Serum and aortic lipid profiles in spontaneous and cholesterol-induced atherosclerosis in Rhesus monkeys

Establishment and ultrasound characteristics of atherosclerosis in rhesus monkey

Background

Atherosclerosis is one of the main risk factors cause acute cerebral-cardio vascular diseases. It's of great significance to establish an atherosclerosis animal model that can mimic the characteristics and nature course of human patients. Therefore, a rhesus monkey model was induced by high-fat diet to monitor their lipid profile and intima-media thickness (IMT) of artery walls and study atherosclerosis progression.

Methods

Fifty male rhesus monkeys were enrolled in this study. All of these monkeys were aged 7 to 14 years with BMI >30 kg/m². They were fed with high-fat diet containing 10% of fat for the first 48 weeks. Use ultrasound to measure the IMT at bilateral common carotid arteries and their bifurcations and aorta (AO) of the monkeys, and screen out the individuals with thickened IMT for the next phase. In the next 48 weeks, some of these monkeys (n = 4) were fed with standard diet containing 3% fat. Meanwhile the other monkeys (n = 5) were fed with high-fat diet for another 48 weeks. Their serum lipid level was monitored and arterial IMT was also determined periodically.

Results

Serum lipid level of all 50 monkeys elevated after fed with high-fat diet for the first 48 weeks. IMT thickening at right common carotid bifurcation and aorta (AO) was thickened in 9 monkeys. Furthermore, 4 of these 9 monkeys were fed with standard diet and other 5 monkeys were fed with high-fat diet in the following 48 weeks. The serum lipid level of the 4 monkeys recovered and their IMT at RBIF and AO did not progress. However, the lipid level of other 5 monkeys remained high, and their IMT thickening of AO progressed, and plaques and calcification focuses were found at the anterior wall of aorta near the bifurcation of common iliac artery.

Conclusions

After high-fat diet induction for 96 weeks, serum lipid levels of rhesus monkeys elevated significantly, which subsequently caused IMT thickening and plaques formation. When IMT thickening occurred, further vascular injury may be prevented by reducing diet fat content. Our study indicates that vascular injury of high-fat diet induced rhesus monkey is similar to that of human in position and progression.

Effect of selective depletion of fibrinogen on the evolution of cholesterol-induced atherosclerosis in rabbits

Atherosclerosis was produced by induced alimentary hyperlipaemia in four groups of rabbits. Animals of groups II and III received cholesterol feeds daily for 2 months while in groups IV and V this was followed by another 3 months of intermittent feeding. Group I comprised normal control rabbits. Selective fibrinogen depletion was produced in groups III and V with Arvin so as to maintain the plasma fibrinogen around 100 mg/dl over the last 2 months of cholesterol feeding. Serum lipids, blood coagulation and euglobulin clot lysis as well as the post mortem histopathology of aorta, heart, kidneys, liver and lungs did not reveal any significant differences between corresponding groups of hyperlipaemic animals treated with (groups III and V) or without (groups II and IV) Arvin. It appears that fibrinogen or fibrin incorporation does not play a significant role in the pathogenesis of atherosclerotic lesions induced in rabbits by cholesterol feeding.