Maternal Folic Acid Over-Supplementation Impairs Cardiac Function in Mice Offspring by Inhibiting SOD1 Expression

Obstetrics and Gynecology Cardiovascular System Life Sciences Medicine
folic acid over-supplementation cardiac function superoxide dismutase 1 N-acetylcysteine

Background

Folic Acid (FA) supplementation during pregnancy is widely recommended to reduce the risk of fetal congenital defects, particularly in the prevention of neural tube defects and congenital heart disease. However, despite the significant benefits of FA supplementation in preventing certain diseases, whether excessive FA supplementation may have negative effects on fetal health remains a controversial topic. In recent years, growing evidence suggests that maternal over-supplementation of FA may lead to metabolic dysfunction, autism, retinoblastoma, and other health issues in offspring. Nevertheless, the impact of excessive FA supplementation on cardiac function, especially its long-term effects on offspring heart health, has not been thoroughly studied.

To address this issue, a research team from Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, and Fudan University in China conducted a study to evaluate the effects of maternal over-supplementation of FA on cardiac function in mouse offspring and to uncover the underlying molecular mechanisms. This research not only provides new scientific evidence for the safety of FA supplementation but also offers important insights into the relationship between maternal nutritional status and offspring health.

Source of the Study

The study was conducted by Ke Cai, Feng Wang, Hai-Qun Shi, and other researchers from Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, and the Children’s Hospital of Fudan University. The paper was published online on September 10, 2024, in the journal Cardiovascular Research, titled “Maternal folic acid over-supplementation impairs cardiac function in mice offspring by inhibiting SOD1 expression.”

Research Process and Results

1. Experimental Design and Animal Model

The study used 8-week-old pregnant C57BL/6J mice, which were randomly divided into control and over-supplementation groups. The control group received a daily dose of 4 mg/kg FA, while the over-supplementation groups received 20 mg/kg (5× group) and 40 mg/kg (10× group) of FA, respectively. FA supplementation lasted from the first day of mating until embryonic day 8.5 (E8.5), after which all mice were returned to a standard diet.

2. Cardiac Function Assessment

Cardiac function in the offspring was assessed using echocardiography. The results showed that maternal over-supplementation of FA led to a significant decrease in left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in the offspring, indicating impaired cardiac function. Additionally, the left ventricular internal dimensions at end-diastole (LVIDd) and end-systole (LVIDs) increased, while the thickness of the interventricular septum and left ventricular posterior wall decreased in the over-supplementation groups, further confirming the decline in cardiac function.

3. Histological Analysis of Cardiac Tissue

Masson’s trichrome staining and wheat germ agglutinin (WGA) staining were used to analyze cardiac tissue. The results revealed significant increases in cardiac fibrosis and cardiomyocyte area in the over-supplementation groups. Furthermore, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining showed an increased number of apoptotic cells in the cardiac tissue of the over-supplementation groups, indicating chronic damage to cardiomyocytes.

4. Proteomics and Gene Expression Analysis

Proteomic analysis of cardiac tissue revealed that over-supplementation of FA led to the downregulation of multiple genes related to cardiac function, including SOD1, PEBP1, MYL3, and MYL6. Real-time quantitative PCR (qRT-PCR) further confirmed the transcriptional downregulation of these genes. Additionally, targeted bisulfite sequencing showed a significant increase in DNA methylation of these genes, suggesting that excessive FA may inhibit their expression through increased DNA methylation.

5. Intervention with Antioxidant NAC

To validate the relationship between SOD1 downregulation and impaired cardiac function, the researchers used the antioxidant N-acetylcysteine (NAC) for intervention. The results showed that NAC supplementation reversed the inhibition of SOD1 expression caused by excessive FA and reduced reactive oxygen species (ROS) levels in cardiac tissue. Echocardiography and histological analysis further confirmed that NAC supplementation significantly improved cardiac function in the offspring, reducing myocardial fibrosis and cell apoptosis.

Conclusions and Significance

This study is the first to reveal the negative impact of maternal over-supplementation of FA on offspring cardiac function and to elucidate the underlying molecular mechanisms. The research demonstrates that excessive FA inhibits the expression of key genes such as SOD1 through increased DNA methylation, leading to impaired cardiac function. This finding not only provides new scientific evidence for the safety of FA supplementation but also offers important insights into the relationship between maternal nutritional status and offspring health.

Highlights of the Study

  1. Key Finding: Maternal over-supplementation of FA impairs cardiac function in mouse offspring, providing new scientific evidence for the safety of FA supplementation.
  2. Molecular Mechanism: The study reveals that excessive FA inhibits the expression of key genes such as SOD1 through increased DNA methylation, leading to impaired cardiac function.
  3. Intervention Strategy: By using the antioxidant NAC, the research team successfully reversed the cardiac dysfunction caused by excessive FA, offering a potential strategy for prevention and treatment.
  4. Innovation: This study is the first to link excessive FA supplementation with cardiac dysfunction and to uncover its epigenetic regulatory mechanisms, holding significant scientific value and application potential.

Additional Valuable Information

The study also suggests that while FA supplementation plays a crucial role in preventing congenital defects, excessive supplementation may pose potential health risks. Therefore, future research should further explore the optimal dosage of FA supplementation to ensure its benefits in disease prevention without negatively impacting offspring health. Additionally, this study provides a new perspective on the relationship between maternal nutritional status and offspring health, laying the foundation for further research into the long-term effects of maternal nutrition on offspring health.

Through this research, we have gained a deeper understanding of the safety of FA supplementation and provided important evidence for future guidelines on FA supplementation.