657: Maternal obesity and regulation of DNA methylation in the preimplantation stage (original) (raw)

2016, American Journal of Obstetrics and Gynecology

OBJECTIVE: DNA methylation, a regulatory mechanism that affects gene activity, is important in fetal development and is likely responsible for fetal programming of adult diseases. Obesity is well known to alter fetal programming and lead to long term adverse outcomes in the offspring. The objective of this study was to test the hypothesis that pre-pregnancy obesity affects DNA methylation as early as the blastocyst stage and prior to implantation. STUDY DESIGN: CD-1 female mice were fed high fat diet for 3 months prior to pregnancy (HF group, n¼3). Control mice were fed chow containing standard amount of fat (SF group, n¼3). Mice were bred and pregnancy was established by the presence of a plug (day 1). On day 4, mice were sacrificed and uterus and ovaries extracted. Blastocysts were flushed from uterus, evaluated for development, and frozen until analysis. cDNA and real time quantitative PCR were used to determine expression levels of genes regulating methylation (Dnmt1, Dnmt3a, Dnmt3b) and active demethylation (Tet1, Tet2, Tet3, Tdg, Ape1). Mann-Whitney test was used for statistical analysis (significance P <.05). RESULTS: On days 1 and 4 HF mice had significantly higher total body weight (P¼0.01 and P¼0.02, respectively). mRNA levels of Dnmt3b, Tdg and Tet3 tended to be lower in HF blastocysts as compared to SF group. No differences in Dnmt1, Dnmt3a, Tet1, Tet2, and Ape1 gene expressions were noted. CONCLUSION: This pilot study demonstrates that pre-pregnancy obesity alters genes that control DNA methylation in the blastocyst. This is the earliest evidence of fetal programming and indicates that preventive measures should be aimed at the pre-pregnancy period.