Abstract
BACKGROUND: Vitamin E suppresses the development of atherosclerosis but does not regress established
hypercholesterolemic atherosclerosis.
OBJECTIVES: To investigate whether vitamin E slows the progression of established atherosclerosis,
and whether this effect is associated with reductions in serum lipids and oxidative
stress.
METHODS: The present study was performed in four groups of rabbits: group I, regular diet
(control); group II, 0.25% cholesterol diet (two months); group III, 0.25% cholesterol
diet (four months); and group IV, 0.25% cholesterol diet (two months) followed by
0.25% cholesterol and vitamin E (two months). Serum lipids and the chemi- luminescent
activity of white blood cells (WBC-CL), a measure of oxygen radical production by
white blood cells, were measured before and at monthly intervals for the duration
of the study. Aortas were removed at the end of the protocol for assessment of atherosclerosis
and the chemi-luminescent activity of aortic tissue (aortic-CL), a measure of antioxidant
reserve.
RESULTS: Atherosclerosis was associated with hyperlipidemia and increased oxidative stress,
indicated by increased nonactivated WBC-CL and alteration of the aortic-CL. Significant
areas of the intimal surfaces of the aortas from group II (26.54%±4.11%), group III
(69.37%±5.34%) and group IV (65.96%±7.86%) were covered with atherosclerotic lesions.
Vitamin E did not alter serum lipids, aortic antioxidant reserve or WBC-CL. Vitamin
E was ineffective in slowing the progression of hypercholesterolemic atherosclerosis.
CONCLUSION: Vitamin E did not slow the progression of hypercho- lesterolemic atherosclerosis,
and this effect was associated with its ineffectiveness in reducing serum lipids and
oxidative stress.
