| Objective:Di（2-ethylhexyl）phthalate（DEHP）is used in plastic industry,food packing,and medical care products,imparting the softness and flexibility to normally devices.And human can nonoccupational expose to DEHP via ingestion,inhalation and derma widely in daily lives.Although DEHP displays low general toxicity,there is an increasing concern on the effects of endocrine system.Thyroid gland is an important endocrine organ,which products thyroid hormones（THs）to regulate the body function.Still few studies suggest the exposure to DEHP could be connected with THs disordered,and the mechanisms are still unknown.Maternal hypothyroidism during pregnancy can cause adverse effects in the fetus.In order to investigate the association between gestational and lactational DEHP exposure and the thyroid function of pups and elucidate how DEHP disturbs the THs,THs synthesis-related proteins,deiodinases were measured.Methods:The pregnant female Wistar rats were randomly divided into four groups and received gavage in dosages at 0,30,300,750mg/kg/day for the first day of gestation（GD0）to the 21st day after the births of offspring（PND 21）.On PND 7,PND 14,PND 21and PND 28,the serum THs levels of pups were measured.On PND 7,the thyroid gland of pups were observed by transmission electron microscope.THs-Related gene expressions and protein of pups were measured by RT-PCR on PND 14 and PND 21.Results:1.Significant reductions in TT4 and significant increased TSH were shown in DEHP 30 exposure group,DEHP 300 exposure group and DEHP 750 exposure group on PND 7 and PND 14 when compared with the controls（P<0.05）.There was the same phenomenon found in DEHP 300 exposure group and DEHP 750 exposure group on PND 21,while only the same tendency but no significant alterations found in DEHP 30exposure group on PND 21.On PND 28,the levels of TSH had no discrepancy between four groups,TT4 showed up a decrease feature but had no significant meanings（P>0.05）.It was no difference found in four groups on PND 7,PND 14,PND 21,and PND 28about TT3,except significant reductions in DEHP 30 exposure group and DEHP 750exposure group（P<0.05）.2.The thyroid gland was hypervascularized and mainly consisted of hypertrophied follicular cells with dense microvilli,endoplasmic reticulums,Golgi apparatus and lysosome were obviously found in the horizon;the nuclei were regular and the position of mitochondrial crest were orderly in control group.With the increasing of exposure concentration,the portion of microvilli fractured,the lysosome increased apparently,ER cisternae were much more dilated,mitochondrial crest became swollen and disordered,and nuclei were irregular,Golgi apparatus scattered.Finally,the structure of thyroid cells destroyed.3.On PND 14 and PND 21,RT-PCR showed that the mRNA expressions of NIS,PAX-8 and TTF-1 on DEHP 750 exposure groups had increased significantly compared with the controls（P<0.05）.Except for PAX-8,mRNA levels of DEHP 300 exposure group also had statistical significance in comparison to DEHP 0 exposure group on PND 14 and PND 21（P<0.05）.And DEHP obviously up-regulated the protein levels,all the DEHP 750 exposure groups were significant increased on PND 14 and PND 21（P<0.05）.The protein level of NIS of DEHP 300exposure group had statistical significance compared to the controls on PND 14,and each DEHP exposure groups all had increasing significantly compared with controls of protein NIS on PND 21（P<0.05）.Whereas there was a meaningful trend on DEHP 300exposure group on PND 21 compared with the controls of protein TTF-1 and PAX-8（P<0.05）.4.On PND 14 and PND 21,both RT-PCR and Western blot showed that the mRNA expressions and protein levels of TPO on DEHP 750 exposure groups had increased significantly compared with the controls（P<0.05）.While DEHP 30 and 300exposure group had a trend but no significant meanings on PND 14 and PND 21.5.On PND 14 and PND 21,all the DEHP exposure groups had significant changes in comparison to the controls except DEHP 30 exposure group of expression of Dio1 on PND 14.Dio1 and Dio2 levels revealed a dose-dependent upregulation（P<0.05）.Conversely,mRNA expression of Dio3 was respectively decreased compared to DEHP 0exposure group（P<0.05）.Conclusion:1.Gestational and lactational DEHP exposure of female rats damaged the thyroid follicular epithelial cells of pups,which can cause pups THs functional disordered.2.Gestational and lactational DEHP exposure of female rats can influence serum THs levels of pups by up-regulating thyroid functional protein such as TTF-1,PAX-8,NIS,TPO.3.Gestational and lactational DEHP exposure of female rats can cause pups THs functional disordered by up-regulating Dio1、Dio2 and down-regulating Dio3. |
