Fasting Plasma Non-esterified Fatty Acid Research Articles

Role of Adiponectin in the Androgen-Mediated Cardiometabolic Complications in a Rat Model of Polycystic Ovary Syndrome

Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women and is associated with a high prevalence of obesity, adipose insulin resistance (adipose IR), and insulin resistance (IR). Adipose IR is an early metabolic defect in the development of whole-body IR. Specific evaluation of adipose IR and its consequences on the whole-body metabolic state in women with PCOS has not been thoroughly investigated. Adiponectin is a peptide secreted by adipocytes that increases insulin sensitivity. PEG-BHD1028 is a novel potent peptide adiponectin receptor agonist. Despite that PEG-BHD1028 modulates insulin sensitivity in different models of diabetes, the potential of PEG-BHD1028 to attenuate androgen-mediated adipose IR and obesity remains unknown. Hypothesis: We tested the hypothesis that PEG-BHD1028 attenuates adipose IR and obesity in a rat model of PCOS. Methods: To induce PCOS, four-week-old female Sprague Dawley rats were implanted with dihydrotestosterone (DHT) silastic tubes (7.5 mg) or placebo (PBO) for 90 days (n=4-8/group). During the final three weeks of DHT treatment, rats received PEG-BHD1028 (25 μg/kg/day) subcutaneously. Body weight (BW) by gravimetry, fat and lean mass were measured by Echo-MRI. Fasting plasma insulin was measured by ELISA. Fasting plasma glucose and non-esterified fatty acids (NEFA) were measured with a clinical chemistry analyzer. HOMA-IR, an index of systemic IR, and adipose IR (fasting insulin x fasting NEFA) were calculated. Protein levels of insulin signaling markers including IRS1, p-IRS1 (Ser1101), PI3 kinase p110, Akt, p-Akt (SER473), GLUT4, mTOR, p-mTOR (Ser2481) were quantified in the retroperitoneal fat by Western-blot. Results: DHT significantly (p<0.05) increased BW (352.67± 6.93 vs 250.88 ± 5.26 g), fat mass (20.82 ± 1.48 vs 9.44 ± 1.81 g), and lean mass (316.92 ± 4.15 vs 224.45 ± 4.79 g), compared to PBO group. DHT significantly (p<0.05) increased HOMA-IR and adipose IR by 75% and 80%, respectively, compared to PBO group. DHT downregulated retroperitoneal fat p-IRS-1, IRS-1, p-mTOR, mTOR, GLUT4, PI3 kinase and Akt protein expression by 50% to 70% while upregulating p-Akt by 1.8- fold compared to the PBO group. PEG-BHD1028 significantly decreased BW, fat mass and lean mass while attenuating IR by 34.7% reduction in HOMA-IR and significantly (p<0.05) decreased adipose IR by 51.6% in PCOS rats. Interestingly, PEG-BHD1028 significantly (p<0.05) upregulated p-IRS-1, IRS-1, p-mTOR, mTOR and p-AKT levels by 2.6-, 3-, 2.2-, 4-, 2.6- fold, respectively with no impact on the other insulin signaling markers compared to vehicle-treated group. Conclusion: PCOS rats exhibit obesity and lower adiponectin levels that are associated with both adipose and whole-body insulin resistance. Activating adiponectin receptors with PEG-BHD1028 attenuated PCOS-associated obesity and adipose IR. Significance: Targeting adiponectin signaling could be a novel and effective therapeutic approach to mitigate metabolic dysfunction in females with excess androgens. Supported by NIH-NIGMS grant P20GM121334 (L.L.Y.C. and D.G.R.), NIH-NIGMS grant P20GM121334, P20GM104357, NIH-NHLBI grant P01HL51971, NIH-NIMHD-P50MD017338 and University of Mississippi Medical Center Medical Student Research Program (R.C.) and the Robert M. Hearin Foundation (R.C.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Clusters of adipose tissue dysfunction in adults with type 2 diabetes identify those with worse lipidomic profile despite similar glycaemic control.

To investigate clusters of adipose tissue dysfunction, that is, with adipose tissue insulin resistance (ADIPO-IR) and large waist circumference (WC), identify a worse lipidomic profile characterised by a high proportion of lipids rich in saturated fatty acids (SFA). Hierarchical clustering based on WC and ADIPO-IR (calculated as fasting plasma non-esterified fatty acids times fasting plasma insulin, FFA×INS), was performed in 192 adults with overweight/obesity and type 2 diabetes (T2D) treated with metformin (HbA1c=7.8%). Free fatty acid composition and lipidomic profile were measured by mass spectrometry (GC-MS and LC-MSQTOF). Indexes of fatty acid desaturation (stearoyl-coA desaturase-1 activity, SCD116=palmitoleic acid/palmitic acid and SCD118=oleic acid/stearic acid) and of insulin resistance (HOMA-IR) were also calculated. Three clusters were identified: CL1 (ADIPO-IR=4.9±2.4 and WC=96±7cm, mean±SD), CL2 (ADIPO-IR=6.5±2.5 and WC=114±7cm), and CL3 (ADIPO-IR=15.0±4.7 and WC=107±8cm). Insulin concentrations, ADIPO-IR, and HOMA-IR significantly increased from CL1 to CL3 (all p<0.001), while fasting glucose concentrations, HbA1c, dietary lipids and caloric intake were similar. Moreover, CL3 showed significantly higher concentrations of monounsaturated free fatty acids, oleic and palmitoleic acids, triglycerides (TAG) rich in saturated FA and associated with de novo lipogenesis (i.e., TAG 46-50), higher SCD116, SCD118, ceramide (d18:0/18:0), and phosphatidylcholine aa(36:5) compared with CL1/CL2 (all p<0.005). High ADIPO-IR and large WC identify a worse lipid profile in T2D characterised by complex lipids rich in SFA, likely due to de novo synthesis given higher plasma monounsaturated FFA and increased desaturase activity indexes. ID NCT00700856 https://clinicaltrials.gov.

Intrauterine Growth-Restricted Piglets Are Predisposed to Develop Metabolic Disorders in Adulthood When Fed With Parenteral Nutrition in the Neonatal Period

ObjectivesTotal parenteral nutrition (TPN) is lifesaving yet non-normal nutrition regimen during the neonatal period. However, studies have shown that TPN feeding early in life can permanently alter metabolism at later ages. Moreover, intrauterine growth restricted (IUGR) neonates also have a higher risk of developing metabolic diseases (such as obesity and dyslipidemia) in later life. Because a substantial proportion of IUGR neonates receive TPN in early life, we wondered if the metabolic effects of feeding TPN early in life would exacerbate these effects of IUGR? We hypothesized that feeding TPN to IUGR neonates would aggravate the risk of developing obesity and dyslipidemia in adulthood.MethodsSixteen normal weight female piglets (7 d old) were randomized to sow-fed (SF) or early TPN (TPN-CON); 8 (IUGR or runt) piglets were fed TPN as a third group (TPN-IUGR). After 2 weeks of TPN or suckling, all pigs were fed a normal grower diet for 8 mo. At 8 mo, catheters were implanted and in vivo metabolic tests were conducted.ResultsTPN-IUGR pigs demonstrated catch-up growth by 4 mo, and body weights were not different among groups at 8 mo. The metabolic effects of feeding TPN persisted into adulthood, as indicated by higher postprandial plasma triglycerides (TG) and fasting plasma non-esterified fatty acids (NEFA), compared to SF (P < 0.05). IUGR exacerbated TPN-induced risk for diseases by worsening obesity outcomes with greater subcutaneous fat deposition (P < 0.05) and greater ectopic TG deposition in the liver (P < 0.05) and muscle (P < 0.05). Furthermore, IUGR led to dyslipidemia as indicated by higher cholesterol in fasted plasma LDL (P < 0.05), slower postprandial TG clearance (P < 0.05), higher fasting plasma NEFA (P < 0.001) and higher plasma dimethylglycine (P < 0.05), compared to the TPN-CON. IUGR pigs had greater VLDL secretion, as suggested by higher microsomal transfer protein mRNA (P < 0.05). Early TPN programmed reduced lipogenesis, as indicated by lower fatty acid synthase mRNA (P < 0.05), compared to SF.ConclusionsCollectively, these findings conclude that although TPN is a lifesaving measure, feeding TPN to IUGR neonates has long-term metabolic consequences predisposing them to develop metabolic disorders in adulthood.Funding SourcesCanadian Institutes of Health Research.

Associations Between Brain Gray Matter Volumes and Adipose Tissue Metabolism in Healthy Adults.

Gray matter (GM) volume in different brain loci has been shown to vary in obesity and diabetes, and elevated fasting plasma nonesterified fatty acid (NEFA) levels have been suggested as one potential mechanism. The hypothesis presented in this study is that brown adipose tissue (BAT) activity may correlate with GM volume in areas negatively associated with obesity and diabetes. A total of 36 healthy patients (M/F: 12/24, age 39.7 ± 9.4 years, BMI 27.5 ± 5.6 kg/m2 ) were imaged with positron emission tomography using fatty acid analog [18 F]FTHA to measure NEFA uptake and with [15 O]H2 O to measure perfusion during cold exposure, at room temperature during fasting, or during a postprandial state. A 2-hour hyperinsulinemic euglycemic clamp was performed to measure whole-body insulin sensitivity (M value, mean 7.6 ± 3.9 mg/kg/min). T1-weighted magnetic resonance imaging at 1.5 T was performed on all patients. BAT NEFA uptake was associated directly with GM volume in anterior cerebellum and occipital lobe (P ≤ 0.04) when adjusted for age, gender, and intra-abdominal fat volume and with anterior cerebellum, limbic lobe, and temporal lobe GM volumes when adjusted for M value. BAT NEFA metabolism may participate in protection from cognitive degeneration associated with cardiometabolic risk factors, such as central obesity and insulin resistance. Potential causal relationships between BAT activity and GM volumes remain to be examined.

Intermittent energy restriction is comparable to continuous energy restriction for cardiometabolic health in adults with central obesity: A randomized controlled trial; the Met-IER study

Short bouts of severe energy restriction may have additional, beneficial cardiometabolic effects beyond that of weight loss. We aimed to assess the short-term effects of intermittent fasting on insulin sensitivity and related cardiometabolic mechanisms. This parallel arm, randomized controlled trial compared the short-term effects of intermittent and continuous energy restriction (IER and CER) diets on markers of cardiometabolic health in individuals with central obesity, aiming for equivalent weight loss on both diets. Outcomes were assessed in non-smoking men and women (35-75y), following 4-wk IER (48h 600kcal/d followed by 5-day healthy eating advice) or CER diets (-500kcal/d healthy eating advice). The primary outcome was the revised quantitative insulin sensitivity check index (R-QUICKI), an indirect estimate of insulin sensitivity. Secondary outcomes included ambulatory blood pressure (ABP), indicators of sympathetic activity (heart rate variability (HRV) and normetanephrine), and markers of glucose homeostasis/insulin resistance, adiposity, lipids and inflammation. Forty-three participants completed the study. Reductions in body weight were equivalent in both groups: mean loss (%)-2.6; 95% CI-3.3,-1.9 and-2.9;-3.6,-2.1 for CER and IER, respectively, P=0.464). R-QUICKI increased following IER and CER, with no between-diet differences (overall mean increase (%) 6.6; 3.6, 9.6). Fasting plasma glucose concentrations decreased after CER but not after IER (mean difference CER-IER - 4.8% (0.7, 8.9), P<0.05) and fasting plasma non-esterified fatty acid concentrations were lower after IER compared to CER (mean difference CER-IER 0.15mmol/L (0.06, 0.24), P<0.005). There were no differences in lipids, adipokine/inflammatory markers, ABP or HRV between diets. Short-term CER or IER diets are comparable in their effects on most markers of cardiometabolic risk, although adaptive changes in glucose and fatty acid metabolism occur. This study is registered at clinicaltrials.gov as NCT02679989.

Adipose glucocorticoid action influences whole-body metabolism via modulation of hepatic insulin action.

The connection between adipose glucocorticoid action and whole-body metabolism is incompletely understood. Thus, we generated adipose tissue-specific glucocorticoid receptor-knockout (Ad-GcR-/-) mice to explore potential mechanisms. Ad-GcR-/- mice had a lower concentration of fasting plasma nonesterified fatty acids and less hepatic steatosis. This was associated with increased protein kinase B phosphorylation and increased hepatic glycogen synthesis after an oral glucose challenge. High-fat diet (HFD)-fed Ad-GcR-/- mice were protected against the development of hepatic steatosis and diacylglycerol-PKCε-induced impairments in hepatic insulin signaling. Under hyperinsulinemic-euglycemic conditions, hepatic insulin response was ∼10-fold higher in HFD-fed Ad-GcR-/- mice. Insulin-mediated suppression of adipose lipolysis was improved by 40% in Ad-GcR-/- mice. Adipose triglyceride lipase expression was decreased and insulin-mediated perilipin dephosphorylation was increased in Ad-GcR-/- mice. In metabolic cages, food intake decreased by 3 kcal/kg per hour in Ad-GcR-/- mice. Therefore, physiologic adipose glucocorticoid action appears to drive hepatic lipid accumulation during stressors such as fasting. The resultant hepatic insulin resistance prevents hepatic glycogen synthesis, preserving glucose for glucose-dependent organs. Absence of adipose glucocorticoid action attenuates HFD-induced hepatic insulin resistance; potential explanations for reduction in hepatic steatosis include reductions in adipose lipolysis and food intake.-Abulizi, A., Camporez, J.-P., Jurczak, M. J., Høyer, K. F., Zhang, D., Cline, G. W., Samuel, V. T., Shulman, G. I., Vatner, D. F. Adipose glucocorticoid action influences whole-body metabolism via modulation of hepatic insulin action.

Molecular adaptations in human subcutaneous adipose tissue after ten weeks of endurance exercise training in healthy males.

Endurance exercise training induces adaptations in metabolically active organs, but adaptations in human subcutaneous adipose tissue (scAT) remains incompletely understood. On the basis of animal studies, we hypothesized that endurance exercise training would increase the expression of proteins involved in lipolysis and glucose uptake in scAT. To test these hypotheses, 19 young and healthy males were randomized to either endurance exercise training (TR; age 18-24 yr; BMI 19.0-25.4 kg/m2) or a nonexercising control group (CON; age 21-35 yr; BMI 20.5-28.8 kg/m2). Abdominal subcutaneous fat biopsies and blood were obtained at rest before and after intervention. By using Western blotting and PCR, we determined expression of lipid droplet-associated proteins, various proteins involved in substrate metabolism, and mRNA abundance of cell surface G protein-coupled receptors (GPCRs). Adipose tissue insulin sensitivity was determined from fasting plasma insulin and nonesterified fatty acids (adipose tissue insulin resistance index; Adipo-IR). Adipo-IR improved in TR compared with CON ( P = 0.03). This was accompanied by increased insulin receptor (IR) protein expression in scAT with a 1.54-fold (SD 0.79) change from baseline in TR vs. 0.85 (SD 0.30) in CON ( P = 0.007). Additionally, hexokinase II (HKII) and succinate dehydrogenase complex subunit A (SDHA) protein increased in TR compared with CON ( P = 0.006 and P = 0.04, respectively). We did not observe changes in lipid droplet-associated proteins or mRNA abundance of GPCRs. Collectively, 10 weeks of endurance exercise training improved adipose tissue insulin sensitivity, which was accompanied by increased IR, HKII, and SDHA protein expression in scAT. We suggest that these adaptations contribute to an improved metabolic flexibility. NEW & NOTEWORTHY This study is the first to investigate the molecular adaptations in human subcutaneous adipose tissue (scAT) after endurance exercise training compared with a nonexercising control group. We show that endurance exercise training improves insulin sensitivity in human scAT, and this is accompanied by increased expression of insulin receptor, hexokinase II, and succinate dehydrogenase complex subunit A. Collectively, our data suggest that endurance exercise training induces molecular adaptations in human scAT, which may contribute to an improved metabolic flexibility.

Alterations in plasma non-esterified fatty acid (NEFA) kinetics and relationship with insulin resistance in polycystic ovary syndrome.

Are non-esterified fatty acid (NEFA) kinetics altered in women with polycystic ovary syndrome (PCOS)? Women with PCOS, particularly obese subjects, have dysregulated plasma NEFA kinetics in response to changes in plasma insulin and glucose levels, which are associated with insulin resistance (IR) independently of the fasting plasma NEFA levels. Elevated plasma NEFA levels are associated with IR in many disorders, although the homeostasis of NEFA kinetics and its relationship to IR in women with PCOS is unknown. We prospectively compared insulin sensitivity and NEFA kinetics in 29 PCOS and 29 healthy controls women matched for BMI. This study was conducted in a tertiary institution. Plasma NEFA, glucose and insulin levels were assessed during a modified frequently sampled intravenous glucose tolerance test (mFSIVGTT). Minimal models were used to assess insulin sensitivity (Si) and NEFA kinetics (i.e. model-derived initial plasma NEFA level [NEFA0], phi constant [Φ], reflecting glucose-mediated inhibition of lipolysis and measures of maximum rate of lipolysis [SFFA] and NEFA uptake from plasma [KFFA]). The study provides new evidence that women with PCOS have defective NEFA kinetics characterized by: (i) lower basal plasma NEFA levels, measured directly and modeled (NEFA0), and (ii) a greater glucose-mediated inhibition of lipolysis in the remote or interstitial space (reflected by a lower affinity constant [Φ]). There were no differences, however, in the maximal rates of adipose tissue lipolysis (SFFA) and the rate at which NEFA leaves the plasma pool (KFFA). The differences observed in NEFA kinetics were exacerbated, and almost exclusively observed, in the obese PCOS subjects. Our study did not study NEFA subtypes. It was also cross-sectional and based on women affected by PCOS as defined by the 1990 National Institutes of Health (NIH) criteria (i.e. Phenotypes A and B) and identified in the clinical setting. Consequently, extrapolation of the present data to other phenotypes of PCOS should be made with caution. Furthermore, our data is exploratory and therefore requires validation with a larger sample size. Dysfunction in NEFA kinetics may be a marker of metabolic dysfunction in nondiabetic obese women with PCOS and may be more important than simply assessing circulating NEFA levels at a single point in time for understanding the mechanism(s) underlying the IR of PCOS. This work was supported by NIH grants R01-DK073632 and R01-HD29364 to R.A.; a Career Development Award from MD Medical Group, Moscow, RF, to D.L. and Augusta University funds to Y.-H.C. RA serves as consultant to Ansh Labs, Medtronics, Spruce Biosciences and Latitude Capital. U.E., Z.A., D.L., R.M., Y.-H.C., R.C.B. and Y.D.I.C. have no competing interests to declare. Not applicable.

Rosiglitazone Elicits an Adiponectin-Mediated Insulin-Sensitizing Action at the Adipose Tissue-Liver Axis in Otsuka Long-Evans Tokushima Fatty Rats.

Rosiglitazone is an agonist of peroxisome proliferator-activated receptor- (PPAR-) γ that is principally associated with insulin action. The exact mechanisms underlying its insulin-sensitizing action are still not fully elucidated. It is well known that adiponectin mostly secreted in adipose tissue is an insulin sensitizer. Here, we found that treatment of Otsuka Long-Evans Tokushima Fatty (OLETF) rats with rosiglitazone (3 mg/kg, once daily, by oral gavage for 33 weeks) attenuated the increase in fasting plasma insulin concentrations and the index of the homeostasis model assessment of insulin resistance along with the age growth and glucose concentrations during an oral glucose tolerance test. In addition, the increase in plasma alanine aminotransferase activity, concentrations of fasting plasma nonesterified fatty acids and triglyceride, and hepatic triglyceride content was also suppressed. The hepatic protein expression profile revealed that rosiglitazone increased the downregulated total protein expression of insulin receptor substrate 1 (IRS-1) and IRS-2. Furthermore, the treatment suppressed the upregulated phosphorylation of IRS-1 at Ser307 and IRS-2 at Ser731. The results indicate that rosiglitazone ameliorates hepatic and systemic insulin resistance, hepatic inflammation, and fatty liver. Mechanistically, rosiglitazone suppressed hepatic protein overexpression of both phosphorylated nuclear factor- (NF-) κBp65 and inhibitory-κB kinase-α/β, a transcription factor that primarily regulates chronic inflammatory responses and the upstream NF-κB signal transduction cascades which are necessary for activating NF-κB, respectively. More importantly, rosiglitazone attenuated the decreases in adipose adiponectin mRNA level, plasma adiponectin concentrations, and hepatic protein expression of adiponectin receptor-1 and receptor-2. Thus, we can draw the conclusion that rosiglitazone elicits an adiponectin-mediated insulin-sensitizing action at the adipose tissue-liver axis in obese rats. Our findings may provide new insights into the mechanisms of action of rosiglitazone.

Fecal Enterobacteriales enrichment is associated with increased invivo intestinal permeability in humans.

Type 2 diabetes (T2D) has been linked with increased intestinal permeability, but the clinical significance of this phenomenon remains unknown. The objective of this study was to investigate the potential link between glucose control, intestinal permeability, diet and intestinal microbiota in patients with T2D. Thirty‐two males with well‐controlled T2D and 30 age‐matched male controls without diabetes were enrolled in a case–control study. Metabolic parameters, inflammatory markers, endotoxemia, and intestinal microbiota in individuals subdivided into high (HP) and normal (LP) colonic permeability groups, were the main outcomes. In T2D, the HP group had significantly higher fasting glucose (P = 0.034) and plasma nonesterified fatty acid levels (P = 0.049) compared with the LP group. Increased colonic permeability was also linked with altered abundances of selected microbial taxa. The microbiota of both T2D and control HP groups was enriched with Enterobacteriales. In conclusion, high intestinal permeability was associated with poorer fasting glucose control in T2D patients and changes in some microbial taxa in both T2D patients and nondiabetic controls. Therefore, enrichment in the gram‐negative order Enterobacteriales may characterize impaired colonic permeability prior to/independently from a disruption in glucose tolerance.

Preliminary evaluation of a differential effect of an α-linolenate-rich supplement on ketogenesis and plasma ω-3 fatty acids in young and older adults

ObjectivesThe aim of the present study was to compare the effects of an α-linolenic acid-rich supplement (ALA-RS) on the ketogenic response and plasma long-chain ω-3 polyunsaturated fatty acid in healthy young adults and older individuals. MethodsTen young (25 ± 0.9 y) and 10 older adults (73.1 ± 2.2 y) consumed a flaxseed oil supplement providing 2 g/d of ALA for 4 wk. Plasma ketones, nonesterified fatty acids (NEFA), triacylglycerols, glucose, and insulin were measured over 6 h, before and after supplementation. Total body fat mass was assessed before and after the ALA-RS. ResultsThe ALA-RS did not significantly modify fasting ketones but postprandial production of β-hydroxybutyrate was increased by 26% (P = 0.037) only in the young adult group. Fasting plasma ketones were positively correlated to fasting plasma NEFA (P < 0.01) in both groups. However, the relation was shifted to the right in the older group, suggesting that older adults needed higher plasma NEFA levels to achieve the same ketone amounts as young adults. At baseline, the older group had 47% higher total plasma fatty acids than the young group (P = 0.007). After the ALA-RS, plasma ALA doubled in both groups (P < 0.01), an effect that was associated in the older group with a 40% higher eicosapentaenoic acid (EPA; P = 0.004), but no difference in docosahexaenoic acid. The postsupplementation increase in plasma ALA correlated positively with percent total body fat, especially in the older group (r2 = 0.77; P = 0.0016). ConclusionIn young adults, ALA-RS mildly stimulated postprandial ketogenesis, whereas in the older group, it favored increased plasma ALA and EPA.

Resistant starch-rich wx/ae brown rice prevents insulin resistance and hypertriglyceridaemia in type 2 diabetic NSY mice

A rice cultivar called ‘wx/ae’, double mutant in waxy (wx) and amylose extender (ae) genes, is rich in resistant starch. Type 2 diabetic NSY mice were fed a test diet containing 30% roasted wx/ae brown rice (wx/ae group) or its parental rice cultivar Kinmaze brown rice (WT group) for 16 weeks. The insulin sensitivity of the wx/ae group was significantly higher than that of the WT group, and the concentrations of fasting plasma triacylglycerol and non-esterified fatty acids were lower. Gene expression analysis of the liver revealed that expression levels of insulin-dependent genes and bile acid-related genes in the two groups were significantly different. Moreover, expression of the G protein-coupled receptor 43 gene in the epididymal white adipose tissue was significantly higher in the wx/ae group. These results indicate that wx/ae brown rice is a good candidate food for the prevention of type 2 diabetes and hypertriglyceridaemia.

Apolipoprotein E (APOE) genotype regulates body weight and fatty acid utilization-Studies in gene-targeted replacement mice.

Of the three human apolipoprotein E (APOE) alleles, the ε3 allele is most common, which may be a result of adaptive evolution. In this study, we investigated whether the APOE genotype affects body weight and energy metabolism through regulation of fatty acid utilization. Targeted replacement mice expressing the human APOE3 were significantly heavier on low- and high-fat diets compared to APOE4 mice. Particularly on high-fat feeding, food intake and dietary energy yields as well as fat mass were increased in APOE3 mice. Fatty acid mobilization determined as activation of adipose tissue lipase and fasting plasma nonesterified fatty acid levels were significantly lower in APOE3 than APOE4 mice. APOE4 mice, in contrast, exhibited higher expression of proteins involved in fatty acid oxidation in skeletal muscle. Our data suggest that APOE3 is associated with the potential to more efficiently harvest dietary energy and to deposit fat in adipose tissue, while APOE4 carriers tend to increase fatty acid mobilization and utilization as fuel substrates especially under high-fat intake. The different handling of dietary energy may have contributed to the evolution and worldwide distribution of the ε3 allele.

Comparison of the effects of three persimmon cultivars on lipid and glucose metabolism in high-fat diet-fed mice.

We compared the effects of three persimmon cultivars, one nonastringent-type fruit (Fuyu) and two astringent-type fruits (Hiratanenashi and Hachiya), on the lipid and glucose metabolism of high-fat diet-fed mice. Persimmon samples prepared from young fruits of the three cultivars contained around 80% dietary fiber and differed in their bile acid-binding abilities and tannin contents. C57BL/6J mice were fed a modified AIN76 high-fat diet supplemented with 2% of each persimmon sample instead of cellulose for 10 wk. All cultivars significantly accelerated fecal bile acid secretion, depending on the bile acid-binding ability of the cultivars. Hiratanenashi and Hachiya, the cultivars with a strong bile acid-binding ability, prevented any increase in fasting blood glucose and plasma nonesterified fatty acid levels. Hachiya, the cultivar with the highest tannin content, also tended to prevent an increase in plasma non-high-density lipoprotein cholesterol levels. However, Fuyu, the cultivar with the lowest bile acid-binding ability and tannin content, had no effect on lipid or glucose metabolism. These effects linked to expression of the genes related to lipid and energy metabolism, including the cytochrome P450 7A1 gene in the liver and the uncoupling protein 3 gene in the brown adipose tissue. These results indicate that the beneficial effects of these cultivars on lipid and glucose metabolism are closely related to their bile acid-binding ability and tannin content.

Muscle insulin resistance resulting from impaired microvascular insulin sensitivity in Sprague Dawley rats

Enhanced microvascular perfusion of skeletal muscle is important for nutrient exchange and contributes ∼40% insulin-mediated muscle glucose disposal. High fat-fed (36% fat wt./wt.) rats are a commonly used model of insulin-resistance that exhibit impairment of insulin-mediated microvascular recruitment and muscle glucose uptake, which is accompanied by myocyte insulin-resistance. Distinguishing the contribution of impaired microvascular recruitment and impaired insulin action in the myocyte to decreased muscle glucose uptake in these high-fat models is difficult. It is unclear whether microvascular and myocyte insulin-resistance develop simultaneously. To assess this, we used a rat diet model with a moderate increase (two-fold) in dietary fat. Sprague Dawley rats fed normal (4.8% fat wt./wt., 5FD) or high (9.0% fat wt./wt., 9FD) fat diets for 4 weeks were subject to euglycaemic hyperinsulinemic clamp (10 mU/min/kg insulin or saline) or isolated hindlimb perfusion (1.5 or 15 nM insulin or saline). Body weight, epididymal fat mass, and fasting plasma glucose were unaffected by diet. Fasting plasma insulin and non-esterified fatty acid concentrations were significantly elevated in 9FD. Glucose infusion rate and muscle glucose uptake were significantly impaired during insulin clamps in 9FD. Insulin-stimulated microvascular recruitment was significantly blunted in 9FD. Insulin-mediated muscle glucose uptake between 5FD and 9FD were not different during hindlimb perfusion. Impaired insulin-mediated muscle glucose uptake in vivo can be the direct result of reduced microvascular blood flow responses to insulin, and can result from small (two-fold) increases in dietary fat. Thus, microvascular insulin-resistance can occur independently to the development of myocyte insulin-resistance.

Restricted feeding of goats during the last third of gestation modifies both metabolic parameters and behaviour

Underfeeding of gestating dairy goats can occur for a number of reasons. If underfeeding is severe it can provoke pregnancy toxaemia which can lead to welfare problems and even mortality. Behaviour may also be modified in the context of underfeeding and it is important to integrate this information in management practices. The objectives of this experiment were to study the effect of restricted feeding during the last third of gestation on metabolism and behaviour of goats. Special attention was paid to the feed restricted group of goats to define characteristics which could be used to identify animals at risk before they develop pregnancy toxaemia. A total of 60 Alpine and Saanen dairy goats were used. Starting from −8 weeks before parturition the goats were allocated to one of two dietary treatments, control (C) or restricted (R). The C group was fed ad libitum (5% feed refusals) a TMR (C, n = 30) and the R group (R, n = 30) was given the same TMR but the quantity corresponded to 50% of the amount given to the C group between −8 and −4 weeks, 60% between −5 and −4 weeks, 70% between −4 and −3 weeks and 80% from −2 weeks to parturition. The R goats were also given free access to straw. Both metabolism and behaviour were modified by food restriction. The R goats put on less weight and their body condition score (BCS) decreased more steeply than the C goats during late gestation. Plasma glucose and β-hydroxybutyrate (BHB) were lower while non-esterified fatty acids (NEFA) were higher in the R goats compared to the C goats during the period of feed restriction. The R goats spent more time in activities involved with feeding and moving than the C goats. Four of the R goats developed pregnancy toxaemia as a result of dietary restriction. A principal component analysis (PCA) was performed on variables analysed before the start of dietary restriction: liveweight (LW), BCS, fasting plasma glucose, urea, NEFA and BHB. The four R animals that developed toxaemia were characterised by high NEFA and low plasma glucose together with low BCS and high urea before dietary restriction. This particular profile may therefore be used to determine which animals are at risk of developing pregnancy toxaemia.

Fasting and postprandial adiponectin alterations anticipate NEFA and TNF-α changes in prepubertal obese children

Background and aims It has been suggested that adipokine changes might precede changes in plasma non-esterified fatty acids and other obesity metabolic biomarkers. The aim of the present study was to evaluate changes in fasting and postprandial plasma levels of adiponectin, non-esterified fatty acids, and tumor necrosis factor-alpha in prepubertal obese children and age-matched normal-weight children. Methods and results Fifty-four children of prepubertal age (34 obese, comprising 23 males and 11 females, and 20 normal-weight comprising 11 males and 9 females) were studied. A standard 438 kcal breakfast was given to both groups. Baseline measurements included anthropometry and plasma lipids. The following parameters were determined in plasma before and after breakfast: glucose, insulin, and C-peptide at baseline and 2 h and non-esterified fatty acids, adiponectin, and tumor necrosis factor-alpha at baseline and 1, 2, and 3 h. Fasting plasma non-esterified fatty acid levels were lower in the obese versus normal-weight children ( P = 0.021). Both at baseline and postprandially, plasma adiponectin levels were lower in the obese versus normal-weight children ( P < 0.001). A trend was observed ( P = 0.06) that levels of tumor necrosis factor-alpha were lower in the obese versus normal-weight children. Adiponectin was inversely associated with insulin in the obese children after adjustment for BMI and sex ( r = −0.401, P = 0.025). Conclusion At prepubertal age, obese children show lower fasting and postprandial plasma adiponectin levels in comparison to normal-weight children, whereas non-esterified fatty acids and tumor necrosis factor-alpha were not yet increased. Therefore, adiponectin appears to be a good marker of early metabolic alterations associated with childhood obesity.

Selective Association of Plasma Non-esterified Fatty Acid Species with Circulating Interleukin-8 Concentrations in Humans

Elevated plasma concentrations of non-esterified fatty acids (NEFA), due to high fat intake and/or adipose tissue lipolysis, are a hallmark of the metabolic syndrome. We assessed whether certain plasma NEFA species contribute to the chronic low-grade inflammatory state seen in the metabolic syndrome. We determined the fasting plasma NEFA patterns of 75 overweight non-diabetic subjects and analysed their relationship with plasma inflammatory parameters. After adjustment for gender, age, body fat, and waist-hip ratio, no strong correlations of single NEFA species with leukocyte number, C-reactive protein, interleukin-6, tumour necrosis factor-alpha, or monocyte chemoattractant protein-1 were detected. However, oleate was negatively (r=-0.36, p=0.0015) and myristate (r=0.41, p=0.0003) as well as the omega3-polyunsaturated NEFA alpha-linolenate (r=0.37, p=0.0011), eicosapentaenoate (r=0.40, p=0.0003), and docosahexaenoate (r=0.40, p=0.0004) were positively associated with interleukin-8 concentrations. The other NEFA species as well as the total plasma NEFA concentration did not correlate with interleukin-8. The correlations of myristate, oleate, and the sum of all omega3-polyunsaturated NEFA with interleukin-8 were independent of plasma tumour necrosis factor-alpha and overall adiposity. Our data demonstrate close and selective associations of oleate, myristate, and omega3-polyunsaturated NEFA with plasma concentrations of the pro-inflammatory chemokine interleukin-8. Thus, these NEFA species may represent specific determinants of plasma interleukin-8.

Fatty Acid Metabolism in Patients with PPARγ Mutations

PPARG mutations may cause insulin resistance and dyslipidemia, but little is known about the mechanisms of the abnormalities of lipid metabolism. We hypothesized that in PPARG mutations, abnormal adipose tissue triglyceride storage causes insulin resistance. Whole-body and adipose tissue-specific metabolic phenotyping through arteriovenous blood sampling was made before and after a mixed meal including 13C-palmitic acid. Studies were performed in a 32-yr-old male with partial lipodystrophy and type 2 diabetes, heterozygous for the PPARG P467L mutation and in an apparently phenotypically normal 32-yr-old male heterozygous for the PPARG n.AAA553T mutation. Comparator groups were age- and sex-matched healthy participants (n=10) and type 2 diabetes sex-matched participants (n=6). The P467L patient had elevated unmodulated fasting and postprandial plasma nonesterified fatty acid (NEFA) concentrations, despite a low adipose tissue NEFA output. Instead, NEFA appeared to originate directly from triglyceride-rich lipoproteins: 13C-palmitic acid accumulated rapidly in the NEFA fraction, as a sign of impaired fatty acid trapping in tissues. In contrast to the Pparg haploinsufficient mouse, the patient with n.AAA553T mutation did not exhibit paradoxically insulin sensitive and showed a mostly normal metabolic pattern. The lipodystrophic PPARG P467L phenotype include excessive and uncontrolled generation of NEFA directly from triglyceride-rich lipoproteins, explaining high systemic NEFA concentrations, whereas the human PPARG haploinsufficiency is metabolically almost normal.

Long-standing, insulin-treated type 2 diabetes patients with complications respond well to short-term resistance and interval exercise training

To determine the feasibility and the benefits of combined resistance and interval exercise training on phenotype characteristics and skeletal muscle function in deconditioned, type 2 diabetes (T2D) patients with polyneuropathy. Short-term, single-arm intervention trial. Eleven male T2D patients (age: 59.1+/-7.5 years; body mass index: 32.2+/-4.0 kg/m2) performed progressive resistance and interval exercise training thrice a week for 10 weeks. Besides primary diabetes outcome measures, muscle strength (MUST), maximal workload capacity (Wmax), whole-body peak oxygen uptake (VO2peak) and muscle oxidative capacity (MUOX), intramyocellular lipid (IMCL) and glycogen (IMCG) storage, and systemic inflammation markers were determined before and after training. Daily exogenous insulin requirements (EIR) and historic individualized EIR were gathered and analysed. MUST and Wmax increased with 17% (90% confidence intervals 9-24%) and 14% (6-21) respectively. Furthermore, mean arterial blood pressure declined with 5.5 mmHg (-9.7 to -1.4). EIR dropped with 5.0 IU/d (-11.5 to 1.5) compared with baseline. A decline of respectively -0.7 mmol/l (-2.9 to 1.5) and -147 micromol/l (-296 to 2) in fasting plasma glucose and non-esterified fatty acids concentrations were observed following the intervention, but these were not accompanied by changes in VO2peak, MUOX, IMCL or IMCG, and blood glycolysated haemoglobin, adiponectin, tumor necrosis factor-alpha and/or cholesterol concentrations. Short-term resistance and interval exercise training is feasible in deconditioned T2D patients with polyneuropathy and accompanied by moderate improvements in muscle function and blood pressure. Such a specific exercise regimen may provide a better framework for future exercise intervention programmes in the treatment of deconditioned T2D patients.