Study On The Mechanism Of Regulating The Metabolism Of Cholesterol By SREBP - 2 In

Backgrounds:Hyperlipidemia is a common and frequently-occurring disease.It manifests mainly as the increased levels of TC,TG,LDL with or without the decreased level of HDL.It can seriously damage cardiovascular system and is the risk factor of atherosclerosis and coronary heart disease. Cholesterol-lowering drug has a certain effect and also has the bad reaction of abnormal liver or renal function tests, myopathy and rhabdomyolysis. Huazhuo Qushi Decoction clinical studies showed that it can effectively reduce serum CHOL levels. The latest hotspot of research showes that SREBP-2,HMGCR,LDLR and PCSK9 are the target genes of CHOL metabolism. We speculate that Huazhuo Qushi Decoction adjusts cholesterol metabolism depending on SREBP-2 and targeting genes. This research aims to discuss the aspects of target gene and molecular mechanisms that Huazhuo Qushi Decoction adjusts cholesterol metabolism by means of serum biochemistries, histopathological manifestations and gene expression.Objective:To observe the effect of Huazhuo Qushi Decoction on serum cholesterol of hyperlipidemia SD rat models, to observe the effect of Qushi Huazhuo Decoction on lipid content in the liver and to investigate the mechanism of Huazhuo Qushi Decoction on regulating cholesterol metabolism.Methods:96 SD rats were randomly selected,18 rats were fed basic forage as blank group and the rest 78 rats were fed fat forage. After 4 weeks, in order to confirm that rat models established successfully, all rats were taken inner canthal orbital vein blood to measurement of serum lipid concentration.78 established rat models were divided into model group 18 rats, simvastatin group 12 rats, gynostemma group 12 rats, low Huazhuo Qushi Decoction group 12 rats, middle Huazhuo Qushi Decoction group 12 rats and high Huazhuo Qushi Decoction group 12 rats. All groups were orally administered. Blank group and model group were given high-purity water, simvastatin group was given simvastatin solution, gynostemma group was given HerbaGynostemmae’s total saponin solution, low Huazhuo Qushi Decoction group was given low-dose Huazhuo Qushi solution, middle Huazhuo Qushi Decoction group was given medium-dose Huazhuo Qushi solution, high Huazhuo Qushi Decoction group was given high-dose Huazhuo Qushi solution. All rats were treated at the dose of 1ml/100g, once a day for 12 weeks. Body weight was measured every day and recorded weekly.4 weeks after modeling and 4,8,12 weeks after treating, blood was taken to detected the level of CHOL,LDL-C,HDL-C and VLDL. ALT,AST,BUN and Cr were also detected after 12 weeks treating.4 weeks after modeling,4 rats were andomly and respectively selected from blank group and model group to acquire the liver tissue. And 4 rats were andomly and respectively selected from every group to acquire the liver tissue after 12 weeks treating. All liver tissue were observed lipid levels of liver by oil-red O staining through a microscope. After 12 weeks treating,6 rats were andomly and respectively selected from every group to acquire the liver tissue using Real-time PCR to identify SREBP-2 mRNA,HMGCR mRNA,PCSK8 mRNA and LDLR mRNA.Results:After 8 weeks treating, middle Huazhuo Qushi Decoction group showed effect on reducing CHOL. Compared with the model group, CHOL decreased obviously(P< 0.05). and there was no significant difference comparing wiith blank control group in the matter of CHOL. After 8 weeks treating, simvastatin group, low Huazhuo Qushi Decoction group, middle Huazhuo Qushi Decoction group and high Huazhuo Qushi Decoction group showed effect on reducing CHOL and there was no significant difference comparing wiith blank control group. Compared with the model group, CHOL reduced obviously(P<0.05) in low Huazhuo Qushi Decoction group, middle Huazhuo Qushi Decoction group and high Huazhuo Qushi Decoction group. After 12 weeks treating, LDL-C was not decreased significantly except high Huazhuo Qushi Decoction group. After 12 weeks treating, VLDL was decreased significantly except gynostemma group. There were no noticeable changes in the matter of HDL-C,ALT,AST,BUN and Cr. After 12 weeks treating, All therapeutic groups except gynostemma group, oil-red O staining showed that liver cell swelling were relieved or disappeared, nucleus were stained blue, the size and the amount of lipid droplets diminished or liver cells contained only a few lipid droplet. The content of liver cell lipid droplets in simvastatin group and middle Huazhuo Qushi Decoction group were very close to that in blank group. After 12 weeks treating, in descending order of SREBP-2 mRNA expression levels were gynostemma group, high Huazhuo Qushi Decoction group, simvastatin group, blank group, low Huazhuo Qushi Decoction group, middle Huazhuo Qushi Decoction group, model group, and there were no noticeable changes except model group. In descending order of HMGCR mRNA expression levels were gynostemma group, high Huazhuo Qushi Decoction group, simvastatin group, blank group, model group,middle Huazhuo Qushi Decoction group, low Huazhuo Qushi Decoction group, and there were no noticeable changes except low Huazhuo Qushi Decoction group and middle Huazhuo Qushi Decoction group. In descending order of PCSK9 mRNA expression levels were blank group, simvastatin group, high Huazhuo Qushi Decoction group, gynostemma group, middle Huazhuo Qushi Decoction group, low Huazhuo Qushi Decoction group, model group, and there were no noticeable changes except low Huazhuo Qushi Decoction group and middle Huazhuo Qushi Decoction group. In descending order of LDLR mRNA expression levels were simvastatin group, gynostemma group, low Huazhuo Qushi Decoction group, middle Huazhuo Qushi Decoction group, high Huazhuo Qushi Decoction group, model group, blank group, and there were no noticeable changes in any group.Conclusions:Huazhuo Qushi Decoction can effectively reduce CHOL, which is probably related to inhibition of SREBP-2 mRNA and HMGCR mRNA expression and prevention of cholesterol synthesis. Prof. Lu Zhizheng conformed to principles of regulating the spleen and stomach, dispelling wet and dissolving turbid. In order to against the retention of phlegmatic dampness, transportation and transformation disorder and pathogenic factor for internal damage of spleen and stomach, Prof. Lu Zhizheng conducts the early-stage interference and strengthens the spleen and the stomach before the formation of phlegm and dampness. Prof. Lu Zhizheng treats the original form to prevent cholesterol synthesis, which is accordant with the thought of "Preventive Treatment of Disease" and "preventing disease from exacerbating" in TCM and provide a new pathway of preventing and treating of Hyperlipidemia in clinical.