Abstract:

OBJECTIVE: To investigate the effects of soybean isoflavone and di-(2-ethylhexyl) phthalate(DEHP) on the hormone level in female rats. METHODS:Thirty-two female Sprague-Dawley rats were randomly divided into 4 groups:86 mg/kg soybean isoflavone group, 68 mg/kg DEHP group, isoflavone(86 mg/kg)+DEHP(68 mg/kg) group and control group, 8 rats in each group. Food intake and body weight were recorded weekly, at the end of the fourth week, rats were sacrificed, blood collected and viscera weighed. High performance liquid chromatography (HPLC) was used to measure serum DEHP content and radioimmunoassay method was used to assess serum estrogen and testosterone levels. The expression of ERα in endometrium was tested by immunohistochemistry. RESULTS:When compared to the control group, no significant difference was found in all of the treated groups with respect to weight gain (P value were all >0.05). DEHP significantly increased the organ/body ratio of spleen and liver when compared to the control group (P<0.05). The levels of serum DEHP in the DEHP group and isoflavone+DEHP group were significantly higher than that in the control group (P<0.05) and the isoflavone+DEHP group had significant lower DEHP level than the DEHP group (P<0.05). Furthermore, testosterone level was not significantly different among different groups, however, serum estrogen in isoflavone+DEHP and DEHP group was significantly lower than that in the control group (P<0.05). Immunohistochemistry suggested although 86 mg/kg soybean isoflavone group, 68 mg/kg DEHP group and isoflavone+DEHP group had higher expresson level of ERα in rats'endometrium tissue, no significant difference was found among them(P>0.05). CONCLUSION:DEHP could significantly increase the organ/body ratio of the liver and spleen and it also could reduce serum estrogen level in female rats. Soybean isoflavone could reduce the residual serum DEHP to some extent.

Key words: soybean isoflavone, di-(2-ethylhexyl) phthalate, estrogen, testosterone