An Animal Model Of Hyperlipidemia And Phytosterol Esters Lowering Cholesterol Animal Studies

ObjectivesIt is important to study and evaluate hypolipidemic substances by animal hyperlipidemia models.The aim of this research was to establish three types of animal hyperlipidemia models consisting of combined Hyperlipemia model, Hypercholesterolemia model and Hypertriglyceridemia model.Studied on the effect of cholesterol-lowering by phytosterol esters on two Hypercholesterolemia animalThe model for experiment to verify the validity and stability of model,meanwhile, explored effective dose and possible mechanism of phytosterol esters.MethodEstablishment of Hyperlipemia modelsSD rats and hamsters were served as establishing three types of hyperglycemia models which were requested to be similar with human disease.Those hyperglycemia models were formed by feeding corresponding high fat food.The high fat food of hyperlipidemia model was followed:SD rat combined Hyperlipemia composed of 1%cholesterol,10%lard,10% yolk,0.2%bile salt powder and 79%normal diet;SD rat hypercholesterolemia model with three types of high fat food:(1) 5%yolk powder,1%cholesterol and 94%normal diet,(2) 1%cholesterol,0.2%bile salt and 98.8%normal die,(3) 5%lard,1%cholesterol,0.2%bile salt and 93.8%normal die.The high fat food of hamster hypercholesterolemia model composed of 0.2% cholesterol and 99.8%normal diet.SD rat hypertriglyceridemia models with three types of high fat food:(1) 15%lard and 85%normal diet,(2) 15%lard,10%sucrose and 75%normal diet, (3) 15%lard,10%fructose and 75%normal diet.Hamster hypertriglyceridemia models also with two types of high fat food:(1) 20%lard and 80%normal diet,(2) 20%lard,10%sucrose and 70%normal diet.SD rats and hamsters were allotted to control groups and model groups by weight and TC or TG.Control group and model groups were provided with normal diet and high fat food respectively for four to eight weeks.Blood was taken every week from SD rats or every two weeks from hamsters.Serum was isolated;TC and TG were measured by biochemistry methods.At end of experiment,liver tissue was taken from animals for detecting level of TG and TC in liver tissue.Animal experiments on cholesterol-lowering by phytosterol estersIn vivo experiment,SD rats were allotted to 6 subgroups including control group, model group and four dose groups randomly by weight and tail blood TC;hamsters also were allotted to 7 subgroups randomly by weight directly.Both were provided with phytosterol esters and high fat food for 12 weeks.Tail blood was taken from SD rat to detect TG,TC,LDL-C,and HDL-C every four weeks;hamster's blood was taken in the end and the same as SD rat to detect.Both animal liver issues and aortic arches were prepared at the end of experiment.The concentration of blood Apo A I,Apo B,Apo E,ox-LDL and CETP were detected by ELISA methods,and expression of liver issue LDLR mRNA gene was tested by reverse transcriptase PCR(RT-PCR).Conclusion1.Both SD rat and hamster hypercholesterolemia models were successfully established by feeding high fat food.According to experiment results,Food was composed of 1% cholesterol,0.2%bile salt and 98.8%normal die for SD rat,and 0.2%cholesterol and 99.8%normal die for hamster.2.Model animal needed to screen by weight gain of second week and appropriate proportion,which was to optimize SD rat hypertriglyceridemia model.3.Hamster hypercholesterolemia was significant lowed by phytosterol esters,but not in SD rat hypercholesterolemia,which suggests hamster hypercholesterolemia model better to evaluate cholesterol-lowering on functional health food than SD rat model.4.The study results showed that hamster blood TC and LDL-C were lowered by 1.0g/kgBW/d phytosterol esters with Statistical differences.This study considered 1.0g/kgBW/d as the least effect dose of phytosterol esters.5.In all of blood lipid index that appeared effect,the phytosterol esters dose of cholesterol etherification was the lowest,suggested that Cholesterol etherification was the sensitive marker on cholesterol-lowering by phytosterol esters.6.One of the mechanisms of cholesterol -lowering by Phytosterol Esters was to reduce Apo B concentration and increase the level of LDLR mRNA expression.