Effect of lovastatin on suppression and regression of atherosclerosis in lipid-fed rabbits

The present study was designed to evaluate the effects of lovastatin on suppression and regression of atherosclerosis in the lipid-fed rabbit. Fifty-seven New Zealand rabbits in six groups were fed a 0.3% cholesterol diet for 10 weeks. In the progression phase of the study, group C10 served as a control and received 1 ml of DMSO daily by gavage. Two other groups, L10 and H10, received low (L)-dose (10 mg/day) or high (H)-dose (20 mg/day) lovastatin dissolved in 1 ml of DMSO for 10 weeks. In the regression phase of the study, three groups of rabbits received the high lipid diet for 10 weeks and were then shifted to a normal diet for the second 10 weeks. During the second 10 weeks, the control group C20 received 1 ml of DMSO daily, and groups L20 and H20 received 10 and 20 mg/day of lovastatin by gavage, respectively. In the progression phase of the study, lovastatin significantly attenuated the percent of aortic lesions in groups L10 (8 +/- 7%) and H10 (9 +/- 14%) vs. the control group C10 (31 +/- 17%; p less than 0.01). There was a similar reduction in pulmonary lesions in groups L10 (10 +/- 6%) and H10 (4 +/- 5%) compared to the control group C10 (30 +/- 16%; p less than 0.01). There was also a reduction in plaque thickness in both the aorta and pulmonary artery, and hence an even greater reduction in estimated plaque volume. In the regression phase of the study, lovastatin also significantly reduced the percent of aortic lesions (groups L20 and H20 vs. C20: 27 +/- 18 and 22 +/- 7% vs. 40 +/- 17%; p less than 0.05) and pulmonary lesions (21 +/- 10 and 17 +/- 6% vs. 26 +/- 9%; p greater than 0.05 and p less than 0.05, respectively); the average maximum plaque thickness of aorta (0.24 and 0.26 mm vs. 0.49 mm; p less than 0.01); and the standardized plaque volume per unit area of aorta (4.5 and 3.4 vs. 12.1 mm-%; p less than 0.05 and p less than 0.01, respectively). However, there was no significant difference in the percent of aortic lesions between groups L20 and H20 and group C10 (27 +/- 18 and 22 +/- 7 vs. 31 +/- 17%; p greater than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)