The Research On The Effect Of DEHP On The Progesterone Synthesis And The StAR,P450scc MRNA Expression Of Ovaries In Rats

ObjectiveTo explore the effect of di-2-ethylhexyl phthalate(DEHP) exposure on the levels ofprogesterone in blood of rats and the expression of steroidogenic acute regulatoryprotein(StAR) mRNA and cytochome P450cholesterol side chain cleavage enzyme（P450scc） mRNA in ovarian tissue of rats. Pubertal female rats were exposed toDEHP for short period. Analysis of the gene expression level which participate inhormone synthesis, and to discuss the possible mechanism of DEHP on femalereproductive toxicity. Expected results will provide basic data for the research onreproductive endocrine disruption of DEHP, to elucidate the mechanism of reproductiveendocrine disruptors, and can provide some scientific bases to develop an effectivestrategy to control the DEHP harm.Methods1. Thirty-two pubertal female rats were randomly divided into control group andthree experimental groups，8in each，every day treated with DEHP at the dose of10,100,1000mg/kg through gavage for experimental groups and corn oil for control.2. Lavage for10consecutive days, blood was collected and the serum was isolatedto measure the progesterone level by electro-chemiluminescence immunoassay. Removethe ovarian tissue of rats to extract total mRNA. Reverse Transcription PolymeraseChain Reaction （RT-PCR） was used to analyze the levels of StAR mRNA andP450scc mRNA．3. All of the data was input by Excel. SPSS19.0was used for statistical analysis,and α=0.05is the standard of difference significant or not. Results1. The effect of model ratsMEHP is the primary metabolite of DEHP, MEHP levels in serum increased withexposure dose upward trend, indicating that the animals exposed to DEHP successful.2. The change of weight and ovary weight in ratsThe weight of rats in each groups were increased as the exposure time prolonged.The amount of weight gain decreased with the increasing dose. With the increase ofinfected dose bilateral ovaries weight gradually decreased. There were statisticallysignificant differences of ovary weight in rats among high does treatment（1000mg/kg）and control group(P＜0.05).3. The result of serum progesterone levelThe serum progesterone level of low dose group（10mg/kg） was slightly higherthan control group（0mg/kg） and middle dose group（100mg/kg）. But there were nostatistically significant differences of serum progesterone level among the three groups.The levels of progesterone in high does（1000mg/kg）group was significantly higherthan other groups（P<0.01）.4. Relative expression level of StAR mRNA and P450scc mRNA in each dosagegroup rats.The expression levels of StAR mRNA and P450scc mRNA decreasedas the dose increases. Compared with the control group, the expression levels of StARmRNA and P450scc mRNA in middle dose(100mg/kg) or high does(1000mg/kg)treatment groups were lower(P＜0.05、P＜0.01).Conclusion1. DEHP may affect ovarian development in adolescent rats.2. Exposure the high dose of DEHP may increase the levels of progesterone.3. DEHP exposure by the oral route can decreased the transcription levels of StARand P450scc genes.