Alzheimer disease and Parkinson disease have shown that, by decreasing homocysteine levels, dietary folic acid can be neuroprotective
  • The current average daily calorie intake of Americans is approximately 2700 for women and more than 3000 for men
  • Nathan Goodyear on 25 Jun 12
     
    what you eat and how many calories you eat effects you brain and your risk of neurodegenerative diseases, such as Parkinson's and Alzheimer's disease.
Nathan Goodyear

ingentaconnect The Role of Orexin System in Antipsychotics Induced Weight Gain - 0 views

www.ingentaconnect.com/...art00002

orexin eating feeding weight-loss overweight obesity weight gain

shared by Nathan Goodyear on 02 Dec 11 - No Cached
  • The orexins modulate feeding behavior, some metabolic processes and arousal.
  • Nathan Goodyear on 02 Dec 11
     
    antipsychotics are associated with significant weight gain.  One proposed mechanism is the increased activation of orexin neurons in the areas of the brain (lateral hypothalamus and perifornical area) that regulate eating.  Amphetamines stimulate the same, just a drastically reduced levels
Nathan Goodyear

Metabolic influences on neuroendocrine regulation of reproduction - 0 views

www.ncbi.nlm.nih.gov/...PMC3898855

metabolism metabolic regulation reproduction Leptin Ghrelin Insulin Kisspeptin GNRH

shared by Nathan Goodyear on 17 Feb 14 - No Cached
  • Energy storage occurs mainly at the level of white adipose tissue, where adipocytes secrete the anorexigenic adipokine leptin
  • humans and laboratory animals with leptin or insulin deficiency or resistance and/or increased ghrelin levels exhibit delayed or absent puberty and frequently display hypogonadotropic hypogonadism, which prevents fertility
  • Ghrelin suppresses pulsatile gonadotropin-releasing hormone (GnRH) release [14,15], thus serving as a signal to suppress reproduction in times of famine
  • ...4 more annotations...
  • GnRH neurons have been shown to express insulin receptor mRNA and protein [27] and are activated by insulin
  • AgRP and NPY have the opposite (orexigenic) effect, inducing food intake.
  • Neuropeptides derived from POMC/CART neurons exert a potent anorectic action, thus decreasing food intake and body weight
  • Kisspeptins (encoded by KISS1) have been identified in the last decade as the most potent secretagogues of GnRH release.
  • Nathan Goodyear on 17 Feb 14
     
    Good, although brief, discussion of the interaction between metabolism and hormones.  Kisspeptin is a GNRH secreatagogue "upstream".   Insulin, Leptin, and Gherlin can inhibit GNRH through resistance and low levels.  Probably a U shaped graph of optimal activity.
Nathan Goodyear

Oxidative damage in multiple sclerosis lesions - 0 views

brain.oxfordjournals.org/...1914.short

MS multiple sclerosis oxidative damage brain oligodendrocytes

shared by Nathan Goodyear on 19 Mar 14 - No Cached
  • Nathan Goodyear on 19 Mar 14
     
    Lesions in MS, found to have extensive oxidative damage of oligodendrocytes and neurons.
Nathan Goodyear

The combined effects of exercise and foods in preventing neurological and cognitive dis... - 0 views

www.ncbi.nlm.nih.gov/...PMC3258093

diet nutrition exercise BDNF omega-3 omega 3 n-3 brain derived neurotrophic factor curcumin polyphenols neuroplasticity memory sugar saturated fats

shared by Nathan Goodyear on 01 Nov 13 - No Cached
  • The most prevalent types of cognitive impairments include disturbances in attention and learning and memory function
  • An association between BDNF and learning and memory was found when measuring the performance of rats on the Morris water maze task
  • exercise and BDNF have been associated with reducing depression and promoting cognitive enhancement.
  • ...3 more annotations...
  • In addition to reducing oxidative stress and inflammation, DHA serves to improve neuronal function by supporting synaptic membrane fluidity
  • Curcumin has also been shown to protect the hippocampus and to counteract learning impairment
  • insufficient DHA in the brain can compromise neuronal function with subsequent effects on a broad range of neurological and behavioral faculties.
  • Nathan Goodyear on 01 Nov 13
     
    diet and exercise increases BDNF.  Diets rich in omega 3, curcumin, and polyphenols increase BDNF and thus increase neuroplasticity and associated cognition.   In contrast, sugar and saturated fats in crease oxidative stress and worsened spatial learning.  This study is a review.  
Nathan Goodyear

Glutamate and the glutamate receptor system: a tar... [Int J Geriatr Psychiatry. 2003] ... - 0 views

www.ncbi.nlm.nih.gov/...12973748

glutamate glutamic acid excitotoxicity Parkinson's MS Alzheimer's Huntington's disease neurodegenerative

shared by Nathan Goodyear on 18 Mar 11 - No Cached
  • Under certain conditions, glutamate has a toxic action resulting from an activation of specific glutamate receptors, which leads to acute or chronic death of nerve cells.
  • Nathan Goodyear on 18 Mar 11
     
    deep, heavy read on glutamate excitotoxicity and neuronal death leading to neurodegenerative disease
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