Eicosapentaenoic acid, but not oleic acid, stimulates β‐oxidation in adipocytes

Abstract

The beneficial roles of dietary fish oil in lowering serum TAG levels in animals and humans have been attributed in part to the high content of two n-3 polyunsaturated very long-chain FA, EPA, and DHA. Recent studies show that EPA induces mitochondrial beta-oxidation in hepatocytes, which might contribute to the systemic lipid-lowering effect. Whether EPA affects FA storage or oxidation in adipocytes is not clear. To investigate this possibility, 3T3-L1 adipocytes incubated with EPA (100 microM) for 24 h were assayed for beta-oxidation, carnitine palmitoyl transferase 1 (CPT-1) activity, protein, and mRNA expression of CPT-1. For comparison, cells treated with oleic acid, octanoic acid, and clofibrate, a synthetic ligand for peroxisome proliferator-activated receptor alpha were also analyzed. Mitochondria were isolated by differential centrifugation, and the mitochondrial membrane acyl chain composition was measured by GLC. EPA increased the oxidation of endogenous FA but did not inhibit lipogenesis. Oleic acid and clofibrate did not affect FA oxidation or lipogenesis, whereas octanoic acid suppressed the oxidation of endogenous FA and inhibited lipogenesis. Increased beta-oxidation by EPA was associated with increased CPT-1 activity but without changes in its mRNA and protein expression. EPA treatment increased the percentage of this FA in the mitochondrial membrane lipids. We suggest that EPA increased the activity of CPT-1 and beta-oxidation in adipocytes by altering the structure or dynamics of the mitochondrial membranes.

Randomly Interesterified Triacylglycerol Containing Medium- and Long-Chain Fatty Acids Stimulates Fatty Acid Metabolism in White Adipose Tissue of Rats

“…29) In addition, recent studies have shown that different types of dietary fat diversely influenced endogenous fatty acid oxidation in adipocytes. [30][31][32] In the present study, MLCT significantly enhanced CPT activity and its mRNA level in comparison with LCT in perirenal adipose tissue (Table 5, Fig. 2).…”

Performance-enhancing role of dietary fatty acids in a long-distance migrant shorebird: the semipalmated sandpiper

“…The fatty acid composition of flight muscle membranes and adipose tissue reserves become more similar to that of Corophium volutator while the shorebirds prepare for long-distance migration (Fig.·6). In addition to membrane-related effects, EPA and DHA are also known to trigger mitochondrial and peroxisomal proliferation (Froyland et al, 1997;Jump, 2002a;Jump, 2002b;Totland et al, 2000;Yamazaki et al, 1987), and to increase the activities of key Krebs Cycle and ␤-oxidation enzymes (Froyland et al, 1997;Guo et al, 2005;Jump and Clarke, 1999;Sanz et al, 2000;Yamazaki et al, 1987). This study shows that massive consumption of n-3 PUFA causes a rapid increase in the unsaturation levels of muscle PL and adipose tissue NL.…”

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

“…The theory proposes that membrane composition sets metabolic rate by modulating the molecular activity of integral proteins. It is based on the fact that the functional properties of membrane proteins such as electron transport chain enzymes, ion pumps and other ATPases can be affected by their local lipid environment (Guo et al, 2005;Leaf et al, 2005;Swanson et al, 1989;Turner et al, 2005). In trout, experiments where dietary fatty acids were used to manipulate membrane composition of red muscle have provided mixed results.…”