Objective To study the effect of taurine on the apoptosis of vascular smooth muscle cells in atherosclerotic model of rabbits and the mechanism of anti-atherosclerosis.
Methods 21 male Japanese white rabbits were divided into three groups: normol control group, high cholesterol group and taurine group. The normal control group were fed with standard chow diet and two other groups with a high fat diet. The taurine group were fed with taurine solution once a day, two other groups were given normal saline gastric feeding. Twelve weeks later the modelling was determined successful, all rabbits were killed with air embolism method and exposed the heart, isolated and cut aorta from aortic valve to the bifurcation of abdominal aorta blood vessel. Observing the pathomorphological changes in aorta wall and ultra-structures of VSMCS were observed by electronic microscopy, the apototic rate of VSMCs detected by flow cytometry, expression of bcl-2 and bax proteins were detected by immunohistochemistry and expression of caspase-3 proteins were detected by Western blot.
Results The aortic intima of normal control group was smooth, no plaque formation; the high cholesterol group was uneven and rough, there were many needle-like white mastoid processes, some fused into pieces; the above-mentioned diseases of the taurine group were less. Three-tier structure of the normal control group were observed clearly through light microscope (HE × 400), vessel wall was smooth and VSMCs arranged regularly; the intima of the high cholesterol group was thicker significantly and irregular foam cells were aggregation, a large number of lipid could be seen at elastic plates and cell gap, smooth muscle cells arranged irregularly; three-tier structure of the vessel wall in the taurine group could be seen clearly, the intima is thick partly, foam cells were less, lipid is deposition rarely, smooth muscle cells are still arranged neatly, the intima and intima-to-media were significantly decrease (p<0.01). In high cholesterol group the apoptotic rate of VSMCs was higher than that in normal control group (p<0.01), the expression of bcl-2 proteins was lower (p<0.01), but the expression of bax and caspase-3 proteins was higher (p<0.01). The visible atheromatous plaque which caused the serious stenosis were observed and the apoptotic VSMCs were more in the atheromatous plaque in high cholesterol group. In taurine group the apoptotic rate of VSMCs was lower than that in high cholesterol group (p<0.01), the expression of bcl-2 proteins was higher (p<0.01), but the expression of bax and caspase-3 proteins were lower (p<0.01). The atheromatous plaque were decreased and the stenosis were reduced, and the apoptotic VSMCs were less and not typical.
Conclusions Taurine can prevent the formation of atherosclerosis and inhibit the apoptosis of VSMCs in the atherosclerotic plaque by regulating the bcl-2, bax and caspase-3 proteins.