Lower Non-esterified Fatty Acid Levels Research Articles

Leptin Concentration, Obesity, and Plasma Non-esterified Fatty Acid Levels in Children.

The association between obesity and higher non-esterified fatty acid (NEFA) levels has been established in adults. In contrast, lower NEFA levels have been described in children with obesity although the reason behind this association remains unclear. Leptin, which regulates body weight and plays a role in lipolysis, could be involved in this relationship. We evaluated the influence of leptin in the association between obesity and NEFA concentrations in children, analyzing two cohorts including 684 6- to 8-year-olds and 836 12- to 16-year-old children, respectively. After adjusting by leptin, insulin levels remained significantly higher in adolescents with obesity as compared with levels in those without obesity. However, insulin levels showed no differences between prepubertal children with and without obesity. The significantly lower NEFA concentrations observed in 6- to 8-year-old girls with obesity disappeared when comparing NEFA levels between girls with and without obesity after adjusting by leptin. We report an influence of leptin levels on the association between obesity and insulin and NEFA in young children that is not observed in adolescents. Our findings add information about factors that may contribute to explain the lower NEFA levels described in prepubertal children with obesity.

Association of Serum Nonesterified Fatty Acids with Cardiovascular Event in Patients with Chronic Kidney Disease.

BackgroundChronic kidney disease (CKD) has been suggested to be associated with a high risk of cardiovascular diseases (CVD). The study aimed to evaluate the prognostic significance of nonesterified fatty acid (NEFA), also well known as free fatty acid, on predicting cardiovascular events in patients with CKD.MethodsA total of 957 hospitalized patients with CKD in a stable clinical condition were enrolled at baseline. Then, the serum NEFA levels were measured. These included patients were prospectively followed up for a median of 10.2 years (range=0.4–11.5 years). We assessed whether serum NEFA levels at baseline can predict cardiovascular event during the follow-up.ResultsA total of 278 (29.1%) patients experienced cardiovascular events during follow-up. The Kaplan–Meier curve demonstrated that patients with higher serum NEFA levels (≥19.8 mg/dl) had a higher rate of cardiovascular events than patients with lower NEFA levels (<19.8 mg/dl). Multivariate Cox regression analysis suggested that elevated serum NEFA levels (HR=1.62; 95% CI 1.40–2.16, P<0.001) were independently associated with increased risk of cardiovascular events after correction for clinical confounding factors.ConclusionElevated serum NEFA levels were associated with higher risk of cardiovascular events and may be a new parameter predicting cardiovascular events in patients with CKD, which may strengthen its potential effect in clinical practice.

The Effect of Energy Metabolism up to the Peak of Lactation on the Main Fractions of Fatty Acids in the Milk of Selected Dairy Cow Breeds.

Simple SummaryThe metabolism of cows up to the peak of lactation significantly influences production parameters and the quality of the production cycle. The aim of this study was to analyze the energy metabolism of selected breed groups of cows and its variability in different stages of early lactation. The analysis was performed using data on the following parameters: body condition score (BCS), fatty acid (FA) fractions, basic milk constituents, and serum parameters (BHBA, glucose, and leptin). Holstein-Friesian (HF) cows and HF crossbreds with Black-and-White Lowland (BW) bulls generally had higher daily yields and reached the peak of lactation earlier. These cows, however, suffered the greatest loss in BCS, which led to higher levels of non-esterified fatty acid (NEFA) in the blood than in the other groups. Cows entering the peak of lactation with less intensive production were shown to have lower levels of leptin and higher glucose concentrations in the blood. The smaller loss of BCS in these cows did not lead to rapid lipolysis, and therefore the release of large amounts of non-esterified fatty acids and β-hydroxybutyrate into the blood was limited. The milk of breed groups that had somewhat lower yield and reached the peak of lactation about 11 days later (Simmental and Black-and-White Lowland) had a more beneficial fatty acid profile and casein content. The results indicate that one of the important factors influencing the intensity of lipolysis is leptin, which regulates appetite. The Simmental and Black-and-White Lowland groups had lower concentrations of leptin. This suggests the need for further research on how appetite and the prolongation of feed intake is linked to longer availability of nutrients, including glucose.During early lactation in dairy cows, metabolic processes are adopted to provide energy and nutrients for the synthesis of milk compounds. High milk production potential includes sudden changes in energy metabolism (negative energy balance (NEB)) that can induce uncontrolled lipomobilization and high blood free fatty acid (FFA) levels. Destabilization of cows’ energy may interfere with endocrine homeostasis, such as the secretion of leptin, a co-regulator of the appetite center. Therefore, it is important to analyze the physiological aspects of the maintenance of energy homeostasis in various dairy breeds. Usually it is crucial for the health of cows, influences the production cycle and lifetime yield, and determines the profitability of production and milk quality. The aim of this study was to analyze the energy metabolism of selected breed groups of cows and its variability in different stages of early lactation. The analysis was performed using data on the following parameters: body condition score (BCS), fatty acid (FA) fractions, basic milk constituents, and serum parameters (BHBA, glucose, and leptin). These results were analyzed in relation to parameters of energy metabolism during the stage up to the peak of lactation. An earlier peak of lactation was shown to be conducive to an increase in the content of non-esterified fatty acids (NEFAs) and of casein and κ-casein. During the study period, parameters characterizing the maintenance of energy homeostasis were usually lower in the Simmental and Black-and-White Lowland cows. Compared to the group with the highest production, their yield was from 2.8 to 4.7 kg lower, but the milk had a more beneficial fatty acid profile and nutrient content, determining suitability for cheese making. At the same time, they had lower levels of NEFAs and β-hydroxybutyrate in the blood, which indicates less spontaneous lipolysis of fat reserves. Concentrations of the appetite regulator leptin in the blood were correlated negatively (p ≤ 0.05) with the glucose concentration (–0.259) and positively with NEFA (0.416). The level of NEFAs was at the same time positively correlated with the content of saturated fatty acids in the milk (0.282–0.652; p ≤ 0.05). These results contribute to our knowledge of the effect of production intensity on the maintenance of homeostasis up to the peak of lactation in dairy breeds with differing production potential. In practice, this may increase the possibilities of improving milk quality and the profitability of production.

Use of monensin in lactating crossbred dairy cows (Holstein × Gyr) raised on tropical pastures with concentrate supplementation

Monensin is a feed additive produced by a strain of Streptomyces cinnamonensis that has been used to improve milk production and feed efficiency by a mechanism linked to rumen fermentation of lactating dairy cows. Evaluation on performance, digestibility and blood parameters of crossbred dairy cows supplemented with monensin is still scarce. Thus, the objective of this study was to determine the effects of monensin supplementation on intake, digestibility of nutrients, lactational performance and blood parameters in crossbred dairy cows grazing tropical pasture subjected to rotational stocking and supplemented with concentrate. Sixteen crossbred Holstein-Gyr cows (initial milk yield=20kg/d; body weight=505.5kg±47.64) were blocked according to stage of lactation and milk production, and assigned to two treatments in a crossover design. The treatments were (1) control diet (pasture and concentrate) or (2) control diet plus 300mg per cow per day of sodium monensin. There were 24 paddocks used of 1750m2 each (total of 42,000m2) with Tanzania Guinea grass (Panicum maximum), irrigated and managed under intermittent stocking systems. Concentrate supplementation was offered after milking in individual stalls (12.5m2). The first 18days were considered an adaptation period, followed by 10days of the sampling period of milk, feces, blood, pasture and concentrate. The intakes of dry matter (DM), crude protein (CP), neutral detergent fiber (NDFom) and total digestible nutrients (TDN), and concentrate as well as the digestibility of CP were similar between treatments. Monensin supplementation increased the coefficient of total tract apparent digestibility (CTTAD) of DM (P=0.03) and NDFom of crossbred dairy cows. Blood parameters such as glucose and urea were similar among the two groups. Monensin did not affect milk yield and 3.5% fat-corrected milk, but fat and total solids contents were reduced in cows fed ionophore. There was a tendency for the beta-hydroxybutyrate (BHBA) level to be lower, while the nonesterified fatty acid (NEFA) concentration was reduced in dairy cows supplemented with feed monensin additive. These results demonstrate that monensin may increase the nutrient digestibility and fiber digestion. Furthermore, ionophore use could be beneficial to reduce fat mobilization as the ionophore tended to reduce BHBA with lower NEFA levels. Therefore, monensin has the potential to be used as an additive for crossbred dairy cows grazing on Tanzania-grass pasture (Panicum maximum) under tropical conditions.

Paradoxical role of tumor necrosis factor on metabolic dysfunction and adipose tissue expansion in mice.

Tumor necrosis factor (TNF) is a well-known cytokine that triggers insulin resistance during obesity development. On the other hand, it is also known that TNF induces a fat mass loss during acute diseases. However, whether TNF has a protective and physiological role to control adipose tissue expansion during obesity still needs to be verified. The aim of this study was to evaluate whether the ablation of TNF receptor 1 (TNFR1) alters fat mass and insulin resistance induced by a highly refined carbohydrate-containing (HC) diet. Male C57 BL/6 wild-type (WT) mice and TNFR1 knockout (TNFR1-/-) mice were fed with chow or with the HC diet for 16wk. TNFR1-/- mice gained more body weight than the WT groups independent of the diet composition. TNFR1-/- mice fed with the chow diet showed higher adiposity, accompanied by higher serum leptin levels. However, these mice showed lower non-esterified fatty acid levels. Furthermore, TNFR1-/- mice had suppressed TNF, interleukin (IL)-6, and IL-10 levels in adipose tissue compared with WT mice. TNFR1-/- mice fed with the HC diet were protected from increased adiposity and glucose intolerance induced by the HC diet and exhibited lower serum resistin levels. TNF signaling appears to have a paradoxical role on metabolism. Ablation of TNFR1 leads to a reduction of inflammatory cytokines in adipose tissue that is accompanied by higher adiposity in mice fed with chow diet. However, when these mice are given the HC diet, the loss of TNFR1 improves insulin sensitivity and protects mice against additional fat mass.

Variation in the promoter of the human hormone sensitive lipase gene shows gender specific effects on insulin and lipid levels: results from the Ely study

We previously identified a hormone sensitive lipase ( HSL) promoter variant, −60C>G, which in vitro exhibits 40% reduced promoter activity. In this study we examined the effect of the −60C>G on glycemic and lipid measures in the population based Ely study of metabolic function and insulin resistance in 218 middle-aged men and 276 middle-aged women. Adipose tissue HSL is the rate-limiting step in triglyceride lipolysis, generating free fatty acids for energy utilization. HSL is also expressed in pancreatic β-cells where its activity therefore may affect insulin secretion. In the women, carriers of the HSL −60G allele had significantly lower fasting insulin levels ( P=0.0005) and a lower total area under the curve for insulin during the oral glucose tolerance test ( P=0.005). There was no demonstrable association in men with these measures of insulin sensitivity but carriers of the −60G allele had significantly lower fasting non-esterified fatty acid (NEFA) levels ( P=0.025) and higher low density lipoprotein cholesterol levels ( P=0.02) than men who were non-carriers. This study provides additional evidence for a role for HSL in the development of insulin resistance, from which carriers of the −60G allele, associated here with markers of insulin sensitivity in women, and with lower NEFA levels in men, might be protected.