OBJECTIVETo investigate the preventive effect of the phytoestrogen daidzein on prostatic hyperplasia induced by testosterone in rats.

METHODSThirty-six male adult Sprague-Dawley rats were equally randomized into 6 groups: Group I and II (normal control and model, treated with 1 ml distilled water by oral gavage), and Group III-VI (low-, medium- and high-dose daidzein and positive control, respectively given daidzein at 2, 20 and 100 mg/kg and diethylstilbestrol at 0.1 mg/kg once a day for 90 days). From the 91st day , Group III-VI were treated with subcutaneous injection of testosterone at 7.5 mg/kg/d for 10 days to induce prostatic hyperplasia. The wet weight and the index of the prostate were obtained, its morphological changes detected and the changes of ERalphaa and ERbeta expressions in the prostate observed by immunohistochemistry.

RESULTSCompared with the model group, the wet weight and the index of the prostate were significantly reduced in the 3 daidzein groups and the positive control group (P < 0.05 or P < 0.01). Medium- and high-dose daidzein induced a more obvious alleviation of prostate hyperplasia, characterized by thinner epithelia, decreased secretions in the glandular cavity and reduced interstitial tissues. The expression of ERalpha showed no significant difference between the model group and the other groups, while that of ERbeta was markedly decreased in the daidzein-treated groups as compared with the normal control or the model group.

CONCLUSIONThe phytoestrogen daidzein has some preventive effect on prostatic hyperplasia induced by testosterone in rats.