The Changes Of Autophagy In The Different Stages Of Common Carotid Atherosclerosis In ApoE^-/- Mice

Objective.To research the regulation of autophagy at the different times of the common carotid atherosclerosis(AS)in apolipoprotein E gene knockout(Apo E-/-)mice.Methods.(1)40 male Apo E-/-mice about 6 weeks old were randomly divided into 2 groups(the control group with 10 mice and the model group with 30 mice).The common diet and water were provided optionally for 2 weeks before surgery.(2)The mice in the control group received a sham operation and kept the common diet for the next 8 weeks.While the mice in the model group received a right common carotid artery cannulation.Then the mice were randomized into another 3 groups(the 2 weeks,the 4 weeks and the 8 weeks)and fed with the high fat diet for 2 weeks,4 weeks and 8 weeks correspondingly.(3)The levels of the total cholesterol(TC),the triglyceride(TG)and the low density lipoprotein cholesterol(LDL-c)in the serum of Apo E-/-mice were studied via the biochemical analysis.(4)The right common carotid arteries were split out for the histopathological and the transmission electron microscopy(TEM)study.(5)Real-time quantitative PCR(q RT-PCR)and Western-blot were operated to discover the relative expression levels of the m RNA and protein of ATG5 and Beclin1.Results.(1)The levels of TC,TG and LDL-c were increased in the model group compared to the control group.The levels especially of TG and LDL-c were time-relatively increased as the time of the surgery extend.(2)The histopathological study showed that there was few cells infiltrated in carotid artery wall of the Apo E-/-mice in the 2 weeks,although the vascular wall was still not damaged.The wall of the carotid artery of the mice in the 4 weeks was messy and thrombus existed in the vascular lumen.The thickness of the carotid artery of the mice in the 8 weeks was higher than those of the rest groups and its elastic membranes significantly decreased.(3)From the TEM results,no abnormal autophagic vacuole aggregations were found in the control group.Whereas in the 2 weeks,a few number of lipid droplets and the activated autophagosomes were found.In the 4 weeks,autophagosomes and lipid droplets significantly increased.However,the autophagosomes were decreased in the 8 weeks compared to the 4 weeks although the lipid droplets still increased.(4)The q RT-PCR and the western-blot results indicated that the m RNA and protein level of ATG5 and Beclin1 in the 4 weeks was higher than the level in the 2 weeks and the 8 weeks,and the m RNA and protein level of ATG5 and Beclin1 in the 8 weeks was higher than the level in the 2 weeks.Conclusions.Autophagy was incessantly stimulated during the AS formation,but the levels of autophagy will not always increase but decrease after reaching the peak at a time in this research.