The effect of maternal exposure to di‐(2‐ethylhexyl)‐phthalate on fetal cardiac development in mice

Sun²,

2020

Preprint

Background: It is unclear whether the offspring of subclinical hypothyroidism (SCH) pregnant rats have abnormal cardiac development, and whether early intervention with L-T4 can improve the abnormality of these offspring. Therefore, the aim of this study was to investigate the effect of early L-T4 intervention on the heart development of offspring of SCH pregnant rats and its possible molecular mechanism. Methods: Eighty female Wistar rats were randomly divided into Sham group (placebo control), SCH group, LT4-E10 group (L-T4 treatment started on the 10th day of gestation), and LT4-E13 group (L-T4 treatment started on the 13th day of gestation). Each group was further divided into E16, E18, P5 (postnatal day 5 rats), and P10 (postnatal day 10 rats) subgroups. The levels of serum TT4 and TSH, the ratio of heart weight to body weight of offspring rats, the expression of metabolic enzymes, and the histopathology of cardiomyocytes were determined. To elucidate the effects of L-T4 on cardiac development of offspring of SCH pregnant rats, the expression levels of GATA4, Nkx2-5 and proteins involved in BMP4/Smad4 signaling pathway were detected by immunohistochemistry, real time quantitative polymerase chain reaction and Western blotting to elucidate the molecular mechanism of L-T4 regulating the heart development of the offspring of SCH pregnant rats. Results: Compared with Sham group, serum TSH was significantly increased in SCH pregnant rats. Moreover, early L-T4 intervention significantly reduced the levels of serum TSH. Compared with the offspring in the SCH group, early L-T4 intervention significantly increased the heart weight, heart weight to body weight ratio, the activities of succinate dehydrogenase (SDH), Na + /K + -ATPase and Ca 2+ -ATPase, but reduced myocardial cell shrinkage and nuclear staining, hyperemia/congestion and vacuolar degeneration. In addition, early L-T4 intervention not only significantly increased the mRNA and protein expression of Gata4 and Nkx2-5, but also increased the protein expression involved in BMP4/Smad4 signal pathway in myocardium of the offspring of SCH pregnant rats. Conclusions : Early L-T4 intervention can regulate the cardiac development of the offspring of SCH pregnant rats by activating BMP4/Smad4 signaling pathway and increasing the expression of Gata4 and Nkx2-5 proteins.

Section: Discussionmentioning

confidence: 99%

Early L-T4 intervention improves fetal heart development in pregnant rats with subclinical hypothyroidism rats by activating BMP4/Smad4 signaling pathway

Sun²,

2020

Preprint

“…Remarkably, L-T4 early intervention not only significantly increased the mRNA and protein levels of Gata4 and Nkx2-5, but also activated the BMP4/Smad4 signaling pathway in the myocardium of the offspring of SCH pregnant rats. It was reported that exposure of pregnant rats to di (2-ethylhexyl) phthalate caused cardiac malformation in the offspring, which may be related to the inhibition of cardiac Gata4/mef2c/ch expression by activating Peroxisome proliferator-activated receptor gamma (PPARγ) [36]. Similar to the results of this study, a study found that the potential toxicity of PM2.5 to fetal heart tissue was related to the down-regulation of transcriptional factors Gata4 and Nkx2-5, which were functionally associated with to embryonic heart development and abnormalities of fetal heart structure and function [37].…”

Section: Discussionmentioning

confidence: 99%

Early L-T4 Intervention Improves Fetal Heart Development in Pregnant Rats with Subclinical Hypothyroidism Rats by Activating BMP4/Smad4 Signaling Pathway

Sun²,

2020

Preprint

Background: It is unclear whether the offspring of SCH pregnant rats still have abnormal cardiac development, and whether early intervention with L-T4 can improve the abnormality of these offspring. Therefore, the aim of this study was to investigate the effect of early L-T4 intervention on the heart development of offspring of SCH pregnant rats and its possible molecular mechanism.Methods: Eighty female Wistar rats were randomly divided into Sham group (placebo control), SCH group, LT4-E10 group (L-T4 treatment started on the 10th day of gestation), and LT4-E13 group (L-T4 treatment started on the 13th day of gestation). Each group was further divided into E16, E18, P5 (postnatal day 5 rats), and P10 (postnatal day 10 rats) subgroups. The levels of serum TT4 and TSH, the ratio of heart weight to body weight of offspring rats, the expression of metabolic enzymes, and the histopathology of cardiomyocytes were determined. To elucidate the effects of L-T4 on cardiac development of offspring of SCH pregnant rats, the expression levels of GATA4, Nkx2-5 and proteins involved in BMP4/Smad4 signaling pathway were detected by immunohistochemistry, real time quantitative polymerase chain reaction and Western blotting to elucidate the molecular mechanism of L-T4 regulating the heart development of the offspring of SCH pregnant rats.Results: Compared with Sham group, serum TSH was significantly increased in SCH pregnant rats. Moreover, early L-T4 intervention significantly reduced the levels of serum TSH. Compared with the offspring in the SCH group, early L-T4 intervention significantly increased the heart weight, heart weight to body weight ratio, the activities of succinate dehydrogenase (SDH), Na+/K+-ATPase and Ca2+-ATPase, but reduced myocardial cell shrinkage and nuclear staining, hyperemia/congestion and vacuolar degeneration. In addition, early L-T4 intervention not only significantly increased the mRNA and protein expression of Gata4 and Nkx2-5, but also increased the protein expression involved in BMP4/Smad4 signal pathway in myocardium of the offspring of SCH pregnant rats.Conclusions: Early L-T4 intervention can regulate the cardiac development of the offspring of SCH pregnant rats by activating BMP4/Smad4 signaling pathway and increasing the expression of Gata4 and Nkx2-5 proteins.

“…Remarkably, L-T4 early intervention not only signi cantly increased the mRNA and protein levels of Gata4 and Nkx2-5, but also activated the BMP4/Smad4 signaling pathway in the myocardium of the offspring of SCH pregnant rats. It was reported that exposure of pregnant rats to di (2-ethylhexyl) phthalate caused cardiac malformation in the offspring, which may be related to the inhibition of cardiac Gata4/mef2c/ch expression by activating Peroxisome proliferator-activated receptor gamma (PPARγ) [36]. Similar to the results of this study, a study found that the potential toxicity of PM2.5 to fetal heart tissue was related to the down-regulation of transcriptional factors Gata4 and Nkx2-5, which were functionally associated with to embryonic heart development and abnormalities of fetal heart structure and function [37].…”

Section: Discussionmentioning

confidence: 99%

Early L-T4 intervention improves fetal heart development in pregnant rats with subclinical hypothyroidism rats by activating BMP4/Smad4 signaling pathway

Sun²,

2020

Preprint

Background: It is unclear whether the offspring of SCH pregnant rats still have abnormal cardiac development, and whether early intervention with L-T4 can improve the abnormality of these offspring. Therefore, the aim of this study was to investigate the effect of early L-T4 intervention on the heart development of offspring of SCH pregnant rats and its possible molecular mechanism. Methods: Eighty female Wistar rats were randomly divided into Sham group (placebo control), SCH group, LT4-E10 group (L-T4 treatment started on the 10th day of gestation), and LT4-E13 group (L-T4 treatment started on the 13th day of gestation). Each group was further divided into E16, E18, P5 (postnatal day 5 rats), and P10 (postnatal day 10 rats) subgroups. The levels of serum TT4 and TSH, the ratio of heart weight to body weight of offspring rats, the expression of metabolic enzymes, and the histopathology of cardiomyocytes were determined. To elucidate the effects of L-T4 on cardiac development of offspring of SCH pregnant rats, the expression levels of GATA4, Nkx2-5 and proteins involved in BMP4/Smad4 signaling pathway were detected by immunohistochemistry, real time quantitative polymerase chain reaction and Western blotting to elucidate the molecular mechanism of L-T4 regulating the heart development of the offspring of SCH pregnant rats. Results: Compared with Sham group, serum TSH was significantly increased in SCH pregnant rats. Moreover, early L-T4 intervention significantly reduced the levels of serum TSH. Compared with the offspring in the SCH group, early L-T4 intervention significantly increased the heart weight, heart weight to body weight ratio, the activities of succinate dehydrogenase (SDH), Na+/K+-ATPase and Ca2+-ATPase, but reduced myocardial cell shrinkage and nuclear staining, hyperemia/congestion and vacuolar degeneration. In addition, early L-T4 intervention not only significantly increased the mRNA and protein expression of Gata4 and Nkx2-5, but also increased the protein expression involved in BMP4/Smad4 signal pathway in myocardium of the offspring of SCH pregnant rats. Conclusions: Early L-T4 intervention can regulate the cardiac development of the offspring of SCH pregnant rats by activating BMP4/Smad4 signaling pathway and increasing the expression of Gata4 and Nkx2-5 proteins.