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MORE Programs Poster Presentation

December 1, 2006

Aileen Ariosa

TITLE:ALTERATION OF LECITHIN:CHOLESTEROL ACYLTRANSFERASE AND CHOLESTERYL ESTER TRANSFER PROTEIN ACTIVITIES IN CHOLESTEROL AND JOJOBA OIL FED RABBITS

Authors: Aileen R. Ariosa, Maritza Hernandez and Raymond E. Garcia, PhD.

Abstract: 

Elevated concentrations of serum cholesterol conduces the formation of atherosclerotic plaques in arteries leading to cardiovascular disease. New Zealand White (NZW) rabbits fed a cholesterol-rich diet (1% w/w) exhibit a decrease in high density lipoprotein cholesterol concentration ([HDL-C]), whereas those fed a cholesterol-rich (1% w/w) diet supplemented with jojoba oil (3% w/w) maintain normal (HDL-C). The objective of this project is to determine the mechanism behind these observations by quantifying the activities of enzymes involved in cholesterol metabolism when rabbits are fed these diets. Our hypothesis is that dietary jojoba oil, in the presence or absence of dietary cholesterol, stimulates lecithin:cholesterol acyltransferase (LCAT) and inhibits cholesteryl ester transfer protein (CETP). Blood samples were obtained at 0 and 7 days. NZW rabbits are fed either a normal (N), 3% jojoba oil (J), 1% cholesterol (C), or 1% cholesterol + 3% jojoba oil (CJ) diet. Total cholesterol (TC) and free cholesterol (FC) concentrations were measured using enzymatic assays. Cholesteryl ester (CE) concentrations were calculated from TC and FC concentrations. LCAT activity was determined by measuring the disappearance of FC over time and CETP via a fluorometric assay. Rabbits showed greater [HDL-CE] in J- and CJ-fed rabbits compared to N- and C-fed rabbits correspondingly. LCAT activities were determined in µmol/dL/h: CJ=217.8±14.2 > C=157.3±22.8; J=37.9±2.3 ≈ N=40.4±2.9. CETP rates were measured in nmol/mL/h: C=22.5 > (CJ=20.25 ≈ J=18.87 ≈ N=18.92). Results indicate that dietary jojoba oil stimulates LCAT and inhibits CETP whenever cholesterol is present in the diet. (NIH-MARC Grant T34 GM 08228).