Polyunsaturated fatty acids and conjugated linoleic acid isomers in breast milk are associated with plasma non-esterified and erythrocyte membrane fatty acid composition in lactating women

Maternal adipose tissue is a major contributor to breast milk long-chain fatty acids, probably through the pool of plasma NEFA. The fatty acid composition of the erythrocyte membrane (EM) is a biochemical index of the intake of fatty acids not synthesized endogenously and of PUFA and long-chain PUFA fatty acid status. The present study investigated the associations between breast milk fatty acid composition and the composition of plasma NEFA and of EM fatty acids with special reference to PUFA, long-chain PUFA and conjugated linoleic acid (CLA). The detailed fatty acid composition of mature breast milk was also reported. Thirty-three healthy, lactating Brazilian women donated milk samples; of these, twenty-four also donated blood samples in an observational cross-sectional study. Breast milk fatty acid composition presented several associations with NEFA and EM composition, which explained most (> or =50 %) of the variability of selected milk PUFA, long-chain PUFA and CLA. Milk CLA was associated with fatty acids that are markers of dairy fat intake in the diet, NEFA and EM. In general, breast milk n-3 fatty acids and CLA, but not n-6 fatty acids, were associated with EM composition, whereas both the n-6 and n-3 fatty acids and CLA in milk were associated with NEFA composition, possibly owing to its role as a direct source of fatty acids for breast milk. These findings emphasize the contribution of the NEFA pool derived from the adipose tissue to the long-chain fatty acid composition of breast milk.     

Involvement of lipoic acid in plasma metabolites, hepatic oxygen consumption, and metabolic response to a beta-agonist in broiler chickens

The present study was conducted to determine the role of alpha-lipoic acid (LA) in plasma metabolites, hepatic O2 consumption, and beta-adrenergic response in broilers. In Expt 1, 12-d-old female broiler chicks were divided into three dietary groups and fed on diets with or without LA (5 or 50 mg/kg) until 4 or 6 weeks of age, as a 2 x 3 factorial arrangement. The dietary LA had no effect on growth rates (body weight, abdominal fat, breast muscle, and liver). The higher level of LA increased plasma non-esterified fatty acid and decreased plasma triacylglycerol concentrations only at 6 weeks of age. A 42% increase in hepatic respiration was observed in the 4-week-old chickens given 50 mg LA/kg diet. In Expt 2, 3-d-old female broiler chicks were treated with or without dietary LA at 50 mg/kg. At 30 and 31 d old, isoproterenol (2 mg/kg body weight per h) was continuously infused into a wing vein for 2 h, and changes in plasma glucose, triacylglycerol, and non-esterified fatty acid concentrations were analysed. Isoproterenol increased plasma glucose over basal levels maximally at 60 min. Furthermore, the glucose increase in the LA-treated chickens was 35% greater than that of the controls at this time. Plasma non-esterified fatty acid and triacylglycerol concentrations were decreased by the isoproterenol infusion, regardless of LA administration. Therefore, the present study suggests that dietary LA has repartitioning effects on energy metabolism in chickens (although this depends on age-related metabolic state) and is a possible facilitator in the beta-adrenergic response of plasma glucose to a beta-agonist.     

Effects of dietary lipoic acid on plasma lipid, in vivo insulin sensitivity, metabolic response to corticosterone and in vitro lipolysis in broiler chickens

The present study consisted of two experiments. The first experiment was conducted to determine the effects of lipoic acid (ALA; 200 mg/kg) on plasma lipids and insulin sensitivity of whole-body tissue in broilers treated with or without corticosterone (5 mg/kg). Chickens received these agents from 2 to 5 weeks of age in a 2 x 2 factorial arrangement. Thereafter, from 39 to 42 d of age, insulin sensitivity was estimated using the euglycaemic and hyperinsulinaemic clamp technique. Experiment 2 examined whether ALA supplementation for 5 weeks (400 mg/kg) would alter short-chain acyl-CoA concentration in the liver and in vitro lipolysis of an adipose tissue slice, in relation to noradrenaline (10 microM) supplementation. In experiment 1, ALA had no effect on the corticosterone-induced negative growth performance. ALA lowered plasma glucose level (P<0.05) and, in contrast, increased triacylglycerol level (P<0.05). These responses to ALA had, however, no interrelationship with corticosterone. The rate of glucose uptake of whole-body tissue was enhanced in the ALA-fed chickens (P<0.05), regardless of corticosterone treatment. In experiment 2, ALA increased only the plasma free glycerol concentration (P<0.01). The rate of free glycerol release from an adipose tissue slice was enhanced by ALA feeding (P<0.05) but was not affected by noradrenaline supplementation. This study suggests that ALA stimulates the insulin sensitivity of tissues regardless of corticosterone-dependent metabolism and that the ALA-induced fatty acid metabolism of broilers differs between the liver and adipose tissue.     

Relations between plasma non-esterified fatty acid metabolism and body fat mobilization in primiparous lactating goats

During early lactation ruminants can mobilize considerable amounts of body fat to maintain milk production. The aim of the present study was to evaluate the efficacy of tritiated water (TOH) and non-esterified fatty acid (NEFA) kinetics as means of monitoring adipose tissue fat mobilization in lactating goats. Body fat, as estimated by a two-pool model of TOH kinetics, and NEFA entry rate were measured in four primiparous goats at days 11, 37 and 72 post partum. Estimated body fat decreased by an average of 64 g/d between days 11 and 37 of lactation, tending to increase between days 37 and 72. Plasma NEFA concentrations and NEFA entry rate decreased as lactation advanced, being significantly lower at day 72 than at day 11 of lactation. Both plasma concentrations of NEFA and NEFA entry rate were negatively correlated with calculated energy balance. Plasma NEFA concentrations and NEFA entry rate at days 11 and 37 of lactation were positively related to average body fat losses over the subsequent stage of lactation. These results demonstrate that NEFA kinetics reflect fat mobilization in primiparous lactating goats, particularly during negative energy balance.     

Insulin response and changes in composition of non-esterified fatty acids in blood plasma of middle-aged men following isoenergetic fatty and carbohydrate breakfasts

It was previously shown that a high plasma concentration of non-esterified fatty acids (NEFA) persisted after a fatty breakfast, but not after an isoenergetic carbohydrate breakfast, adversely affecting glucose tolerance. The higher concentration after the fatty breakfast may in part have been a result of different mobilization rates of fatty acids. This factor can be investigated as NEFA mobilized from tissues are monounsaturated to a greater extent than those deposited from a typical meal. Twenty-four middle-aged healthy Caucasian men were given oral glucose tolerance tests (OGTT), and for 28 d isoenergetic breakfasts of similar fat composition but of low (L) or moderate (M) fat content. The composition of NEFA in fasting and postprandial plasma was determined on days 1 and 29. No significant treatment differences in fasting NEFA composition occurred on day 29. During the OGTT and 0-1 h following breakfast there was an increase in plasma long-chain saturated NEFA but a decrease in monounsaturated NEFA (microg/100 microg total NEFA; P<0.001). Between 1 and 3 h following breakfast treatment differences occurred for total saturated and total monounsaturated fatty acids (microg/100 microg total NEFA; P<0.05), expressed as an increase in 18 : 1 and decreases in 16 : 0 and 17 : 0 in treatment M relative to treatment L (P<0.05). Serum insulin attained 35 and 65 mU/l in treatments M and L respectively during this period. Negative correlations were found between 16 : 0 in fasting plasma and both waist:hip circumference (P=0.0009) and insulin response curve area during OGTT (within treatment M, P=0.0001). It is concluded that a normal postprandial insulin response is associated with a rapid change in plasma saturated:monounsaturated NEFA. It is proposed that this change is the result of a variable suppression of fat mobilization, which may partly account for a large difference in postprandial total plasma NEFA between fatty and carbohydrate meals.     

Energy restriction reduces long-chain saturated fatty acids associated with plasma lipids in aging male rats

Energy restriction is associated with decreased plasma insulin and glucose concentrations, whereas long-chain saturated fatty acids (LCSFA) are strongly associated with insulin resistance. Our hypothesis is that energy restriction reduces LCSFA associated with plasma lipids in adult aging rats. Plasma LCSFA associated with triglycerides (TG), nonesterified fatty acids and phospholipids, as well as glucose, insulin, free fatty acids, TG and adipocyte glucose transport and insulin-sensitive glucose transporter (GLUT4) content were determined in aging, energy restricted [ER; 60% of ad libitum (AL) intake] and AL rats. In ER rats, plasma glucose concentrations were lower than in AL rats at each age. In contrast, body weight and plasma TG concentrations increased with age in both groups, but especially in the AL rats. In AL rats, combined LCSFA associated with plasma lipids was greater than in ER rats (P < 0.0001). Adipocyte insulin-stimulated glucose transport decreased in both groups with age but was most severe in AL rats, whereas GLUT4 was reduced only in AL rats. In ER rats it is possible that decreased plasma LCSFA contribute to reduced blood glucose concentrations as well as increased adipocyte GLUT4 compared with AL rats.     

Relations between plasma non-esterified fatty acid metabolism and body tissue mobilization during chronic undernutrition in goats

1. Eleven mature goats were offered 140 kJ metabolizable energy/kg per d (M) of lucerne (Medicago sativa) hay-oaten grain (1:1, w/w) for at least 1 month before plasma non-esterified fatty acid (NEFA) kinetics and tritiated water space (TS) were determined. 2. Goats were then fed at M, 0.5 M or 0.25 M for 34 (SE 6) d, at which time the experimental procedures were repeated. 3. Chronic undernutrition resulted in elevated NEFA concentrations and NEFA entry rate, with a tendency for the ratio plasma NEFA:glycerol to increase, suggesting that body-fat mobilization during prolonged underfeeding is due more to decreased lipogenesis and intracellular NEFA re-esterification rather than to increased lipolysis. 4. Plasma NEFA concentrations and NEFA entry rate, as well as being highly correlated with each other, were significantly related to calculated energy balance and body fat losses estimated from changes in live weight and TS. 5. Increases in NEFA entry rate were highly correlated with, and of the same magnitude as, body fat losses, confirming that NEFA kinetics do quantitatively reflect lipid mobilization.     

Effect of intravenous omega-3 fatty acid infusion and hemodialysis on fatty acid composition of free fatty acids and phospholipids in patients with end-stage renal disease

Background: Patients treated with hemodialysis (HD) have been reported to have decreased levels of ω‐3 polyunsaturated fatty acids (PUFAs) in plasma and cells. The aim of this study was to investigate the effect of ω‐3 PUFAs administered intravenously during HD, as well as the effect of HD treatment, on the fatty acid composition of plasma free fatty acids (FFAs), plasma phospholipids, and platelet phospholipids. Methods: Forty‐four HD patients were randomized to groups receiving either a single dose of a lipid emulsion containing 4.1 g of ω‐3 PUFAs or placebo (saline) administered intravenously during HD. Blood was drawn immediately before (baseline) and after (4 hours) HD and before the next HD session (48 hours). Fatty acid composition was measured using gas chromatography. Results: The increase in ω‐3 FFAs was greater in the ω‐3 PUFA group compared with the placebo group, whereas the increase in total FFAs was similar between the 2 groups. In the ω‐3 PUFA group, ω‐3 PUFAs in plasma phospholipids were higher after 48 hours than at baseline, and in platelet phospholipids, ω‐3 PUFAs increased after 4 hours. In the placebo group, no changes were observed in ω‐3 PUFAs in plasma and platelet phospholipids. Conclusions: Intravenous ω‐3 PUFAs administered during HD caused a transient selective increase in ω‐3 FFA concentration. Furthermore, ω‐3 PUFAs were rapidly incorporated into platelets, and the content of ω‐3 PUFAs in plasma phospholipids increased after 48 hours.     

A method for separation of phosphatidylcholine, triacylglycerol, non-esterified fatty acids and cholesterol esters from plasma by solid-phase extraction

Efficient isolation of individual lipid classes is a critical step in the analysis of plasma and lipoprotein fatty acid compositions. Whilst good separations of total lipid extracts are possible by TLC, this method is time consuming and a major rate-limiting step when processing large numbers of specimens. A method for rapid separation of phosphatidylcholine (PC), non-esterified fatty acids (NEFA), cholesterol ester (CE) and triacylglycerol (TAG) from total plasma lipid extracts by solid-phase extraction (SPE) using aminopropyl silica columns has been developed and validated. Following initial separation of polar and neutral lipids, individual classes were isolated by application of solvents with increasing polarity. Recoveries for combined plasma extraction with chloroform-methanol and SPE were (%): PC 74.2 (SD 7.5), NEFA 73.6 (SD 8.3), CE 84.9 (SD 4.9), and TAG 86.8 (SD 4.9), which were significantly greater for TAG and NEFA than by TLC Both GC-flame ionisation detector and GC-MS analysis of fatty acid methyl esters demonstrated that there was no cross-contamination between lipid classes. Measurements of repeatability of fatty acid composition for TAG, PC, CE and NEFA fractions showed similar CV for each fatty acid. The magnitude of the CV appeared to be related inversely to the fractional fatty acid concentration, and was greatest at concentrations of less than 1 g/100 g total fatty acids. There was no evidence of selective elution of individual fatty acid or CE species. In conclusion, this method represents an efficient, rapid alternative to TLC for isolation of these lipid classes from plasma.     

Effects of supplementation with fish oil-derived n-3 fatty acids and gamma-linolenic acid on circulating plasma lipids and fatty acid profiles in women

BACKGROUND: Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and gamma-linolenic acid (GLA) have lipid-modifying and antiinflammatory properties. The effects of supplement mixtures of these fatty acids on plasma lipids and the fatty acid compositions of serum phospholipids have received little attention. OBJECTIVE: The objective was to determine the effects of different levels of GLA supplementation together with a constant intake of EPA plus DHA on the triacylglycerol-lowering effect of EPA plus DHA alone and on the fatty acid patterns (eicosanoid precursors) of serum phospholipids. DESIGN: Thirty-one women were assigned to 1 of 4 groups, equalized on the basis of their fasting triacylglycerol concentrations. They received supplements providing 4 g EPA+DHA (4:0, EPA+DHA:GLA; control group), 4 g EPA+DHA plus 1 g GLA (4:1), 2 g GLA (4:2), or 4 g GLA (4:4) daily for 28 d. Plasma lipids and fatty acids of serum phospholipids were measured on days 0 and 28. RESULTS: Plasma triacylglycerol concentrations were significantly lower on day 28 than on day 0 in the 4:0, 4:1, and 4:2 groups. LDL cholesterol decreased significantly (by 11.3%) in the 4:2 group. Dihomo-gamma-linolenic acid increased significantly in serum phospholipids only in the 4:2 and 4:4 groups; however, total n-3 fatty acids increased in all 4 groups. CONCLUSIONS: A mixture of 4 g EPA+DHA and 2 g GLA favorably altered blood lipid and fatty acid profiles in healthy women. On the basis of calculated PROCAM values, the 4:2 group was estimated to have a 43% reduction in the 10-y risk of myocardial infarction.     

Decrease of polyunsaturated fatty acids and elevation of the oleic/stearic acid ratio in plasma and red blood cell lipids of malnourished cancer patients

The fatty acids profiles of plasma and red blood cell lipids have been evaluated in 12 malnourished cancer patients in comparison with samples from eight healthy controls. In such patients, significantly lower levels of linoleic acid (LA) as percentage of total fatty acids were observed in plasma phospholipids (PL) and cholesterol esters (CE), and in red blood cells PL. The levels of arachidonic acid (AA) and the unsaturation index of the two lipid classes were also reduced in plasma CE but not in PL. In spite of the marked reduction of LA and, more generally, of total polyunsaturated fatty acids (PUFA), no elevation of eicosatrienoic acid (20:3 n-9) was observed, such acid being considered a typical index of essential fatty deficiency. Moreover, no modification of the parameters indicating impairment of the fatty acid desaturation activity was shown. In addition, the levels of palmitic and oleic acids were significantly higher in both plasma PL and CE and in red blood cells PL. The reported elevation of the oleic to stearic acid ratio in lipids of red blood cells from malnourished cancer patients, already observed by other authors, was confirmed in our study. This ratio was even more markedly elevated in plasma lipids of the patients. A very good correlation was found between the reduction of linoleic acid levels, especially in plasma CE, and weight loss, suggesting enhanced utilization of this fatty acid in association with extensive depletion of lipid stores, in this pathological state.     

Stimulation of intestinal mucosal growth with intracolonic infusion of short-chain fatty acids

Dietary fiber, which stimulates intestinal mucosal growth, is fermented by anaerobic bacteria in the rat hindgut to the short-chain fatty acids (SCFA) acetate, propionate, and butyrate. Butyrate is the preferred oxidative fuel of the colonocyte in vitro, and the provision of preferred intestinal fuels has been shown to stimulate mucosal proliferation in vivo. This study determined whether chronic colonic infusion of butyrate or a combination of SCFA would stimulate intestinal mucosal growth in an animal deprived of its normal source of SCFA, fiber fermentation in the cecum. Adult male Sprague-Dawley rats were fed a fat- and fiber-free elemental liquid diet and underwent cecectomy, ileocolic anastomosis, and insertion of a proximal colonic infusion catheter. Rats were then assigned to receive either a continuous infusion of butyrate (20 mM, 40 mM, or 150 mM), SCFA (70 mM acetate + 35 mM propionate + 20 mM butyrate), or saline, or to receive no infusion. A seventh group underwent proximal colonic transection and reanastomosis. After 7 days, jejunal, ileal, and proximal colonic segments were analyzed for mucosal weight, protein, RNA, and DNA. In the colon, the 40-mM butyrate infusion resulted in significant elevations in all mucosal parameters relative to all three control groups, saline infusion, no infusion, and transection. Both the 20-mM butyrate and the SCFA groups showed increased colonic mucosal DNA compared to controls. In the jejunum and ileum, mucosal DNA content was significantly greater in the SCFA group than in the control groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary essential amino acid deficiencies on immunological variables in broiler chickens

Two experiments were conducted to determine the effects of essential amino acid deficiencies on several immunological variables in male broiler chickens. Essential amino acids were classified into five groups as follows: S-containing amino acids (SAA; methionine + cysteine), aromatic amino acids (AAA; phenylalanine + tyrosine), branched-chain amino acids (BCAA; isoleucine + leucine + valine), arginine plus lysine (Arg + Lys), and other essential amino acids (OEAA; glycine + serine + histidine + threonine + tryptophan). Chickens were fed ad libitum from 10 to 24 d of age on a control diet or amino-acid-deficient diets formulated to contain each amino acid group at 50% and 16% (Expt 1) at 50% (Expt 2) of the recommended requirements (National Research Council, 1984). Effects of feed consumption on immune responses were also considered by setting pair-feeding (Expt 1) or restricted-feeding (Expt 2) groups fed on the control diet. In Expt 1, changes in lymphoid organ weights varied with the type and degree of deficiency of amino acid groups, with BCAA deficiency markedly decreasing weights. The haemagglutinin titres against sheep erythrocytes did not change in any amino-acid-deficient chickens except that the titres were lower in chickens fed on the 50%- and 16%-BCAA diets as compared with their pair-fed counterparts. In Expt 2, the splenocyte proliferative response to concanavalin A was higher in the chickens fed on the BCAA- and Arg + Lys-deficient diets and lower in chickens fed on the SAA- and AAA-deficient diets than the control chickens, independent of feed consumption. These results suggest that the effects of specific amino acid deficiencies on immune responses cannot be generalized, and that BCAA have the greatest potential to modulate immune responses among the amino acids in chickens.     

Intravascular metabolism of different fatty acids during lipid infusion in man

The differential intravascular metabolism of individual fatty acids contained in triacylglycerol-rich particles was studied by infusing 6 normal subjects for 5h with a conventional soy-based emulsion and an experimental olive oil-based emulsion. Both emulsions contained similar amounts of palmitate (11%) and stearate (3-4%) but the former was quite rich in linoleate (54%) and alpha-linolenate (7%), while the latter was rich in oleate (69%). During hydrolysis of circulating triacylglycerols by endothelial lipases, the associated rise of non-esterified fatty acids (FFA) in plasma represents the balance between fatty acid release and tissue uptake. Plasma levels of triacylglycerols and FFA increased about 3 fold and total body fat oxidation was raised to similar values with both emulsions. Fatty acid pattern quickly changed in plasma triacylglycerols to resemble the composition of emulsion particles, with an exception for palmitate which increased markedly more, suggesting a high level of hepatic re-esterification and re-appearance in nascent very low density lipoprotein triglycerides (VLDL-TG) secreted into the circulation. In plasma FFA, stearate and palmitate increased more and alpha-linolenate much less than expected from their content in the emulsion, indicating probably low tissue uptake for the former ones but avid removal for the latter.     

Bread enriched with microencapsulated tuna oil increases plasma docosahexaenoic acid and total omega-3 fatty acids in humans

The aim of this study was to determine the acute and chronic effects of low doses of long chain (LC) n-3 polyunsaturated fatty acids (PUFA) (<100 mg per day) on plasma LC n-3 PUFA levels using a novel delivery form; bread containing microencapsulated tuna oil (MTO). Six omnivores (three men and three women) participated in the acute study, which involved ingesting a prototype MTO bread containing approximately 80 mg of LC n-3 PUFA/four slices. Plasma triacylglycerol fatty acid compositions were measured after an overnight fast and postprandially at 2 and 4 h. In the chronic study, 10 vegetarian subjects (nine men and one woman) consumed MTO bread at six to eight slices/day (comprising 60 mg of LC n-3 PUFA) as the only dietary source of these PUFA for three weeks. Fasting plasma total and phospholipid fatty acid compositions were measured at baseline and endpoint. In the acute study, the proportions of 22:6 n-3 and total n-3 PUFA in plasma triacylglycerol were significantly increased (P < 0.05). In the chronic study, the proportions of 20:5 n-3, 22:5 n-3, 22:6 n-3, total n-3 PUFA in plasma, and 22:6 n-3 and total n-3 PUFA in plasma phospholipid fractions were significantly increased (P < 0.05) at the endpoint compared with the baseline. This study showed that a low dose of LC n-3 PUFA, consumed as MTO-enriched bread, was bioavailable, as measured by an increase in LC n-3 PUFA levels in the plasma of human subjects.     

Phytanic acid: measurement of plasma concentrations by gas-liquid chromatography-mass spectrometry analysis and associations with diet and other plasma fatty acids

Epidemiological data suggest that a diet rich in animal foods may be associated with an increased risk of several cancers, including cancers of the prostate, colorectum and breast, but the possible mechanism is unclear. It is hypothesised that phytanic acid, a C20 branched-chain fatty acid found predominantly in foods from ruminant animals, may be involved in early cancer development because it has been shown to up regulate activity of alpha-methylacyl-coenzyme A racemase, an enzyme commonly found to be over-expressed in tumour cells compared with normal tissue. However, little is known about the distribution of plasma phytanic acid concentrations or its dietary determinants in the general population. The primary aim of the present cross-sectional study was to determine circulating phytanic acid concentrations among ninety-six meat-eating, lacto-ovo-vegetarian and vegan women, aged 20-69 years, recruited into the Oxford component of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Meat-eaters had, on average, a 6.7-fold higher geometric mean plasma phytanic acid concentration than the vegans (5.77 v. 0.86 micromol/l; P < 0.0001) and a 47 % higher mean concentration than the vegetarians (5.77 v. 3.93 micromol/l; P = 0.016). The strongest determinant of plasma phytanic acid concentration appeared to be dairy fat intake (r 0.68; P < 0.0001); phytanic acid levels were not associated with age or other lifestyle factors. These data show that a diet high in fat from dairy products is associated with increased plasma phytanic acid concentration, which may play a role in cancer development.     

肥胖儿童血浆长链脂肪酸的变化

【目的】观察单纯性肥胖儿童血浆各脂肪酸水平的变化,探讨其与瘦素及可溶性瘦素受体(soluble leptin-R,sOB-R)之间的关系。【方法】于2006年选取36例3~6岁的单纯性肥胖儿童及按性别、年龄1∶1配对的36例正常儿童为研究对象,采用气相色谱分析法测定其血浆各脂肪酸含量,瘦素及sOB-R的测定采用ELISA方法。【结果】肥胖儿童血浆软油酸(C16∶1n-7)、油酸(C18∶1n-9)和二十碳五烯酸(EPA,C20∶5n-3)含量(1.94%±0.58%,18.55%±3.04%和1.31%±0.04%)均显著高于正常儿童(1.50%±0.32%,17.12%±1.77%和1.10%±0.05%)(P<0.05),同时C16∶1n-7/棕榈酸(C16∶0)比值与C18∶1n-9/硬脂酸(C18∶0)比值(0.09±0.01和2.50±0.37)亦较正常儿童(0.07±0.01和2.21±0.31)显著升高(P<0.01);相反,血浆亚油酸(LA,C18∶2n-6)及花生四烯酸(AA,C20∶4n-6)含量(32.97±1.04%和7.08±0.20%)较正常儿童(35.50±0.41%和7.64±0.20%)明显降低(P<0.05)。相关性分析显示,血浆EPA与瘦素之间呈正相关,与sOB-R呈负相关;而LA及AA与瘦素呈负相关,与sOB-R呈正相关(P<0.05)。【结论】肥胖时机体Δ-9去饱和酶活性增加,n-3脂肪酸的代谢强于n-6脂肪酸,这可能是肥胖状态下机体为降低血脂水平、以及抵抗其它病理生理反应而进行的反应性调节现象;同时脂肪酸的代谢紊乱可能在某种程度上参与了瘦素抵抗的发生。     

Effect of dietary conjugated linoleic acid on body composition and energy balance in broiler chickens

The effect of dietary conjugated linoleic acid (CLA) on body composition and energy metabolism was investigated in broiler chickens. Male broiler chicks were assigned to receive either a control diet (1 % sunflower oil) or a diet containing CLA (1 % of a 1:1 mixture of trans-10, cis-12 and cis-9, trans-11 isomers of octadecadienoic acid). The diets were fed ad libitum for 3 weeks and there were eight replicates per diet, each replicate including four chickens so that each treatment had thirty-two animals. The proportion of body fat was lower in the control group than in the CLA group. No significant differences as to the proportions of body water, ash and protein were observed. Feed and energy intake were significantly lower in CLA-fed birds. The percentage of ingested energy lost in excreta was higher after CLA feeding and heat expenditure as a percentage of ingested energy was lower in the CLA-fed group. The CLA-fed group showed a higher percentage of SFA and lower percentages of MUFA and PUFA in carcass fat. It is concluded that CLA stimulated de novo fatty acid synthesis and lowered desaturase activity.