Effects Of Prenatal Exposure To Local Airborne Fine Particulate Matter On Cardiovascular System In Rats

2.1 ObjectiveTo investigate the effects and mechanisms of prenatal exposure to ambient PM₂.5 on cardiovascular development in Fuzhou.2.2 MethodsSD rats were randomly allocated into 4 groups?n = 8 per group?: control group?PBS buffer?,low dose group?0.26?g/?l of PM₂.5 suspension liquid?,middle dose group?0.55?g/?l of PM₂.5 suspension liquid?and high dose group?1.10?g/?l of PM₂.5 suspension liquid?.The animals were anesthetized,intubated,and submitted to the instillation of 30 ?l of the following PM₂.5 suspension at different concentrations every three days from three weeks before pregnancy till postpartum.For the control group,rats were exposed to PBS buffer by the same way.The neonatal rats were raised together with their dams until weaning?postnatal day 21?,and the hearts of the young rats were harvested.The lungs from the high dose group were histopathologically examined by hematoxylin and eosin staining.The hearts were histopathologically examined by light microscopy?hematoxylin and eosin staining?,transmission electron microscopy and TUNEL examination method.The expressions of GATA4,NKX2-5 and Caspase3 protein and mRNA in the heart tissue of the young rats were assayed by Western-blotting and Real time PCR,respectively.The concentrations of TNF-?,IL-1? in the plasma of the young rats' hearts were measured by ELISA.2.3 Results 2.3.1 Prenatal exposure to ambient PM₂.5 derived locally from Fuzhou area by tracheal instillation had no significant adverse effects on litter size and weight of male or female rats in the postnatal 0d,7d,14 d and 21 d rats.2.3.2 Under light microscopy,visible particle deposition and pulmonary inflammatory lesions appeared in the lungs from the high dose group.The changes of myocardial cells and chromatin structure were morphologically appeared in the high dose group.2.3.3 Under electron microscopy,the middle dose group and the high dose group exhibited abnormal changes in nucleus heterochromatin,mitochondria,myofiber to certain degree,which were more obviously seen in the high dose group.2.3.4 Both the middle dose and high dose groups were noted in lowering the levels of Nkx2-5 protein in the heart tissue of young rats,and the high dose group was additionally effective in lowering the levels of GATA4 protein in the heart tissue of the young rats?P <0.05?.2.3.5 Both the middle dose and high dose groups were noted in lowering the levels of Caspase-3 protein in the heart tissue of young rats,and the levels of Caspase-3 mRNA in the heart tissue of the young rats higher than those in control group?P <0.05?.2.4 Conclusions 2.4.1 Prenatal exposure of environmental fine particles collected from the city of Fuzhou,China promotes visible particle deposition in the lung of maternal rats challenged with high dose of PM₂.5.2.4.2 Prenatal exposure of environment fine particles?0.55,1.10 ?g /?l PM₂.5?in the city of Fuzhou,China promotes adverse effects on fetal heart development,resulting in the changes in myocardial cells and chromatin structure and abnormal changes in nucleus heterochromatin,mitochondria and myofiber,lower levels of GATA4,Nkx2-5,Caspase-3 protein and higher levels of Caspase-3 mRNA in the heart tissue of young rats.