ABSTRACT
<p><b>OBJECTIVES</b>To study the inhibitory mechanism of tamoxifen on benign prostatic hyperplasia.</p><p><b>METHODS</b>The Wistar male adult rats were injected into muscle with testosterone propionate 4-6 mg/kg, simultaneously were irrigated into stomach with tamoxifen citrate 0.21 mg/kg. The partly rats of each group were decapitated at 7, 15 and 30 days, then their index numbers of prostate were calculated, and the structural changes of the prostatic histocyte were observed in the light microscopy and scan electronic microscopy.</p><p><b>RESULTS</b>At the 7th, 15th, and 30th day, the index numbers of prostate of those rats which had been injected only with testosterone propionate were higher than that of the control group and the irrigating group(P < 0.05). The hyperplasia of the prostatic epithelial cells and the ground substance of those rats, which had been irrigated with tamoxifen citrate, had not happened in light microscopy and the scan electronic microscopy.</p><p><b>CONCLUSIONS</b>Tamoxifen could block the effect of the estrogen, which could suppress the prostatic hyperplasia. This study could provide the experimental evidences for using Tamoxifen to treat the human benign prostatic hyperplasia.</p>