Effect Of PFOA Exposure On The Corpus Luteum Of Ovaries In Pregnant Mice

Objective:Perfluorooctanoic acid?PFOA?is a synthetic perfluorooctacarbon organic chemical.Since the 1950s,it has been widely used in various hydrophobic products because of its excellent stability and hydrophobic lipophobic properties.PFOA can persist in nature and cause bioaccumulation in organisms.Studies have shown that food packaging,dust,air,especially water,and dietary are potential important sources of PFOA.Many evidences indicated that PFOA had an extensive biotoxic effects on organisms.The reproductive toxicity of PFOA had been reported.But its toxicity mechanism was not clear yet.Studies had shown that PFOA as an environmental endocrine disruptor may affect the endocrine function of the body by affecting the synthesis of related hormones and the expression of related genes or altering the activity of its synthetase.The ovarian corpus luteum might play a very important role in the development of pregnancy by secreting related hormones in the early and middle trimester.However,the existing researches about effect of PFOA on the pregnancy mainly focused on the placenta level.It had not been reported yet whether PFOA could affect the occurrence of pregnancy by affecting the function of the corpus luteum during the early and middle stage of pregnancy.Therefore,pregnant rats were treated with different concentrations of PFOA by gavage,and observed the differences in the number and weight of implanted embryos.We elucidated the effect of PFOA on the ovarian corpus luteum of pregnancy by calculating the numbers and areas of the corpus luteum,and levels of serum estrogen and progesterone.We also explored the mechanism about the effect of PFOA on early and mid-term corpus luteum by detecting expression of ovarian steroid hormone synthase,ovarian oxidative stress injury,and ovarian cell apoptosis in pregnant mice.It will provide the basic scientific data for clinical treatment and develop a new drug in PFOA exposure.Method:Adult female Kunming mice?6-8 weeks,25-30g?were selected and given different doses of PFOA?2.5,5,10 mg/kg/day?from gestational day 1?GD1?,and the control group was given an equivalent volume of distilled water.On the GD 7 and GD 13,mice were sacrificed for blood collection and the uterus,placenta,and ovary tissue were removed and photographed and weighed and counted for embryo implantation.The levels of estrogen and progesterone in serum were measured by radioimmunoassay.The changes in the number and area of corpus luteum were observed.The expression levels of ovarian steroid hormone synthase StAR,Cyp11a1and Hsd3b1 were detected by qPCR.The levels of MDA,CAT,SOD,and H₂O₂ were observed in ovarian tissues.The expression levels of apoptosis-related proteins Bcl-2,Bax,and P53 were observed by Western blotting.Result:?1?PFOA exposure did not significantly affect the number of embryos implanted on GD7 and GD 13?P>0.05?.However,on GD 13,10 mg/kg/day PFOA treatment significantly increased the numbers of resorbed embryo?P<0.05?.?2?On GD7,levels of serum estradiol was significantly increased at 10mg/kg/day?P<0.05?,but various doses of PFOA treatment had no obvious effect on the levels of serum progesterone?P>0.05?.In GD13,levels of serum progesterone were significantly inhibited in the 5 mg/kg/day and 10 mg/kg/day PFOA exposure groups?P<0.05 or P<0.01?.However,no statistically significant difference was observed in the levels of serum estradiol between the control and PFOA-treated animals at any dose level?P>0.05?.?3?On GD7 and GD13,the PFOA exposure group had no significant effect on the ovarian weight ratio?P>0.05?.However,after PFOA treatment,the number and area ratio of corpus luteum in the ovary was significantly reduced compared with the control group?P<0.05 or P<0.001?,but 10 mg/kg/day on GD 7 and 2.5 mg/kg/day on GD 13 had no obvious effect on the numbers of corpora lutea?P>0.05?.?4?All doses PFOA exposure significantly inhibited the ovarian StAR,Cyp11a1and Hsd3b1 mRNA levels compared with the control group on GD7 and GD13.?5?On GD7 and GD13,activity of ovarian CAT was significantly reduced in the5 mg/kg/day and 10 mg/kg/day PFOA-exposed groups?P<0.05 or P<0.001?.On GD7,SOD activity was not significantly affected by different doses of PFOA exposure?P>0.05?.However,on GD13,PFOA significantly inhibited SOD activity?all P<0.001?.Compared with the control group,MDA significantly increased on GD7 and GD13 and H₂O₂ on GD13 in the ovarian PFOA-exposed group?P<0.05 or P<0.01,respectively?.But on GD7,5mg/kg/day and 10mg/kg/day PFOA had no significant effect on H₂O₂?P>0.05?.?6?Western blot analysis had showed that PFOA exposure could down-regulate the expression of Bcl-2 and up-regulate the expression of Bax and P53 proteins?P<0.05 or P<0.001?.However,exposure to 2.5mg/kg/day PFOA on GD13 had no significant effect on the expression of Bax protein?P>0.05?.Conclusion:PFOA exposure significantly inhibits luteal function via oxidative stress and apoptosis in pregnant mice.