Abstract: ObjectiveTo evaluate effects of nonylphenol(NP)on rat prostate tissue apoptosis and expressions of caspase-3,caspase-8,and caspase-9 mRNA. MethodsFifty healthy Wistar rats were randomly divided into five groups(one olive control group and 4 groups exposed to NP at the doses of 12.5,25,50,and 100 mg/kg)based on body weight.The exposure groups were admimistered 1 mg/kg of NP hypodermic injection once a day for 30 days.The prostate tissue apoptosis was observed with teminal transferase-mediated biotin dUTP nick end labeling(TUNEL)and expressions of caspase-3,caspase-8,and caspase-9mRNA in prostate tissue were detected with real-time reverse transcription PCR(RT-PCR). ResultsThe prostate apoptosis rate in 12.5,25,50,and 100 mg/kg NP group were 3.07±1.31%,5.21±1.47%,6.31±1.29%,and 8.90±0.18%,all lower than that in the control group(12.73±2.19%)(P<0.05 for all).The expressions of caspase-3 mRNA,caspase-8 mRNA,and caspase-9 mRNA in all NP exposed groups were lower than those in the control group(P<0.05 for all). ConclusionNP decreases the apoptosis of prostate tissue in male Wistar rats,which may be one of the mechanisms for prostate hyperplasia in rats caused by NP.