The present study aims to examine the effects of a palm-oil-derived vitamin E mixture containing tocotrienol (approximately 70%) and tocopherol (approximately 30%) on plasma lipids and on the formation of atherosclerotic plaques in rabbits given a 2% cholesterol diet. Eighteen New Zealand White rabbits (2.2-2.8 kg) were divided into three groups; group 1 (control) was fed a normal diet, group 2 (AT) was fed a 2% cholesterol diet and group 3 (PV) was fed a 2% cholesterol diet with oral palm vitamin E (60 mg/kg body weight) given daily for 10 weeks. There were no differences in the total cholesterol and triacylglycerol levels between the AT and PV groups. The PV group had a significantly higher concentrations of HDL-c and a lower TC/HDL-c ratio compared to the AT group (P < 0.003). The aortic tissue content of cholesterol and atherosclerotic lesions were comparable in both the AT and PV groups. However, the PV group had a lower content of plasma and aortic tissue malondialdehyde (P < 0.005). Our findings suggest that despite a highly atherogenic diet, palm vitamin E improved some important plasma lipid parameters, reduced lipid peroxidation but did not have an effect on the atherosclerotic plaque formation.
Nicardipine has been shown to have an anti-atherogenic effect in rabbits given a 2% cholesterol diet. Current evidence suggests that lipid peroxidation plays an important role in atherogenesis. This study examines the effect of nicardipine on lipid peroxidation in rabbits given a 2% cholesterol diet, 8 of these rabbits given nicardipine 0.5 mg/kg twice daily intramuscularly for ten weeks while the remaining untreated 6 were controls. After ten weeks, serum malondialdehyde in the control group was significantly higher compared to their baseline levels (P < 0.05). However, there was no increase in serum malondialdehyde in the nicardipine group after 10 weeks. The area of Sudan IV positive intimal lesions (atherosclerotic plaques) were significantly decreased (P < 0.01) in the treated group compared to the control group. The aortic tissue content of cholesterol and diene conjugates were also decreased in the nicardipine group (P < 0.01). These findings suggest a possible link between nicardipine and lipid peroxidation in mediating its antiatherogenic effects.