Effects of soybean isoflavone on growth factors and its receptor on prostatic hyperplasia in rats.

Objective To investigate the inhibitive effect of soybean isoflavone(SI) on benign prostatic hyperplasia(BPH) in rats and to study its regulation mechanism of growth factors.Methods Rats were induced to prostate hyperplasia by sc injection of testosterone and were randomly divided into normal control group,BPH model group,and three SI groups(60,120,and 240 mg/kg).Treated by ig administration four weeks later,the prostate wet weight and prostatic index(PI) were measured.The levels of IGF-1,EGF,VEGF,bFGF,and TGFβ in serum were determined by ELISA,and the change of EGF-R was detected by immunohistochemistry.Results The prostate wet weight and PI increased in BPH model group;The prostate wet weight and PI decreased in all SI dose groups,and the levels of IGF-1,EGF,VEGF,and bFGF in serum and the expression of EGF-R in prostatic epithelial tissue also decreased,compared to the model group.However,the level of TGF-β increased significantly.The effect of 120 mg/kg SI group was the most potent.Conclusion SI has good inhibition on prostate hyperplasia and its mechanism may be related to reducing the levels of IGF-1,EGF,VEGF,and bFGF,raising the level of TGF-β,and down-regulating the expression of EGF-R.