Effects of conjugated linoleic acid isomers on the hepatic microsomal desaturation activities <i>in vitro</i>

Brétillon, Lionel; Chardigny, Jean‐Michel; Grégoire, Stéphane; Berdeaux, Olivier; Sébédio, Jean‐Louis

doi:10.1007/s11745-999-0446-9

Cited by 141 publications

(100 citation statements)

References 30 publications

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“…These results were also consistent with those of Geiger et al [26] who showed that there is always preferential ∆6-desaturation of the fatty acids of the n-3 family. On the basis of the above experimental conditions, ∆6-desaturase activities in cultured rat hepatocytes were consistent with the values obtained with freshly extracted microsomes from rat liver [10,[26][27][28][29][30].…”

Section: Discussionsupporting

confidence: 85%

Myristic acid increases Δ6-desaturase activity in cultured rat hepatocytes

Jan¹,

Guillou²,

d’Andréa³

et al. 2004

Reprod. Nutr. Dev.

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-In order to study the effects of saturated fatty acids on ∆6-desaturase activity, rat hepatocytes in primary culture were incubated with lauric (C12:0), myristic (C14:0) or palmitic (C16:0) acids. After optimization, the standard in vitro conditions for the measurement of ∆6-desaturase activity were as follows: 60 µmol·L -1 α-linolenic acid (C18:3n-3), reaction time of 20 min and protein content of 0.4 mg. Data showed that cell treatment with 0.5 mmol·L -1 myristic acid during 43 h specifically increased ∆6-desaturase activity. This improvement, reproducible for three substrates of ∆6-desaturase, i.e. oleic acid (C18:1n-9), linoleic acid (C18:2n-6) and α-linoleic acid (C18:3n-3) was dose-dependent in the range 0.1-0.5 mmol·L -1 myristic acid concentration. myristic acid / ∆6-desaturase / saturated fatty acids / cultured rat hepatocytes

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Section: Discussionsupporting

confidence: 85%

Myristic acid increases Δ6-desaturase activity in cultured rat hepatocytes

Jan¹,

Guillou²,

d’Andréa³

et al. 2004

Reprod. Nutr. Dev.

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“…The inhibition of LPL activity is significantly correlated with the suppressing effect of CLA on lipogenesis. 13,58,59,71 The mRNA levels of lipogenic enzymes, FAS and ACC, showed marked decreases in female C57BL/6J mice after 5 months of supplementation with 1% CLA. 20 The expression of lipogenic enzymes is regulated by the transcription factor sterol regulatory element-binding protein (SREBP)-1.…”

Section: Conjugated Linoleic Acid and Obesitymentioning

confidence: 99%

“…57 Dietary CLA has also been shown to suppress the expression and activity of PPARg. 30,57 Many studies have demonstrated that CLA possesses a capacity to inhibit the expression and activity of SCD 30,58,59 and GLUT-4. 20,37,57 Consequently, several studies have demonstrated that CLA inhibits differentiation and represses adipocyte gene expression during the in vitro differentiation of mouse 3T3-L1 preadipocytes into adipocytes.…”

Section: Cla Alters Preadipocyte Differentiationmentioning

confidence: 99%

“…Many in vitro studies have shown that CLA causes lipid mobilization, resulting in decreased concentrations of intracellular triglyceride and glycerol and increased free glycerol in the culture medium of 3T3-L1 preadipocytes. 10,13,58,59,71,73,74 A most recent study has shown that t10c12, but not c9t11, CLA decreases the triglyceride content of human adipocytes in culture by decreasing glucose and fatty acid uptake. 30 The inhibitory effect of CLA on the lipogenesis has been observed in cows and the cultures of human preadipocytes.…”

Section: Conjugated Linoleic Acid and Obesitymentioning

confidence: 99%

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Conjugated linoleic acid and obesity control: efficacy and mechanisms

2004

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Obesity is associated with high blood cholesterol and high risk for developing diabetes and cardiovascular disease. Therefore, management of body weight and obesity are increasingly considered as an important approach to maintaining healthy cholesterol profiles and reducing cardiovascular risk. The present review addresses the effects of conjugated linoleic acid (CLA) on fat deposition, body weight and composition, safety, as well as mechanisms involved in animals and humans. Animal studies have shown promising effects of CLA on body weight and fat deposition. The majority of the animal studies have been conducted using CLA mixtures that contained approximately equal amounts of trans-10, cis-12 (t10c12) and cis-9, trans-11 (c9t11) isomers. Results of a few studies in mice fed CLA mixtures with different ratios of c9t11 and t10c12 isomers have indicated that the t10c12 isomer CLA may be the active form of CLA affecting weight gain and fat deposition. Inductions of leptin reduction and insulin resistance are the adverse effects of CLA observed in only mice. In pigs, the effects of CLA on weight gain and fat deposition are inconsistent, and no adverse effects of CLA have been reported. A number of human studies suggest that CLA supplementation has no effect on body weight and insulin sensitivity. Although it is suggested that the t10c12 CLA is the antiadipogenic isomer of CLA in humans, the effects of CLA on fat deposition are marginal and more equivocal as compared to results observed in animal studies. Mechanisms through which CLA reduces body weight and fat deposition remain to be fully understood. Proposed antiobesity mechanisms of CLA include decreased energy/food intake and increased energy expenditure, decreased preadipocyte differentiation and proliferation, decreased lipogenesis, and increased lipolysis and fat oxidation. In summary, CLA reduces weight gain and fat deposition in rodents, while produces less significant and inconsistent effects on body weight and composition in pigs and humans. New studies are required to examine isomer-specific effects and mechanisms of CLA in animals and humans using purified individual CLA isomers.

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“…The outflow from the column was split between a flame-ionization detector (10%) and a copper oxide oven heated at 700 °C in order to transform labelled FA into [1-14 C] CO 2 (90%). The radioactivity was determined with a radiodetector (GC-RAM, Lablogic, Sheffield, UK) by counting [1-14 C] CO 2 as previously described by Bretillon et al [28]. Data were computed using Laura software (Lablogic, Sheffield, UK).…”

Section: Determination Of Fa Bioconversionmentioning

confidence: 99%

In vitro metabolism of rumenic acid in bovine liver slices

et al. 2005

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-Ruminant products are the major source of CLA for humans. However, during periods of fat mobilization, the liver might play an important role in CLA metabolism which would limit the availability of the latter for muscles and milk. In this context, rumenic acid (cis-9, trans-11 CLA) metabolism in the bovine liver (n = 5) was compared to that of oleic acid (n = 3) by using the in vitro liver slice method. Liver slices were incubated for 17 h in a medium containing 0.75 mM of FA mixture and 55 µM of either [1-14 C] rumenic acid or [1-14 C] oleic acid at 37 °C under an atmosphere of 95% O 2 -5% CO 2 . Rumenic acid uptake by liver slices was twice (P = 0.009) that of oleic acid. Hepatic oxidation of both FA (> 50% of incorporated FA) led essentially to the production of acidsoluble products and to a lower extent to CO 2 production. Rumenic acid was partly converted (> 12% of incorporated rumenic acid) into conjugated C18:3. CLA and its conjugated derivatives were mainly esterified into polar lipids (71.7%), whereas oleic acid was preferentially esterified into neutral lipids (59.8%). Rumenic acid secretion as part of VLDL particles was very low and was onefourth lower than that of oleic acid. In conclusion, rumenic acid was highly metabolized by bovine hepatocytes, especially by the oxidation pathway and by its conversion into conjugated C18:3 for which the biological properties need to be elucidated. rumenic acid / oleic acid / metabolism / liver / bovine Abbreviations: ASP, acid-soluble products; BSA, bovine serum albumin; CLA, conjugated linoleic acid; FA, fatty acids; NL, neutral lipids; PL, polar lipids; VLDL, very-low density lipoproteins.

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Effects of conjugated linoleic acid isomers on the hepatic microsomal desaturation activities in vitro

Cited by 141 publications

References 30 publications

Myristic acid increases Δ6-desaturase activity in cultured rat hepatocytes

Myristic acid increases Δ6-desaturase activity in cultured rat hepatocytes

Conjugated linoleic acid and obesity control: efficacy and mechanisms

In vitro metabolism of rumenic acid in bovine liver slices

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