Effects of Dietary Cholesterol and Jojoba Seed Oil on High Density Lipoprotein Subclasses in New Zealand White Rabbits
Authors:Oleg Gontal, Tarek Karam, James Wang
Mentor:Raymond Garcia, Professor of Biochemistry, California State University Los Angeles
The reverse cholesterol transport system (RCT) is a multi-step process that results in the net movement of cholesterol, by high-density lipoproteins (HDL), from the peripheral tissues to the liver where it is degraded into bile. Among our studies with oils, we have shown that the characteristic decrease of serum HDL concentrations of hypercholesterolemic New Zealand White (NZW) rabbits is hindered by jojoba oil, a liquid wax produced in the seed of the jojoba plant (Simmondsia chinensis). In this study, we investigated which HDL subfraction, HDL2 or HDL3, is affected by dietary jojoba oil. NZW rabbits were divided into four experimental groups and placed on either a normal chow diet (N), or a normal diet supplemented with either 3% jojoba seed oil (J), 1% cholesterol (C), or 1% cholesterol + 3% jojoba seed oil (CJ) for one week. Rabbits were bled and serum samples were extracted prior and post the one week feeding. Through careful manipulation of serum density, HDL2 and HDL3 subfractions were isolated via ultracentrifugation at 98,000 xg; cholesterol ester (HDL-CE) concentrations in the HDL2 and HDL3 fractions were then measured enzymatically. Our results show a significant interaction between the HDL2-CE concentrations, total serum HDL concentration, and the C- and J- diet (two-factor ANOVA; P ≤ 0.005). These findings indicate that dietary jojoba oil regulates HDL metabolism, specifically HDL2-CE concentration, and has a potential protective effect against atherosclerosis, the leading cause of mortality in the Western world. (Supported by NSF CSU-LSAMP Grant # HRD-0802628).