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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #106649
Title: CONJUGATED LINOLEIC ACID MODULATES THE DIFFERENTIATION OF PORCINE ADIPOCYTES IN VITRO

Author
item DING, SHIH-TORNG - BAYLOR COLLEGE OF MED.
item MCNEEL, RONALD - BAYLOR COLLEGE OF MED.
item Mersmann, Harry

Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2000
Publication Date: 12/1/2000
Citation: N/A

Interpretive Summary: Conjugated linoleic acid (CLA) is a fatty acid found in ruminant animals, and human beings ingest it in cow milk as well as other sources. Dietary CLA has been shown in studies to reduce the fat concentration of cow milk, and to reduce the amount of body fat in mice and pigs, so it is an increasingly interesting focal point in an era when human obesity is becoming rampant on a national scale. Adipose (fat) tissue grows as preadipocytes, or precursor cells, differentiate into fat cells. Therefore, we wanted to determine the effects of CLA on pig vascular cells in regard to their differentiation into fat cells in culture. We also measured the effects of CLA on transcript levels, examining the RNA for certain proteins involved in this differentiation process. We used linoleic acid (LA) for purposes of comparison. LA is a much more prevalent fatty acid that is very similar to CLA, but LA has not been shown to reduce fat deposition. Our results showed that CLA stimulates and acutely increases short-term differentiation of pig fat cells but inhibits it in the long term, as evidenced by decreased transcript concentrations. In contrast, LA stimulates differentiation in the short term but does not inhibit it in the long term. These are very interesting findings that contribute useful information to the scientific progress made in evaluating the long-term effects of CLA and understanding fat cell development.

Technical Abstract: Individual fatty acids can modulate adipocyte differentiation and conjugated linoleic acid (CLA) either stimulates or inhibits 3T3-L1 clonal cell differentiation. We tested the effects of 9cis, 11trans-CLA (9,11- CLA), 10trans, 12cis-CLA (10,12-CLA), and linoleic acid (C18:2) on differentiation of porcine stromal-vascular cells in vitro and on adipocyte etranscription factor and adipocyte-characteristic protein mRNA concentrations. The effects of the two CLA isomers were similar, but occasionally 9,11-CLA was numerically more effective than 10,12-CLA. After 1 day, C18:2 tended to, and both CLA isomers increased differentiation. There was cell loss after 2 days incubation with CLA and extensive loss after 5 days with C18:2 or CLA. Peroxisome proliferator-activated receptor gamma(PPARgamma) mRNA was decreased by CLA after 2 or 5 days, but not by C18:2. Lipoprotein lipase (LPL) mRNA was decreased by either CLA isomer after 2 days, but not by C18:2. Adipocyte fatty acid binding protein aP2) mRNA concentration was increased by C18:2 and both isomers of CLA. In summary, both CLA isomers and C18:2 increased differentiation of porcine stromal-vascular cells after 1 day. By 2 days, CLA inhibited differentiation of porcine stromal-vascular cells after 1 day. By 2 days, CLA inhibited differentiation as evidenced by decreased PPARgamma and LPL transcript concentrations. The aP2 mRNA was elevated by C18:2 and both CLA isomers. Perhaps the regulation of aP2 transcription was not through increased transcription and translation of PPARgamma, but through activity of metabolites of the unsaturated fatty acids.