Plasma FFA Research Articles

Tangzhiping Decoction Improves Glucose and Lipid Metabolism and Exerts Protective Effects Against White Adipose Tissue Dysfunction in Prediabetic Mice.

Prediabetes, characterized by a series of metabolic abnormalities, increases the risk of diabetes and cardiovascular diseases. Tangzhiping (TZP), a clinically validated traditional Chinese medicine formula, is used to treat impaired glucose tolerance. However, the underlying mechanism of TZP in intervening prediabetes is not fully elucidated. The current study aimed to evaluate the protective effect of TZP against prediabetes mice and explore its potential mechanism. After establishing a prediabetic animal model through 12 weeks of high-fat diet (HFD) feeding, mice were subjected to TZP for 8 weeks. Various parameters related to body weight, glucose and lipid metabolism, and insulin sensitivity were measured. Histopathological examinations observed adipose cell size and liver lipid deposition. The Sable Promethion system assessed energy metabolism activity. Transcriptomic analysis of Epididymal white adipose tissue (EWAT) identified enriched pathways and genes. The key genes in the enriched pathways were identified through RT-PCR. Our data revealed that the administration of TZP reduced body weight and fat mass in a prediabetes mouse model. TZP normalized the glucose and insulin levels, improved insulin resistance, and decreased plasma TC and FFA. The alleviation of adipose tissue hypertrophy and lipid deposition by TZP was demonstrated through pathological examination. Indirect calorimetry measurements indicated a potential increase in VO2 and EE levels with TZP. The results of EWAT transcription showed that TZP reversed pathways and genes related to inflammation and catabolic metabolism. RT-PCR demonstrated that the mRNA expression of inflammation and lipolysis, including Tlr2, Ccr5, Ccl9, Itgb2, Lipe, Pnpla2, Cdo1, Ces1d, Echs1, and Acad11, were changed by TZP treatment. TZP effectively alleviates obesity, impaired glucose and lipid metabolism, and insulin resistance. The effect of TZP might be associated with the regulation of gene expression in dysfunctional adipose tissue.

Metabolite profiling and biochemical investigation of the antidiabetic potential of Loranthus pulverulentus Wall n-butanol fraction in diabetic animal models

Ethnopharmacological relevanceGlobally, 537 million individuals are estimated to have diabetes. The traditional use of herbs for ameliorating diabetes symptoms is a common practice in Pakistan and use of Loranthus pulverulentus Wall (L. pulverulentus) by local people in Azad Jammu and Kashmir has been reported. Aim of the studyIn the present study, the antidiabetic potential of standardized n-butanol fraction of leaves of L. pulverulentus Wall, which is a parasite of Dalbergia sisso Roxb was assessed in both alloxan (ALX) and streptozotocin (STZ) diabetic animal models. Materials and methodsChemical characterization of BF was performed using HPLC, GCMS and UHPLC-MS. The effect of the fraction (250 mg/kg) on insulin, plasma free fatty acids, L-lactate, pyruvate, MDA, HbA1c and glycogen levels in ALX and STZ animal models was determined. Liver and renal profiles were analyzed in the STZ model. Toxicological studies were performed by hemolytic, Ames mutagenicity, DNA protection, and thrombolytic assays. Histopathological analysis of the pancreas, liver, and kidney was performed. ResultsBF demonstrated highly significant (p < 0.001) antidiabetic potential in both diabetic models. BF significantly (p < 0.05) improved OGTT results in alloxanized diabetic mice and blocked the absorption of glucose from the gut. A significant (p < 0.001) increase in insulin levels and glycogen content in liver tissue and a decrease in plasma FFA, MDA, HbA1c, L-lactate, and pyruvate levels in STZ-diabetic mice were recorded. GC-MS and chromatographic analysis showed the presence of catechin, eugenol, longifolene, caryophyllene, Ar-tumerone and Geranyl-alpha-terpinene. Various metabolites with antidiabetic potential, including 4-hydroxycinnamyl alcohol 4-D-glucoside, zingerone glucoside, trans-trismethoxy resveratrol-d4, epigallocatechin 3-O-cinnamate, and β-glucogallin, were identified using UHPLC-MS. Animals treated with BF showed marked improvements in cellular structures of the pancreas, liver and kidneys. This fraction is non-mutagenic and protects the DNA. ConclusionThe experimental fraction contained potential antidiabetic bioactive compounds responsible for alleviating diabetes-associated biochemical dysregulation. The fraction increased insulin levels and enhanced glycogen storage in muscles and the liver. It blocked glucose absorption from the intestine and substantially decreased HbA1c, lactate, pyruvate, free fatty acids, lipid, liver and kidney damage. Therefore, the use of BF for the treatment of type-2 diabetes may be beneficial.

Whole Body Substrate Metabolism during Different Exercise Intensities with Special Emphasis on Blood Protein Changes in Trained Subjects-A Pilot Study.

Contrary to carbohydrate and fat metabolism, the influence of a single exercise dose on protein metabolism has not been adequately explored yet. We assessed the effects of different exercise intensities and durations on blood protein changes and their association with carbohydrate (CHO) and fat metabolism in six eligible trained subjects. Subjects performed maximal incremental (IE100: at 100%VO2max) and submaximal continuous exercise (CE) at 75%VO2max for 30 min (CE75) and at 50%VO2max for 90 min (CE50). Blood samples were collected at rest (R), end of exercise (EE), and 1 h after recovery to assess blood urea nitrogen (BUN), plasma amino acids (AA), glucose, lactate, FFA, and glycerol. In IE100 blood lactate, CHO-oxidation (g/min), energy expenditure (kcal/min), and RER were significantly increased during rest (p < 0.05). CE50 induced significantly higher BUN, FFA, glycerol, and fat oxidation (g/min) (p < 0.05). At recovery, the mean sum of the free AA pool (µmol/L) reduced by 8% (p < 0.03) during CE50. Values for CE75 were between IE100 and CE50. Beside lipolysis, also proteolysis (BUN) was an important source of fuel for low-to-moderate intensity CE50. An increased uptake of AA from the plasma bed during CE50 suggests the importance for oxidation and synthesis of other metabolic sources such as gluconeogenesis necessary for recovery. Therefore, one needs to be cautious of protein diet following prolonged cycle exercise training.

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

1660-P: Lactate Inhibits Lipolysis in Healthy Males—A Randomized Crossover Trial

Background: The intermediary metabolite lactate has signaling capacities through the lactate specific receptor GPR81/HCA1. Ex-vivo, lactate inhibits lipolysis through GPR81, but in-vivo human data are scarce. Lactate-mediated inhibition of lipolysis could improve insulin sensitivity. The aim of the study was to investigate if hyperlactatemia at physiological concentrations inhibits palmitate lipolysis and affects glucose metabolism in healthy males. Methods: In a randomized cross-over design, eight healthy men were studied after an overnight fast on two occasions 1) during a sodium-lactate infusion (LAC) and 2) during a NaCl infusion (CTL). Both study days comprised a 3-hour basal period followed by a 3-hour hyperinsulinemic euglycemic clamp (HEC) period. Lipolysis rate and endogenous glucose production (EGP) were evaluated using [9,10-3H]-palmitate and [3H]-glucose tracers. Average glucose infusion rate (mg/kg/min) during the last 30 min of the HEC (M-value) was used as a measure of insulin sensitivity. Data are mean±SD Results: Plasma lactate increased to 2.6 ±0.6 mmol/L during LAC vs. 0.8 ±0.3 mmol/L during CTL (p&amp;lt;0.001). At the end of the basal period, palmitate flux was 30% lower during LAC compared with CTL (84 ±32 μmol/min vs. 120 ±35 μmol/min, p=0.003). At the end of the HEC, palmitate flux was similarly suppressed during both interventions (p=0.7). Plasma FFA were lower during LAC compared with CTL (0.2 ±0.1 mmol/L vs. 0.3 ±0.1 mmol/L, p=0.03) at the end of the basal period and equally suppressed during both interventions at the end of the HEC (p=0.7). EGP was unaffected by LAC compared with CTL at the end of the basal period (p=1.0) and suppressed at the end of the HEC during both interventions (p=1.0). M-value was unaffected by LAC compared with CTL (p=0.8). Conclusion: Lactate inhibits palmitate lipolysis by 30 %, an effect which per se may improve insulin sensitivity. Hyperlactatemia did not affect EGP or insulin sensitivity, possibly because lactate intrinsically may induce insulin resistance. Disclosure M.G.B.Pedersen: None. N.Rittig: Research Support; ARLA. E.Søndergaard: None. L.C.Gormsen: None. N.Møller: Other Relationship; Aarhus University/Ketlace.

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

367-OR: E-cigarette Vaping Exposure Increases Adipose 11ß-HSD1 Expression and Disturbs Glucose Homeostasis in Mice

Electronic cigarette (E-cigs) use may increase the prediabetic risk, but the underlying mechanisms remain underexplored. Pre-receptor activation of glucocorticoids (GCs) via 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in adipose tissues has been identified as an important mediator of insulin resistance and type 2 diabetes. However, little is known about the effects of E-cig vaping on 11β-HSD1 and glucose homeostasis. To address this issue, we conducted animal model studies with mice exposed to aerosolized PBS, nicotine-free or nicotine-containing E-cigs, with concurrent exposure to either vehicle or the GC receptor (GR) antagonist RU486. We observed that exposure of E-cig vaping nicotine for 4 weeks increased 11β-HSD1 expression and induced lipase HSL and ATGL abundance within the adipose tissues with induction of hypercortisolemia in response to elevated plasma nicotine levels in mice compared with those of aerosolized E-cig vaping vehicle or PBS controls. Induction of adipose 11β-HSD1 was correlated with elevated the expression of hepatic gluconeogenic enzymes PEPCK and G6Pase and corresponded to the elevated fasting glucose levels. Moreover, E-cig vaping nicotine also increased glucose intolerance, but decreased the glucose-lowing effects of insulin and elevated plasma FFA levels in mice compared with PBS controls. However, E-cig vapor without nicotine did not affect these metabolic parameters. Furthermore, RU486 treatment attenuated E-cig vaping nicotine-induced adipose 11β-HSD1 and lipase expression. In addition, RU486 also attenuated the E-cig-mediated activation of hepatic PEPCK and G6Pase and decreased plasma FFA levels, but did not change the elevated plasma corticosterone levels in mice on E-cig vaping nicotine. These data indicate that E-cig vapor exposure harmfully affects glucose homeostasis and these effects may arise, in part, from aerosol nicotine-induced adipose 11β-HSD1 and GR expression. Disclosure J.Wang: None. T.Friedman: None. M.Jiang: None. Y.Liu: None. J.Liu: None. Y.Wang: None. S.C.J.Kim: None. E.Espinal: None. R.Yang: None. H.Zhong: None. X.M.Shao: None. K.Lutfy: None. Funding Tobacco-Related Disease Research Program (T31IR1603)

GLUT4 degradation by GLUTFOURINH® in mice resembles moderate-obese diabetes of human with hyperglycemia and low lipid accumulation

Backgrounds and aimsType 2 diabetes mellitus (T2D) is a chronic disease characterized by insulin resistance and hyperglycemia. To investigate T2D, genetic and chemical induced hyper-obese rodent models have been experimentally developed. However, establishment of moderate-obese diabetes model will confer diverse opportunities for translational studies. In this study, we found the chemical, GLUTFOURINH® (GFI), induces post-translational degradation of glucose transporter 4 (GLUT4). We aimed to establish novel diabetic model by using GFI. Methods and resultsLow plasma membrane GLUT4 (pmGLUT4) levels by GFI resulted in reduction of intracellular glucose uptake and TG, and increase of intracellular FFA in A204 cells. Likewise, GFI treatment decreased intracellular TG and increased intracellular FFA levels in Hep3B and 3T3-L1 cells. Mice were administered with GFI (16 mg/kg) for short-term (3-day) and long-term (28- and 31-day) to compared with vehicle injection, HFD model, and T2D model, respectively. Short-term and long-term GFI treatments induced hyperglycemia and hyperinsulinemia with low pmGLUT4 levels. Compared to HFD model, long-term GFI with HFD reduced adipose weight and intracellular TG accumulation, but increased plasma FFA. GFI treatment resulted in insulin resistance by showing low QUICKI and high HOMA-IR values, and low insulin response during insulin tolerance test. Additionally, low pmGLUT4 by GFI heightened hyperglycemia, hyperinsulinemia, and insulin resistance compared to T2D model. ConclusionsIn summary, we report GLUT4 degradation by novel chemical (GFI) induces moderate-obese diabetes representing hyperglycemia, insulin resistance and low intracellular lipid accumulation. The GLUT4 degradation by GFI has translational value for studying diseases related to moderate-obese diabetes.

Metabolomic profiling for dyslipidemia in pediatric patients with sickle cell disease, on behalf of the IHCC consortium

BackgroundPrevious study has shown that dyslipidemia is common in patients with Sickle cell disease (SCD) and is associated with more serious SCD complications.MethodsThis study investigated systematically dyslipidemia in SCD using a state-of-art nuclear magnetic resonance (NMR) metabolomics platform, including 147 pediatric cases with SCD and 1234 controls without SCD. We examined 249 metabolomic biomarkers, including 98 biomarkers for lipoprotein subclasses, 70 biomarkers for relative lipoprotein lipid concentrations, plus biomarkers for fatty acids and phospholipids.ResultsSpecific patterns of hypolipoproteinemia and hypocholesterolemia in pediatric SCD were observed in lipoprotein subclasses other than larger VLDL subclasses. Triglycerides are not significantly changed in SCD, except increased relative concentrations in lipoprotein subclasses. Decreased plasma FFAs (including total-FA, SFA, PUFA, Omega-6, and linoleic acid) and decreased plasma phospholipids were observed in SCD.ConclusionThis study scrutinized, for the first time, lipoprotein subclasses in pediatric patients with SCD, and identified SCD-specific dyslipidemia from altered lipoprotein metabolism. The findings of this study depict a broad panorama of lipid metabolism and nutrition in SCD, suggesting the potential of specific dietary supplementation of the deficient nutrients for the management of SCD.

Effect of neonatal isolation on responses to subsequent exposure to isolation stress in young chickens

The aim of the present study was to investigate effects of isolation at an early age on behavioral and physiological responses of chickens to an isolation challenge at two weeks of age. Birds were assigned to a control group or to one of three treatments where chicks were isolated for 5 min per day. The groups were 1) no isolation (control); 2) early isolation (EI; 2 to 4 days of age); 3) late isolation (LI; 5 to 7 days of age); or 4) full isolation (FI; 2 to 7 days of age). All groups of chicks were challenged with isolation for 5 min at two weeks of age, with distress vocalizations (DV), stepping and jumping behavior measured. Hypothalamic and blood samples were collected at the end of isolation challenges. There were no significant differences between groups in body weight gain at 2 weeks of age. Latency of jump was lower in the LI group compared with the control group, but DV and number of steps were not affected by isolation treatment during the neonatal period. There were no significant differences among groups in plasma glucose or FFA concentrations. Gene expression for hypothalamic corticotropin-releasing hormone, was lower in the EI than the control group, with no differences in expression between control and LI or control and FI groups. There were no significant differences among groups in the expression of arginine vasotocin, thyrotropin-releasing hormone, neuropeptide Y, proopiomelanocortin, and orexin genes. These results suggest that isolation in the first week of life may affect responses to isolation of chicks when they are older, and that there may be a critical period of several days for this effect to occur.

54-LB: Distinct Mechanisms Are Responsible for the Increase in Endogenous Glucose Production and Ketone Formation following Empagliflozin in T2DM Patients

Aim: To examine the mechanisms responsible for the increase in glucose and ketone production caused by SGLT2 inhibition with empagliflozin in T2DM patients. Research Design and Methods: 12 T2DM subjects (Age = 53; BMI = 31.7; HbA1c = 7.4%) participated in two studies performed in random order. At 0700h following an overnight fast subjects received an 8-hour infusion of 6,6D2-glucose to measure endogenous (hepatic) glucose production. At 0900 h an infusion of 3H-norepinephrine was started. At 1000h subjects ingested 25 mg of empagliflozin (n=8) or matching placebo (n=4) and were followed for 5 hours (1500 h) . Within 1 week subjects returned for a repeat study with pancreatic clamp to maintain plasma insulin and glucagon concentrations constant at the basal level. As per study one, subjects ingested empagliflozin 25 mg or placebo prior to the pancreatic clamp. Results: When empagliflozin was ingested under fasting conditions, EGP increased by 31% in association with a decrease in plasma glucose (-34 mg/dl) and insulin (-52%) concentrations and increases in plasma glucagon (+19%) , FFA (+29%) and β-hydroxybutyrate (β-HB) (+48%) concentrations. When empagliflozin was ingested under pancreatic clamp conditions, plasma insulin and glucagon concentrations remained unchanged, and the increase in plasma FFA and ketone concentrations was completely blocked, while the increase in EGP persisted. Total-body NE turnover rate increased significantly in subjects receiving empagliflozin (+67%) compared to placebo under both fasting and pancreatic clamp conditions. No difference in plasma norepinephrine concentration was observed in either study. Conclusion: The decrease in plasma insulin and increase in plasma glucagon concentration caused by empagliflozin is responsible for the increase in plasma FFA concentration and ketone production. The increase in EGP caused by empagliflozin is independent of the change in plasma insulin or glucagon concentrations and is explained by the increase in total-body NE turnover. Disclosure S. Abdelgani: None. J. M. Adams: None. G. Daniele: n/a. F. Almulla: None. R. A. Defronzo: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Intarcia Therapeutics, Inc., Novo Nordisk, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Merck &amp; Co., Inc., Speaker’s Bureau; AstraZeneca. M. Abdul-ghani: None. M. Abu-farha: None. S. Del prato: Advisory Panel; Applied Therapeutics, Eli Lilly and Company, Novartis Pharmaceuticals Corporation, Novo Nordisk A/S, Sanofi, Consultant; Menarini Group, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Speaker’s Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Merck &amp; Co., Inc., Sanofi, Stock/Shareholder; Novo Nordisk A/S. Funding National Institute of Health, Boehringer Ingelheim provided empagliflozin and placebo

Extreme duration exercise affects old and younger men differently.

Aim & MethodsExtreme endurance exercise provides a valuable research model for understanding the adaptive metabolic response of older and younger individuals to intense physical activity. Here, we compare a wide range of metabolic and physiologic parameters in two cohorts of seven trained men, age 30 ± 5 years or age 65 ± 6 years, before and after the participants travelled ≈3000 km by bicycle over 15 days.ResultsOver the 15‐day exercise intervention, participants lost 2–3 kg fat mass with no significant change in body weight. V̇O2max did not change in younger cyclists, but decreased (p = 0.06) in the older cohort. The resting plasma FFA concentration decreased markedly in both groups, and plasma glucose increased in the younger group. In the older cohort, plasma LDL‐cholesterol and plasma triglyceride decreased. In skeletal muscle, fat transporters CD36 and FABPm remained unchanged. The glucose handling proteins GLUT4 and SNAP23 increased in both groups. Mitochondrial ROS production decreased in both groups, and ADP sensitivity increased in skeletal muscle in the older but not in the younger cohort.ConclusionIn summary, these data suggest that older but not younger individuals experience a negative adaptive response affecting cardiovascular function in response to extreme endurance exercise, while a positive response to the same exercise intervention is observed in peripheral tissues in younger and older men. The results also suggest that the adaptive thresholds differ in younger and old men, and this difference primarily affects central cardiovascular functions in older men after extreme endurance exercise.

The SGLT2 inhibitor dapagliflozin promotes systemic FFA mobilization, enhances hepatic β-oxidation, and induces ketosis

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to increase ketone bodies in patients with type 2 diabetes; however, the underlying mechanisms have not been fully elucidated. Here we examined the effect of the SGLT2 inhibitor dapagliflozin (1 mg/kg/day, formulated in a water, PEG400, ethanol, propylene glycol solution, 4 weeks) on lipid metabolism in obese Zucker rats. Fasting FFA metabolism was assessed in the anesthetized state using a [9,10-3H(N)]-palmitic acid tracer by estimating rates of plasma FFA appearance (Ra), whole-body FFA oxidation (Rox), and nonoxidative disposal (Rst). In the liver, clearance (Kβ-ox) and flux (Rβ-ox) of FFA into β-oxidation were estimated using [9,10-3H]-(R)-bromopalmitate/[U-14C]palmitate tracers. As expected, dapagliflozin induced glycosuria and a robust antidiabetic effect; treatment reduced fasting plasma glucose and insulin, lowered glycated hemoglobin, and increased pancreatic insulin content compared with vehicle controls. Dapagliflozin also increased plasma FFA, Ra, Rox, and Rst with enhanced channeling toward oxidation versus storage. In the liver, there was also enhanced channeling of FFA to β-oxidation, with increased Kβ-ox, Rβ-ox and tissue acetyl-CoA, compared with controls. Finally, dapagliflozin increased hepatic HMG-CoA and plasma β-hydroxybutyrate, consistent with a specific enhancement of ketogenesis. Since ketogenesis has not been directly measured, we cannot exclude an additional contribution of impaired ketone body clearance to the ketosis. In conclusion, this study provides evidence that the dapagliflozin-induced increase in plasma ketone bodies is driven by the combined action of FFA mobilization from adipose tissue and diversion of hepatic FFA toward β-oxidation.

Therapeutic drug monitoring of fenfluramine in clinical practice: Pharmacokinetic variability and impact of concomitant antiseizure medications.

This study was undertaken to determine the plasma concentration and pharmacokinetic variability of fenfluramine (FFA) and its main active metabolite norfenfluramine (norFFA) in relation to the prevalence of adverse effects in patients with refractory epilepsy treated with FFA. In addition, the interaction with concomitant antiseizure medications including stiripentol (STP) is studied. Patients were recruited at our center from two open-label sources, an investigator-initiated observational study and an international multicenter extension study. Venous blood samples were collected between June 2015 and December 2020. Plasma FFA and norFFA concentrations were determined by liquid chromatography tandem spectrometric analysis. Clinical data were collected retrospectively. Intrapatient coefficient of variation was calculated for all patients with at least three samples. Interpatient variability was calculated based on the concentration to weight-adjusted dose ratio (C/D) of all patients. We collected 321 samples from 61 patients (49 with Dravet syndrome, seven with Lennox-Gastaut syndrome, and five with a developmental and epileptic encephalopathy). With a mean daily dose of .33mg/kg/day (SD =±.16), the median FFA plasma concentration was 41.4µg/L (range = 5.1-712.5) and median norFFA concentration 28.1µg/L (range = 2.6-149.6). The FFA plasma concentration was linearly related to the daily dose (p<.001) and norFFA levels (p<.001). The C/D of FFA increased with age (p<.001). Median FFA C/D was 428% higher (p<.001), norFFA C/D 83% lower (p<.001), and norFFA/FFA 23% lower (p<.001) in patients treated with STP comedication. Higher FFA concentration was associated with fatigue (p=.001) and somnolence (p<.001), but not anorexia (p=.0619) or reduction in seizure frequency (p=.772). Gender and other ASMs were not associated with significant variations in (nor)FFA C/D ratio. Most FFA levels are in the lower range (<50µg/L), although a high interpatient and intrapatient variability is present. In combination with STP, the dose of FFA should be reduced.

257-OR: Short-Term Hyperglucagonemia Induces Adipose Tissue Insulin Resistance and Inflammation In Vivo

Although the effect of glucagon on glucose metabolism has been well characterized, its effect on adipose tissue and lipid metabolism in humans in vivo has been poorly studied with controversial results. We examined the effect of short-term hyperglucagonemia on adipocyte metabolism in 8 healthy normal glucose tolerant subjects (5M/3F, age=35±5, BMI = 24±1) who received a 12-hour (6PM to 6AM) glucagon infusion (6ng/kg/min) with 14C-glycerol infusion; subcutaneous abdominal adipose tissue biopsy was obtained at 6AM. 8 weeks later subjects returned for a repeat study with 12-hour infusion of normal saline. Plasma glucagon increased from 57±3 to 219±21 pg/ml within one hour and remained elevated throughout the study. Glycerol turnover rate (5.1±0.6 vs. 3.8±0.6 µmol/kg•min, p&amp;lt;0.05) increased by 34%, and the adipose tissue insulin resistance index (fasting plasma FFA x Insulin) more than doubled (5.8±0.8 vs. 2.8±0.7 mM•mU/L, p&amp;lt;0.05) after 12-hour glucagon infusion compared to saline. mRNA expression of genes involved in lipolysis in adipose tissue were upregulated after glucagon infusion (ATGL, 1.14±0.07 vs. 0.77±0.03; HSL, 1.17±0.03 vs. 0.9±0.13; MGL, 1.2±0.04 vs. 0.82±0.2, all p&amp;lt;0.05). Plasma concentration of proinflammatory markers (IL-1β, 0.65±0.05 vs. 0.49±0.05 pg/mL; TNF-α, 2.03±0.23 vs. 1.75±0.17 pg/mL, both p&amp;lt;0.05) and lipidomes involved in inflammatory pathways (lysophosphatidylcholine, 126±11 vs. 51±7 nmol/ml, p&amp;lt;0.005; phosphatidylcholine, 385±24 vs. 306±25 nmol/ml, p&amp;lt;0.01; ceramide, 1.7±0.2 vs. 1.2±0.2 nmol/ml, p&amp;lt;0.01) also increased after 12-hour glucagon infusion. H&amp;E and CD68 immunofluorescence staining in adipose tissue displayed the crown-like structures (CLS) and increased infiltration of macrophages following glucagon infusion. Conclusion: Short-term (12-hour) physiologic hyperglucagonemia stimulates adipose tissue lipolysis, induces adipocyte insulin resistance, and promotes adipose tissue and systemic inflammation. Disclosure X. Chen: None. M. Fourcaudot: None. L. Norton: None. R. A. Defronzo: Other Relationship; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Novo Nordisk, Research Support; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc., Speaker’s Bureau; Self; AstraZeneca, Novo Nordisk. D. Tripathy: None. Funding Foundation for Advancing Veterans’ Health Research

Red blood cell triglycerides—a unique pool that incorporates plasma-free fatty acids and relates to metabolic health

Most research into red blood cell (RBC) lipids focuses on membrane phospholipids and their relationships to metabolic conditions and diet. Triglycerides (TGs) exist in most cells; the TG-fatty acids serve as readily available fuel for oxidative phosphorylation. Because RBCs lack mitochondria, they would not be expected to store fatty acids in TG. We followed up on a previous in vitro study that found FFA can be incorporated into RBC-TG by testing whether intravenously infused [U-13C]palmitate could be detected in RBC-TG. We also quantified RBC-TG fatty acid concentrations and profiles as they relate to plasma FFA and lipid concentrations. We found that 1) RBC-TG concentrations measured by glycerol and LC/MS were correlated (r = 0.77; P < 0.001) and averaged <50 nmol/ml RBC; 2) RBC-TG concentrations were stable over 18 h; 3) [U-13C]palmitate was detectable in RBC-TG from half the participants; 4) RBC-TGs were enriched in saturated fatty acids and depleted in unsaturated fatty acid compared with plasma FFA and previously reported RBC membrane phospholipids; 5) RBC-TG fatty acid profiles differed significantly between obese and nonobese adults; 6) weight loss altered the RBC-TG fatty acid profile in the obese group; and 7) the RBC-TG fatty acid composition correlated with plasma lipid concentrations. This is the first report showing that plasma FFA contributes to RBC-TG in vivo, in humans, and that the RBC-TG fatty acid profile is related to metabolic health. The storage of saturated fatty acids in RBC-TG stands in stark contrast to the highly unsaturated profile reported in RBC membrane phospholipids.

Effects of exercise before breakfast on plasma free fatty acid profile and 24-h fat oxidation

BackgroundFree fatty acids (FFAs) are an important source of energy, and also serve as signaling molecules to regulate gene expression. Exercise performed in a post-absorptive state, in contrast to that performed in a postprandial state, increases 24-h fat oxidation under an energy-balanced condition. The primary aim of the present study was to clarify whether the effects of exercise on the concentration and composition of plasma FFAs, which may underlie distinct effects of exercise on 24-h fat oxidation, depend on the nutritional state of the individual when performing the exercise. MethodsTen healthy young men underwent 3 trials of indirect calorimetry in a metabolic chamber. The subjects performed exercise at 60% of VO2max for 60 min in either a post-absorptive or postprandial state, or remained sedentary without an exercise session (control). All trials were designed to be energy balanced over 24 h. Blood samples were collected immediately before and after exercise. ResultsFat oxidation over 24 h was increased only when exercise was performed in a post-absorptive state (control, 531 ± 60; post-absorptive, 779 ± 70; postprandial, 569 ± 37 kcal/24 h). The increase in the 24-h fat oxidation was related to the magnitude of the transient carbohydrate deficit after exercise. The plasma FFA concentration after exercise was higher in the post-absorptive trial (0.38 ± 0.04) than in the control (0.13 ± 0.01) and postprandial (0.15 ± 0.02 mM) trials. The ratio of unsaturated to saturated (U/S) fatty acids after exercise was higher in the post-absorptive trial (1.76 ± 0.06) than in the control (1.56 ± 0.07) and postprandial (1.53 ± 0.08) trials. On the other hand, the plasma FFA concentration after exercise in a postprandial state did not differ significantly from that in the control trial. ConclusionExercise performed in a post-absorptive state effectively increased the plasma FFA concentration and U/S ratio to a greater degree than exercise performed in a postprandial state, underlying the increase in the 24-h fat oxidation. The increase in the plasma FFA concentration was related to the transient carbohydrate deficit after exercise.

1914-P: Prolonged (12-Hour) Glucagon Infusion Stimulates Adipocyte Lipolysis and Inflammation In Vivo in Humans

Hyperglucagonemia is a characteristic feature of T2DM and contributes to the metabolic disturbances. Although some rodent studies have suggested that glucagon stimulates lipolysis in adipocytes, the long-term effect of hyperglucagonemia on adipose tissue metabolism and glucose homeostasis in vivo in humans is unclear. The aim of the present study was to examine the effect of 12-hour glucagon infusion on hepatic glucose production (HGP) and adipocyte metabolism in healthy individuals. 8 NGT subjects (5M/3F, age=35±5, BMI = 24±1) received a 12-hour (6PM to 6AM) glucagon infusion (6ng/kg/min) with 3-3H-glucose infusion followed by subcutaneous adipose tissue biopsy at 6AM. On a different day the subjects returned for a repeat study with infusion (6PM to 6AM) of normal saline. Plasma glucagon increased from 57±3 to 219±21 pg/ml. Plasma glucose increased transiently after the start of glucagon and declined to baseline levels at 6AM. Plasma insulin levels increased significantly following glucagon compared to saline (20±7 vs. 8±3 mU/L, p&amp;lt;0.05) and remained elevated at 6AM. Basal HGP (3.2±0.1 vs. 2.9±0.1 mg/kg/min, p&amp;lt;0.01) and fasting plasma FFA concentrations (0.70±0.1 vs. 0.39±0.1 mM, p&amp;lt;0.01) were increased after 12-hour glucagon infusion despite increased plasma insulin levels, indicating severe hepatic and adipocyte insulin resistance. Lipolysis-related gene expression in adipose tissue biopsy were upregulated following 12-hour glucagon infusion (ATGL, 1.14±0.07 vs. 0.77±0.03; HSL, 1.17±0.03 vs. 0.9±0.13; MGL, 1.2±0.04 vs. 0.82±0.2, all p&amp;lt;0.05). Plasma concentration of inflammatory markers were also increased after 12-hour glucagon infusion (IL-1β, 0.65±0.05 vs. 0.49±0.05 pg/mL; TNF-α, 2.03±0.23 vs. 1.75±0.17 pg/mL, both p&amp;lt;0.05). Overall, these results demonstrate that prolonged physiologic hyperglucagonemia causes marked hepatic and adipocyte insulin resistances, stimulates lipolysis and increases plasma FFA, and induces adipocyte and systemic inflammation. Disclosure D. Tripathy: None. M. Fourcaudot: None. L. Norton: None. R.A. DeFronzo: None. X. Chen: None.

1707-P: Differential Effect of Prolonged Glucagon Infusion on Plasma Lipidome in Humans

Hyperglucagonemia plays an important role in pathogenesis of T2DM. The effect of glucagon on the plasma lipidome has not been studied in humans. We examined the effect of prolonged glucagon infusion on plasma lipid metabolites in healthy subjects. 8 NGT subjects (5M/3F, age=35±5, BMI=24±1, A1c=5.3±0.3%) received 12-hour (6PM to 6AM) glucagon infusion (6ng/kg/min). On a different day the subjects returned for a repeat study with infusion (6PM to 6AM) of normal saline. Top-ranking plasma lipidomes were measured by shotgun lipidomics including Phosphatidylethanolamine (PE), Lysophosphatidylethanolamine (LPE), Phosphatidylcholine (PC), Lysophosphatidylcholine (LPC), Ceramide (CER), Sphingomyelin (SM), Acylcarnitine (AC), Phosphatidylglycerol (PG), Phosphatidylinositol (PI), Phosphatidylserine (PS), Triacylglycerol (TAG), Fatty Acyl Chains in TAG (FA). Plasma glucagon increased from 57±3 to 219±21 pg/ml. Plasma insulin increased significantly following glucagon compared to saline (20±7 vs. 8±3 mU/L, p&amp;lt;0.05) and remained elevated. Plasma LPE, PC, LPC, CER, SM, FFA, AC increased, plasma PE, PS declined, and PG, PI, FA did not change following 12-hour glucagon infusion. The greatest increase occurred with Lysophosphatidylcholine (LPC, 18:2) which rose ∼2.5 fold (126±11 vs. 51±7 nmol/ml, p&amp;lt;0.005) following glucagon infusion. LPCs and LPEs are generated after activation of phospholipase A2, along with the release of fatty acids, and have been reported to induce inflammation and the effector of fatty acid induced insulin resistance. On the other hand, reduced PE is observed in animal models of obesity, supporting its role as a substrate of phospholipase A2 activation. Increased ceramide levels also have been shown to incite inflammation. In conclusion, prolonged glucagon infusion modulates novel lipid metabolites involved in inflammation and represents a fundamental mechanism by which glucagon activates inflammation pathways, contributing to insulin resistance. Disclosure X. Chen: None. X. Han: None. J. Trejo: None. E. Case: None. R.A. DeFronzo: None. D. Tripathy: None. Funding Foundation for Advancement of Veteran’s Health and Research

SAT-591 Lack of Adipose-Specific Hexose-6-Phosphate Dehydrogenase Improves Fat Metabolic Phenotype and Increases Insulin Sensitivity in Mice

Lack of adipose-specific hexose-6-phosphate dehydrogenase improves fat metabolic phenotype and increases insulin sensitivity in mice.ABSTRACTIncreased glucocorticoids (GCs) production in adipose tissue promotes the development of visceral obesity and the MS. The action of GCs in adipose tissue is tightly regulated by 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6PDH). However, the phenotypic consequences of reduction of fat-specific GC action caused by inactivation of H6PDH specifically in adipose tissue have not been explored. To better understand the physiological effects of adipose H6PDH, we generated a tissue-specific animal model of adipocyte-specific H6PDH deletion under the control of the murine adipocyte-specific adiponectin promoter (H6PDHAcKO mice). H6PDHAcKO mice exhibited complete absence of H6PDH expression and decreased GC production with reduction of 11β-HSD1 in adipose tissue. These mice had decreased abdominal fat mass with decreased adipose lipogenic gene expression associated with reduction of their transcription factor C/EBPs mRNA levels. Moreover, H6PDHAcKO mice also decreased adipose lipolysis and reduced plasma FFA levels. In addition, H6PDHAcKO mice decreased fasting glucose levels and increase tolerance to glucose and insulin. These data suggest that H6PDHAcKO mice may provide a good model for study the potential contribution of fat-specific H6PDH inhibition to improve the metabolic phenotype in vivo.