Conjugated Linoleic Acid In Tissue Research Articles

Conjugated Linoleic Acid Regulates Body Composition and Locomotor Activity in a Sex‐Dependent Manner in Drosophila melanogaster

Conjugated linoleic acid (CLA) has been reported to be a bioactive food component. However, there is limited knowledge on the sex-dependent effects of CLA on energy metabolism. In the present study, Drosophila melanogaster was used to investigate the sex-dependent effects of CLA with respect to body fat, muscle, locomotion, and a key metabolic regulator, AMP-activated protein kinase α (AMPKα). Adult flies were fed a cornmeal-based fly food with 0.5% of CLA oil (50:50 of cis-9,trans-11 and trans-10,cis-12 CLA isomers in triacylglycerol (TAG) form), 0.5% safflower oil (high in linoleic acid [LNA] as control), or 0.5% water (as blank) for 5 days. Accumulation of CLA in tissue was verified using gas chromatography-mass spectrometry. CLA-fed flies had reduced TAG and increased locomotor activity when compared to LNA-fed control flies. In addition, CLA increased the muscle content when compared to the blank. Moreover, following CLA supplementation, increased AMPKα activity was observed in females, but not in males. These sex-dependent metabolic effects of CLA may be due to physiological differences in lipid metabolism and nutrient requirements. In conclusion, CLA promoted the body composition and locomotion behavior in D. melanogaster and regulated the sex-specific metabolism in part via AMPKα. As key physiological processes are conserved between fly and human, information obtained from this research could provide valuable insights into sex-dependent responses to CLA in humans.

Effects of conjugated linoleic acid on growth, body composition, antioxidant status, lipid metabolism and immunity parameters of juvenile Chu's croaker,Nibea coibor

A-56 days feeding trial was conducted to evaluate the growth performance, feed utilization, biochemical composition, antioxidant status, lipid metabolism and immunity parameters of Chu's croaker Nibea coibor fed diets supplemented with different levels of conjugated linoleic acid (CLA): 0% (control), 0.5%, 1%, 1.5% and 2%. Each diet was randomly assigned to triplicate groups of 25 fish (initial body weight: 12.8 ± 0.1 g) in 15 floating cage. Weight gain (WG) and specific growth rate (SGR) were not significantly affected. 2% of dietary CLA led to significant lower lipid content in both whole body and liver (p < .05). Muscle lipid content was significantly lower in fish fed 1.5% and 2% CLA (p < .05). Saturated fatty acid (SFA) increased while monounsaturated fatty acid (MUFA) decreased with increasing dietary CLA in tissues (p < .05). Increasing CLA significantly promoted hepatic lipase (HL), lipoprotein lipase (LPL), serum lysozyme (LSZ) and immunoglobulin M (IgM) while decreased serum triglyceride (TG) in both liver and serum (p < .05). Liver Superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (t-AOC) increased while malondialdehyde (MDA) decreased (p < .05). Our study shown that Chu's croaker can successfully incorporate CLA in tissues up to 2% dietary lipid without growth inhibition, and that CLA increased fish quality due to the increased parameters of lipid metabolism, specific immunity, hepatic antioxidant and CLA accumulation, and the reduction of tissue fat deposition.

Incorporation of conjugated linoleic acid into brain lipids is not necessary for conjugated linoleic acid–induced reductions in feed intake or body fat in mice

Dietary conjugated linoleic acid (CLA) causes reduced feed intake (FI) and body fat (BF). It is unknown, though, if CLA incorporation into tissues, alterations in serum hormones, and/or appetite-regulating neuropeptides are involved. We hypothesized that CLA incorporation into brain lipids would be correlated with changes in appetite-regulating neuropeptide expression and reductions in FI and BF. Male mice (n = 150; 9 weeks old, ICR) received the control diet ad libitum (CON), 2% CLA diet ad libitum (CLA), or control diet pair-fed to the intake of CLA-fed mice for 1, 2, 3, 5, or 7 days. Both FI and body weight were measured daily, and a BF index was calculated. Liver, adipose, and brain fatty acids; serum insulin, leptin, and peptide YY; and arcuate nucleus neuropeptide Y, agouti-related protein, and α-melanocyte–stimulating hormone protein were determined. Mice fed CLA ate less (P < .05) than did the CON on days 1, 2, 3, and 7 but were leaner (P < .05) only on day 7. Mice that received the control diet pair-fed to the intake of CLA-fed mice did not differ in BF from the CON. By days 1 and 2, CLA isomers were incorporated into the liver and adipose but not in the brain. Insulin was increased in CLA-fed mice on days 5 and 7, and leptin was decreased on day 7. Peptide YY and the neuropeptides did not differ. Tissue CLA was not correlated with FI, body weight, or BF but was positively correlated with insulin and negatively correlated with leptin. The reduction in FI is not sufficient to cause the reduction in BF, and tissue CLA accumulation does not appear to be required.

Biological activities of conjugated fatty acids: conjugated eicosadienoic (conj. 20:2?), eicosatrienoic (conj. 20:3?), and heneicosadienoic (conj. 21:2?) acids and other metabolites of conjugated linoleic acid

The elongated form of conjugated linoleic acid (CLA), conjugated eicosadienoic acid (CEA, conj. 20:2Δ c11,t13/t12,c14 ), was generated from CLA by liver microsomal fractions. Subsequent testing showed that dietary CEA significantly reduced body fat, and increased lean mass similar to CLA when compared to controls. CEA also decreased lipoprotein lipase activity and triacylglyceride, and increased glycerol release in 3T3-L1 adipocytes, correlated with the trans -12, cis -14 isomer, but CEA required a longer incubation period than cells treated with CLA. Based on the fact that CEA fed animals had CLA in tissue, we suggest that the effect of CEA is due to the CLA converted from CEA in the system. The delta-6 desaturated and elongated form of trans -10, cis -12 CLA (conjugated eicosatrienoic acid, CETA, conj. 20:3Δ c8,t12,c14 ) inhibited LPL activity and increased glycerol release but was less active than trans -10, cis -12 CLA or CEA. The 21-carbon conjugated fatty acid, conjugated heneicosadienoic acid (CHDA, conj. 21:2Δ c12,t14/c13,t15 ), was not active on LPL inhibition, triacylglyceride, or glycerol release in 3T3-L1 adipocytes. We also provide evidence that CLA was metabolized to conjugated dodecadienoic acid (conj. 12:2Δ c3,t5/t4,c6 ). In addition, there were indications of the presence of conjugated tetradecadienoic acid (conj. 14:2Δ c5,t7/t6,c8 ), suggesting that CLA can be metabolized through fatty acid β-oxidation. This is the first work to report the presence of conjugated 12 and 14 carbon fatty acids, originated from CLA, and the biological activities of CEA, CETA and CHDA.

Biological activities of conjugated fatty acids: conjugated eicosadienoic (conj. 20:2Δ c11,t13/t12,c14), eicosatrienoic (conj. 20:3Δ c8,t12,c14), and heneicosadienoic (conj. 21:2Δ c12,t14/c13,t15) acids and other metabolites of conjugated linoleic acid

The elongated form of conjugated linoleic acid (CLA), conjugated eicosadienoic acid (CEA, conj. 20:2Δ c11,t13/t12,c14), was generated from CLA by liver microsomal fractions. Subsequent testing showed that dietary CEA significantly reduced body fat, and increased lean mass similar to CLA when compared to controls. CEA also decreased lipoprotein lipase activity and triacylglyceride, and increased glycerol release in 3T3-L1 adipocytes, correlated with the trans-12, cis-14 isomer, but CEA required a longer incubation period than cells treated with CLA. Based on the fact that CEA fed animals had CLA in tissue, we suggest that the effect of CEA is due to the CLA converted from CEA in the system. The delta-6 desaturated and elongated form of trans-10, cis-12 CLA (conjugated eicosatrienoic acid, CETA, conj. 20:3Δ c8,t12,c14) inhibited LPL activity and increased glycerol release but was less active than trans-10, cis-12 CLA or CEA. The 21-carbon conjugated fatty acid, conjugated heneicosadienoic acid (CHDA, conj. 21:2Δ c12,t14/c13,t15), was not active on LPL inhibition, triacylglyceride, or glycerol release in 3T3-L1 adipocytes. We also provide evidence that CLA was metabolized to conjugated dodecadienoic acid (conj. 12:2Δ c3,t5/t4,c6). In addition, there were indications of the presence of conjugated tetradecadienoic acid (conj. 14:2Δ c5,t7/t6,c8), suggesting that CLA can be metabolized through fatty acid β-oxidation. This is the first work to report the presence of conjugated 12 and 14 carbon fatty acids, originated from CLA, and the biological activities of CEA, CETA and CHDA.

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on fatty acid composition of adipose tissues in beef cattle.

Thirty-six Angus x Hereford heifers (365 +/- 60 kg) were used to determine the effects of supplemental dietary lipid sources on fatty acid composition of i.m., perianal (p.a.), and s.c. lipid depots. Lipid was supplied to diets as either corn oil or a rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed. Following an initial 56-d feeding period, heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% rumen-protected CLA salt (RPCLA) containing 31% CLA. The trans-10, cis-12 CLA concentration was greatest (P < 0.05) for heifers fed RPCLA and OIL diets and least (P < 0.05) for CON, regardless of time on dietary treatment. Heifers fed supplemental RPCLA had greater (P < 0.05) total CLA content than either CON- or OIL-fed heifers. Adipose tissue concentration of trans-11 vaccenic acid (TVA) was less (P < 0.05) for CON than OIL or RPCLA, which did not differ (P > 0.05). Percentages of C18:1 trans-10 were least (P < 0.05) in i.m. lipid compared with p.a. and s.c., which did not differ (P > 0.05). Following 60 d of lipid supplementation, heifers fed OIL and RPCLA had lower (P < 0.05) concentrations of oleic acid and total monounsaturated fatty acids (MUFA) compared with CON. The ratio of cis-9, trans-11 CLA:TVA was higher (P < 0.05) for heifers fed 60 vs. 32 d, but did not differ (P > 0.05) between adipose depots. Feeding OIL increased (P < 0.05) adipose concentration of C18:2 fatty acid, whereas feeding RPCLA increased (P < 0.05) total CLA isomers by 22%. Intramuscular lipid contained the lowest (P < 0.05) percentage of cis-9, trans-11 CLA, total CLA, C18:1 cis-9, C18:1 trans-10, and TVA. Total CLA and cis-9, trans-11 CLA isomers were increased (P < 0.05) in p.a. and s.c. adipose depots, whereas i.m. adipose tissue contained increased (P < 0.05) amounts of total PUFA. Results from this study indicate that short-term lipid supplementation to feedlot cattle can increase adipose tissue CLA concentrations, but only marginally (8.3 to 17.5%). Moreover, observed decreases in oleic acid and total MUFA concentrations of adipose tissues from heifers fed rumen-protected CLA or corn oil suggest that lipid supplementation may decrease delta9 desaturase activity in adipose tissues, which in turn would lower the conversion of TVA to cis-9, trans-11 CLA isomer.

Volatile Profiles and Lipid Oxidation of Irradiated Cooked Chicken Meat from Laying Hens Fed Diets Containing Conjugated Linoleic Acid

The objective of this study was to determine the influence of dietary conjugated linoleic acid (CLA) on lipid oxidation, volatile profiles, and sensory characteristics of irradiated cooked chicken meat. Forty-eight 27-wk-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5, or 5.0% CLA. After 12 wk of feeding trial, hens were slaughtered, and boneless, skinless breast and thigh muscles were separated. Meats of three birds from a dietary treatment were pooled and ground together through a 9-mm and a 3-mm plate, and patties were prepared. Patties were individually packaged and cooked in a water bath at 85 C for 15 min. After cooling to room temperature, patties were repackaged in oxygen-permeable or oxygen-impermeable bags, irradiated at 0 or 3 kiloGray (kGy) with an electron beam irradiator, and analyzed for lipid oxidation, volatile profiles, and sensory characteristics at 0 and 5 d of storage at 4 C. Cooked meat patties from hens fed CLA diets had lower TBA-reactive substances values and produced less hexanal and pentanal than the control. The irradiated and nonirradiated cooked chicken meat with aerobic packaging developed severe lipid oxidation during the 5-d storage at 4 C. Irradiation accelerated lipid oxidation in aerobic-packaged cooked chicken meat, but its effect was not as significant as that of the packaging. No odor differences were found among the cooked chicken meats from the different dietary CLA treatments. The increased storage stability of cooked meat from hens fed CLA diets was caused by the increased saturated fatty acids and CLA content in meat lipids. Tissue CLA was stable from oxidative changes and had minimal effect on volatile production in irradiated and nonirradiated cooked chicken meat during storage.

Effect of dietary supplementation with either conjugated linoleic acid (CLA) or linoleic acid rich oil on the CLA content of lamb tissues

Conjugated linoleic acid (CLA) is produced in the rumen by isomerization of linoleic acid and has been shown to be a potent anticarcinogen in animal model studies. The objective of this study was to compare the relative increase in the CLA content of lamb tissues by dietary CLA supplementation (0.33 g/d for 21 days prior to weaning) to milk-replacer of pre-ruminant lambs or by feeding linoleic acid rich oil (Safflower oil, 6% DM-SAFF) to weaned ruminating lambs with that of lambs receiving unsupplemented milk-replacer and pelleted feed. Thirteen lambs were randomized to three dietary treatments (CLA-4, SAFF-4 and Control-5) and fed the pelleted diet for 80 days after weaning. Lambs were slaughtered at an average weight of 45 kg and tissue samples were procured from pars costalis diaphragmatis, leg, rib, subcutaneous adipose and liver for determination of fat and CLA content and fatty acid composition. Dietary supplementation with safflower oil increased fat content of subcutaneous adipose tissue only, but the CLA content of all the tissues was increased ( P < 0.05) by more than 200%. Dietary safflower oil increased ( P < 0.05) C18:2 in all tissues and C16:0 in the diaphragm, and decreased ( P < 0.05) C18:1 and C18:3 content in all tissues. Supplementation of the diet with pre-formed CLA prior to weaning decreased ( P < 0.05) fat content of the adipose tissue with decreases occurring in C18:0 relative to animals receiving the unsupplemented diet, however, tissue CLA content was not affected by provision of dietary CLA to pre-ruminant lambs. Results indicated that supplementation of lamb feedlot diets with a source of linoleic acid was a successful method of increasing CLA content of tissues.

Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid.

Two experiments were conducted. In Experiment 1, 8-wk-old mice were fed control diet or diet supplemented with 0.5% conjugated linoleic acid (CLA) to study the effect of CLA on body composition (CLA: 40.8-41.1% c-9,t-11 isomer, 43.5-44.9% t-10,c-12 isomer). The data for CLA-fed mice vs. controls described parallel but significantly distinct responses for both absolute and relative changes in body fat mass (reduced in CLA-fed mice) and for relative changes in whole body protein and whole body water (both of which were increased in CLA-fed mice). In the CLA-fed mice, the effect on whole body protein appeared to precede the reduction in body fat mass. In Experiment 2, weanling mice were fed control diet or diet supplemented with 0.5% CLA for 4 wk (test group), at which time all mice were fed control diet devoid of added CLA. The test group exhibited significantly reduced body fat and significantly enhanced whole body water relative to controls at the time of diet change. Time trends for changes in relative body composition were described by parallel lines where the test group exhibited significantly less body fat but significantly more whole body protein, whole body water, and whole body ash than controls. Tissue CLA levels declined following the withdrawal of CLA from the diet. In skeletal muscle of mice fed CLA-supplemented diet, the t-10,c-12 isomer was cleared significantly faster than the c-9,t-11 CLA isomer.

Conjugated Linoleic Acid (9,11- and 10,12-Octadecadienoic Acid) Is Produced in Conventional but Not Germ-Free Rats Fed Linoleic Acid

Conjugated linoleic acid (CLA) is an anticarcinogen in several model animal systems. Conjugated linoleic acid occurs naturally in food and is present at higher concentrations in products from ruminant animals. Given that certain rumen microorganisms produce CLA from free linoleic acid, we studied the effect of feeding free or esterified linoleic acid on tissue CLA concentrations using conventional and germ-free rats. Conventional rats were fed a 5% (wt/wt) corn oil control diet alone or supplemented with 5% free linoleic acid or 8.63% corn oil (equivalent to 5% linoleic acid in triglyceride). Germ-free rats were fed autoclavable nonpurified diet alone or supplemented with 5% free linoleic acid. Analyses of CLA concentrations were performed on lipids extracted from liver, lung, kidney, skeletal muscle and abdominal adipose tissue, and on liver phospholipid and neutral lipid fractions. Tissue CLA concentrations were higher in conventional rats fed free linoleic acid (the major isomers were cis-9, trans-11 and trans-9, cis-11) than in control animals. Conjugated linoleic acid concentrations in free linoleic acid-fed rats were maximal at 4 wk, and levels were 5-10 times higher than those of controls. Elevated CLA concentrations were also observed in liver phospholipid and neutral lipid fractions. In contrast, CLA concentrations in the tissues of germ-free rats were not affected by diet. Feeding the corn oil-fortified diet to conventional rats did not increase CLA concentration in the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)