Placenta detachment: unexpected high concentrations of 5-hydroxytryptamine (serotonin) in fetal blood and its mitogenic effect on placental cells in bovine

Kellie Fecteau, University of Tennessee, Knoxville
Hugo Eiler, University of Tennessee, Knoxville

Abstract

The purpose of this study was twofold: (1) to determine whether there is a profile of 5-hydroxytryptamine (5-HT, serotonin) concentrations in fetal bovine blood and tissues during pregnancy, parturition and the early neonatal period and (2) to determine whether 5-HT has a 'mitogenic' effect on cultured placentome cells in bovine. Results revealed a 5-HT concentration profile in fetal blood. Overall concentrations of 5-HT in fetal blood were 6.6 times (P< 0.001) that of adult cows and 2.8 times (P< 0.001) that of blood collected during caesarean section (from umbilical veins) and from 18-72 h old calves. Mid-term and full-term pregnancy fetuses were not statistically different from each other. Overall concentrations of 5-HT in the intestinal wall of the fetus were 4.4 times higher (P< 0.05) than in the 24 h calf. Concentration of 5-HT in full-term muscle was 3.5 times higher than in mid-term muscle and 2.8 times higher than in 24 h old calf muscle (P< 0.05). Concentrations of 5-HT in mid-term and full-term cotyledon were 4.4 times higher (P< 0.05) than in post partum cotyledon. Characterized trophoblast cells and a heterogeneous population of bovine cotyledon cells treated with 5-HT (2.5, 5.0 and 10.0 microm) incorporated between 2.0 and 3.0 times more(3)[H]-thymidine than untreated controls, indicating a dose-dependent (r=0.94) positive mitogenic effect of 5-HT. Both groups of cultured cells responded equally. Five-HT treatment did not affect either cell number or cell size. It was concluded that a 5-HT concentration profile exists in fetal bovine blood and tissues and that 5-HT has the ability to act as a mitogen in bovine placental cells.