BETA-CAROTENE AND ALPHA-TOCOPHEROL INHIBIT THE DEVELOPMENT OF ATHEROSCLEROTIC LESIONS IN HYPERCHOLESTEROLEMIC RABBITS

Male New Zealand White rabbits were made hypercholesterolemic by feedi ng an atherogenic diet (0.5% cholesterol, 3% peanut oil, and 3% coconu t oil) with or without (control) antioxidants for 8 weeks. The antioxi dant 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 increa sed plasma and LDL antioxidant levels in the above three groups. Intra venous injection of beta-carotene significantly decreased total and LD L cholesterol concentrations, thoracic atherosclerotic lesion area, an d intimal thickness, but had no effects on LDL oxidation ex vivo as co mpared to control. Added dietary alpha-tocopherol significantly decrea sed the susceptibility of LDL to oxidation ex vivo, aortic atheroscler otic lesion area and intimal thickness, but had no effects on plasma c holesterol levels as compared to control. Combination of both antioxid ants significantly decreased total and LDL cholesterol concentrations, susceptibility of LDL to oxidation ex vivo, as well as atheroscleroti c lesion area and intimal thickness at aortic arch and thoracic aorta as compared to control, but not beta-carotene or alpha-tocopherol grou ps. These data suggest that the antihyper-cholesterolemic effects of b eta-carotene and antioxidant effects of alpha-tocopherol may benefit r abbits fed an atherogenic diet by inhibiting the development of athero sclerotic lesions.