Coconut oil induces short-term changes in lipid composition and enzyme activity of chick hepatic mitochondria.

We studied the short-term effects of a 20% coconut oil supplementation to the chick diet on lipid composition of liver and hepatic mitochondria, and changes that occurred in mitochondrial-associated enzymes as a result of this diet. No significant differences were observed in the lipid contents of liver when young chicks were fed the experimental diet, whereas hepatic mitochondria rapidly changed in response to this diet. Total cholesterol significantly increased in mitochondria at 24 hours of coconut oil diet feeding and decreased when dietary treatment was prolonged for 5 to 14 days.

Differential effects of dietary fat on chick plasma and liver composition and HMG-CoA reductase activity.

The comparative effects of diet supplementation with 10% saturated fat rich in 12:0 and 14:0 fatty acids (coconut oil), without and with 1% added cholesterol, and with 10% unsaturated fat rich in n-3 polyunsaturated fatty acids (menhaden oil) on cholesterol metabolism in neonatal chicks were examined to clarify the different mechanisms of their hyper- and hypolipidemic action. Supplementation of coconut oil produced a significant hypercholesterolemia after 7 days of treatment, with a similar increase in the amount of both free and esterified cholesterol. Supplementation of coconut oil plus cholesterol produced a higher increase of plasma cholesterol levels (approximately two to three times higher than those found with standard diet).

Differential translational effects of myristic acid and eicosapentaenoic acid on 3-hydroxy-3-methylglutaryl-CoA reductase from Reuber H35 hepatoma cells.

The mechanisms by which saturated and polyunsaturated fatty acids may exert their effects on levels of blood cholesterol and human atherosclerosis have not been fully established. In this work, we studied the translational effects of myristic (14:0) and eicosapentaenoic (20:5) acids on 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase from Reuber H35 hepatoma cells. This enzyme is an intrinsic membrane, 96-kDa protein whose proteolysis releases an enzymatically active, 52- to 56-kDa, soluble fragment.

Influence of fasting status on the effects of coconut oil on chick plasma and lipoprotein composition.

For a better understanding of the hyperlipidemic function of saturated fat, we have studied the effects of diet supplementation with 10-20% coconut oil on the chick plasma and lipoprotein composition under postprandial and starvation conditions. A significant hypercholesterolemia was found in chicks fed the standard diet after 12 h of food deprivation. In these conditions, LDL-cholesterol also increased, whereas triglyceride levels were reduced in HDL, VLDL and chylomicron fractions.

Modification of phospholipids fatty acid composition in reuber H35 hepatoma cells: effect on HMG-CoA reductase activity.

There is controversy about the effect of saturated and polyunsaturated fats on 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, the main regulatory enzyme of cholesterogenic pathway. Results from dietary studies are difficult to interpret because diets normally contain a mixture of fatty acids. Therefore, we have used Reuber H35 hepatoma cells whose phospholipids were enriched in different individual fatty acids and have studied their effects on the cellular reductase activity.