Postprandial lipemia and lipoprotein lipase in the rabbit are modified by olive and coconut oil

Abstract

Feeding a 14% coconut oil/0.5% cholesterol (CNO/chol) diet to rabbits resulted in plasma triglycerides that were, on average, 15 times higher than basal levels. Plasma triglycerides in rabbits fed a 14% olive oil/0.5% cholesterol (OO/chol) diet were significantly below baseline levels. Differences in postprandial triglyceride response and postheparin plasma lipoprotein lipase activity (LPL) in various feeding conditions were studied to determine the mechanism of the hypertriglyceridemia. Postprandial triglyceride responses after the first high fat/cholesterol meal were more prolonged in CNO/chol rabbits than in OO/chol rabbits; postprandial triglyceride responses after chronic CNO/chol feeding were significantly greater compared to OO/chol rabbits. When long-term CNO/chol rabbits were given one OO/chol or corn oil/chol meal, postprandial triglyceride peaks were greatly diminished, suggesting that these unsaturated fat meals may alter triglyceride clearance capacity. LPL activity was 400% higher than basal levels in chronically fed OO/chol rabbits but changed very little in chronically fed CNO/chol rabbits. Twenty-four hours after a single OO/chol meal was fed to chow-fed rabbits, LPL doubled; one CNO/chol meal was associated with only a 40% increase. Feeding a single OO/chol or corn oil/chol meal to chronically fed CNO/chol rabbits resulted in a 30% to 50% increase in LPL by 24 hours. Thus, the hypertriglyceridemia in CNO/chol rabbits may result in part from a decreased clearance capacity due to a lack of increase in LPL activity, while increased LPL may be partially responsible for the hypotriglyceridemia observed in OO/chol feeding. Aortic cholesterol was substantially higher in CNO/chol rabbits. Triglyceride was approximately eight times greater in livers from CNO/chol-fed rabbits than in those fed OO/chol, but liver cholesterol was only about one-third as much as that in OO/chol rabbits.