Maternal Exposure To Titanium Dioxide Nanoparticles Affects Placental Growth And Development In Pregnant Mice

Background and aim:In the late 1980 s a new high technology was emerged and suddenly raised--nanotechnology.With the arrival of its time,nanomaterials were widely used in industrial and agricultural,food and medical fields.Titanium dioxide nanoparticles?TiO₂ NPS?was one of the most widely used nanomaterials with large production and consumption.In recent years,people have begun to pay close attention to its impact on biological systems.At present,there are a lot of research on biological effects and safety analysis through a large number of in vivo or in vitro model of nano-titanium dioxide,and existing studies have shown that exposure to TiO₂ NPS during pregnancy can significantly increase fetal malformations and mortality.However,the potential impact of exposure to TiO₂ NPS during pregnancy on placenta in mice has not yet been determined.Therefore,we propose to explore the effect of and its mechanism TiO₂ NPS exposure on placenta growth and development by forced gavage in mice.Methods:1.Experimental animals and treatment: The female Kunming mice were given the different doses of TiO₂ NPS?0,1,10 mg/kg/day?by forced gavage from the first day of gestational days?GD1?and we took the mice liver,kidney,ovary,placenta organ specimens on the 13 of gestational days?GD13?.2.The effect of TiO₂ NPS exposure during pregnancy on placental structure of mice was observed by HE staining on GD13.3.The effect of TiO₂ NPS exposure on placental growth and developmental marker gene expression was analyzed by real-time quantitative PCR in mice on GD13.4.Immunohistochemical method was used to observe the effect of TiO₂ NPS exposure on labyrinth vascular,decidual uNK cells and cell proliferation of placenta in mice on GD13.5.The effect of TiO₂ NPS exposure on the ultra-structure of placental tissue wasobserved by transmission electron microscopy?TEM?in mice on GD13.6.The effect of TiO₂ NPS exposure on placental apoptosis protein was analyzed,and the possible signal pathways were explored by western blot in mice on GD13.Results:1.Compared with the control group,there was no significant difference on the liver,spleen,kidney and ovary weight and organ coefficient after exposure to different doses of TiO₂ NPS?all P>0.05?in mice GD13.Compared with the control group,the number of implanted embryos,the number of resorbed embryos and the weight of placenta were not significantly changed after exposure to different doses TiO₂ NPS?all P>0.05?.However,1 mg/kg/day TiO₂ NPS treatment significantly reduced placental organ coefficient in GD13 mice?P<0.05?.2.Compared with the control group,the results of HE staining showed that the area of placental spongiotrophoblast cells was significantly increased and the area of labyrinth cells was decreased in GD13 mice after exposure to 10 mg/kg/day TiO₂ NPS?P<0.05?.3.Compared with the control group,real-time quantitative PCR results showed that the expression levels of Hand1,Esx1,Eomes,Hand2,Ascl2 and Fra1 mRNA were significantly inhibited in placenta of GD13 mice after exposure to TiO₂ NPS?P<0.001?.4.Compared with the control group,immunohistochemical results showed that GD13 mice placental labyrinthine vascular grid structure disappeared,vascular collapse and atresia after exposure to TiO₂ NPS.The number of uNK cells in the placental decidua was obviously decreased?P<0.001?and the number of PCNA positive cells in the placental was significantly declined?P<0.05,P<0.001?.5.Compared with the control group,transmission electron microscopy?TEM?showed that nuclear pyknosis,expansion of sliding endoplasmic reticulum and abscission of rough endoplasmic reticulum ribosome were observed in placental tissue of GD13 mice after exposure to TiO₂ NPS.6.Compared to control group,western blot data showed the expression of Bcl-2protein decreased?P<0.01,P<0.001?,Bax protein was significantly increased?P<0.05,P<0.001?,Caspase-3 protein was cleaved to active fragments after exposureto 1,10mg/kg/day TiO₂ NPS and the level of phosphor-Erk1/2 was increased?P<0.001?in 10 mg/kg/day TiO₂ NPS.Conclusions:Maternal exposure to titanium dioxide nanoparticles significantly disrupted the growth and development of mice placenta,possibly mediated by the impact of angiogenesis,cell proliferation and apoptosis pathways.