Increased Non-esterified Fatty Acids Levels Research Articles

Nutzung der Haptoglobinkonzentration im Blutserum als Indikator im Tiergesundheitsmonitoring bei Milchkühen

To investigate the association between haptoglobin concentration in the blood and the occurrence of ketosis, selected clinical parameters as well as lameness in dairy cows. The data was collected on 39 dairy farms in Bavaria over a period of 8 months. In 712 Simmental and Brown Swiss cows, clinical examinations as well as milk and blood samplings were performed between 10 and 30 days after calving. In these blood samples, the concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA) and haptoglobin (Hp) were determined. Analysis of the milk included milk constituents (fat, protein, urea, lactose and acetone), BHBA, NEFA and the somatic cell count (SCC). Significant correlations were found between increased Hp-concentration on the one hand and increased NEFA levels in blood and milk (p < 0.001), increased somatic cell count (p < 0.001), lameness (p < 0.001), as well as reduced lactose content (p < 0.001) and protein content in the milk (p = 0.001) on the other hand. Animals sampled during the warmer summer months showed significantly higher serum Hp-concentrations (p < 0,001). Heifers exhibited significantly higher Hp-values than multiparous individuals (p < 0.001). By dividing the examined cows into 4 clusters, a Hp-threshold value could be determined at 0.18 mg/ml. Combined with a SCC threshold of 40 500 cells/ml milk, the majority of animals with subclinical and clinical abnormalities could be identified. Measurement of the Hp-concentration in blood is a pertinent approach in animal health monitoring during the postpartum period. In combination with evaluations of milk amount and contents, deviations from the physiological status may be recognized and affected individuals treated early on. Haptoglobin may be used to assess the health status of the individual animal as well as an indicator of herd health in the context of animal health monitoring.

Effect of interferon gamma on neutral lipid levels, lipid droplet formation, and antiviral responses in pancreatic islets and INS‐1 β cells

Interferon (IFN)‐regulated pathways play a critical role in the development of type 1 diabetes (T1D) following exposure to environmental insults including viral infection. IFNs have been shown to modulate lipid metabolism in both immune and non‐hematopoietic cells in response to pathogens. Little is known, however, about the impact of IFN signaling on lipid metabolism in pancreatic β cells and whether IFN‐induced changes in β cell lipid metabolism are associated with antiviral responses and β cell dysfunction. To characterize islet lipid changes potentially mediated by IFNs during initiation of β cell autoimmunity in vivo, juvenile LEW.1WR1 rats (an IFN‐dependent, inducible‐T1D model) were treated with the viral analog polyinosinic:polycytidylic (PIC) every other day for 6 days then islets were isolated 16h and 48h post last treatment for gene expression and non‐targeted lipidomics, respectively. Islets from PIC‐treated animals displayed a robust induction of IFN gamma (IFNγ) target genes, e.g. IFNγ‐inducible protein and ubiquitin D, and significantly increased islet triacylglyceride (TAG) and non‐esterified fatty acids (NEFA). Similar increases in TAG and NEFA were observed when isolated human islets were treated ex vivo for 24h with mixtures of IFNγ and IL1β, or IFNγ and TNFα, suggesting that IFNγ drives TAG synthesis or accumulation. To investigate the direct effect of IFNγ, INS‐1 β cells were treated with IFNγ for 24h. Consistent with the in vivo and ex vivo islet results, IFNγ‐treated cells had significantly higher TAG levels. IFNγ also increased mRNA levels of genes involved in lipid droplet (LD) formation and clustering (e.g. perilipins and fat‐induced storage membrane protein 1) and led to the appearance of clusters of large cytoplasmic LDs. Treatment of INS‐1 cells with IFNγ also increased NEFA levels, most notably arachidonic acid. Although the source for increased TAG and NEFA is uncertain, IFNγ induced fatty acid synthase (FASN) gene expression suggesting increased de novo FA synthesis. IFNγ‐mediated changes in lipid metabolism were associated with impaired insulin secretion. IFNγ, however, did not increase the expression of endoplasmic reticulum (ER) stress markers, but sensitized INS‐1 cells to TNFα‐ or IL1β‐induced ER stress and apoptosis. Importantly, pretreatment of INS‐1 β cells with IFNγ for 12 h markedly increased PIC‐induced expression of antiviral genes (e.g. Ifnb, Mx1) and this synergistic response was abrogated by the FASN inhibitor C75. Inhibition of FASN with C75 also led to a redistribution of IFNγ‐mediated LD clusters into more discrete LDs. Overall, these data suggest that IFNγ promotes LD formation and clustering in β cells, and these LD clusters serve as scaffolds to enhance expression of antiviral response genes. Unfortunately, these lipid metabolism changes are also associated with impaired secretory function and increased susceptibility to cytokine‐induced ER stress and β cell death.Support or Funding InformationJDRF grant 3‐SRE‐2014‐43‐Q‐R to LKO.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Body condition loss and increased serum levels of nonesterified fatty acids enhance progesterone levels at estrus and reduce estrous activity and insemination rates in postpartum dairy cows

Data from 96 Holstein Friesian cows on a commercial dairy farm were used to investigate whether body condition and serum levels of nonesterified fatty acids (NEFAs) postpartum (pp) affect progesterone (P4) levels, estrous activity, and fertility in dairy cows. The examination period started 14 days before the expected calving date and ended either when a cow was inseminated or at a maximum of 90 days pp. Body condition score (BCS; 1-5 scale) and backfat thickness (BFT) were determined every 2 weeks. Blood for analysis of NEFA and P4 concentrations was sampled weekly during the first 35 days pp and then every 48 hours until an ovulation was observed. Transrectal ultrasonography of the ovaries started at 21 days pp and was performed after blood sampling. If cows were not inseminated because of silent ovulation, sampling and ultrasonography continued on Days 7, 14, and 18 after ovulation and again every 48 hours until the next ovulation. Estrous activity was continuously measured with the Heatime estrus detection system. Pregnancy controls were performed ultrasonographically 28 and 42 days after AI. Cows with increased NEFA levels at 28 days pp had an increased risk of maintaining minimum P4 levels above 0.4 ng/mL at first recognized estrus (P = 0.03). Higher NEFA levels at Day 7 were associated with lower probability for a cow to have elevated P4 levels (≥2 ng/mL) by Day 35 pp, indicating delayed commencement of luteal activity (C-LA). Estrous activity was not influenced (P > 0.10) by minimum P4 concentrations at estrus, but more animals with C-LA until Day 35 pp showed estrous activity compared to cows without C-LA throughout this period (P = 0.006). Estrous activity was lower in cows with a low BCS 14 days pp (P = 0.02) and with a low BFT 42 days pp (P = 0.03). Moreover, the probability to exhibit estrus was reduced with higher NEFA levels at 21 days pp (P = 0.01). Eighty-five cows were inseminated and 37 (44%) got pregnant after insemination. Higher NEFA levels, especially 14, 28, and 42 days pp, were associated with lower probability to inseminate a cow. Regarding the cows that were inseminated, no influence of BCS, BFT, or NEFA levels on pregnancy per artificial insemination was found. In conclusion, cows with higher loss of body condition and elevated NEFA concentrations had higher P4 concentrations during estrus, a reduced estrous activity and insemination rate, but no depression in pregnancy per artificial insemination.

Perilipin 5 improves hepatic lipotoxicity by inhibiting lipolysis.

Abnormal metabolism of nonesterified fatty acids (NEFAs) and their derivatives has been reported to be the main cause of intracellular lipotoxic injury. Normally, NEFAs are stored in lipid droplets (LDs) in the form of triglyceride (TG), which could reduce the lipotoxicity of cytosolic NEFAs. Previous studies have implicated that Perilipin 5 (Plin5), an LD-binding protein, regulates the storage and hydrolysis of TG in LD. However, its roles and underlying mechanisms in the liver remain unknown. Here we found that Plin5 expression was increased in steatotic livers. Using Plin5 knockout mice, we found that Plin5 deficiency resulted in reduced hepatic lipid content and smaller-sized LDs, which was due to the elevated lipolysis rate and fatty acid utilization. Plin5-deficient hepatocytes showed increased mitochondria proliferation, which could be explained by the increased expression and activity of PPARα stimulated by the increased NEFA levels. Meanwhile, Plin5-deficient livers also exhibited enhanced mitochondrial oxidative capacity. We also found that Plin5 deficiency induces lipotoxic injury in hepatocytes, attributed to lipid peroxidation. Mechanistically, we found that Plin5 blocks adipose triglyceride lipase (ATGL)-mediated lipolysis by competitively binding to comparative gene identification-58 (CGI-58) and disrupting the interaction between CGI-58 and ATGL. Plin5 is an important protective factor against hepatic lipotoxicity induced by NEFAs generated from lipolysis. This provides an important new insight into the regulation of hepatic lipid storage and relation between lipid storage and lipotoxicity.

Mitochondrial dysfunction induced by pancreatic and crotalic ( Crotalus durissus terrificus) phospholipases A 2 on rabbit proximal tubules suspensions

In the present study we show that phospholipases A2 isolated from porcine pancreas (PP-PLA2) and Crotalus durissus terrificus snake venom (SV-PLA2) induced dose-dependent increases of LDH release from rabbit proximal tubules in suspension. Both porcine and crotalic PLA(2)s induced increases in non-esterified fatty acid (NEFA) levels (microg of NEFA/mg of tubule protein). It was observed that the NEFA levels in the pellets were higher than in the supernatant for both PLA2, and were dose-dependent for the crotalic PLA2 group. Furthermore, snake venom PLA2 induced a decrease in mitochondrial membrane potential (DeltaPsi(m)) assessed by both JC-1 uptake and safranin O uptake. Porcine PLA2 produced no effects on JC-1 uptake with the highest concentrations and an unexpected increase in the group treated with the lowest concentration. In contrast, the safranin O method revealed decreases of energization with both phospholipases, so it had higher sensitivity to the presence of the increased NEFA levels. Addition of delipidated bovine serum albumin (dBSA) completely reversed the effects induced by phospholipases on DeltaPsi(m) measured with safranin O. Incubation with pancreatic and crotalic phospholipases A2 produced no changes on cell ATP levels. We conclude that the treatment of proximal tubule suspensions with porcine or crotalic phospholipases disturbed membrane integrity as well as mitochondrial function. Specific early NEFA-mediated mitochondrial effects of the phospholipases used in the present study are indicated by the benefit provided by dBSA.

Non-esterified fatty acids and blood pressure elevation: a mechanism for hypertension in subjects with obesity/insulin resistance?

The prevalence of hypertension in individuals with obesity or type II diabetes is substantially elevated. Increased levels of non-esterified fatty acids (NEFAs) in abdominally obese subjects were reported to contribute in the development of various disturbances related to the metabolic syndrome, such as hepatic and peripheral insulin resistance (IR), dyslipidaemia, beta-cell apoptosis, endothelial dysfunction and others. However, the involvement of NEFAs in the development of hypertension has been much less studied in comparison to other mechanisms linking IR and central obesity with blood pressure (BP) elevation. This article reviews the existing evidence on the relation between NEFA and hypertension in an attempt to shed a light on it. In vivo data from both animal and human studies support that acute plasma NEFA elevation leads to increase in BP levels, whereas epidemiological evidence suggests a link between increased NEFA levels and hypertension. Further, accumulating data indicate the existence of several pathways through which NEFAs could promote BP elevation, that is alpha(1)-adrenergic stimulation, endothelial dysfunction, increase in oxidant stress, stimulation of vascular cell's growth and others. The above data support a possible important role of NEFA in hypertension development in patients with obesity and the metabolic syndrome and raise hypotheses for future research.

Enhanced Non‐esterified Fatty Acids and Corticosterone in Blood Plasma of Chickens Treated with Insulin are Significantly Depleted by Reverse T3: Minor Changes in Hypoglycaemia

Previously, it has been observed that dexamethasone or adrenaline-induced hyperlipaemia in blood of chicken was significantly reduced after administration of reverse triiodothyronine (rT3). The present experiment was performed on chicken to determine the altered circulating non-esterified fatty acids (NEFA) induced by physiologically enhanced endogenous corticosterone and catecholamines may also be influenced by rT3. Rise of both hormones were induced by insulin administration. Changes in circulating glucose, corticosterone and catecholamines were additionally measured. Following insulin injection blood glucose fell on the average by 32.7% below control at 2 h of the experiment. Additional treatment with rT3 (rT3 + insulin group) gradually attenuated this decrease and at 4 and 6 h of the experiment it was 17.1% and 12.9% below control, respectively, suggesting on slight inhibition by rT3 of insulin-stimulated glucose utilization. Exposure to insulin significantly increased NEFA levels to about 670% above control group. Additional treatment with rT3 reduced this increase to 309% of control, suggesting inhibition of lipolysis by rT3. Similar alterations were observed in plasma corticosterone levels. Insulin treatment peaked the corticosterone levels maximally by 507.6% above control. Additional treatment with rT3 abolished this rise in the averages to 194.2% above control, possibly by interaction of rT3 with hypothalamo-adrenal axis. Insulin injection increased plasma catecholamines on the average by 21.5% and 53.4% for adrenaline and noradrenaline respectively. Supplementary treatment with rT3 intensified this rise by 55.6% and 71.6% respectively. The obtained results suggest on inhibitory effect of rT3 on hypoglycaemia, hyperlipaemia and plasma corticosterone concentrations in chickens treated with insulin. Contrary to this, rT3 enhanced the rise of plasma catecholamines due to insulin treatment. The obtained data favour the assumption that hypometabolic properties of rT3 depends mainly upon reduced supply of NEFA as a result of restricted lipolysis and to a lesser extent upon the supply of glucose.

Improvement in insulin sensitivity without concomitant changes in body composition and cardiovascular risk markers following fixed administration of a very low growth hormone (GH) dose in adults with severe GH deficiency

Untreated GH-deficient adults are predisposed to insulin resistance and excess cardiovascular mortality. We showed previously that short-term treatment with a very low GH dose (LGH) enhanced insulin sensitivity in young healthy adults. The present study was therefore designed to explore the hypothesis that LGH, in contrast to the standard GH dose titrated to normalize serum IGF-I levels (SGH), may have differing effects on insulin sensitivity, body composition, and cardiovascular risk markers [lipid profile, C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and adiponectin] in adults with severe GH deficiency. In this 12-month open, prospective study, 25 GH-deficient adults were randomized to receive either a fixed LGH (0.10 mg/day, n = 13) or SGH (mean dose 0.48 mg/day, n = 12), and eight age- and body mass index (BMI)-matched GH-deficient adults acted as untreated controls. Fasting blood samples were collected at baseline and at months 1, 3, 6, 9 and 12. Assessments of insulin sensitivity, using the hyperinsulinaemic euglycaemic clamp technique, and body composition, using dual-energy X-ray absorptiometry, were performed at baseline and at month 12. The LGH decreased fasting glucose levels (P < 0.01) and enhanced insulin sensitivity (P < 0.02), but body composition, nonesterified fatty acid (NEFA) levels and cardiovascular risk markers were unchanged. The SGH did not modify insulin sensitivity, decreased truncal fat mass (P < 0.05), CRP (P < 0.05) and IL-6 (P < 0.05) levels, and increased NEFA levels (P < 0.05). No changes were observed with the untreated controls. Our data indicate that, in contrast to the SGH, fixed administration of the LGH enhances insulin sensitivity with no apparent effects on body composition, lipolysis and other surrogate cardiovascular risk markers in adults with severe GH deficiency. Thus, the LGH may potentially be a beneficial replacement dose in reducing type 2 diabetes risk in adults with severe GH deficiency.

Correlations of plasma lipid metabolites with hibernation and lactation in wild black bears Ursus americanus

During the denning period, black bears (Ursus americanus) are capable of enduring several months without food. At the same time, female bears that are pregnant or lactating have an added metabolic stress. Based on laboratory studies, much of the energy required to support metabolism and lactation during denning in black bears comes from lipid reserves. These lipid reserves are mobilized and the most metabolically active lipid fraction in the blood are nonesterified fatty acids (NEFA). Therefore, we hypothesized that plasma NEFAs would be higher in denning relative to active bears and in lactating relative to non-lactating female bears. We further hypothesized that in bears with elevated plasma NEFA levels, other lipid-related parameters (e.g., ketone bodies, albumin, cholesterol, lipase) would also be elevated in the plasma. Denning bears had significantly increased NEFA levels in all classes (saturates, monoenes, and polyenes). A doubling of plasma NEFA levels and a 33% increase in albumin, the plasma fatty acid binding protein, in denning bears, resulted in NEFA/albumin ratios that were higher in denning bears (4:1) compared to those of active bears (3:1). Bears became relatively ketonemic with a 17-fold increase in D-beta-hydroxybutyrate levels during the denning period. Plasma cholesterol approximately doubled and lipase was ten-fold lower in denning relative to active bears. These findings indicate a strong correlation between plasma lipid metabolites and the denning period in a wild population of black bears.

Cross-sectional but not longitudinal associations between non-esterified fatty acid levels and glucose intolerance and other features of the metabolic syndrome.

Cross-sectional studies have demonstrated an association between high non-esterified fatty acid (NEFA) concentrations and glucose intolerance. However, the direction of causality in these studies is uncertain. The aim of this study was to examine whether NEFA levels predicted the development of glucose intolerance in a prospective population-based cohort study. Four hundred and eighty-one women and 345 men participated in a prospective cohort study in which NEFA concentrations and glucose tolerance were measured at baseline and then repeated at follow-up 4.5 years later. The data do not show longitudinal relationships between baseline NEFA levels and either glucose intolerance or other features of the metabolic syndrome at follow-up. In contrast, strong cross-sectional associations were observed between NEFA measures and glucose intolerance (and other features of the metabolic syndrome) in both baseline and follow-up studies. At follow-up, fasting NEFA levels and two measures of NEFA suppression were markedly different in subjects with features of the metabolic syndrome, compared to subjects with normal glucose tolerance (NGT) (NGT vs. metabolic syndrome for each NEFA value, P< 0.001). These results support the hypothesis that plasma NEFA levels change as a consequence of the metabolic syndrome and do not support the notion that increased NEFA levels cause either the metabolic syndrome or diabetes.

Brain indoleamines in alloxan- and streptozotocin-induced diabetic rats.

Previous work by other authors has shown that alloxan-induced diabetes increases whereas streptozotocin-induced diabetes does not alter nonesterified fatty acid (NEFA) plasma levels. The present study replicates these results and demonstrates that fasted, streptozotocin-induced diabetic animals also have increased NEFA levels. In addition, brain levels of 5-hydroxytryptamine (5-HT) and of its immediate precursor and metabolite were measured. Alloxan- and fasted, streptozotocin-induced diabetic rats showed significant increases in brain indoleamine concentrations, whereas fed, streptozotocin-induced diabetic rats had unchanged levels of the same compounds. Levels of brain indoleamines exhibited a strong positive correlation with wet-dog shakes (an index of 5-HT activity) elicited by hippocampal stimulation. Blockade of wet-dog shakes by 5-HT receptor antagonists strengthens the proposal that this behavior is a good index of central 5-HT activity. The increased content of brain indoleamines in alloxan- and fasted, streptozotocin-induced diabetic rats may be related to the increased NEFA plasma levels seen in the same animals. This hypothesis is supported by the positive correlation demonstrated between NEFA and 5-HT levels. In conclusion, it is suggested that alloxan-induced diabetes may represent a useful model for studying the various behavioral changes known to occur in diabetics.

Norepinephrine Induced Hypocalcemia in Sheep

Increased plasma levels of non-esterified fatty acids (NEFA) may lead to several physiological changes e.g. increased insulin secretion with a concomitant reduction of blood glucose, decreased glucose utilization in heart and skeletal musculature and increased blood acetone levels. High NEFA levels also cause fat infiltration in various organs especially the liver. Recently Akgun & Rudman (1969) showed that ACTH induced NEFA mobilization in rabbits was followed by hypocalcemia. Serum calcium decreased about 30 %, while the calcium content in adipose tissue increased up to 1000 %. This finding could also be verified in vitro. When adipose tissue was incubated in serum containing lipolytic hormones, lipolysis was stimulated and there was a shift of calcium from serum to tissue. A negative correlation between serum calcium and NEFA in hypocalcemic cows was reported earlier (Luthman & Jonson 1969). The purpose of the present investigation was to study the effect of increased NEFA levels on serum calcium in sheep. The animals used were ewes in late pregnancy. Lipolysis was stimulated by norepinephrine (Norexadrin, Astra). The animals were given a continuous intravenous infusion during 8 hrs. at a rate of 1 μg/kg/min. The methods of analysis were the same as described before (Luthman & Jonson).