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Inhibitory Effect of Pueraria Isoflavones on Prostatic Hyperplasia in Rats

??OBJECTIVE To investigate the inhibitory effect and possible mechanisms of puerariae isoflavone(PI) on prostatic hyperplasia induced by testosterone propionate.METHODS Forty-eight male Wistar rats were randomly divided into six groups according to their body weight including normal control group, model group, 40, 80, 160 mg??kg^-1??d^-1 PI group, and finasteride positive control group. In addition to the sham operation for rats in the normal control group, the rats in other five groups performed castration surgery. After the restoration, the five groups of rats were subcutaneously injected with testosterone propionate (10 mg??kg^-1??d^-1) for 10 d to establish a benign prostatic hyperplasia model and then the subcutaneous injection was maintained every 2 d. High, middle and low dose PI groups were intragastrically administered (40, 80, 160 mg??kg^-1??d^-1) from the second day when the benign prostatic hyperplasia model was successfully constructed. The positive control group was given finasteride (1.0 mg??kg^-1??d^-1) .Rats in normal and model groups were given an equal volume of saline for 28 d. After the last administration, the prostate and seminal vesicles were separated under anesthesia in rats, the wet weight and volume of the prostate and seminal vesicles were measured. The prostate and seminal vesicles index were calculated too. Rat blood was drawn and dihydrotestosterone(DHT) and estradiol (E2) in the serum were measured. Nitric oxide (NO), nitric oxide synthase (NOS), superoxide dismutase (SOD) and malondialdehyde (MDA) levels in prostate tissues were measured. The prostate tissue in each group was randomly selected for HE staining. The pathological structure of the prostate tissue was observed under an optical microscope.RESULTS Compared with the normal control group, the prostate gland index and seminal vesicle gland index of the model group increased significantly (P<0.01), and the DHT and E2 levels in serum increased significantly (P<0.01). MDA content was increased while NO levels, NOS and SOD activities were significantly decreased (P<0.01). HE staining showed that the size of the prostate gland in the model group was different, there were obvious dilation, hyperplasia and papillary protrusions, and the cavity was full of pink and homogeneous density. The interstitial tissue showed obvious dilations of blood vessels, infiltration of inflammatory cells, and proliferation of fibrous connective tissues. Compared with the model group, the index and volume of prostate and seminal vesicles in the PI and positive control groups were significantly decreased (P<0.05 or P<0.01), and the levels of serum DHT and E2 in the middle and high doses PI groups were significantly lower (P<0.05 or P<0.01). In all treatment groups, MDA content was decreased and NO, NOS, and SOD levels were increased (P<0.05 or P<0.01) except the low-dose PI groups. There was moderately hyperplasia in low-dose PI group, mild prostatic hyperplasia in positive control group and middle-dose PI group, basically no hyperplasia in high-dose PI group.CONCLUSION PI has a certain inhibitory effect on prostate hyperplasia induced by testosterone propionate, especially in the medium and high dose PI groups. The mechanism may be related to the effects of pueraria isoflavone on antioxidant,free radical scavenging in vivo, increasing NOS activity and increasing NO level.