Differential Serotonin Uptake Mechanisms at the Human Maternal-Fetal Interface

Area of Science:

• Neuroscience
• Reproductive Biology
• Pharmacology

Background:

• Serotonin (5-HT) is crucial for placental physiology and fetal development.
• Cellular uptake regulates local 5-HT concentrations, impacting molecular targets.
• Understanding 5-HT transport is vital for maternal-fetal health.

Purpose of the Study:

• To investigate 5-HT uptake mechanisms in human primary placental cells and cord blood platelets.
• To characterize the transporters involved and their affinities.
• To assess the implications for drug sensitivity at the maternal-fetal interface.

Main Methods:

• Isolation of human primary placental cells (trophoblasts, feto-placental endothelial cells) and cord blood platelets.
• Measurement of 5-HT uptake kinetics (Km values).
• Inhibition studies using SERT-targeting drugs.
• Analysis of mRNA expression for SERT, PMAT, and OCT transporters.

Main Results:

• Trophoblasts and platelets exhibit high-affinity 5-HT uptake via SERT (Km ~0.6 microM), sensitive to SERT inhibitors.
• Feto-placental endothelial cells show low-affinity 5-HT uptake (Km ~782 microM), unaffected by SERT blockers.
• SERT mRNA is abundant in trophoblasts, sparse in endothelial cells; PMAT mRNA shows the opposite distribution.
• OCT1, OCT2, and OCT3 mRNAs are minimally expressed in both cell types.

Conclusions:

• Functional high- and low-affinity 5-HT uptake systems exist in cells at the maternal-fetal interface.
• Trophoblast 5-HT transport is sensitive to psychotropic drugs, highlighting potential maternal-fetal transfer implications.
• Multiple 5-HT transport systems underscore the importance of maintaining 5-HT homeostasis during pregnancy.