Session Speaker
Morphologic Changes of Aortic Endothelial Cells Observed by
Atomic Force Microscopy in Atherosclerotic Spontaneously Hypertensive
Rats and the Effect of Probucol plus Atorvastatin
Li Yun-zhi, Yang Ting-shu, Zhou Yu-jie
Objective: To establish an experimental model of atherosclerosis in
spontaneously hypertensive rats and to observe the morphlogic changes
of aortic endothelial cells with atomic force microscopy and to study
the roles of probucol and atorvastatin.
Methods: SHR(n=92) were randomly divided into 5 groups: control group(n=12),
fed with normal diet; model group(n=20), fed with high cholesterol
diet; probucol group(n=20), fed with high cholesterol diet plus probucol
(150mg/kg.d); atorvastatin group(n=20), fed with high cholesterol
diet plus atorvastatin (10mg/kg.d); probucol plus atorvastatin group(n=20),
fed with high cholesterol diet and probucol(150mg/kg.d) plus atorvastatin(10mg/kg.d).
Normal wistar-kyoto(WKY) rats were used as negative control group,
fed with normal diet. At the beginning of test, SHR with high cholesterol
diet were injected with a single dose of vitamin D3
(700000U/kg) and vein blood of 10 rats of each group was drawn for
measurement. At the end of 4th and
8th week 6-10 rats of each group
were sacrificed and blood was drawn from heart for analysis of serum
total cholesterol, triglyceride, low density cholesterol, high density
cholesterol, and serum nitric oxide, endothin-1 and oxidized low density
lipoprotein, meanwhile aortas were harvested. The arches of thoracic
aortas were stained with hematoxylin-eosin. The pathological changes
were observed by light microscope technique. The lower segments of
thoracic aortas were fixed on glass slide for the observation of endothelial
morphologic changes with atomic force microscope.
Results:
1. Levels of blood cholesterol in WKY control group and SHR control
group did not have obvious changes during the test(P>0.05). Compared
with the two control groups, levels of blood cholesterol in model
group and each medicine group were increased greatly (P<0.05);
they were lower in each medicine group than in model group, and they
were lowest in probucol plus atorvastatin group (P<0.01).
2. At the end of 8th weeks, compared
with control groups, levels of serum NO?ET-1 and ox-LDL in model group
and medicine group were increased obliviously (P<0.01);level of
serum NO were higher in medicine groups than in model group; levels
of serum ET-1 and ox-LDL were lower in medicine groups than in model
group.
3. Observation by light microscope: Aorta wall of two control groups
was thin, ductility and complete and their intimae was lined up in
order and had no plaque on surface. As test progressed, aorta intimae
of model group became thicker, endotheliocyte desquamated, middle
smooth muscle cells were hyperplasia, and elasticity fibrage was not
lined up in order. However, the degree of pathology was less serious
in each medicine group than in model group, especially in probucol
plus atorvastatin group.
4. Observations of AFM: Endothelial cells of thoracic aortas of two
control groups were lined up regulated and fusiform and their macroaxis
was parallel with the direction of hemokinesis. Their membrane was
made up with many round smooth particle eminences with similar diameter.
It was distinct boundary among eminences. However, endothelial morphologic
changes with time in model and medicine groups. They became irregularity
and aligned confused and swell. The membranes were made up from particle
eminences with different diameter. Boundaries among eminences changed
to vague and pore spaces were seen occasionally. Meanwhile, endothelial
morphologic changes in medicine groups were also changed but less
obvious than those of model group in the same period, and intended
to be like those of control group, especially those of probucol plus
atorvastatin group. The mean roughness of endothelial surface in model
group and each medicine group were greatly increased with time progressing
and those in model group was obvious higher than those in medicine.
Conclusion:
1. The method that SHR were fed with high cholesterol diet and were
injected with vitamin D, which can make the levels of serum TC and
LDL-C increased greatly, can cause the pathological changes of atherosclerosis.
2. Morphologic changes of endothelial cells in atherosclerosis progressing
could be observed perspicuously by AFM which was a good method for
the observation of membrane surface.
3. In atherogenesis morphologic changes of endothelial cells was dynamic
which suggested that endothelium damage was essential in initiation
and development of atherosclerosis.
4. Probucol plus atorvastatin could prevent the evolvment of atherosclerosis
by lowing cholesterol, increasing NO, decreasing ET-1 and ox-LDL and
protect the endothelium ultramicrostructure.
Key words: atomic force microscope, spontaneously hypertensive rats,
endothelial cells, atherosclerosis, probucol, atorvastatin.
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