| Objectives:To observe the effects of green tea polyphenols on insulin sensitivity, glucose tolerance, blood pressure, serum lipid in model rats of insulin resistance and to study the mechanism produced by berberine.Methods:SPF level 56 health SD rats were randomly selected group of 10 normal (sham), the rest is in the model. Normal group was feed on normal diet, the others on high-fat-sugar-salt diet and free alternative to drink sugar-salt water (4% sugar,1% salt) and fructose water (6%). Blood pressure were measured at the end of 0,4th,8th,10th 12th week, and the end of 8th week, three rats died and removed two rats (BP<120mmHg) and one low weight rat of the model group. Then allocated the model group into 4 groups, such as model, GTP(200mg/kg), GTP(50mg/kg), and Captopril group(25mg/kg),each group has 10 rats. Normal group and model group were given distilled water; other groups were given the different doses of green tea polyphenols or captopril orally. drugs were administered by intragastric administration respectively, once a day for 4 weeks. At the end of 12th week, measure the weight, length and heart ultrasound of the rats; The levels of, serum glucose, serum lipid serum insulin, TNF-α, TGF-β1, AngⅡ, NO, MDA, the activity of SOD, NOS were measured. The insulin-sensitivity index and obesity index were calculated at the end of the experiment. Whole heart and left ventricle was weighted respectively, and then index of cardiac weight and myocardium proliferation was calculated. Hearts were collected to observe the histological changes.Results:Compared with normal rats, body weight, body mass index, index of cardiac weight and myocardium prolife ration of the model group was higher than the normal group (P<0.05), serum glucose, serum insulin levels were significantly increased insulin resistance index (ISI) (P<0.05); while cardiac ultrasound showed:model group left ventricular posterior wall thickening, ejection fraction (EF) increased fractional shortening (FS) decreased (P<0.05); myocardial pathological examination showed that the model group myocardial showed hypertrophy and hyperplasia and other changes. Compared with model group, Both GTP groups FSG, FINS significantly reduced, ISI increased (P<0.05), blood pressure increased (P<0.05).Compared with model group, green tea polyphenols reduce blood pressure of each dose group, FSG, FINS significantly reduced, ISI increased (P<0.05); TNF-a, TGF-β1, and Ang II levels and decreased MDA and NO levels, NOS activity Decreased, SOD activity was enhanced (P <0.05). High dose of serum TC, TG, LDL-C decreased (P<0.05), low dose group TC, LDL-C decreased (P<0.05), HDL levels high and low dose group were higher (P<0.05). Cardiac ultrasound showed green tea polyphenols group, left ventricular posterior wall thickening lessened, FS increased (P<0.05), high dose green tea polyphenols reduced EF (P<0.05). GTP cardiac pathology examination revealed proliferation of rat cardiac hypertrophy to change light, degree of pathological changes between the normal and model groups.Conclusions:1. For 12 weeks high fat-sugar-salt, sugar-salt water/fructose water diet fructose established insulin resistance-left ventricular hypertrophy model in rats. The model has high success rate and low death rate; 2. Green tea polyphenols can low blood pressure, mediate lipids, increase the role of insulin sensitivity index of IR-LVH rats; 3. Green tea polyphenols can reverse or inhibit left ventricular hypertrophy which cause by insulin resistance, and the effect of high dose is better; 4. Mechanism of green tea polyphenols in rats of reversing LVH may increased antioxidant capacity, reduced AngⅡ, TGF-β1, TNF-a levels, improved insulin resistanc; 5. The results suggest that high dose green tea polyphenols on left ventricular hypertrophy and insulin resistance antioxidant intervention is better than positive drug captopril group, but the exact role needs to be further clinical observation.
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