Effect of a hypercholesterolaemic diet and a single injection of polyunsaturated phosphatidyl choline solution on the activities of lipolytic enzymes, acyl-CoA synthetase and acyl-CoA cholesterol acyl-transferase in rabbit tissues

Abstract

In rabbits fed a high cholesterol diet for 12 weeks the following were found: in serum, a decrease in lipase and no changes in phospholipase A and cholesterol esterase activities; in the aorta, decreased cholesterol esterase and acyl-CoA cholesterol acyltransferase (ACAT) activities and no changes in phospholipase A, lipase and acyl-CoA synthetase (ACS) activities; in the liver, increased phospholipase A, cholesterol esterase and ACAT activities, and decreased lipase and ACS activities. A single injection of polyunsaturated phosphatidyl choline in 4% sodium deoxycholate (EPL solution) in control and hypercholesterolaemic rabbits resulted in different effects on the enzyme activities. The stimulating, diet-independent and heparin-like effect of the drug on lipase consisted of increased activities of the enzyme in serum and liver and decreased activity in the aorta. Diet-dependent changes of the enzyme activities were as follows: in serum, decreased phospholipase A activity in control and increased phospholipase A activity in hypercholesterolaemic diet; in the aorta, decreased cholesterol esterase and elevated cholesterol ester synthesis/hydrolysis ratio in control and increased phospholipase A activity, decreased ACS activity and lowered cholesterol ester synthesis/hydrolysis ratio in hypercholesterolaemic diet; in the liver, increased phospholipase A and ACAT activities and decreased ACS activity with the ratio of cholesterol ester synthesis/hydrolysis elevated in control and this ratio unchanged in hypercholesterolaemic diet. Possible mechanisms of the enzyme activity changes are discussed.