Effects of astragaloside Ⅳ on insulin resistance and MAPK/ERK pathway in obese rat model of polycystic ovary syndrome
AIM To investigate the effects of astragaloside IV on improving insulin resistance(IR)in obese rat model of polycystic ovary syndrome(PCOS),and to analyze its effect on ovarian MAPK/ERK pathway as well.METHODS The obese PCOS rat models established by feeding of letrozole combined with high-fat and high-sugar diet were randomly divided into the model group,the metformin(135 mg/kg)group and the low-dose and high-dose astragaloside Ⅳ(25,50 mg/kg)groups,with 8 rats in each group in contrast to those of the control group.After 21 days oral administration,the rats had their body weight recorded;their ovarian index calculated;their levels of fasting blood glucose(FBG),serum triglyceride(TG),total cholesterol(TC),follicle-stimulating hormone(FSH),testosterone(T),estradiol(E2),luteinizing hormone(LH)and fasting insulin(FINS)measured;their HOMA-IR and LH/FSH values calculated;their ovarian expressions of MAPK/ERK pathway related proteins detected by Western blot;and their ovarian expression of vascular endothelial growth factor(VEGF)protein detected by immunofluorescence staining.RESULTS Compared with the control group,the model group showed increased polycystic pathological changes,levels of body weight,ovarian index,serum TG,TC,LH,FSH,T,FINS,and FBG,values of LH/FSH and HOMA-IR,and ovarian p-ERK1/2/ERK1/2,p-MEK1/2/MEK1/2,p-Raf/Raf,and VEGF protein expressions(P<0.01);and decreased serum E2 level(P<0.01).Compared with the model group,both astragaloside Ⅳ and metformin groups shared significantly alleviated ovarian polycystic lesions,and decreased body weight,levels of ovarian index,serum TG,TC,LH,FSH,T,FINS,and FBG,values of LH/FSH and HOMA-IR,ovarian p-ERK1/2/ERK1/2,p-MEK1/2/MEK1/2,p-Raf/Raf,and VEGF protein expressions(P<0.05,P<0.01),and increased serum E2 level(P<0.05,P<0.01).CONCLUSION Upon the obese PCOS rat models,astragaloside Ⅳ can antagonize their IR,improve their hormone levels and alleviate their ovarian lesions via inhibiting the activation of MAPK/ERK pathway.
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