Nonesterified Fatty Acid Oxidation Research Articles

The lipidosis of the liver of dairy cows: Part 1 - Role of insulin and the Growth Hormone-IGF-1 axis

Lipidosis of the liver of dairy cows is a metabolic disease known since many years and is caused by an uptake of nonesterified fatty acids (NEFA) into the liver cells, limited metabolism of NEFA (oxidation and production of β-hydroxybutyrate), and resynthesis in relation to a low efflux as triglyceride (TG). The pathogenesis of lipidosis includes a) an augmented release of NEFA by mobilisation of adipose tissue, b) uptake of NEFA into the liver cells, c) metabolism of NEFA and d) re-synthesis of triglyceride and e) an efflux of TG as very low density lipoprotein (VLDL). The steps a-e are postpartum modified by hormones as an increase of growth hormone, a pronounced insulin resistance in combination with a decreased insulin and of IGF-1 concentrations. These hormonal changes are related to an uncoupling of the growth hormone-IGF-1-axis with enhanced lipolysis and consequences mentioned above. These alterations are associated with inflammation, oxidative and endoplasmatic stress. The metabolic and hormonal alterations are the result of the selection of dairy cows primarily for milk production without adequate food intake with the consequence of lipidosis, ketosis and further health risks (production diseases).

Regulation of Postabsorptive and Postprandial Glucose Metabolism by Insulin-Dependent and Insulin-Independent Mechanisms: An Integrative Approach.

Glucose levels in blood must be constantly maintained within a tight physiological range to sustain anabolism. Insulin regulates glucose homeostasis via its effects on glucose production from the liver and kidneys and glucose disposal in peripheral tissues (mainly skeletal muscle). Blood levels of glucose are regulated simultaneously by insulin-mediated rates of glucose production from the liver (and kidneys) and removal from muscle; adipose tissue is a key partner in this scenario, providing nonesterified fatty acids (NEFA) as an alternative fuel for skeletal muscle and liver when blood glucose levels are depleted. During sleep at night, the gradual development of insulin resistance, due to growth hormone and cortisol surges, ensures that blood glucose levels will be maintained within normal levels by: (a) switching from glucose to NEFA oxidation in muscle; (b) modulating glucose production from the liver/kidneys. After meals, several mechanisms (sequence/composition of meals, gastric emptying/intestinal glucose absorption, gastrointestinal hormones, hyperglycemia mass action effects, insulin/glucagon secretion/action, de novo lipogenesis and glucose disposal) operate in concert for optimal regulation of postprandial glucose fluctuations. The contribution of the liver in postprandial glucose homeostasis is critical. The liver is preferentially used to dispose over 50% of the ingested glucose and restrict the acute increases of glucose and insulin in the bloodstream after meals, thus protecting the circulation and tissues from the adverse effects of marked hyperglycemia and hyperinsulinemia.

1866-P: Adipocyte Hypertrophy Is Associated with Increased Dietary Fatty Acid Storage in Adipose Tissue and Reduced Postprandial Hepatic Fatty Acid Uptake and Esterification in Humans

Introduction: Excessive exposure of lean tissues to nonesterified fatty acids (NEFA) leads to insulin resistance (IR). Adipocyte hypertrophy is associated with IR and increase in adipose tissue intracellular triglyceride lipolysis and in NEFA levels, that may contribute to hepatic steatosis and IR. The effect of adipocyte hypertrophy on postprandial hepatic NEFA flux and metabolism and dietary fatty acids (DFA) storage in adipose tissues has not been studied, however. Methods: In 28 healthy adult subjects, fat cell size (FCS) was determined via histomorphologic analysis of abdominal subcutaneous fat tissue. Adipose tissue DFA storage was measured using oral administration of 18FTHA with positron emission tomography (PET). Postprandial hepatic NEFA uptake, oxidation, and esterification were determined using intravenous 11C-palmitate with dynamic PET acquisition. Results: As expected, FCS was correlated positively with fasting glycemia (ρ=0.44, P-value=0.029), homeostasis model assessment-estimated insulin resistance (HOMA-IR) (ρ=0.43, P-value=0.049), and hepatic fat content from CT radiodensity (ρ=0.32, P-value=0.10). FCS was correlated positively with DFA storage in intra-abdominal adipose tissues (ρ=0.48, P-value=0.022) and negatively with postprandial hepatic NEFA uptake (ρ=-0.42, P-value=0.027) and esterification (ρ=-0.58, P-value=0.0080). Conclusion: Adipocyte hypertrophy is associated with increased DFA storage in intra-abdominal adipose tissues and reduced postprandial hepatic NEFA uptake and esterification, despite being associated with greater hepatic fat content, fasting glycemia and HOMA-IR. Adipocyte hypertrophy is thus associated with adipose tissue metabolic adaptation that limits the exposure of the liver to fatty acids in the postprandial period. Disclosure R. Ye: None. S. Phoenix: None. C. Noll: None. E. Montastier: None. F. Frisch: None. L. Bouffard: None. M. Amrani: None. E.E. Turcotte: None. A.C. Carpentier: Advisory Panel; Self; HLS Therapeutics, Inc. Funding Canadian Institutes of Health Research (MOP53094); Centre de recherche du CHUS; Centre d’imagerie moléculaire de Sherbrooke; Faculté de médecine et des sciences de la santé de l’Université de Sherbrooke

Relationship between body condition score loss and mRNA of genes related to fatty acid metabolism and the endocannabinoid system in adipose tissue of periparturient cows

The endocannabinoid system (ECS) controls feed intake and energy balance in nonruminants. Recent studies suggested that dietary management alters the expression of members of the ECS in the liver and endometrium of dairy cows. The aim of this study was to determine the relationship between body condition score (BCS) loss and the mRNA abundance of genes related to fatty acid metabolism and the ECS in the subcutaneous adipose tissue (AT) of dairy cows. The BCS was determined in multiparous (3.2 ± 0.5 lactations) Holstein cows at −21 and 42 days relative to calving (designated as d = 0). Cows were grouped into three categories according to BCS loss between both assessments as follows: (1) lost ≤0.25 unit (n = 8, low BCS loss (LBL)), (2) lost between 0.5 and 0.75 units (n = 8, moderate BCS loss (MBL)) and (3) lost ≥1 unit (n = 8, high BCS loss (HBL)). Concentrations of haptoglobin and non-esterified fatty acids (NEFAs) were determined in plasma. Real-time PCR was used to determine mRNA abundance of key genes related to fatty acid metabolism, inflammation and ECS in AT. Milk yield (kg/day) between week 2 and 6 post-calving was greater in the LBL group (49.4 ± 0.75) compared to MBL (47.9 ± 0.56) and HBL (47.4 ± 0.62) groups (P < 0.05). The overall mean plasma haptoglobin and NEFA concentrations were greater in MBL and HBL groups compared with the LBL group (P < 0.05). The mRNA abundance of TNF-α, Interleukin-6 (IL-6) and IL-1β was greatest at 21 and 42 days post-calving in HBL, intermediate in MBL and lowest in LBL groups, respectively. Cows in the HBL group had the greatest AT gene expression for carnitine palmitoyltransferase 1A, hormone sensitive lipase and adipose triglyceride lipase at 21 and 42 days post-calving (P < 0.05). Overall, mRNA abundance for very long chain acyl-CoA dehydrogenase and peroxisome proliferator-activated receptor gamma, which are related to NEFA oxidation, were greater in MBL and HBL groups compared to the LBL group at 42 days post-calving. However, mRNA abundance of fatty acid amide hydrolase was lower at 21 and 42 days post-calving in HBL cows than in LBL cows (P < 0.05). In summary, results showed a positive association between increased degree of BCS loss, inflammation and activation of the ECS network in AT of dairy cows. Findings suggest that the ECS might play an important role in fatty acid metabolism, development of inflammation and cow’s adaptation to onset of lactation.

Traffic-Related Air Pollution Exposure and Altered Fatty Acid Oxidation among Adolescents and Young Adults – the Interplay with Obesity

S01: Mapping the Air Pollution Metabolome: Applications, Limitations, and the Path Forward, Room 217, Floor 2, August 26, 2019, 10:30 AM - 12:00 PM Background/Aim: Air pollution exposure has been shown to increase the risk of obesity and metabolic dysfunction in animal models and human studies. However, the metabolic pathways altered by air pollution exposure are unclear, especially in adolescents and young adults who are at a critical period for developing cardio-metabolic diseases. The aim of this study was to examine the associations of exposures to traffic-related and regional air pollutants with indices of fatty acid and amino acid metabolism. Methods: A total of 173 young adults (18-23 years) from eight Children’s Health Study (CHS) Southern California communities were examined from 2014-2018. Exposures to traffic-related [freeway and non-freeway nitrogen oxides (NOx)] and regional air pollutants (nitrogen dioxide, ozone and particulate matter) were estimated based on participants’ residential addresses. Serum concentrations of 64 targeted metabolites including amino acids, acylcarnitines, ketones and total non-esterified fatty acid (NEFA) were measured in fasting serum samples. Principal component analysis (PCA) of metabolites was performed to identify metabolite clusters that represent key metabolic pathways. Mixed effects models were used to analyze the associations of air pollution exposure with metabolomic principal component (PC) scores and individual metabolite concentrations adjusting for potential confounders. Results: Higher long-term (lagged one-year average) exposure to non-freeway NOx was associated with higher concentrations of NEFA oxidation byproducts and higher NEFA-related PC score (all p’s<0.01). The effect sizes were larger among obese and Non-Hispanic White individuals (interaction p’s≤0.002). Among females, higher exposure to freeway NOx was associated with a higher NEFA-related PC score (p=0.006). Additionally, among all participants, higher exposure to freeway NOx was associated with a lower PC score for lower concentrations of short- and median-chain acylcarnitines (p=0.042). Conclusions: Results of this study indicate that traffic-related air pollution exposure is associated with altered fatty acid metabolism, which contributes to the metabolic perturbation in obese youth.

Near-roadway air pollution exposure and altered fatty acid oxidation among adolescents and young adults – The interplay with obesity

BackgroundAir pollution exposure has been shown to increase the risk of obesity and metabolic dysfunction in animal models and human studies. However, the metabolic pathways altered by air pollution exposure are unclear, especially in adolescents and young adults who are at a critical period in the development of cardio-metabolic diseases. ObjectivesThe aim of this study was to examine the associations between air pollution exposure and indices of fatty acid and amino acid metabolism. MethodsA total of 173 young adults (18–23 years) from eight Children's Health Study (CHS) Southern California communities were examined from 2014 to 2018. Near-roadway air pollution (NRAP) exposure (freeway and non-freeway) and regional air pollution exposure (nitrogen dioxide, ozone and particulate matter) during one year before the study visit were estimated based on participants' residential addresses. Serum concentrations of 64 targeted metabolites including amino acids, acylcarnitines, non-esterified fatty acid (NEFA) and glycerol were measured in fasting serum samples. Principal component analysis of metabolites was performed to identify metabolite clusters that represent key metabolic pathways. Mixed effects models were used to analyze the associations of air pollution exposure with metabolomic principal component (PC) scores and individual metabolite concentrations adjusting for potential confounders. ResultsHigher lagged one-year averaged non-freeway NRAP exposure was associated with higher concentrations of NEFA oxidation byproducts and higher NEFA-related PC score (all p's ≤ 0.038). The effect sizes were larger among obese individuals (interaction p = 0.047). Among females, higher freeway NRAP exposure was also associated with a higher NEFA-related PC score (p = 0.042). Among all participants, higher freeway NRAP exposure was associated with a lower PC score for lower concentrations of short- and median-chain acylcarnitines (p = 0.044). ConclusionsResults of this study indicate that NRAP exposure is associated with altered fatty acid metabolism, which could contribute to the metabolic perturbation in obese youth.

Tibetan sheep are better able to cope with low energy intake than Small-tailed Han sheep due to lower maintenance energy requirements and higher nutrient digestibilities

Tibetan sheep are indigenous to the Qinghai-Tibetan Plateau (QTP) and are well-adapted to and even thrive under the harsh alpine conditions. Small-tailed Han sheep were introduced to the plateau because of their high prolificacy and are maintained mainly in feedlots. Because of their different backgrounds, we hypothesised that Tibetan and Small-tailed Han sheep would differ in their utilization of energy intake and predicted that Tibetan sheep would cope better with low energy intake than Small-tailed Han sheep. To test this prediction, we determined nutrient digestibilities, energy requirements for maintenance and blood metabolite and hormone concentrations involved in energy metabolism in these breeds. Sheep of each breed (n = 24 of each, all wethers and 1.5 years of age) were distributed randomly into one of four groups and offered ad libitum diets of different digestible energy (DE) densities: 8.21, 9.33, 10.45 and 11.57 MJ DE/kg Dry matter (DM). Following 42 d of measuring feed intake, a 1-week digestion and metabolism experiment was done. DM intakes did not differ between breeds nor among treatments but, by design, DE intake increased linearly in both breeds as dietary energy level increased (P < 0.001). The average daily gain (ADG) was significantly greater in the Tibetan than Small-tailed Han sheep (P = 0.003) and increased linearly in both breeds (P < 0.001). In addition, from the regression analysis of ADG on DE intake, daily DE maintenance requirements were lower for Tibetan than for Small-tailed Han sheep (0.41 vs 0.50 MJ/BW0.75, P < 0.05). The DE and metabolizable energy (ME) digestibilities were higher in the Tibetan than Small-tailed Han sheep (P < 0.001) and increased linearly as the energy level increased in the diet (P < 0.001). At the lowest energy treatment, Tibetan sheep when compared with Small-tailed Han sheep, had: 1) higher serum glucose and glucagon, but lower insulin concentrations (P < 0.05), which indicated a higher capacity for gluconeogenesis and ability to regulate glucose metabolism; and 2) higher non-esterified fatty acids (NEFA) and lower very low density lipoprotein (VLDL) and triglyceride (TG) concentrations (P < 0.05), which indicated a higher capacity for NEFA oxidation but lower ability for triglyceride (TG) synthesis. We concluded that our prediction was supported as these differences between breeds conferred an advantage for Tibetan over Small-tailed Han sheep to cope better with low energy diets.

Prepartal standing behavior as a parameter for early detection of postpartal subclinical ketosis associated with inflammation and liver function biomarkers in peripartal dairy cows

A degree of negative energy balance is commonly experienced by cows during early lactation. This physiological state, if pronounced or prolonged, leads to partial oxidation of nonesterified fatty acids as an energy source and, consequently, increasing blood β-hydroxybutyrate (BHB) concentrations and potentially development of ketosis in postpartal dairy cows. Twenty-four multiparous Holstein cows received a common prepartal and postpartal diet. Cows were fitted with an accelerometer mounted laterally on the distal left hind leg using vet wrap from -30 to 15 d relative to parturition. A retrospective analysis was performed using the postpartal BHB data at 8 time points from 0 to 15 d in milk measured with the Precision Xtra (Abbott Diabetes Care, Alameda, CA). Cows with an average blood BHB <1.4 mmol/L were designated nonketotic (NONKET; n = 12), and those with ≥1.4 mmol/L were designated ketotic (KET; n = 12). A total of 8 samples per cow were used for this analysis. Subsequent analyses of behavioral patterns and blood biomarkers were performed using this group effect. On average, blood BHB reached subclinical levels (1.4 ± 0.3 mmol/L; mean ± standard error of the mean) at 3 d postpartum for all cows in this study. Behavioral patterns were obtained from accelerometer data, and correlation analysis was performed between these behaviors such as standing and lying time from -30 to 3 d relative to parturition and blood BHB concentration at 3 d postpartum. The strongest correlation was obtained between standing time at 3 d before calving and blood BHB at 3 d postpartum. Dry matter intake was greater (ca. 3 kg/d) in NONKET cows than in KET cows. An interaction of group × time for milk yield resulted in an overall increase of 5.7 kg/d in NONKET cows in comparison with KET. The blood concentrations of biomarkers for liver function (γ-glutamyltransferase and glutamic-oxaloacetic transaminase), inflammation (IL-6), and metabolism (nonesterified fatty acids) were increased at various time points in KET cows in comparison with NONKET during the transition period. Overall, lower bilirubin in NONKET cows than in KET further confirmed an impaired liver function in the latter group of cows. Our findings revealed the potential for establishing correlations between prepartal behavioral patterns derived from accelerometer data and postpartal subclinical ketosis, and further confirming the latter by physiological alterations in biomarkers related to inflammation and liver function. Our data also indicate that cows with a predisposition to postpartal subclinical or clinical ketosis will remain standing for fewer hours during the days leading to parturition, which decreased DMI, and this condition was further reflected in lower milk yield.

Lipoliza i ketogeneza kod krava u ranoj laktaciji

Peripartal metabolic stress is characterized by increased lipid mobilization, when non-esterified fatty acids (NEFA) are increased, as well as by increased ketogenesis, when the concentration of beta-hydroxybutyrate (BHB) is increased. NEFA are metabolized in all tissues but the main organ is the liver. Possible processes are: a) complete oxidation of NEFA, b) partial oxidation and synthesis of ketone bodies (BHB), c) development of triglycerides from NEFA that can be transported or stay in the liver when fatty liver is apparent. Moreover, increased lipolysis and ketogenesis can cause oxidative stress because concentrations of MDA and/or TBARS are positively correlated with NEFA and BHB concentrations. The increase in NEFA during the peripartal period affects the cellular immunologic response by changing intracellular signals, gene expressing control, activation of transcriptional factors, apoptosis induction and by modifying mediators of lipid production. Increased proportion of cows with high NEFA and BHB concentrations in the herd can cause reduced milk yield at the end of a standard 305-day lactation. NEFA concentrations can be related to postpartal ovarian activity, especially given that blood NEFA concentrations represent NEFA concentrations in the ovarian follicular fluid. Cows on farms with lower scores of animal welfare and nutrition have higher concentrations of cortisol, NEFA, BHB, bilirubin, glucose and urea. NEFA and BHB concentrations in early lactation can be used for estimating metabolic adaptation in the first 8 weeks after calving. For the estimation of metabolic adaptation, increased lipolysis has a greater significance than decreased anabolic parameters.

Effect of Chinese herbal medicine treatment on plasma lipid profile and hepatic lipid metabolism in Hetian broiler

The purpose of this study was to investigate whether adding a Chinese herbal hedicine (CHM, including astragalus membranaceus, codonopsis pilosula, poria cocos, bighead atractylodes rhizome, fructus crataegi, folium epimedii, radix saposhnikoviae, and pericarpium citri reticulatae) diet has effects on lipid metabolism in the liver of the broiler. Six-hundred-thirty Hetian broilers were divided into 3 groups including base diet (control), 0.3%, or 1% CHM diets, for 130 days. The results showed that CHM treatment significantly increased the slaughter performance. CHM treatment decreased plasma triglyceride (TG) and nonesterified fatty acid (NEFA) concentrations; up-regulated the expression of peroxisome proliferator activated receptor (PPAR), the transcription factor sterol regulatory element binding protein-1c (SREBP-1c) and its downstream proteins involved in NEFA oxidation including carnitine palmitoyltransferase-1, liver fatty acid binding protein, and PPARα; and it significantly decreased fatty acid synthetase, stearoyl-CoA desaturase, acyl-CoA synthetase long-chain family member 1 and acetyl-CoA carboxylase expression to inhibit NEFA synthesis. In addition, the CHM treatment increased plasma insulin (INS) levels and up-regulated insulin receptors (INSR) glycerol-3-phosphate acyltransferase and mitochondrial and 1-acylglycerol-3-phosphate O-acyltransferase 6 mRNA expression to enhance TG synthesis. The protein levels of phosphatidylinositol 3-hydroxy kinase (PI3K), serine/threonine protein kinase (Akt), S6 kinase (S6K), phospho-serine/threonine protein kinase (p-Akt), and phospho-S6 kinase (p-S6K) also were increased. PI3K, p-Akt, and p-S6K were significantly up-regulated in the liver. These data suggest that the CHM may be a beneficial compound to decrease plasma NEFA and TG levels by activating the INS/INSR-PI3K-Akt-SREBP1c pathway resulting in fat content reduction in the carcass.

The Physiological Regulation of Skeletal Muscle Fatty Acid Supply and Oxidation During Moderate-Intensity Exercise.

Energy substrates that are important to the working muscle at moderate intensities are the non-esterified fatty acids (NEFAs) taken up from the circulation and NEFAs originating from lipolysis of the intramuscular triacylglycerol (IMTAG). Moreover, NEFA from lipolysis via lipoprotein lipase (LPL) in the muscle of the very-low-density lipoproteins and in the (semi) post-prandial state chylomicrons may also contribute. In this review, the NEFA fluxes and oxidation by skeletal muscle during prolonged moderate-intensity exercise are described in terms of the integration of physiological systems. Steps involved in the regulation of the active muscle NEFA uptake include (1) increased energy demand; (2) delivery of NEFA to the muscle; (3) transport of NEFA into the muscle by NEFA transporters; and (4) activation of the NEFAs and either oxidation or re-esterification into IMTAG. The increased metabolic demand of the exercising muscle is the main driving force for all physiological regulatory processes. It elicits functional hyperemia, increasing the recruitment of capillaries and muscle blood flow resulting in increased NEFA delivery and accessibility to NEFA transporters and LPL. It also releases epinephrine that augments adipose tissue NEFA release and thereby NEFA delivery to the active muscle. Moreover, NEFA transporters translocate to the plasma membrane, further increasing the NEFA uptake. The majority of the NEFAs taken up by the active muscle is oxidized and a minor portion is re-esterified to IMTAG. Net IMTAG lipolysis occurs; however, the IMTAG contribution to total fat oxidation is rather limited compared to plasma-derived NEFA oxidation, suggesting a complex role and regulation of IMTAG utilization.

Electrochemical detection of non-esterified fatty acid by layer-by-layer assembled enzyme electrodes

In this study, detection and measurement of non-esterified fatty acids (NEFA) concentration has been achieved by electrochemical method in one operation step. Multilayer films of poly(dimethyldiallyammonium chloride) (PDA) wrapped multi-wall carbon nanotubes (MWCNTs) and two enzymes acyl-CoA synthetase (ACS) and acyl-CoA oxidase (ACOD) were assembled on a carbon screen printed electrode by the layer-by-layer (LbL) immobilization. The fine polymer–enzyme layers produced by the LbL method, allowed mass transport from the reactant cascading down the layers to accomplish the two-step enzyme reactions. The polymer–CNTs and enzyme modified electrode exhibited good electrocatalytical property retaining enzyme activity. Linear increase of anodic current from H2O2 produced from NEFA oxidation was observed with the increasing concentrations of oleic acid. These results indicate a promising technique for a simple, rapid one-step determination of NEFA for diabetes management.

Impaired mitochondrial fatty acid oxidation and insulin resistance in aging: novel protective role of glutathione

Aging is associated with impaired fasted oxidation of nonesterified fatty acids (NEFA) suggesting a mitochondrial defect. Aging is also associated with deficiency of glutathione (GSH), an important mitochondrial antioxidant, and with insulin resistance. This study tested whether GSH deficiency in aging contributes to impaired mitochondrial NEFA oxidation and insulin resistance, and whether GSH restoration reverses these defects. Three studies were conducted: (i) in 82-week-old C57BL/6 mice, the effect of naturally occurring GSH deficiency and its restoration on mitochondrial (13) C1 -palmitate oxidation and glucose metabolism was compared with 22-week-old C57BL/6 mice; (ii) in 20-week C57BL/6 mice, the effect of GSH depletion on mitochondrial oxidation of (13) C1 -palmitate and glucose metabolism was studied; (iii) the effect of GSH deficiency and its restoration on fasted NEFA oxidation and insulin resistance was studied in GSH-deficient elderly humans, and compared with GSH-replete young humans. Chronic GSH deficiency in old mice and elderly humans was associated with decreased fasted mitochondrial NEFA oxidation and insulin resistance, and these defects were reversed with GSH restoration. Acute depletion of GSH in young mice resulted in lower mitochondrial NEFA oxidation, but did not alter glucose metabolism. These data suggest that GSH is a novel regulator of mitochondrial NEFA oxidation and insulin resistance in aging. Chronic GSH deficiency promotes impaired NEFA oxidation and insulin resistance, and GSH restoration reverses these defects. Supplementing diets of elderly humans with cysteine and glycine to correct GSH deficiency could provide significant metabolic benefits.

TNF-related apoptosis-inducing ligand significantly attenuates metabolic abnormalities in high-fat-fed mice reducing adiposity and systemic inflammation

TRAIL [TNF (tumour necrosis factor)-related apoptosis-inducing ligand] has recently been shown to ameliorate the natural history of DM (diabetes mellitus). It has not been determined yet whether systemic TRAIL delivery would prevent the metabolic abnormalities due to an HFD [HF (high-fat) diet]. For this purpose, 27 male C57bl6 mice aged 8 weeks were randomly fed on a standard diet, HFD or HFD+TRAIL for 12 weeks. TRAIL was delivered weekly by intraperitoneal injection. Body composition was evaluated; indirect calorimetry studies, GTT (glucose tolerance test) and ITT (insulin tolerance test) were performed. Pro-inflammatory cytokines, together with adipose tissue gene expression and apoptosis, were measured. TRAIL treatment reduced significantly the increased adiposity associated with an HFD. Moreover, it reduced significantly hyperglycaemia and hyperinsulinaemia during a GTT and it improved significantly the peripheral response to insulin. TRAIL reversed the changes in substrate utilization induced by the HFD and ameliorated skeletal muscle non-esterified fatty acids oxidation rate. This was associated with a significant reduction of pro-inflammatory cytokines together with a modulation of adipose tissue gene expression and apoptosis. These findings shed light on the possible anti-adipogenic and anti-inflammatory effects of TRAIL and open new therapeutic possibilities against obesity, systemic inflammation and T2DM (Type 2 DM).

Insulin Resistance and Progression of Heart Failure in the Older Adult

Heart failure is a disease of advancing age. Despite the advent of effective therapies, the overall outcome among the elderly has not been altered significantly. Aging is also associated with whole body and myocardial insulin resistance. Insulin resistance is accompanied by increased sympathetic nervous system activation and increased nonesterified fatty acid (NEFA) uptake in excess of NEFA oxidation, leading to NEFA accumulation within cardiac myocytes and mitochondria. Myocardial mitochondria demonstrate increased reactive oxygen species and calcium sequestration and decreased protein expression leading to impaired energetic reserves. Although these alterations in myocardial mitochondrial function lead to an accelerated course of heart failure, these changes can be modified and protect against exacerbation of heart failure. In particular, glucagon-like peptide-1, a naturally occurring incretin, has been shown to improve left ventricular ejection fraction and functional status in patients. Further investigation must be pursued for this promising novel therapeutic target for heart failure.

Leptin Induces Nitric Oxide-Mediated Inhibition of Lipolysis and Glyceroneogenesis in Rat White Adipose Tissue

Leptin is secreted by white adipose tissue (WAT) and induces lipolysis and nonesterified fatty acid (NEFA) oxidation. During lipolysis, NEFA efflux is the result of triglyceride breakdown, NEFA oxidation, and re-esterification via glyceroneogenesis. Leptin's effects on glyceroneogenesis remain unexplored. We investigated the effect of a long-term treatment with leptin at a physiological concentration (10μg/L) on lipolysis and glyceroneogenesis in WAT explants and analyzed the underlying mechanisms. Exposure of rat WAT explants to leptin for 2 h resulted in increased NEFA and glycerol efflux. However, a longer treatment with leptin (18 h) did not affect NEFA release and reduced glycerol output. RT-qPCR showed that leptin significantly downregulated the hormone-sensitive lipase (HSL), cytosolic phosphoenolpyruvate carboxykinase (Pck1), andPPARγgenes. In agreement with its effect on mRNA, leptin also decreased the levels of PEPCK-C and HSL proteins. Glyceroneogenesis, monitored by [1-14C] pyruvate incorporation into lipids, was reduced. Because leptin increases nitric oxide (NO) production in adipocytes, we explored the role of NO in the leptin signaling pathway. Pretreatment of explants with the NO synthase inhibitor N?-nitro-L-arginine methyl ester eliminated the effect of leptin on lipolysis, glyceroneogenesis, and expression of theHSL,Pck1, andPPARγgenes. The NO donorS-nitroso-N-acetyl-DL penicillamine mimicked leptin effects, thus demonstrating the role of NO in these pathways. The inverse time-dependent action of leptin on WAT is consistent with a process that limits NEFA re-esterification and energy storage while reducing glycerol release, thus preventing hypertriglyceridemia.

JNK Deficiency Enhances Fatty Acid Utilization and Diverts Glucose From Oxidation to Glycogen Storage in Cultured Myotubes

Although germ-line deletion of c-Jun NH(2)-terminal kinase (JNK) improves overall insulin sensitivity in mice, those studies could not reveal the underlying molecular mechanism and the tissue site(s) in which reduced JNK activity elicits the observed phenotype. Given its importance in nonesterified fatty acids (NEFA) and glucose utilization, we hypothesized that the insulin-sensitive phenotype associated with Jnk deletion originates from loss of JNK function in skeletal muscle. Short hairpin RNA (shRNA)-mediated gene silencing was used to identify the functions of JNK subtypes in regulating energy metabolism and metabolic responses to elevated concentrations of NEFA in C2C12 myotubes, a cellular model of skeletal muscle. We show for the first time that cellular JNK2- and JNK1/JNK2-deficiency divert glucose from oxidation to glycogenesis due to increased glycogen synthase (GS) activity and induction of Pdk4. We further show that JNK2- and JNK1/JNK2-deficiency profoundly increase cellular NEFA oxidation, and their conversion to phospholipids and triglyceride. The increased NEFA utilization was coupled to increased expressions of selective NEFA handling genes including Cd36, Acsl4, and Chka, and enhanced palmitic acid (PA)-dependent suppression of acetyl-CoA carboxylase (Acc). In JNK-intact cells, PA inhibited insulin signaling and glycogenesis. Although silencing Jnk1 and/or Jnk2 prevented PA-induced inhibition of insulin signaling, it did not completely block decreased insulin-mediated glycogenesis, thus indicating JNK-independent pathways in the suppression of glycogenesis by PA. Muscle-specific inhibition of JNK2 (or total JNK) improves the capacity of NEFA utilization and glycogenesis, and is a potential therapeutic target for improving systemic insulin sensitivity in type 2 diabetes (T2D).

Increased Postprandial Nonesterified Fatty Acid Appearance and Oxidation in Type 2 Diabetes Is Not Fully Established in Offspring of Diabetic Subjects

BackgroundIt has been proposed that abnormal postprandial plasma nonesterified fatty acid (NEFA) metabolism may participate in the development of tissue lipotoxicity and type 2 diabetes (T2D). We previously found that non-diabetic offspring of two parents with T2D display increased plasma NEFA appearance and oxidation rates during intravenous administration of a fat emulsion. However, it is currently unknown whether plasma NEFA appearance and oxidation are abnormal during the postprandial state in these subjects at high-risk of developing T2D.MethodologyPalmitate appearance and oxidation rates and glycerol appearance rate were determined in eleven healthy offspring of two parents with T2D (positive family history, FH+), 13 healthy subjects without first-degree relatives with T2D (FH-) and 12 subjects with T2D at fasting, during normoglycemic hyperinsulinemic clamp and during continuous oral intake of a standard liquid meal to achieve steady postprandial NEFA and triacylglycerols (TG) without and with insulin infusion to maintain similar glycemia in all three groups.Principal FindingsPlasma palmitate appearance and oxidation were higher at fasting and during the clamp conditions in the T2D group (all P<0.05). In the postprandial state, palmitate appearance, oxidative and non oxidative rates were all elevated in T2D (all P<0.05) but not in FH+. Both T2D and FH+ displayed elevated postprandial TG vs. FH- (P<0.001). Acute correction of hyperglycemia during the postprandial state did not affect these group differences. Increased waist circumference and BMI were positively associated with elevated postprandial plasma palmitate appearance and oxidation.Conclusions/SignificancePostprandial plasma NEFA intolerance observed in subjects with T2D is not fully established in non-diabetic offspring of both parents with T2D, despite the presence of increased postprandial plasma TG in the later. Elevated postprandial plasma NEFA appearance and oxidation in T2D is observed despite acute correction of the exaggerated glycemic excursion in this group.

Pleiotropic effects of negative energy balance in the postpartum dairy cow on splenic gene expression: repercussions for innate and adaptive immunity

Increased energy demands to support lactation, coupled with lowered feed intake capacity results in negative energy balance (NEB) and is typically characterized by extensive mobilization of body energy reserves in the early postpartum dairy cow. The catabolism of stored lipid leads to an increase in the systemic concentrations of nonesterified fatty acids (NEFA) and β-hydroxy butyrate (BHB). Oxidation of NEFA in the liver result in the increased production of reactive oxygen species and the onset of oxidative stress and can lead to disruption of normal metabolism and physiology. The immune system is depressed in the peripartum period and early lactation and dairy cows are therefore more vulnerable to bacterial infections causing mastitis and or endometritis at this time. A bovine Affymetrix oligonucleotide array was used to determine global gene expression in the spleen of dairy cows in the early postpartum period. Spleen tissue was removed post mortem from five severe NEB (SNEB) and five medium NEB (MNEB) cows 15 days postpartum. SNEB increased systemic concentrations of NEFA and BHB, and white blood cell and lymphocyte numbers were decreased in SNEB animals. A total of 545 genes were altered by SNEB. Network analysis using Ingenuity Pathway Analysis revealed that SNEB was associated with NRF2-mediated oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, natural killer cell signaling, p53 signaling, downregulation of IL-15, BCL-2, and IFN-γ; upregulation of BAX and CHOP and increased apoptosis with a potential negative impact on innate and adaptive immunity.

A pilot study of the effects of pioglitazone and rosiglitazone on de novo lipogenesis in type 2 diabetes

Treatment of type 2 diabetes mellitus (T2DM) patients with pioglitazone results in a more favorable lipid profile, and perhaps more favorable cardiac outcomes, than treatment with rosiglitazone. Pioglitazone treatment increases VLDL-triacylglycerol clearance, but the role of de novo lipogenesis (DNL) has not been explored, and no direct comparison has been made between the thiazolidinediones (TZDs). Twelve subjects with T2DM and hypertriacylglyceridemia were randomized to either rosiglitazone or pioglitazone treatment. Stable isotope infusion studies were performed at baseline and after 20 weeks of treatment. Both treatments reduced glucose and HbA(1c) concentrations equally. Pioglitazone treatment resulted in a 40% reduction in hepatic DNL (P < 0.01) and in a 25% reduction in hepatic glucose production (P < 0.05), while rosiglitazone did not significantly change either parameter, although comparisons of changes between treatments were not significantly different. These pilot results indicate that pioglitazone reduces hepatic DNL while rosiglitazone does not. Larger follow-up studies are required to confirm differential effects of these agents definitively. The reduction in DNL may underlie altered assembly or atherogenicity of lipoprotein particles and may reflect PPARalpha or other non-PPARgamma actions on the liver by pioglitazone. These differences might help explain previously reported differences in lipid profiles and cardiovascular disease outcomes for rosiglitazone and pioglitazone.