Studies On The Anti-Hypertension, Anti-Hyperlipidemia And Anti-Hyperglycaemia, And The Action Mechanisms Of Cactus Pear Fruit Polysaccharide

Objective:To investigate the anti-hypertension,anti-hyperlipidemia and hypoglycemic effects and their mechanisms of cactus pear fruit polysaccharide (CPFP)in spontaneous hypertension rats(SHR)and experimental hyperlipidemia,and diabetic rats for further development of anti-hypertension, anti-hyperlipidemia and hypoglycemic drugs.Methods:1.Raw polysaccharides were isolated from the alcohol extract of cactus pear fruits(Opuntia ficus-indic).The contents of proteins and polysaccharides were determined by ultra-violet spectrometry and sulfuric acid-enol method respectively.2.The dynamic influence of CPFP on the systolic blood pressure(SBP)of SHR was studied by the tail cuff method at 2,4,8,12 and 24 hours after single administration of CPFP;the influence was also studied in the morning of every week during nine-week continuous administration by the same method.The contents of angiotensinⅠ,Ⅱ(AngⅠ,AngⅡ),endothelin (ET),nitric oxide(NO)and noradrenaline(NE)were determined respectively, and the plasma renin activity(RA)was calculated according to forming speed of AngⅠafter nine weeks.The influences of CPFP on left ventricle mass, endothelial cells and vascular smooth muscle cells(VSMC)were also observed. 3.The experimental model of hyperlipidemia in rats was established by administration of high-fatty animal feeds for three weeks.The levels of total cholesterol(TC),triglyceride(TG),low density lipoprotein cholesterol(LDL-C), high density lipoprotein cholesterol(HDL-C)in blood were determined by the enzyme method,and the contents of apolipoprotein AI(ApoAI)and apolipoprotein B(ApoB)in blood were determined by immunoturbidimetry.The improvment of hemorheology was observed by testing whole blood viscosity, plasma viscosity and hematocrit.The activity of superoxide dismutase(SOD) and content of malondialdehyde(MDA)were determined respectively by the enzyme and thio-barbituric acid methods.The pathologic morphology of liver was also monitored using the optical microscopes.4.The experimental model of diabetic rats was induced by streptozotocin(STZ).During an eight-week administration,the consumptions of food and water,body weight as well as information of feces and urine of the rats were recorded.In the corresponding time,the contents of fasting blood glucose(FBG),glycosylated hemoglobin (GHB),TC,TG,LDL-C and HDL-C of rats were determined respectively.The expressions of insulin and relativeβcell volume in pancrea of experimental rats were measured.The effect of CPFP on mRNA expression of the insulin receptor (InsR)in liver and skeletal muscle and the glucose transporter 4(GluT4)in skeletal muscle of experimental rats were analyzed by semi-quantitative RT-PCR.Besides,the levels of MDA and SOD were determined,and the ultra-structure of cardiac muscle was observed by transmission electron microscope.Results:1.The content of CPFP was 71.1%.No absorption peak of any protein was shown by ultra-violet spectrometer scanning.2.The SBP of SHR was significantly lowered(P＜0.05 or P＜0.01);obvious time-effect and dosage-effect were observed at the first administration and during nine weeks. The contents of RA,AngⅡ,ET and NE were decreased respectively,and the concentration of NO was increased in SHR's plasma(P＜0.05 or P＜0.01).The left ventricle mass and the ratio of left ventricle weight to body weight were reduced(P＜0.05 or P＜0.01).The endothelial cells were protected and the proliferation of VSMC was reversed.3.The levels of TC,TG,LDL-C and ApoB were significantly decreased,and the levels of HDL-C and ApoAI were increased in blood of rats(P＜0.05 or P＜0.01).The viscosity of whole blood and plasma and the hematocrit were significantly decreased(P＜0.05 or P＜0.01).The activity of SOD was increased,and the level of MDA was decreased in rats' serum(P＜0.05 or P＜0.01).The liver cell structure and function were also protected.4.In STZ-induced diabetic rats,the level of FBG and GHB were notably decreased(P＜0.05 or P＜0.01),and the amount of insulin and relativeβcell volume were also improved in pancreas(P＜0.05 or P＜0.01).The mRNA expression of InsR in liver and skeletal muscle and that of GluT4 in muscle were increased(P＜0.05 or P＜0.01).The content of MDA was decreased,and the activity of SOD was increased in cardiac muscle(P＜0.05 or P＜0.01).Conclusion:1.CPFP may prevent and treat hypertension mainly by protecting endothelial cells,inhibiting renin-angiotensin system and reversing VSMC proliferation.2.The CPFP shows obvious effects in anti-hyperlipidemia, antioxygen and improving of hemorheology,indicating that it can be used for the prevention and treatment of hyperlipemia and liver adipose degeneration.3. CPFP can improve glycometabolism and lipid metabolism,increase the quantity ofβcells,InsR and GluT4,promote antioxidant capability and repair damaged cells of cardiac muscle,showing a potential for preventing and treating diabetes and diabetic cardiopathy.