EP02.04: Association of fetal adiposity and expression of serotonin system in placenta of pregnant women with overt diabetes mellitus

Serotonin system has been suggested as a key role in predicting fetal adiposity and neurodevelopment across the life course. In this study, we hypothesised that fetal head circumference (HC) and estimated birthweight (EBW) percentiles were associated with expression of the serotonin system in the placenta of women with overt diabetes mellitus (DM), including serotonin transporter gene (SLC6A4) and serotonin receptor gene (HTR2A). Furthermore, we aimed to explore the expression of serotonin system in the placenta as a potential mechanism connecting an adverse prenatal environment and neonatal development. In this retrospective study, 198 participants with DNA and RNA were isolated from samples of tissue taken samples from the fetal side of the placenta immediately after delivery. Sixty-six mothers were diagnosed with DM and 132 mothers had normal glucose test (NGT). SLC6A4 and HTR2A mRNA levels were measured by reverse transcription-quantitative PCR (RT-qPCR). Functional SLC6A4 and HTR2A polymorphisms were genotyped using standard PCR-based procedures. Fetal HC and EBW were measured before delivery and defined as percentiles. Mean level of mRNA expression of placental HTR2A mRNA was higher in women with GDM than in women with NGT (0.15 vs 0.83, p = 0.048). Placental HTR2A mRNA showed a positive correlation with maternal plasma glucose level and EBW percentile (β = 0.006, p 0.013) and a negative correlation with fetal HC percentile (β = -0.008, p 0.020). Our study's results suggest that altered expression of placental serotonin system is associated with fetal adiposity and neurodevelopment in a harmful maternal environment.