| Objective: It is important to interfere and delay the occurrence and development of atherosclerosis (AS), which is a main pathogenesis of stroke. Many studies found that lysophosphatidic acid (LPA) played a key role in pathogenesis of stroke. First, LPA can reflect the activity of blood platelet and increased the danger of stroke. Second, LPA can accelerate the formation of AS and thrombosis in many ways. Many studies have found that Atorvastatin can prevent the development of AS and stabilize the plaque. This therapeutic effective may be relevant to its effect of regulating blood-lipid and nonregulating blood-lipid, included recovering endothelium function, anti-inflammatory, anti-oxidation and decreasing platelet activity and so on. While the molecular mechanism is not very clear. In this study we developed an AS model by feed wistar rats high-fat diet based on injecting a high dose of vitamin D3 in abdominal cavity. Atorvastatin was given to some experimental rats when the model was accomplished. Then the level of plasma LPA, the expression level of tumor necrosis factor-α(TNF-α) and the activity of matrix metalloproteinase-9 (MMP-9) in vascular wall were observed in order to understand the relationship between LPA and AS. Through atorvastatin intervention, we understood it's molecular mechanism and therapeutic value in AS. Methods: Thirty wistar rats were divided into 3 groups randomly: normal control group (group A), AS model group (group B) and atorvastatin treatment group (group C). Each group had 11 rats. The rats in group A were fed on general diet while the rats in group B and group C were fed on high-fat diet (mixed 3% cholesterin, 0.5% sodium cholate, 0.2% propylthiouracil, 5% refined sugar, 10% cooked lard and 81.3% general diet together). At the beginning of study, vitamin D3 600,000 IU/kg was injected into abdominal cavity in group B and group C while the equal volume saline was injected in group A. From the 5th week to the 8th week, the rats in group C were given atorvastatin 10mg/kg by gastrogavage everyday. Group A and group B were given equal volume water. At the end of the 8th week of this study, all rats were anesthetized by soluble pentobarbitone. Then levels of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), high density lipoprotein cholesterol (HDL-C) and plasma LPA were detected. The aortic and carotid tissue was observed by light microscopy through hematoxylin-eosin stain (HE stain). Moreover, the expression level of TNF-αand the activity of MMP-9 in aortic tissue were detected by immunohistochemical staining and gelatin zymography. These graphic results wereanalyzed with computer image-analysis system and the integral optical density (IOD) counts of TNF-αand MMP-9 were calculated. At last, all datas were analyzed by SPSS11.0 version statistic software. Results: (1) Various serum lipid levels after 8 weeks: When the experiment was finished, the levels of TG, TC, LDL-C and VLDL-C in group B were significantly higher than those in group A (all P<0.05). And foregoing items in group C were significantly lower than group B (all P<0.05). The level of HDL-C in group B was more reduced than group A and C (all P<0.05) (2) Plasma LPA level after 8 weeks: When the experiment was finished, the level of LPA in group B (4.66±0.84μmol/L) was significantly higher (P<0.05) than group A (2.34 ±0.63μmol/L). And the level in group C (3.46±0.58μmol/L) was significantly lower than group B (P<0.05). (3) Morphological results by light microscopy: HE staining showed that arterial intima of group A was smooth,endothelial cells were flat and internal elastic membrane was smooth. Many plaques occurred in tunica intima of artery, a fibrous membrane on plaque surface and a mass of matter likes gruel in deep part of plaque in group B. Arterial intima of group C was thickened, vascular smooth muscle cells were grown, internal elastic membrane was destroyed and foam cells occurred, but no plaque occurred. (4) The protein expression level of TNF-αin aorta:Immunohistochemical staining showed that the integra optical density (IOD) of TNF-αin group B (184.05±11.53) was heightened (P<0.05) compared with group A (42.48±7.65). And the IOD in group C (102.72±9.95) were lower than group B (P<0.05). Correlate analysis showed that aortic TNF-αexpression level had a positive correlation with plasm LPA level of experimental rats (r=0.853,P<0.05). (5) The activity of MMP-9 in aorta: Gelatin zymography showed that the IOD of MMP-9 degraded band in group B (404.23±40.12) was increased (P<0.05) compared with that of group A (185.89±25.40). And the IOD in group C (316.75±35.18) was lower than group B (p<0.05). Correlate analysis showed that the activity of MMP-9 in aorta tissue had a positive correlation with plasma LPA level (r=0.736,P<0.05) and TNF-αexpression level (r=0.818,P<0.05) in aorta. Conclusions: (1) The AS model could be induced easily and quickly by high-fat diet for 8 weeks based on a high dose of vitamin D3 injection in celiac. This model can be used to study pathogenesis mechanism of AS and observed medicine therapeutic effective on AS. (2) LPA may be an important risk factor in the occurrence and development of AS. So it is important to decrease LPA level for stroke prevention and treatment. (3) The expression level of TNF-αand the activity of MMP-9 in aortic tissue were increased markedly in AS rats. It indicates that TNF-αand MMP-9 can play important roles in... |
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