beta-Carotene and alpha-tocopherol inhibit the development of atherosclerotic lesions in hypercholesterolemic rabbits

Male New Zealand White rabbits were made hypercholesterolemic by feeding an atherogenic diet (0.5% cholesterol, 3% peanut oil, and 3% coconut oil) with or without (control) antioxidants for 8 weeks. The antioxidant treatments were intravenous injection of beta-carotene (25 mg/kg/BW, twice weekly), dietary supplementation of alpha-tocopherol (0.5%), and a combination of both. Antioxidant treatments significantly increased plasma and LDL antioxidant levels in the above three groups. Intravenous injection of beta-carotene significantly decreased total and LDL cholesterol concentrations, thoracic atherosclerotic lesion area, and intimal thickness, but had no effects on LDL oxidation ex vivo as compared to control. Added dietary alpha-tocopherol significantly decreased the susceptibility of LDL to oxidation ex vivo, aortic atherosclerotic lesion area and intimal thickness, but had no effects on plasma cholesterol levels as compared to control. Combination of both antioxidants significantly decreased total and LDL cholesterol concentrations, susceptibility of LDL to oxidation ex vivo, as well as atherosclerotic lesion area and intimal thickness at aortic arch and thoracic aorta as compared to control, but not beta-carotene or alpha-tocopherol groups. These data suggest that the antihypercholesterolemic effects of beta-carotene and antioxidant effects of alpha-tocopherol may benefit rabbits fed an atherogenic diet by inhibiting the development of atherosclerotic lesions.