Effects Of Exposure To DEHP During Pregnancy On Fetal Growth And Spatial Memory In Offspring

Backgrounds and Objectives Di-(2-ethylhexyl)phthalate(DEHP)is a kind of phthalate esters compound which is widely used in industrial production and everyday consumer goods.DEHP is a typical environmental endocrine disruptor and it is commonly exposed to DEHP in a variety of ways and sources.Numerous studies have shown that DEHP has potential developmental toxicity,including embryonic developmental toxicity and neurodevelopmental toxicity.The purpose of this study is to investigate whether the effects of DEHP exposure during pregnancy on the growth and development of the fetus have gender difference and their sensitive period,the effects of DEHP exposure during different gestation periods on the spatial learning and memory ability of offspring.Methods This study was divided into the following three parts:In the first part,healthy ICR pregnant mice were randomly divided into three groups: control group(corn oil group)、50 mg/kg DEHP group、200 mg/kg DEHP group.The pregnant mice were gavaged from GD0 to GD17 by 1% of the weight,the body weight and food consumption of pregnant mice were recorded daily.Pregnant mice were sacrificed at GD18 and the weight of uterus with fetal,body weight and crown-rump length of the fetuses were recorded in a timely manner and the gender of the fetuses was identified,if not sure,can be judged by dissecting the genitals.At the same time,the number of dead fetuses,live fetuses and resorptions were recorded.In the second part,healthy ICR pregnant mice were randomly divided into 6 groups,the treatment groups were given 200 mg/kg DEHP and the treatment time was first trimester(GD0-GD6),second trimester(GD7-GD12),third trimester(GD12-GD17),and set the corresponding control groups given corn oil gavage,recorded the weight of pregnant mice and food consumption daily.Pregnant mice were sacrificed in GD18,and the weight of uterus with fetuses,placental weight,placental diameter,fetal weight and crown-rump length were recorded in a timely manner and the gender of the fetuses was identified,if not sure,can be judged by dissecting the genitals.The number of dead fetuses,live fetuses and resorptions were recorded.The pathological sections of placentas were tested by immunohistochemistry and H&E staining to observe the distribution and expression of Ki67 positive cells and the ratio of sinusoids in labyrinthine region.In the third part,healthy ICR pregnant mice were randomly divided into four groups,the treatment groups were given 200 mg/kg DEHP and the treatment time was second trimester(GD7-GD12)and third trimester(GD13-GD17),set the corresponding control groups given corn oil gavage treatment.After the delivery of pregnant mice,the number of newborn mice per litter was adjusted within the group,10/litter,half male and half female.The offspring were weaned at 3 weeks old and the male were kept separately with female.Morris water maze were performed in adulthood to observe the learning and memory ability changes.Results In the first part,the total body weights of the control group and 50 mg/kg and 200 mg/kg were(1.376 ± 0.018)g,(1.271 ± 0.015)g and(1.173 ± 0.026)g respectively.Compared with the control groups,the body weights of the fetuses in the treatment groups was decreased,significantly(F = 26.826,P <0.01).The body weights of the female fetuses were(1.341 ± 0.020)g,(1.245 ± 0.020)g and 1.108 ± 0.030)g,the male fetuses were(1.410 ± 0.016)g,(1.302 ± 0.010)g and(1.220 ± 0.020)g,compared with the control groups,the body weights of both of the male and female fetuses in the treatment groups was decreased,the difference was statistically significant(F = 25.102,P <0.01).In addition,the crown-rump lengths of the treated groups also showed a significant reduction compared with the control groups.In the second part,the total body weights of fetuses in the first,second,third trimester exposure groups and corresponding control groups were(1.338 ± 0.025)g, (1.312 ± 0.025)g,(1.241 ± 0.023)g and(1.401 ± 0.015)g,(1.401 ± 0.025)g and(1.402 ± 0.025)g.Compared with the control groups,the body weights of fetuses in the second and third trimester were decreased significantly(P <0.01).The crown-rump lengths of the fetuses in the first,second,third trimester exposure groups and corresponding control groups were(23.53 ± 0.23)g,(23.27 ± 0.20)g,(23.21 ± 0.21)g and(24.41 ± 0.23)g,(24.42 ± 0.29)g and(24.41 ± 0.22)g.Compared with the control groups,the crown-rump lengths of the fetuses in the early,middle and late stages of pregnancy were significantly lower(P <0.01).The placental weights were(0.086 ± 0.003)g,(0.083 ± 0.004)g,(0.086 ± 0.002)g and(0.098 ± 0.005)g,(0.097 ± 0.002)g and(0.097±0.003)g.Compared with the control groups,the placental weights of fetuses in the second trimester were decreased significantly(P<0.01).In addition,the rate of placental sinusoids area and cell proliferation in the second trimester exposure group were lower than those in the control group,but there was no obvious effect on first and third trimester groups.In the water maze test,compared with the control group,adult female offspring in the second trimester significantly prolonged the latency on the first and third day,but latency on the four to six days back to normal;the latency on the third day of the adult male offspring in the second and third trimester exposure groups was significantly prolonged,but latency on the four to six days back to normal.On the seventh day,the time staying at target and the average movement distance of male adult offspring exposure during third trimester was shorter compared with control group(P<0.05).Conclusions DEHP exposure during pregnancy can lead to fetal intrauterine growth restriction,this injury occurs in both male and female fetuses,there is no gender difference;the sensitive period of fetal intrauterine growth restricted is mainly in the second and third trimester;DEHP exposure during the third trimester can reduce the memory of male offspring.