Whole-body Metabolism Research Articles

Computationally Modelling Cholesterol Metabolism and Atherosclerosis.

Cardiovascular disease (CVD) is the leading cause of death globally. The underlying pathological driver of CVD is atherosclerosis. The primary risk factor for atherosclerosis is elevated low-density lipoprotein cholesterol (LDL-C). Dysregulation of cholesterol metabolism is synonymous with a rise in LDL-C. Due to the complexity of cholesterol metabolism and atherosclerosis mathematical models are routinely used to explore their non-trivial dynamics. Mathematical modelling has generated a wealth of useful biological insights, which have deepened our understanding of these processes. To date however, no model has been developed which fully captures how whole-body cholesterol metabolism intersects with atherosclerosis. The main reason for this is one of scale. Whole body cholesterol metabolism is defined by macroscale physiological processes, while atherosclerosis operates mainly at a microscale. This work describes how a model of cholesterol metabolism was combined with a model of atherosclerotic plaque formation. This new model is capable of reproducing the output from its parent models. Using the new model, we demonstrate how this system can be utilized to identify interventions that lower LDL-C and abrogate plaque formation.

Abstract P3191: Hur Mediates Calcium-driven Thermogenesis In Brown Adipose Tissue

Since the discovery of brown adipose tissue (BAT) in adult humans, its high energy capacity has driven investigations targeting adipose tissue thermogenesis as a supplement to whole-body energy expenditure to mitigate the energy imbalances observed in obesity. Uncoupling protein 1 (UCP1) is the primary driver of thermogenesis, however several additional UCP1-independent pathways have been identified. We previously reported that adipocyte deletion of the RNA binding protein human antigen R (HuR) results in thermogenic dysfunction independent of UCP1. RNA sequencing revealed the downregulation of several genes involved in calcium ion transport upon HuR deletion. Although recently established as a thermogenic mechanism in beige adipocytes, the effects of calcium-mediated thermogenesis in brown fat and its contribution to whole-body metabolism remain unexplored. Therefore, we set out to investigate the impact and regulatory mechanism of HuR on SR calcium cycling and heat generation in BAT. We hypothesize that HuR regulates thermogenesis in brown adipose tissue through control of RyR-mediated SR calcium release and assessed this experimentally using murine models with a BAT-specific deletion of HuR. Brown adipocytes isolated from BAT-HuR -/- mice were imaged for cytosolic calcium and heat using Fluo-4 calcium indicator and ERthermAC dye respectively. Cohorts of mice were also subjected to acute cold challenge or placed on a 12-week high fat diet study to assess whole-body thermal and energy metabolism. We now show that loss of HuR decreases adrenergic-stimulated calcium release and heat generation in brown adipose tissue, and that this effect is rescued by pharmacological stabilization of RyR2. We also report that HuR directly binds RyR2 mRNA in vivo and loss of HuR reduces RyR2 mRNA transcript stability. In assessing whole-body metabolism, we observed impaired thermal tolerance of BAT-HuR -/- mice from controls, as well as sex-dependent effects on diet-induced weight gain between models. Our findings reveal, for the first time, that brown adipocytes participate in calcium-mediated thermogenesis and identify a regulatory role for HuR in coordinating heat production through maintenance of RyR2 calcium release activity.

A blend of medium-chain fatty acids, butyrate, organic acids, and a phenolic compound accelerates microbial maturation in newly weaned piglets.

Inclusion of additive blends is a common dietary strategy to manage post-weaning diarrhea and performance in piglets. However, there is limited mechanistic data on how these additives improve outcomes during this period. To evaluate the effects of Presan FX (MCOA) on the intestinal microbiota and metabolome, diets with or without 0.2% MCOA were compared. Pigs fed MCOA showed improved whole-body metabolism 7 days post-weaning, with decreased (P < 0.05) creatine, creatinine and β-hydroxybutyrate. Alterations in bile-associated metabolites and cholic acid were also observed at the same time-point (P < 0.05), suggesting MCOA increased bile acid production and secretion. Increased cholic acid was accompanied by increased tryptophan metabolites including indole-3-propionic acid (IPA) in systemic circulation (P = 0.004). An accompanying tendency toward increased Lactobacillus sp. in the small intestine was observed (P = 0.05). Many lactobacilli have bile acid tolerance mechanisms and contribute to production of IPA, suggesting increased bile acid production resulted in increased abundance of lactobacilli capable of tryptophan fermentation. Tryptophan metabolism is associated with the mature pig microbiota and many tryptophan metabolites such as IPA are considered beneficial to gut barrier function. In conclusion, MCOA may help maintain tissue metabolism and aid in microbiota re-assembly through bile acid production and secretion.

Autophagy ablation in skeletal muscles worsens sepsis-induced muscle wasting, impairs whole-body metabolism, and decreases survival

Septic patients frequently develop skeletal muscle wasting and weakness, resulting in severe clinical consequences and adverse outcomes. Sepsis triggers sustained induction of autophagy, a key cellular degradative pathway, in skeletal muscles. However, the impact of enhanced autophagy on sepsis-induced muscle dysfunction remains unclear. Using an inducible and muscle-specific Atg7 knockout mouse model (Atg7iSkM-KO), we investigated the functional importance of skeletal muscle autophagy in sepsis using the cecal ligation and puncture model. Atg7iSkM-KO mice exhibited a more severe phenotype in response to sepsis, marked by severe muscle wasting, hypoglycemia, higher ketone levels, and a decreased in survival as compared to mice with intact Atg7. Sepsis and Atg7 deletion resulted in the accumulation of mitochondrial dysfunction, although sepsis did not further worsen mitochondrial dysfunction in Atg7iSkM-KO mice. Overall, our study demonstrates that autophagy inactivation in skeletal muscles triggers significant worsening of sepsis-induced muscle and metabolic dysfunctions and negatively impacts survival.

A Complete Workflow for High Throughput Human Single Skeletal Muscle Fiber Proteomics.

Skeletal muscle is a major regulatory tissue of whole-body metabolism and is composed of a diverse mixture of cell (fiber) types. Aging and several diseases differentially affect the various fiber types, and therefore, investigating the changes in the proteome in a fiber-type specific manner is essential. Recent breakthroughs in isolated single muscle fiber proteomics have started to reveal heterogeneity among fibers. However, existing procedures are slow and laborious, requiring 2 h of mass spectrometry time per single muscle fiber; 50 fibers would take approximately 4 days to analyze. Thus, to capture the high variability in fibers both within and between individuals requires advancements in high throughput single muscle fiber proteomics. Here we use a single cell proteomics method to enable quantification of single muscle fiber proteomes in 15 min total instrument time. As proof of concept, we present data from 53 isolated skeletal muscle fibers obtained from two healthy individuals analyzed in 13.25 h. Adapting single cell data analysis techniques to integrate the data, we can reliably separate type 1 and 2A fibers. Ninety-four proteins were statistically different between clusters indicating alteration of proteins involved in fatty acid oxidation, oxidative phosphorylation, and muscle structure and contractile function. Our results indicate that this method is significantly faster than prior single fiber methods in both data collection and sample preparation while maintaining sufficient proteome depth. We anticipate this assay will enable future studies of single muscle fibers across hundreds of individuals, which has not been possible previously due to limitations in throughput.

Physiology of lipid digestion and absorption in poultry: An updated review on the supplementation of exogenous emulsifiers in broiler diets.

Lipids are a concentrated source of energy with at least twice as much energy as the same amount of carbohydrates and protein. Dietary lipids provide a practical alternative towardincreasing the dietary energy density of feeds for high-performing modern broilers. However, the digestion and absorption of dietary lipids are much more complex than that of the other macronutrients. In addition, young birds are physiologically limited in their capacity to utilise dietary fats and oils effectively. The use of dietary emulsifiers as one of the strategies aimed at improving fat utilisation has been reported to elicit several physiological responses including improved fat digestibility and growth performance. In practical terms, this allows for the incorporation of lipids into lower-energy diets without compromising broiler performance. Such an approach may potentially lower feed costs and raise revenue gains. The current review revisits lipids and the different roles that they perform in diets and whole-body metabolism. Additional information on the process of dietary lipid digestion and absorption in poultry; and the physiological limitation brought about by age on lipid utilisation in the avian gastrointestinal tract have been discussed. Subsequently, the physiological responses resulting from the dietary supplementation of exogenous emulsifiers as a strategy for improved lipid utilisation in broiler nutrition are appraised. Suggestions of nascent areas for a better understanding of exogenous emulsifiers have been highlighted.

Nipsnap1—A regulatory factor required for long-term maintenance of non-shivering thermogenesis

ObjectiveThe activation of non-shivering thermogenesis (NST) has strong potential to combat obesity and metabolic disease. The activation of NST however is extremely temporal and the mechanisms surrounding how the benefits of NST are sustained once fully activated, remain unexplored. The objective of this study is to investigate the role of 4-Nitrophenylphosphatase Domain and Non-Neuronal SNAP25-Like 1 (Nipsnap1) in NST maintenance, which is a critical regulator identified in this study. MethodsThe expression of Nipsnap1 was profiled by immunoblotting and RT-qPCR. We generated Nipsnap1 knockout mice (N1–KO) and investigated the function of Nipsnap1 in NST maintenance and whole-body metabolism using whole body respirometry analyses. We evaluate the metabolic regulatory role of Nipsnap1 using cellular and mitochondrial respiration assay. ResultsHere, we show Nipsnap1 as a critical regulator of long-term thermogenic maintenance in brown adipose tissue (BAT). Nipsnap1 localizes to the mitochondrial matrix and increases its transcript and protein levels in response to both chronic cold and β3 adrenergic signaling. We demonstrated that these mice are unable to sustain activated energy expenditure and have significantly lower body temperature in the face of an extended cold challenge. Furthermore, when mice are exposed to the pharmacological β3 agonist CL 316, 243, the N1–KO mice exhibit significant hyperphagia and altered energy balance. Mechanistically, we demonstrate that Nipsnap1 integrates with lipid metabolism and BAT-specific ablation of Nipsnap1 leads to severe defects in beta-oxidation capacity when exposed to a cold environmental challenge. ConclusionOur findings identify Nipsnap1 as a potent regulator of long-term NST maintenance in BAT.

Adipocyte NMNAT1 expression is essential for nuclear NAD+ biosynthesis but dispensable for regulating thermogenesis and whole-body energy metabolism

Nicotinamide adenine dinucleotide (NAD+) functions as an essential cofactor regulating a variety of biological processes. The purpose of the present study was to determine the role of nuclear NAD+ biosynthesis, mediated by nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1), in thermogenesis and whole-body energy metabolism. We first evaluated the relationship between NMNAT1 expression and thermogenic activity in brown adipose tissue (BAT), a key organ for non-shivering thermogenesis. We found that reduced BAT NMNAT1expression was associated with inactivation of thermogenic gene program induced by obesity and thermoneutrality. Next, we generated and characterized adiponectin-Cre-driven adipocyte-specific Nmnat1 knockout (ANMT1KO) mice. Loss of NMNAT1 markedly reduced nuclear NAD+ concentration by approximately 70% in BAT. Nonetheless, adipocyte-specific Nmnat1 deletion had no impact on thermogenic (rectal temperature, BAT temperature and whole-body oxygen consumption) responses to β-adrenergic ligand norepinephrine administration and acute cold exposure, adrenergic-mediated lipolytic activity, and metabolic responses to obesogenic high-fat diet feeding. In addition, loss of NMNAT1 did not affect nuclear lysine acetylation or thermogenic gene program in BAT. These results demonstrate that adipocyte NMNAT1 expression is required for maintaining nuclear NAD+ concentration, but not for regulating BAT thermogenesis or whole-body energy homeostasis.

1626-P: Activation of Cardiac Mitochondrial Akt1 Enhanced Myocardial Fatty Acid Utilization, Protected against Diabetic Cardiomyopathy, and Improved Whole Body Fat Distribution

Insulin stimulates Akt1 translocation to cardiac mitochondria, and we have recently shown that inhibition of cardiac mitochondria Akt1 led to mitochondrial dysfunction and cardiomyopathy. However, whether activation of mitochondrial Akt1 in cardiac muscle can protect against the development of diabetic cardiomyopathy is not known. To this end, we have generated an inducible heart-specific transgenic mouse harboring a mitochondria-targeting constitutively active Akt1 (CAMCAKT). Long-term high fat-high fructose diet (HFFD) caused myocardial hypertrophy, fibrosis and ventricular dysfunction in control mice, but the impact of HFFD were attenuated in the CAMCAKT mice. After just two months on HFFD, expression of Col1a1 and Col3a1 in CAMCAKT mice were lower than controls (p&amp;lt;0.01). After five months on HFFD, ejection fraction in CA mice was 17 % higher than in controls while fractional shortening was 22% higher (p&amp;lt;0.05). This indicated that activation of mitochondrial Akt protected myocardium against the development of cardiomyopathy in diet-induced diabetes. Metabolically, cardiac mitochondrial Akt1 increased fatty acid uptake in the cardiac muscle, which resulted in redistribution of whole-body fatty acid metabolism. Dynamic PET scans revealed a 65% increase (p&amp;lt;0.001) in heart uptake of fatty acid reporter [18F]fluoro-4-thia-oleate in CAMCAKT mice. CAMCAKT mice had 15% less body fat, 30% lower total cholesterol and expended 13% more energy, compared to controls (p&amp;lt;0.05). Interestingly, fatty liver was reduced in the CAMCAKT mice (p&amp;lt;0.05), suggesting that cardiac mitochondrial Akt modulated fat deposition in the liver by higher myocardial fatty acid metabolism. In summary, activating cardiac mitochondrial Akt protected against diabetic cardiomyopathy, attenuated fatty liver, and induced whole body metabolism in this murine model of diet-induced diabetes. Disclosure A.Ta: None. Y.Chen: None. J.Li: None. E.Salem: None. P.H.Wang: Research Support; ViaCyte, Inc. Funding National Institutes of Health (R01HL096987); Ko Family Foundation

Transgenic mice lacking FGF15/19-SHP phosphorylation display altered bile acids and gut bacteria, promoting nonalcoholic fatty liver disease

Dysregulated bile acid (BA)/lipid metabolism and gut bacteria dysbiosis are tightly associated with the development of obesity and non-alcoholic fatty liver disease (NAFLD). The orphan nuclear receptor, Small Heterodimer Partner (SHP/NR0B2), is a key regulator of BA/lipid metabolism, and its gene-regulating function is markedly enhanced by phosphorylation at Thr-58 mediated by a gut hormone, fibroblast growth factor-15/19 (FGF15/19). To investigate the role of this phosphorylation in whole-body energy metabolism, we generated transgenic SHP-T58A knock-in mice. Compared with wild-type (WT) mice, the phosphorylation-defective SHP-T58A mice gained weight more rapidly with decreased energy expenditure and increased lipid/BA levels. This obesity-prone phenotype was associated with the upregulation of lipid/BA synthesis genes and downregulation of lipophagy/β-oxidation genes. Mechanistically, defective SHP phosphorylation selectively impaired its interaction with LRH-1, resulting in de-repression of SHP/LRH-1 target BA/lipid synthesis genes. Remarkably, BA composition and selective gut bacteria which are known to impact obesity, were also altered in these mice. Upon feeding a high-fat diet, fatty liver developed more severely in SHP-T58A mice compared to WT mice. Treatment with antibiotics substantially improved the fatty liver phenotypes in both groups but had greater effects in the T58A mice so that the difference between the groups was largely eliminated. These results demonstrate that defective phosphorylation at a single nuclear receptor residue can impact whole-body energy metabolism by altering BA/lipid metabolism and gut bacteria, promoting complex metabolic disorders like NAFLD. Since posttranslational modifications generally act in gene- and context-specific manners, the FGF15/19-SHP phosphorylation axis may allow more targeted therapy for NAFLD.

246-LB: Stimulation of Hepatic Lipid Secretion by Glucocorticoid Action in the Nucleus of the Solitary Tract

Dysregulated lipid metabolism is a characteristic of diabetes, insulin resistance, and obesity. Increased glucocorticoid (GC) levels and/or action is associated with elevated levels of circulating triglyceride (TG)-rich very low-density lipoproteins (VLDL-TGs). Lipid metabolism is heavily affected by GCs via its direct actions on peripheral organs, e.g. liver, adipose tissue. However, how GCs modulate hepatic VLDL-TG secretion via their actions in the brain is less known. The nucleus of the solitary tract (NTS) in the hindbrain is responsive to various hormones and is an important region involved in whole-body metabolism. Here, we aimed to assess how GC action in the NTS affects hepatic TG secretion and hypothesized that GC receptor (GR) agonism in the NTS stimulates hepatic TG secretion. Sprague-Dawley rats underwent stereotaxic NTS bilateral cannulation and vascular catheterizations to enable simultaneous direct NTS infusions, intravenous injections, and blood sampling. Hepatic TG secretion rates were measured in 10h-fasted rats after intravenous poloxamer injection with concurrent NTS infusions. NTS GC infusion stimulated TG secretion compared to NTS vehicle controls, but this effect was negated with pharmacological and genetic GR antagonism, suggesting that NTS GCs are mediated via its receptor. The NTS GC-induced increase in VLDL-TG was not associated with changes in liver lipogenic gene expression and protein levels or plasma ApoB48/100. However, plasma FFAs were increased in NTS GC infused rats, and this was associated with increased pHSL:HSL protein levels in white adipose tissue. We herein provide evidence that acute GC action in the NTS stimulates hepatic VLDL-TG secretion and affects adipose tissue lipid metabolism. Increased circulating FFA availability may contribute to the hyperlipidemic effects of NTS GCs. Future studies to assess the role of NTS GC action in diabetic and obesity-related metabolic disease dyslipidemic models are warranted. Disclosure B. Vasilev: None. M. S. Grewal: None. B. Lum: None. J. T. Yue: None. Funding Natural Sciences and Engineering Research Council of Canada (RGPIN-2016-06657); Canada Foundation for Innovation (37267); Canada Research Chairs Tier 2 in Brain Regulation of Metabolism

34-OR: Postprandial Glucagon Action in the Human Brain

While elevated fasting glucagon is linked to hyperglycemia, the impact of postprandial changes in glucagon is less clear. Recent findings suggest potential metabolic benefits of rising glucagon after oral glucose intake. In addition to the prominent hepatic action of the hormone, animal data indicate that glucagon signaling in the brain contributes to its effects on whole-body metabolism. To elucidate the translational relevance of these findings, we studied postprandial effects of glucagon on the human brain. We performed oral glucose tolerance tests combined with fMRI to quantify brain activity and connectivity at fasting, 30- and 60-minutes post glucose load in 29 volunteers. In 14 out of 22 volunteers with physiologically suppressed glucagon during OGTT, a second OGTT with low-dose glucagon infusion was performed (0.5 pmol/kg/min). All participants had their first OGTT with intravenous saline infusion. This was compared to 7 participants with endogenous rising glucagon during OGTT. Low-dose glucagon infusion did not elevate plasma glucose levels during OGTT. Also, no changes in insulin sensitivity and insulin secretion were observed. However, experimentally elevating glucagon during the OGTT significantly increased postprandial brain responsivity in the hippocampal gyrus and in brain regions important for the regulation of food intake and systemic metabolism (i.e. hypothalamus, nucleus accumbens, midbrain). Postprandial brain responsivity during glucagon infusion was directionally consistent with the findings in persons with endogenously rising glucagon. Moreover, the postprandial brain response correlated with the rise in glucagon, regardless of exogenous or endogenous source of glucagon. Our findings demonstrate postprandial effects of glucagon in metabolically relevant human brain areas. This may underly the promising effects on body weight achieved with upcoming pharmacological multi-agonists that activate the glucagon receptor. Disclosure R.Wagner: Advisory Panel; Daiichi Sankyo, Speaker's Bureau; Novo Nordisk, Sanofi. A.Fritsche: Advisory Panel; Novo Nordisk, Lilly, Sanofi, Boehringer-Ingelheim, Speaker's Bureau; AstraZeneca, SYNLAB Holding Deutschland GmbH. A.Peter: None. M.Heni: Advisory Panel; Boehringer-Ingelheim, Sanofi, Research Support; Boehringer Ingelheim Inc., Speaker's Bureau; Lilly, Bayer Inc., Sanofi, Boehringer-Ingelheim, Novo Nordisk, Amryt Pharma Plc. S.Kullmann: None. J.Hummel: None. R.Veit: None. K.Prystupa: Other Relationship; Berlin-Chemie AG. E.Hosenfeld: None. A.L.Birkenfeld: None. H.Häring: None. H.Preissl: None.

302-OR: How Menstrual Cycle Impacts Brain Insulin Action—Results from Young Women

The human brain is an insulin-sensitive organ that modulates whole-body glucose metabolism and adiposity. In case of brain insulin resistance, this regulation is disturbed. In the periphery, insulin sensitivity varies along the menstrual cycle, while the effects on brain insulin action are still unknown. We here investigated the impact of menstrual cycle on brain insulin sensitivity of the human hypothalamus and on brain-derived modulation of peripheral metabolism. In 26 naturally cycling women (age 19-29 years, BMI 18-24 kg/m2), brain insulin action was assessed in both the follicular and the luteal phase using nasal application of 160 U insulin. In fifteen women, we assessed hypothalamic insulin responsiveness by functional MRI combined with nasal insulin. In eleven women, brain-derived modulation of peripheral insulin sensitivity was studied by hyperinsulinemic euglycemic clamps combined with insulin vs placebo spray. Only in the follicular phase, nasal insulin significantly decreased hypothalamic blood flow (p=0.02), indicating proper brain insulin action. In the luteal phase, insulin induced no such effect (p=0.6). During hyperinsulinemic euglycemic clamps in the follicular phase, more glucose had to be infused after insulin compared to placebo spray. This difference remained significant after adjustment for circulating glucose and insulin (p&amp;lt;0.0001), which was not the case in the luteal phase (p=0.1). High estradiol/progesterone ratio, as present during the follicular phase, was linked to a stronger effect of insulin spray on glucose infusion rates than placebo. Brain insulin sensitivity is a regulated process that can rapidly adapt to changing physiologic requirements, as through the menstrual cycle. In the luteal phase, we detected hypothalamic insulin resistance, which likely contributed to the lacking modulation of peripheral insulin sensitivity through brain insulin delivery. Thus, brain insulin resistance could contribute to whole-body insulin resistance in the luteal phase. Disclosure J.Hummel: None. M.Roden: Advisory Panel; Eli Lilly and Company, Consultant; TARGET PharmaSolutions, Inc., Research Support; Boehringer-Ingelheim, Novo Nordisk, Novartis, Sanofi. H.Häring: None. A.Fritsche: Advisory Panel; Novo Nordisk, Lilly, Sanofi, Boehringer-Ingelheim, Speaker's Bureau; AstraZeneca, SYNLAB Holding Deutschland GmbH. A.Peter: None. R.Wagner: Advisory Panel; Daiichi Sankyo, Speaker's Bureau; Novo Nordisk, Sanofi. S.Kullmann: None. M.Heni: Advisory Panel; Boehringer-Ingelheim, Sanofi, Research Support; Boehringer Ingelheim Inc., Speaker's Bureau; Lilly, Bayer Inc., Sanofi, Boehringer-Ingelheim, Novo Nordisk, Amryt Pharma Plc. C.Benkendorff: None. L.Fritsche: None. K.Prystupa: Other Relationship; Berlin-Chemie AG. A.Vosseler: None. S.Gancheva: Consultant; Novo Nordisk, Bayer Inc. S.Trenkamp: None. A.L.Birkenfeld: None. H.Preissl: None. Funding German Federal Ministry of Education and Research

1653-P: Brown Adipocyte–Secreted Factors for Treating Type 1 Diabetes Mellitus

Hyperglycemia during type 1 Diabetes (T1D) is driven not only by a lack of insulin secretion due to autoimmune destruction of the pancreatic β-cells, but also by hypersecretion of glucagon from pancreatic α-cells. Insulin therapy can replace the lack of insulin secretion, but there is no effective therapeutic tool to counter the hyperglucagonemia. Brown adipose tissue (BAT) has gained attention for treating metabolic diseases due to its role as an endocrine organ and its effect on whole-body energy metabolism. Subcutaneous transplantation of embryonic BAT into T1D mouse models reverses hyperglycemia, independent of insulin but accompanied by reduced plasma glucagon levels, which suggests that lowering plasma glucagon plays a central role in restoring euglycemia. However, the molecular mechanism(s) underlying this action remain unclear. Towards discovering these mechanisms, we have examined the effects of secretions from immortalized brown adipocytes (imBAT) on pancreatic α-cells and mouse models of T1D. We show that the large molecule fraction (&amp;gt;100kDa) of imBAT-secreted factors suppresses glucagon secretion from both mouse and human pancreatic α-cells. Live cell fluorescence imaging shows that this fraction inhibits both intracellular Ca2+ and cAMP activities, and these inhibitions are ameliorated by blocking the insulin receptor, suggesting that imBAT-secreted factors act, at least in part, through these receptors. Injecting this imBAT-secreted fraction into the NOD mouse model reverses hyperglycemia (242 ± 47.4 to 146 ± 24.7mg/dL, n=8), suppresses hyperglucagonemia (77.6 ± 55.4 to 10.7 ± 4.75pg/mL, n=8), improves glucose tolerance (n=3), and increases thermogenic activity and differentiation of endogenous BAT (n=7). Our data provide insights into the mechanisms of long-term recovery of euglycemia by BAT transplants, and further fractionation experiments to isolate active factors are ongoing. Disclosure J.Lee: None. D.W.Piston: None. Funding The Leona M. and Harry B. Helmsley Charitable Trust (2305-06050); National Institutes of Health (R01DK123301, P30DK020579)

1616-P: Effects of Hazelnuts Consumption Combined with Physical Activity on Lipid Metabolism and Correlations with Marrow Adiposity Homeostasis

Consumption of hazelnuts has been associated with reduced cardiovascular risk and improved metabolic outcomes. Furthermore, the Bone Marrow Fat (BMF) might contribute to skeletal as well as systemic metabolism, modulating insulin sensitivity and, consequently, cardiovascular risk. Previously, we demonstrated a beneficial effect of hazelnuts and cocoa integration on vascular reactivity and metabolic profile in healthy individuals. Aim of this randomized controlled interventional study with 3 parallel groups was to investigate the effects of a daily supplementation with 30 g of hazelnuts, with or without aerobic physical activity (PA), throughout 8 weeks, on insulin sensitivity and resistance, lipid profile, and on BMF content (evaluated by proton magnetic resonance spectroscopy) in healthy individuals. Twenty-five adults (age 18-50 yrs; BMI 18-28 Kg/m2) were randomized in 3 groups: 9 subjects (5F/4M, age 25.6±8.8 yrs, BMI 23.3±2.5) received 30 g of hazelnuts associated with diet (Group 1); 9 subjects (6F/3M, age 26.3±6.3 yrs, BMI 22.0±2.1) received 30 g of hazelnuts associated with diet and aerobic PA (Group 2); 7 subjects (4 F/3 M, age 29.7±6.4 yrs, BMI 23.3±4.2) received only diet (Group 3). After the 8 weeks-intervention, an improvement in LDL-Cholesterol was found in Groups 1 and 2 [-9.3±11.5% (Group 1) vs -5.0±13.6% (Group 2) vs +21.9±35.7% (Group 3); p=0.02]. BMF content variation negatively correlated with LDL-Cholesterol change in Group 1 (r=-0.802, p=0.054); variations in BMF content and in HDL-Cholesterol positively correlated in Group 2 (r=+0.8687, p=0.011). This study confirms the beneficial effects of hazelnuts, in association with PA in improving lipid profile. The correlations between HDL- and LDL-cholesterol and BFM changes suggest an impact of bone homeostasis on whole-body lipid metabolism, through a rapid utilization of lipids, drawing them out of the circulation and decreasing their deposition in the organ tissues. Disclosure A.Ferrulli: None. S.Massarini: None. C.Macrì: None. P.Senesi: None. I.Terruzzi: None. G.Rosso: Employee; Soremartec Italia Srl, Ferrero Group. M.Charron: Employee; Soremartec Italia Srl, Ferrero Group. R.Menta: Employee; Soremartec Italia Srl, Ferrero Group. L.Luzi: Advisory Panel; Eli Lilly and Company, Medtronic, Research Support; Gelesis, Speaker's Bureau; A. Menarini Diagnostics, Amgen Inc., Boehringer Ingelheim and Eli Lilly Alliance, Eli Lilly and Company, Novo Nordisk, Novartis. Funding IRCCS MultiMedica (Ricerca Corrente)

10-OR: The Triple Roles of Tubular Mitochondria AKT in the Regulation of Renal Function, Insulin Resistance, and Body Composition during Development of Diabetic Nephropathy

Diabetic nephropathy is a major cause of end-stage renal disease. We have recently shown translocation of AKT to mitochondria in proximal tubules played a renoprotective role in murine ischemia/reperfusion injury. In this study, we tested the hypothesis that activation of mitochondrial AKT (mito-AKT) signaling in renal proximal tubules improves kidney function in diabetic nephropathy and modulates overall glucose homeostasis. We used renal tubule-specific bigenic mice that harbor tamoxifen-inducible mitochondria-targeting constitutively active AKT1 (KMCAKT), which were fed with either normal chow diet or high fat and fructose diet (HFFD). Wild type mice fed with HFFD developed nephropathy after 24 wks. Activation of renal tubular mito-AKT significantly attenuated urinary albumin, creatinine, and glucose excretion in the KMCAKT mice on HFFD. Interestingly, activation of tubular mito-AKT also decreased fasting hyperglycemia, and improved glucose tolerance of HFFD-fed mice. Insulin resistance (HOMA-IR) was significantly reduced when tubular mito-AKT was activated. In addition, mito-AKT activation reduced plasma cholesterol. Furthermore, mito-AKT activation increased total body weight and fat mass of HFFD-fed mice, but had no effect on their water and food intake. To dissect the underlying mechanism, we used 18F-fluoro-4-thia-oleate PET scan to define organ specific fatty acid uptake, and revealed a significant increase of uptake in white and brown adipose tissues in KMCAKT mice on HFFD. In conclusion, this is the first report to demonstrate critical roles of mitochondrial AKT in renal tubules in the regulation of whole-body metabolism, insulin sensitivity, and body composition beyond its local effect on kidney function in diabetic nephropathy, which suggests kidney function and nephropathy associated metabolic dysfunction could be mediated through a common pathway in tubular mitochondria. Disclosure E.Salem: None. A.Ta: None. H.Y.H.Lin: None. J.Li: None. P.H.Wang: Research Support; ViaCyte, Inc. Funding Shannon &amp; Amy Ko Foundation

245-LB: Glucagon Infusion into the Mediobasal Hypothalamus Lowers Hepatic Triglyceride Secretion

Diabetes and obesity are associated with dysregulated liver lipid metabolism. Glucagon has an essential role in lipid metabolism, in addition to regulating glucose homeostasis. The brain is a key coordinator of whole-body metabolism. Glucagon signalling in the mediobasal hypothalamus (MBH), a forebrain region that senses hormones and nutrients to regulate metabolism, lowers hepatic glucose production and appetite. However, whether glucagon action in the MBH affects lipid homeostasis in healthy and high-fat diet (HFD)-fed animals remains unknown. We assessed glucagon signaling in the MBH in regulating hepatic TG secretion in chow-fed normolipidemic and HFD-induced hyperlipidemic rats. Stereotaxic MBH cannulation and vascular catheterizations in Sprague-Dawley rats allowed for direct MBH infusions, intravenous (IV) injections, and blood sampling. Plasma TGs were measured in 10h-fasted rats after IV poloxamer injection with concurrent MBH infusions. MBH glucagon decreased TG secretion compared to MBH vehicle control animals. This hypothalamic effect of glucagon was blocked by a simultaneous MBH co-infusion of an antagonist to the glucagon receptor (GCGR) and by protein kinase A (PKA) inhibition in the MBH in chow-fed rats. Direct MBH infusion of a PKA activator recapitulated the TG-lowering effects of MBH glucagon. Together, this suggests that MBH glucagon signals via a MBH GCGR-PKA pathway. Interestingly, both MBH glucagon and MBH PKA activation lowered TG secretion and plasma FFAs in HFD-induced hyperlipidemic animals. However, MBH glucagon did not affect hepatic TG content or liver lipogenic protein levels of MTP, FAS, or pACC:ACC of RC and HFD rats compared to their MBH vehicle controls. We demonstrate that hypothalamic glucagon modulates hepatic TG secretion via a MBH GCGR-PKA signalling pathway, and activating MBH glucagon signalling improves lipid metabolism in hyperlipidemic rats. These findings may provide therapeutic insight on lowering lipids in hyperlipidemia. Disclosure M. S. Grewal: None. B. Vasilev: None. C. M. Soltys: None. B. Lum: None. J. T. Yue: None. Funding Canadian Institutes of Health Research (PJT-378765); Canada Foundation for Innovation (37267); Canada Research Chairs Tier 2 in Brain Regulation of Metabolism

6,6'-2 H2 ] fructose as a deuterium metabolic imaging probe in liver cancer.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths. Imaging plays a crucial role in the early detection of HCC, although current methods are limited in their ability to characterize liver lesions. Most recently, deuterium metabolic imaging (DMI) has been demonstrated as a powerful technique for the imaging of metabolism in vivo. Here, we assess the metabolic flux of [6,6'-2 H2 ] fructose in cell cultures and in subcutaneous mouse models at 9.4 T. We compare these rates with the most widely used DMI probe, [6,6'-2 H2 ] glucose, exploring the possibility of developing 2 H fructose to overcome the limitations of glucose as a novel DMI probe for detecting liver tumors. Comparison of the in vitro metabolic rates implies their similar glycolytic metabolism in the TCA cycle due to comparable production rates of 2 H glutamate/glutamine (glx) for the two precursors, but overall higher glycolytic metabolism from 2 H glucose because of a higher production rate of 2 H lactate. In vivo kinetic studies suggest that HDO can serve as a robust reporter for the consumption of the precursors in liver tumors. As fructose is predominantly metabolized in the liver, deuterated water (HDO) produced from 2 H fructose is probably less contaminated from whole-body metabolism in comparison with glucose. Moreover, in studies of the normal liver, 2 H fructose is readily converted to 2 H glx, enabling the characterization of 2 H fructose kinetics. This overcomes a major limitation of previous 2 H glucose studies in the liver, which were unable to confidently discern metabolic flux due to overlapped signals of 2 H glucose and its metabolic product, 2 H glycogen. This suggests a unique role for 2 H fructose metabolism in HCC and the normal liver, making it a useful approach for assessing liver-related diseases and the progression to oncogenesis.

DMC (2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone) enhances exercise tolerance via the AMPK-SIRT1-PGC-1α pathway in mice fed a high-fat diet.

Obesity is caused by an imbalance between energy intake and energy expenditure. This study aimed to determine the effects and mechanisms of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) on exercise tolerance in high-fat diet (HFD)-fed mice. Male C57BL/6J mice were randomly divided into two categories (7 groups [n = 8]): sedentary (control [CON], HFD, 200 mg/kg DMC, and 500 mg/kg DMC) and swimming (HFD, 200 mg/kg DMC, and 500 mg/kg DMC). Except the CON group, all other groups were fed HFD with or without DMC intervention for 33 days. The swimming groups were subjected to exhaustive swimming (three sessions/week). Changes in swimming time, glucolipid metabolism, body composition, biochemical indicators, histopathology, inflammation, metabolic mediators, and protein expression were assessed. DMC combined with regular exercise improved endurance performance, body composition, glucose and insulin tolerance, lipid profile, and the inflammatory state in a dose-dependent manner. Further, DMC alone or combined with exercise could restore normal tissue morphology, reduce fatigue-associated markers, and boost whole-body metabolism and the protein expression of phospho-AMP-activated protein kinase alpha/total-AMP-activated protein kinase alpha (AMPK), sirtuin-1 (SIRT1), peroxisome-proliferator-activated receptor gamma coactivator 1alpha (PGC-1α), and peroxisome proliferator-activated receptor alpha in the muscle and adipose tissues of HFD-fed mice. DMC exhibits antifatigue effects by regulating glucolipid catabolism, inflammation, and energy homeostasis. Furthermore, DMC exerts a synergistic exercise-related metabolic effect via the AMPK-SIRT1-PGC-1α signaling pathway, suggesting that DMC is a potential natural sports supplement with mimicked or augmented exercise effects for obesity prevention.

A Targeted Mass Spectrometry Approach to Identify Peripheral Changes in Metabolic Pathways of Patients with Alzheimer's Disease.

Alzheimer's disease (AD), a neurodegenerative disorder, is the most common cause of dementia in the elderly population. Since its original description, there has been intense debate regarding the factors that trigger its pathology. It is becoming apparent that AD is more than a brain disease and harms the whole-body metabolism. We analyzed 630 polar and apolar metabolites in the blood of 20 patients with AD and 20 healthy individuals, to determine whether the composition of plasma metabolites could offer additional indicators to evaluate any alterations in the metabolic pathways related to the illness. Multivariate statistical analysis showed that there were at least 25 significantly dysregulated metabolites in patients with AD compared with the controls. Two membrane lipid components, glycerophospholipids and ceramide, were upregulated, whereas glutamic acid, other phospholipids, and sphingolipids were downregulated. The data were analyzed using metabolite set enrichment analysis and pathway analysis using the KEGG library. The results showed that at least five pathways involved in the metabolism of polar compounds were dysregulated in patients with AD. Conversely, the lipid pathways did not show significant alterations. These results support the possibility of using metabolome analysis to understand alterations in the metabolic pathways related to AD pathophysiology.