Stimulation of microperoxisomal β-oxidation in rat heart by high-fat diets

Abstract

1. 1. Heart microperoxisomal β-oxidation activity, measured as cyanide-insensitive palmitoyl-CoA-dependent NAD +-reduction, was detected in a microperoxisome-enriched fraction from rat myocardium. The effect on this microperoxisomal β-oxidation of the fatty acid composition of the dietary oils was investigated. 2. 2. Feeding 15% (w/w) high erucic acid rapeseed oil or partially hydrogenated marine oil for 3 weeks increased the microperoxisomal β-oxidation in the heart 4–5-fold, compared to a soybean oil diet. Increasing amounts (5–30%, w/w) of partially hydrogenated marine oil in the diet led to a 3-fold increase in the microperoxisomal β-oxidation capacity at 20% or more of this oil in the diet. 3. 3. The activity of the microperoxisomal marker enzyme catalase followed closely the cyanide-insensitive palmitoyl-CoA-dependent NAD +-reduction, except when feeding more than 20% (w/w) partially hydrogenated marine oil where a significant decrease in the catalase activity was observed. 4. 4. In rapeseed oil-fed animals the extent of increase of microperoxisomal β-oxidation was directly correlated to the amount of erucic acid (22:1, n−9 cis) in the diet. 5. 5. Feeding partially hydrogenated rapeseed oil or partially hydrogenated soybean oil resulted in activities of microperoxisomal β-oxidation significantly lower than in the corresponding unhydrogenated oils. No significant difference could be detected between diets containing hydrogenated or unhydrogenated marine oil. 6. 6. Addition of 5% soybean oil to the essential fatty acid-deficient, partially hydrogenated marine oil diet did not change the effect on the microperoxisomal β-oxidation activity. 7. 7. Clofibrate feeding increased the heart microperoxisomal β-oxidation capacity 2.5-fold, as compared to a standard pelleted diet. 8. 8. These findings are discussed in relation to the transient nature of the cardiac lipidosis observed with animals fed on diets rich in C 22:1 fatty acids. It is concluded that the heart plays an important part in the adaptation process.