Exposure to manganese and lead disrupt the human placental serotonergic system

Abstract

Objectives: Serotonin is crucial for placental function and fetal development. Maternal exposure to metals can interfere with the placenta functioning and fetal development. The aim of this study is to determine if low concentrations of manganese (Mn) and lead (Pb) alter placental serotonin system. Methods and results: Birth biological samples from a cohort of pregnant women were collected and Mn and Pb levels were measured in maternal and cord blood, and placenta. Expression of placental serotonin 5-HT2A receptor mRNA is lower in high-level groups of Pb and Mn in maternal blood compared to low-level groups. Placental expression of the serotonin transporter (SERT) protein is lower in high-level group of Pb in cord blood compared to low-level group. To better understand the effect of metals on the placental serotonin system, BeWo cell line (trophoblast model) was exposed to increasing concentrations of Mn and Pb. Exposure to 1 nM of Pb reduced SERT expression by 64% in BeWo cells. SERT activity in BeWo cells exposed to Mn (1000 nM) and Pb (0.01 nM) was decreased by 30% and 52%, respectively, and was accompanied by a decrease in serotonin cell level. Conclusion: This study shows that low concentrations of Mn and Pb affect placental serotonin system, which could disturb the proper course of pregnancy and fetal development.