High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbits

The effects of in vivo administration of high density lipoprotein-very high density lipoprotein (HDL-VHDL) on the development of aortic fatty streaks were studied in cholesterol-fed rabbits. The rabbits received a 0.5% cholesterol-rich diet for 8 weeks. During this period, the HDL-VHDL group was intravenously administered with 50 mg/week of homologous HDL-VHDL protein; the control group received normal saline (0.9% NaCl). HDL-VHDL fraction was obtained at density range 1.063 to 1.25 gm/ml by ultracentrifugation of normal rabbit plasma. Along the study, plasma lipid levels followed a similar profile in both groups. At the completion of the study, atherosclerotic-like lipid-rich lesions covered 37.9 ± 6% (X ± SEM) of the intimal aortic surface in the control group, and 14.9 ± 2.1% in the treated group (p < 0.001). The values of total and free cholesterol, esterified cholesterol, and phospholipids deposited within vessel wall were significantly lower in the aortas of the HDL-VHDL treated group than those in the control group. Cholesterol accumulation in the livers was also significantly lower (p < 0.01) in the treated group than in the control. We concluded that administration of homologous HDL-VHDL lipoprotein fraction to cholesterol-fed rabbits, dramatically inhibited the extent of aortic fatty streaks and lowered lipid deposition in the arterial wall and liver without modification of the plasma lipid levels.