ABSTRACT
Objective@#The present study was represented by di-(2-ethylhexyl) phthalate (DEHP), to explore the role of thyroid hormones (THs) disruption in the connection of placenta and neurodevelopmental toxicity.@*Methods@#During fetal mice neural tube closed (pregnancy 9.5 days, E9.5d) to begin synthesis of THs (E15.5 d), all pregnant mice were administered with different concentration of DEHP (0、10、50、200 mg/kg) by gavage once a day(10 mice per group). All pregnant mice were conducted with BrdU administration in E14d by subcutaneous injection. Seven pregnant mice from each group were scarified after anesthesia in E15.5 d, serum and amniotic fluid were collected to determinate the levels of THs(T3, T4, FT3 and FT4) by the automatic biochemical analyzer, detecting fetal mice placental protein expression of monocarboxylate transporter 8 (MCT8), organic anion transporting polypeptide 1C1 (OATP1C1) and deiodinaseⅡ&Ⅲ (DIO2, DIO3) by Western blot. Each group of the remaining three pregnant mices were killed after anesthesia in E18d, take the male fetal brain, BrdU immunohistochemistry was used to detect the proliferation and migration of fetal brain cortical neurons.@*Results@#There was no abnormalities in diet, water intake, body weight and general activity of pregnant mice in each treatment group, and there were no difference in the general physiolo. Results There was no abnormalities in diet, water intake, body weight and general activity of pregnant mice in each treatment group, and there were no difference in the general physiological development status of body weight, brain weight, brain body ratio between the mice of each group. There was no statistically significant differences in serum T3, T4, FT3, FT4 and amniotic fluid FT4 in pregnant mice of each group (P>0.05), Compared with the control group, the FT3 levels in the amniotic fluid of the DEHP 50 and 200 mg/kg groups were significantly decreased(P<0.05). Compared with the control group, the placental MCT8 and DIO2 protein levels of male fetal mice in the DEHP 50 and 200 mg/kg group decreased, and the level of OATP1C1 protein in 200 mg/kg group decreased(P<0.05), and there was no statistically significant difference in DIO3 protein levels among all groups (P>0.05). Compared with the control group, the number of BrdU positive cells in the cerebral cortex of male mice in DEHP 200 mg/kg group decreased, 56.5% was distributed in VZ-SVZ layer, and the percentage of BrdU positive cells in the IZ layer of 50 mg/kg group increased (P<0.05).@*Conclusion@#DEHP 50, 200 mg/kg may affect the proliferation and migration of neural cells in the developing brain, which may be related to its interference with thyroid hormone by placental transport.
ABSTRACT
Objective@#To investigate the effects of developmental exposure to DEHP on learning and memory of mice.@*Methods@#Male littermates of ICR mice randomly assigned to five experimental groups (n=14 for each condition) on PND4 to receive distilled water, vehicle and 10, 50 and 200 mg/ (kg·d) DEHP from PND5 to PND38 by gavage, weighing and recording body weight of mice. Open field task were conducted on PND 26 and Morris water maze task were begun from PND30 to PND 37 to evaluate spontaneous exploration activity and emotion, spatial learning and memory performance of pubertal mice, respectively. On PND39, all animals were killed and hippocampi were isolated on ice, then total proteins of hippocampus were extracted, followed by determining the expression of PSD95 and synapsin I by western blotting.@*Results@#200 mg/ (kg·d) DEHP significantly reduced the growth of body weight of mice and the time staying in the central area in open field, prolonged the time searching the hidden platform in Morris water maze (P<0.05) . 50 mg/ (kg·d) DEHP didn’t change the growth of body weight and the emotion (P>0.05) , but reduced the percent of time and distance in the target quadrant during the probe trial of mice in Morris water maze (P<0.05) . The results of western blotting showed that DEHP significantly reduced the expression of PSD95 in hippocampus of mice with all dose groups (P<0.01) , but only 200 mg/ (kg·d) DEHP reduced the expression of synapsin I (P<0.05) .@*Conclusion@#Developmental exposure to DEHP can damage the development of synapse in hippocampus, adversely impacting spatial memory performance of mice at a dose that are insufficient to significantly influence the general development and result in anxiety.