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

The purpose of this study was twofold: (1) to determine whether there is a profile of 5-hydroxytryptamine (5-HT, serotonin) concentrations in fetal bo vine blood and tissues during pregnancy, parturition and the early neonatal period and (2) to determine whether 5-HT has a 'mitogenic' effect on cultu red placentome cells in bovine. Results revealed a 5-HT concentration profi le in fetal blood. Overall concentrations of 5-HT in fetal blood were 6.6 t imes (P<0.001) that of adult cows and 2.8 times (P<0.001) that of blood col lected during caesarean section (from umbilical veins) and from 18-72 h old calves. Mid-term and full-term pregnancy fetuses were not statistically di fferent from each other. Overall concentrations of 5-HT in the intestinal w all of the fetus were 4.4 times higher (P<0.05) than in the 24 h calf. Conc entration 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). Concent rations 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 co tyledon cells treated with 5-HT (2.5, 5.0 and 10.0 <mu>M) incorporated betw een 2.0 and 3.0 times more (3)[H]-thymidine than untreated controls, indica ting a dose-dependent (r = 0.94) positive mitogenic effect of 5-HT. Both gr oups of cultured cells responded equally. Five-MT 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 abi lity to act as a mitogen in bovine placental cells. (C) 2001 Harcourt Publi shers Ltd.