SITE-SPECIFIC REGULATION OF GENE-EXPRESSION BY N-3 POLYUNSATURATED FATTY-ACIDS IN RAT WHITE ADIPOSE TISSUES

Dietary n-3 polyunsaturated fatty acids (n-3 PUFAs) limit abdominal fa t depot hypertrophy. This could be due to regulation of the expression of proteins involved in adipose tissue metabolism. We investigated in vivo whether fatty acid synthase (FAS), hormone-sensitive lipase (HSL ), lipoprotein lipase (LPL), phosphoenolpyruvate carboxykinase (PEPCK) , CCAAT/enhancer binding protein alpha (C/EBP alpha), and leptin mRNA levels are affected in retroperitoneal (RP) and subcutaneous adipose t issues (SC) of rats fed n-3 PUFAs. For 4 weeks rats were fed high fat diets (20% fat) containing n-3 PUFAs given as eicosapentaenoic acid (E PA group), dos cosahexaenoic acid (DHA group), a mixture of these two fatty acids (MIX group), or native fish oil (FO group). A control grou p was fed with lard plus olive oil (LOG group). Final mean fat cell we ight in RP ranged according to: LOO greater than or equal to EPA great er than or equal to DHA = FO = MIX. There was no difference in fat cel l size of SC when comparing die LOO and MI); groups. The fatty acid co mpositions of RP and SC were similar and resemble that of dietary fat within each experimental group. In RP and compared to the LOO group, F AS, HSL, PEPCK, LPL, C/EBP alpha, and leptin mRNA levels decreased alt hough not significantly in the EPA group, and were 40-75% lower in the DHA and MIX groups. mRNA levels were positively correlated to fat cel l size in RP. In contrast, n-3 PUFAs had no effect on gene expression in SC. We conclude that n-3 PUFAs and mainly 22:6n-3 affect gene expre ssion in a site-dependent manner in white adipose tissues via possible antiadipogenic effects.