Low contribution of n-3 polyunsaturated fatty acids to plasma and erythrocyte membrane lipids in diabetic young adults

Effects of marine-derived and plant-derived omega-3 polyunsaturated fatty acids on erythrocyte fatty acid composition in type 2 diabetic patients

Background

Dietary fatty acids intake affects the composition of erythrocyte fatty acids, which is strongly correlated with glycolipid metabolism disorders. This study aimed at investigating the different effects of marine-derived and plant-derived omega-3 polyunsaturated fatty acid (n-3 PUFA) on the fatty acids of erythrocytes and glycolipid metabolism in patients with type 2 diabetes mellitus (T2DM).

Methods

The randomized double-blinded trial that was performed on 180 T2DM patients. The participants were randomly assigned to three groups for the six-month intervention. The participants were randomly assigned to three groups for the six-month intervention. The fish oil (FO) group was administered with FO at a dose of 3 g/day containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the perilla oil (PO) group was administered with PO at a dose of 3 g/day containing α-linolenic (ALA), the linseed and fish oil (LFO) group was administered with mixed linseed and fish oil at a dose of 3 g/day containing EPA, DHA and ALA. Demographic information were collected and anthropometric indices, glucose and lipid metabolism indexes, erythrocyte fatty acid composition were measured. Statistical analyses were performed using two-way ANOVA.

Results

A total of 150 patients finished the trial, with 52 of them in the FO group, 50 in the PO group and 48 in the LFO group. There were significant effects of time × treatment interaction on fast blood glucose (FBG), insulin, HOMA-IR and C-peptide, TC and triglyceride (TG) levels (P < 0.001). Glucose and C-peptide in PO and LFO groups decreased significantly and serum TG in FO group significantly decreased (P < 0.001) after the intervention. Erythrocyte C22: 5 n-6, ALA, DPA, n-6/n-3 PUFA, AA/EPA levels in the PO group were significantly higher than FO and LFO groups, while EPA, total n-3 PUFA and Omega-3 index were significantly higher in the FO and LFO groups compared to PO group.

Conclusion

Supplementation with perilla oil decreased FBG while fish oil supplementation decreased the TG level. Marine-based and plant-based n-3 PUFAs exhibit different effects on fatty acid compositions of erythrocytes and regulated glycolipid metabolism.

Trial registration

This trial was recorded under Chinese Clinical Trial Registry Center (NO: ChiCTR-IOR-16008435) on May 28 2016.

Saturated and monounsaturated fatty acids in membranes are determined by the gene expression of their metabolizing enzymes SCD1 and ELOVL6 regulated by the intake of dietary fat

PURPOSE

We investigated the effect of dietary fats on the incorporation of saturated (SAFAs) and monounsaturated dietary fatty acids (MUFAs) into plasma phospholipids and the regulation of the expression of lipid-metabolizing enzymes in the liver.

METHODS

Mice were fed different diets containing commonly used dietary fats/oils (coconut fat, margarine, fish oil, sunflower oil, or olive oil) for 4 weeks (n = 6 per diet group). In a second experiment, mice (n = 6 per group) were treated for 7 days with synthetic ligands to activate specific nuclear hormone receptors (NHRs) and the hepatic gene expression of CYP26A1 was investigated. Hepatic gene expression of stearoyl-coenzyme A desaturase 1 (SCD1), elongase 6 (ELOVL6), and CYP26A1 was examined using quantitative real-time PCR (QRT-PCR). Fatty acid composition in mouse plasma phospholipids was analyzed by gas chromatography (GC).

RESULTS

We found significantly reduced hepatic gene expression of SCD1 and ELOVL6 after the fish oil diet compared with the other diets. This resulted in reduced enzyme-specific fatty acid ratios, e.g., 18:1n9/18:0 for SCD1 and 18:0/16:0 and 18:1n7/16:1n7 for ELOVL6 in plasma phospholipids. Furthermore, CYP26A1 a retinoic acid receptor-specific target was revealed as a new player mediating the suppressive effect of fish oil-supplemented diet on SCD1 and ELOVL6 hepatic gene expression.

CONCLUSION

Plasma levels of MUFAs and SAFAs strongly reflect an altered hepatic fatty acid-metabolizing enzyme expression after supplementation with different dietary fats/oils.

Palmitic Acid Induces Müller Cell Inflammation that is Potentiated by Co-treatment with Glucose

Chronic hyperglycemia is thought to be the major stimulator of retinal dysfunction in diabetic retinopathy (DR). Thus, many diabetes-related systemic factors have been overlooked as inducers of DR pathology. Cell culture models of retinal cell types are frequently used to mechanistically study DR, but appropriate stimulators of DR-like factors are difficult to identify. Furthermore, elevated glucose, a gold standard for cell culture treatments, yields little to no response from many primary human retinal cells. Thus, the goal of this project was to demonstrate the effectiveness of the free fatty acid, palmitic acid and compare its use alone and in combination with elevated glucose as a stimulus for human Müller cells, a retinal glial cell type that is activated early in DR pathogenesis and uniquely responsive to fatty acids. Using RNA sequencing, we identified a variety of DR-relevant pathways, including NFκB signaling and inflammation, intracellular lipid signaling, angiogenesis, and MAPK signaling, that were stimulated by palmitic acid, while elevated glucose alone did not significantly alter any diabetes-relevant pathways. Co-treatment of high glucose with palmitic acid potentiated the expression of several DR-relevant angiogenic and inflammatory targets, including PTGS2 (COX-2) and CXCL8 (IL-8).

Diabetic retinopathy: Breaking the barrier

Diabetic retinopathy (DR) remains a major complication of diabetes and a leading cause of blindness among adults worldwide. DR is a progressive disease affecting both type I and type II diabetic patients at any stage of the disease, and targets the retinal microvasculature. DR results from multiple biochemical, molecular and pathophysiological changes to the retinal vasculature, which affect both microcirculatory functions and ultimately photoreceptor function. Several neural, endothelial, and support cell (e.g., pericyte) mechanisms are altered in a pathological fashion in the hyperglycemic environment during diabetes that can disturb important cell surface components in the vasculature producing the features of progressive DR pathophysiology. These include loss of the glycocalyx, blood-retinal barrier dysfunction, increased expression of inflammatory cell markers and adhesion of blood leukocytes and platelets. Included in this review is a discussion of modifications that occur at or near the surface of the retinal vascular endothelial cells, and the consequences of these alterations on the integrity of the retina.

Associations between long chain polyunsaturated fatty acids and cardiovascular lipid risk factors in youth with type 1 diabetes: SEARCH Nutrition Ancillary Study

PURPOSE

In this longitudinal study we explored the relationships between plasma n-3 and n-6 polyunsaturated fatty acids (PUFAs) and Δ5 and Δ6 desaturase activities (D5D and D6D, respectively) and fasting lipids in youth with type 1 diabetes (T1D).

METHODS

Incident cases of T1D in youth <20years of age who were seen for a baseline study visit (N=914) and a 1-year follow-up visit (N=416) were included. Fasting blood samples were obtained at each visit and plasma phospholipid n-6 PUFAs were measured, which included linoleic acid (LA), dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA); n-3 PUFAs included α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Estimated D5D and D6D were calculated as FA product-to-precursor ratios, where D5D=AA/DGLA and D6D=DGLA/LA. To examine the longitudinal relationships between long chain PUFAs, desaturase activities and fasting plasma lipids in youth with T1D mixed effects models were used for each individual PUFAs, D5D and D6D, adjusted for demographics, clinic site, diabetes duration, insulin regimen, insulin dose/kg, HbA1c, insulin sensitivity score, and body mass index with random effects to account for the repeated measurements.

FINDINGS

Favorable lipid associations were found between LA and low-density lipoprotein (LDL) cholesterol (β=-0.58, p<0.05); AA, plasma triglycerides (TG) (β=-0.04, p<0.05) and TG/high-density lipoprotein (HDL)-C ratio (β=-0.04, p<0.05); and D5D, plasma TG (β=-0.2, p<0.05) and TG/HDL-cholesterol ratio (β=-0.23, p<0.05). Findings were mixed for the n-3 PUFAs and DGLA: ALA was positively associated with plasma TG (β=0.33, p<0.05) and HDL cholesterol (β=9.86, p<0.05); EPA was positively associated with total cholesterol (β=8.17, p<0.05), LDL cholesterol (β=5.74, p<0.01) and HDL cholesterol (β=2.27, p<0.01); and DGLA was positively associated with TG/HDL-cholesterol ratio (β=0.05, P<0.05).

CONCLUSION

Findings suggest that the most abundant PUFA, LA as well as its metabolic bi-product AA, may be important targets for CVD lipid risk factor reduction in youth with T1D.

Reference values of whole-blood fatty acids by age and sex from European children aged 3-8 years

OBJECTIVES

To establish reference values for fatty acids (FA) especially for n-3 and n-6 long-chain polyunsaturated FAs (LC PUFA) in whole-blood samples from apparently healthy 3-8-year-old European children. The whole-blood FA composition was analysed and the age- and sex-specific distribution of FA was determined.

DESIGN AND SUBJECTS

Blood samples for FA analysis were taken from 2661 children of the IDEFICS (identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study cohort. Children with obesity (n=454) and other diseases that are known to alter the FA composition (n=450) were excluded leaving 1653 participants in the reference population.

MEASUREMENTS

The FA composition of whole blood was analysed from blood drops by a rapid, validated gas chromatographic method.

RESULTS

Pearson correlation coefficients showed an age-dependent increase of C18:2n-6 and a decrease of C18:1n-9 in a subsample of normal weight boys and girls. Other significant correlations with age were weak and only seen either in boys or in girls, whereas most of the FA did not show any age dependence. For age-dependent n-3 and n-6 PUFA as well as for other FA that are correlated with age (16:0, C18:0 and C18:1n-9) percentiles analysed with the general additive model for location scale and shape are presented. A higher median in boys than in girls was observed for C20:3n-6, C20:4n-6 and C22:4n-6.

CONCLUSIONS

Given the reported associations between FA status and health-related outcome, the provision of FA reference ranges may be useful for the interpretation of the FA status of children in epidemiological and clinical studies.

Low n-3 long-chain polyunsaturated fatty acids in newly diagnosed celiac disease in children with preexisting type 1 diabetes mellitus

OBJECTIVE

Fat malabsorption can occur in celiac disease (CD) owing to villus atrophy and inflammation of small intestinal mucosa. Abnormal fatty acid (FA) status of intestinal mucosa in children with CD was reported earlier. Previously we found significantly reduced availability of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) in children and young adults with type 1 diabetes mellitus (DM). The aim of this study was to investigate FAs in plasma lipid classes in children with newly diagnosed CD with or without preexisting DM.

METHODS

FA composition of plasma samples of children with untreated CD only (n = 20) and with preexisting DM (CDDM, n = 8) were compared with those of healthy controls (n = 21). Detailed analysis of phospholipid, triacylglycerol, and sterol ester FAs was performed by high-resolution capillary gas-liquid chromatography.

RESULTS

Significantly decreased docosapentaenoic (C22:5n-3), docosahexaenoic (C22:6n-3), n-3 polyunsaturated fatty acids (n-3 PUFA), and n-3 LCPUFA values were found in CDDM group compared with controls and patients with CD. When compared with healthy controls, no significant difference was found in plasma FAs of children with newly diagnosed CD only.

CONCLUSIONS

Children with CDDM showed marked signs of reduced availability of n-3 PUFA and n-3 LCPUFA in circulating lipids. Although different tissues express membrane FAs differently, our present study suggests that CD on its own does not necessarily lead to detectable disturbances of essential FA metabolism in plasma and supports the concept that DM has significant impact on plasma FA composition in children.

Erythrocyte membrane docosapentaenoic acid levels are associated with islet autoimmunity: the Diabetes Autoimmunity Study in the Young

AIMS/HYPOTHESES

We previously reported that lower n-3 fatty acid intake and levels in erythrocyte membranes were associated with increased risk of islet autoimmunity (IA) but not progression to type 1 diabetes in children at increased risk for diabetes. We hypothesise that specific n-3 fatty acids and genetic markers contribute synergistically to this increased risk of IA in the Diabetes Autoimmunity Study in the Young (DAISY).

METHODS

DAISY is following 2,547 children at increased risk for type 1 diabetes for the development of IA, defined as being positive for glutamic acid decarboxylase (GAD)65, IA-2 or insulin autoantibodies on two consecutive visits. Using a case-cohort design, erythrocyte membrane fatty acids and dietary intake were measured prospectively in 58 IA-positive children and 299 IA-negative children.

RESULTS

Lower membrane levels of the n-3 fatty acid, docosapentaenoic acid (DPA), were predictive of IA (HR 0.23; 95% CI 0.09, 0.55), while α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were not, adjusting for HLA and diabetes family history. We examined whether the effect of dietary intake of the n-3 fatty acid ALA on IA risk was modified by fatty acid elongation and desaturation genes. Adjusting for HLA, diabetes family history, ethnicity, energy intake and questionnaire type, ALA intake was significantly more protective for IA in the presence of an increasing number of minor alleles at FADS1 rs174556 (pinteraction = 0.017), at FADS2 rs174570 (pinteraction = 0.016) and at FADS2 rs174583 (pinteraction = 0.045).

CONCLUSIONS/INTERPRETATION

The putative protective effect of n-3 fatty acids on IA may result from a complex interaction between intake and genetically controlled fatty acid desaturation.

Effect of high versus low doses of fat and vitamin A dietary supplementation on fatty acid composition of phospholipids in mice

Dietary fat and vitamin A provide important precursors for potent bioactive ligands of nuclear hormone receptors, which regulate various enzymes involved in lipid homeostasis, metabolism and inflammation. We determined the effects of dietary fat and dietary vitamin A on hepatic expression of two fatty acid metabolizing enzymes, elongase 6 (ELOVL6) and stearoyl-coenzyme A desaturase 1 (SCD1) and the concentration of saturated fatty acids (SAFA) and monounsaturated fatty acid (MUFA) of phospholipids in serum and liver. Mice (n = 6) were fed 4 weeks with diets containing 2, 5 and 25 % of fat or vitamin A (0, 2,500 and 326,500 RE/kg as retinyl palmitate). MUFAs and SAFAs were measured using GC and ESI-MS/MS. Hepatic expression of metabolizing enzymes was determined using QRT-PCR. ELOVL6 was significantly down-regulated in response to a high-fat diet (p < 0.001) and significantly up-regulated in response to low-fat diet (p < 0.05). SCD1 expression was significantly lower in high- versus low-fat diet (p < 0.05). The vitamin A content in the diet did not influence the hepatic expression of both enzymes. In plasma, the amounts of MUFAs bound to phospholipids significantly decreased in response to a high-fat diet and increased after a low-fat diet. This tendency was also observed in the liver for various phospholipids sub-classes. In summary, this study shows that fat content in the diet has a stronger impact than the content of vitamin A on hepatic gene expression of SCD1 and ELOVL6 and thereby on MUFA and SAFA concentrations in liver and plasma.

Dietary treatment options for depression among diabetic patient, focusing on macronutrients

There is a bidirectional adverse association between diabetes and depression. The odds for experiencing depressive symptoms in diabetic patients are two times more than nondiabetic persons, and depression is an independent predictor for the onset of diabetes. However, depression has been approximately unrecognized and untreated in two-thirds of diabetic patients, which may lead to worsened diabetes complications. A cornerstone strategy for managing depression among diabetic patients is the use of diet to improve both health problems. Because of similar pathophysiology for chronic diseases and depression, it seems that similar dietary recommendations could be useful. However, few studies have been conducted among diabetic patients. Regarding the complications of diabetes such as renal diseases and coronary heart diseases, the proper range of various macronutrients should be clarified in depressed diabetic patients as well as the proper type of each macronutrient. In this paper, we reviewed the available data on the treatment of depression in diabetic patients.

Examining the role of lipid mediators in diabetic retinopathy

Diabetic retinopathy is the most disabling complication of diabetes, affecting 65% of patients after 10 years of the disease. Current treatment options for diabetic retinopathy are highly invasive and fall short of complete amelioration of the disease. Understanding the pathogenesis of diabetic retinopathy is critical to the development of more effective treatment options. Diabetic hyperglycemia and dyslipidemia are the main metabolic insults that affect retinal degeneration in diabetes. Although the role of hyperglycemia in inducing diabetic retinopathy has been studied in detail, much less attention has been paid to dyslipidemia. Recent clinical studies have demonstrated a strong association between dyslipidemia and development of diabetic retinopathy, highlighting the importance of understanding the exact changes in retinal lipid metabolism in diabetes. This review describes what is known on the role of dyslipidemia in the development of diabetic retinopathy, with a focus on retinal-specific lipid metabolism and its dysregulation in diabetes.

Biological effects of add-on eicosapentaenoic acid supplementation in diabetes mellitus and co-morbid depression: a randomized controlled trial

Background

Eicosapentaenoic acid (EPA) may reduce increased risks for (cardiovascular) morbidity and mortality in patients with diabetes mellitus (DM) and comorbid major depressive depression (MDD). Yet, effects of EPA-supplementation on biological risk factors for adverse outcomes have not been studied in DM-patients with MDD.

Methods

We performed a randomized, double-blind trial (n = 25) comparing add-on ethyl-EPA-supplementation to placebo on (I) oxidative stress, (II) inflammatory, (III) hypothalamic-pituitary-adrenal (HPA)-axis, (IV) one-carbon-cycle, (V) fatty acid metabolism and (VI) lipoprotein parameters during 12-weeks' follow-up.

Results

Besides increases in supplemented α-tocopherol [estimate (95% CI); 3.62 (1.14–6.11) µmol/l; p = 0.006] and plasma and erythrocyte EPA, the intervention did not influence other oxidative stress, inflammatory or one-carbon-cycle parameters compared to placebo. HPA-axis reactivity significantly decreased in the EPA-group (N = 12) [AUC_i: −121.93 (−240.20–−3.47) min×nmol/l; p = 0.045], not in the placebo-group (N = 12). Furthermore, EPA-supplementation increased erythrocyte and plasma docosapentaenoic acid, and decreased plasma arachidonic acid (AA) concentrations [−1.61 (−3.10–−0.11) %; p = 0.036]. Finally, EPA had a multivariate influence on lipoprotein concentrations (p = 0.030), reflected by relative increases in high density lipoprotein [HDL; 0.30 (0.02–0.58) mmol/l; p = 0.039] and total cholesterol concentrations [1.01 (0.29–1.72) mmol/l; p = 0.008].

Conclusion

Overall, add-on EPA-supplementation had limited effects on biological risk factors for adverse outcome in this sample of DM-patients with comorbid MDD. Besides increases in concentrations of supplemented α-tocopherol and EPA, AA decreased, and inconclusive effects on HPA-axis (re)activity and lipoprotein concentrations were observed. Therefore, further studies on the alleged beneficial effects of EPA-supplementation on biological risk factors for adverse outcome in DM-patients with comorbid MDD seem warranted, preferably using clinical outcomes such as (cardiovascular) DM-complications.

Trial Registration

Controlled-Trials.com ISRCTN30877831 ISRCTN30877831

Erythrocyte membrane omega-3 fatty acid levels and omega-3 fatty acid intake are not associated with conversion to type 1 diabetes in children with islet autoimmunity: the Diabetes Autoimmunity Study in the Young (DAISY)

AIM

We investigated whether omega-3 fatty acid intake and erythrocyte membrane omega-3 fatty acid levels are associated with conversion to type 1 diabetes in children with islet autoimmunity (IA).

METHODS

The Diabetes Autoimmunity Study in the Young is following children at increased genetic risk for type 1 diabetes for the development of persistent IA, as defined as being positive for glutamic acid decarboxylase 65, i, or insulin autoantibodies on two consecutive visits, and then for the development of type 1 diabetes, as diagnosed by a physician. One hundred and sixty-seven children with persistent IA were followed for a mean of 4.8 yr, and 45 of these developed type 1 diabetes at a mean age of 8.7 yr. Erythrocyte membrane fatty acids (as a percent of total lipid) and dietary fatty acid intake (estimated via food frequency questionnaire) were analyzed as time-varying covariates in proportional hazards survival analysis, with follow-up time starting at detection of the first autoantibody.

RESULTS

Neither dietary intake of omega-3 fatty acids nor omega-6 fatty acids were associated with conversion to type 1 diabetes, adjusting for human leukocyte antigen (HLA)-DR, family history of type 1 diabetes, age at first IA positivity, maternal age, maternal education, and maternal ethnicity. Adjusting for HLA-DR, family history of type 1 diabetes and age at first IA positivity, omega-3 and omega-6 fatty acid levels of erythrocyte membranes were not associated with conversion to type 1 diabetes.

CONCLUSIONS

In this observational study, omega-3 fatty acid intake and status are not associated with conversion to type 1 diabetes in children with IA.

Effect of synthetic ligands of PPAR α, β/δ, γ, RAR, RXR and LXR on the fatty acid composition of phospholipids in mice

Nuclear hormone receptors are transcription factors that can be activated by nutrition-derived ligands and alter the expression of various specific target genes. Stearoyl-Coenzyme A desaturase (SCD1) converts palmitic acid (16:0) to palmitoleic acid (16:1n-7) as well as stearic acid (18:0) to oleic acid (18:1n-9). At the same time, elongase 6 (ELOVL6) elongates 16:1n-7 and 18:1n-9 to vaccenic acid (18:1n-7) and eicosenoic acid (20:1n-9). We examined how synthetic selective ligands of nuclear hormone receptors alter the gene expression of hepatic enzymes in mice. In addition, we examined how the regulation of these two enzymes influences fatty acid composition of phospholipids in liver and plasma. Mice were gavaged daily for 1 week with synthetic ligands of peroxisome proliferator-activated receptor (PPAR) α, β/δ, γ, liver X receptor (LXR), retinoic acid receptor (RAR) and retinoid-X receptor (RXR) for 1 week. Phospholipids from liver and plasma were analysed using ESI-MS/MS and GC after saponification. Hepatic gene expression of SCD1 and ELOVL6 was measured using QRT-PCR. SCD1 and ELOVL6 expression increased after the gavage of LXR and RXR ligands. The analysis of fatty acid composition of total phospholipids in plasma and liver showed increased percentage contributions of the SCD1 and ELOVL6 products 18:1n-9, 18:1n-7 and 20:1n-9 after LXR and RXR ligand application. Analysis of total phospholipids from plasma and liver revealed a significant increase in monounsaturated fatty acids bound in phosphatidylcholine (PtdCho) and lysophosphatidylcholine (PtdEtn) after LXR and RXR ligand administration. Increased hepatic gene expression of SCD1 and ELOVL6 after gavage of selective RXR or LXR ligands to mice resulted in increased concentrations of their metabolic products in phospholipids of liver and plasma.

Fatty acid composition of plasma lipid classes in chronic alcoholic pancreatitis

BACKGROUND/AIMS

Supplementation of n-3 long-chain polyunsaturated fatty acids (LCPUFA) is considered as adjuvant therapy in acute pancreatitis. We investigated plasma fatty acid status in chronic pancreatitis (CP).

METHODS

Patients with alcoholic CP (n = 56, gender: 33/23 male/female, age: 60.0 [14.0] years (median [IQR]), who reported giving up alcohol consumption several years ago and 51 control subjects were included into the study. The fatty acid composition of plasma phospholipids (PL), triacylglycerols (TG) and sterol esters (STE) was analyzed.

RESULTS

The sum of monounsaturated fatty acids was significantly higher in patients with CP than in controls (PL: 12.83 [3.35] vs. 12.20 [1.95], TG: 40.51 [6.02] vs. 37.52 [5.80], STE: 20.58 [7.22] vs. 17.54 [3.48], CP vs. control, % weight/weight, median [IQR], p < 0.05). Values of arachidonic acid were significantly lower in patients with CP than in controls (PL: 10.57 [3.56] vs. 11.66 [3.25], STE: 8.14 [2.63] vs. 9.24 [2.86], p < 0.05). Values of eicosapentaenoic acid and docosahexaenoic acid did not differ and there was no difference in the ratio of n-3 to n-6 LCPUFA.

CONCLUSION

Our present data do not furnish evidence for the supplementation of n-3 LCPUFA to the diet of CP patients in relatively good clinical condition.

Analysis of Retina and Erythrocyte Glycerophospholipid Alterations in a Rat Model of Type 1 Diabetes

An automated tandem mass spectrometry based analysis employing precursor ion and neutral loss scans in a triple quadrupole mass spectrometer has been employed to identify and quantify changes in the abundances of glycerophospholipids extracted from retina and erythrocytes in a rat streptozotocin model of type 1 diabetes, 6 weeks and 36 weeks following induction of diabetes, compared to age matched nondiabetic controls. The utility of an 'internal standard' method compared to an 'internal standard free' method for quantification of differences in the abundances of specific lipid ions was evaluated in both retina and erythrocyte lipid extracts. In retina, equivalent results were obtained by using the internal standard and 'internal standard free' methods for quantification. In erythrocytes, the two methods of analysis yielded significantly different results, suggesting that factors intrinsic to particular sample types may influence the outcome of label-free lipidome quantification approaches.Overall increases (~25% to ~35%) in the abundances of major retina glycerophospholipid classes were demonstrated in rats at 6 weeks of diabetes, relative to control animals. However, at 36 weeks of diabetes, subsequent overall decreases in retina glycerophosphocholine and glycerophosphoethanolamine abundances of 16% and 33%, respectively, were observed. Additionally, retina and erythrocyte glycerophosphocholine lipids at both 6 week and 36 weeks of diabetes exhibited increased incorporation of linoleic acid((18:2n6)) and a decrease in docosahexaenoic acid (DHA((22:6n3))) content. Finally, an approximately 5-fold increase in the abundances of specific glycated glycerophosphoethanolamine (Amadori-GPEtn) lipids were observed in the retina of 36 week diabetic rats, with a corresponding 1.6 fold increase of Amadori-GPEtn lipids in diabetic erythrocytes.

Association of n-6 long-chain polyunsaturated fatty acids to -866 G/A genotypes of the human uncoupling protein 2 gene in obese children

AIM

To investigate the association of plasma fatty acids with the -866 G/A polymorphism of uncoupling protein 2 (UCP2) in obese children.

METHODS

Fatty acid composition of plasma phospholipids and sterol esters were investigated in 80 obese children.

RESULTS

Values of dihomo-gamma-linolenic acid (C20:3n-6) were significantly lower in children with the -866 A/A (n = 12) than in those with the -866 G/A (n = 34) or -866 G/G (n = 34) genotype in plasma phospholipids (3.01 [0.42] vs. 3.56 [1.02] vs. 3.53 [0.84], % weight/weight, median [interquartile range], p < 0.05), and were significantly lower in children with the -866 A/A genotype than in the other two groups in plasma sterol esters (0.73 [0.22] vs. 0.92 [0.23] vs. 0.94 [0.25], p < 0.05). Phospholipid C20:3n-6 and arachidonic acid (C20:4n-6) values showed only in children with the -866 G/G and -866 G/A genotypes significant positive correlations with plasma insulin concentrations.

CONCLUSIONS

Significantly lower values of C20:3n-6 can be detected in obese children with the homozygous (-866 A/A) mutation of UCP2 than in equally obese children with heterozygous mutation or the normal genotype. High glucose-stimulated insulin response is associated with high plasma C20:3n-6 and C20:4n-6 values only in obese children with the G allele of the -866 G/A polymorphism.