Human embryo modulates placental function in the first trimester; effects of neural tissues upon chorionic gonadotropin and progesterone secretion.

We investigated the effect of embryonal neural and adrenal tissues (7-14 weeks gestational age) upon beta hCG secretion by homologous placental explants in static and dynamic cultures. In static co-culture significant inhibition by SC and brain was noted at 7-9 weeks. Similarly, in superfusion, using a novel co-chambering technique there was a significant reduction in the area under the curve but not peak frequency of spontaneous pulsatile beta hCG secretion. Incubations with neural tissues 11 weeks and above caused a stimulatory effect upon beta hCG secretion in both models. The effect of adrenal tissue in static cultures was different, namely slightly inhibitory at 7-9 weeks and inhibitory at 11 weeks and above. In superfusion, the effect of adrenal tissue was not significant. Extracted neural tissue 7-9 weeks incubated with placental explants exhibited inhibitory effects upon beta hCG secretion as well. Buffer-based extracts of neural tissues effect was more pronounced than alcohol-based extracts regarding beta hCG secretion. The effect of extracts was dose-dependent and effects were noted up until a 2000-fold dilution. In contrast, the buffer SC extract had no effect on progesterone (P) secretion while the alcohol extract effect was inhibitory at 7-9 weeks and stimulatory at greater than 11 weeks. Superfused explants pattern of beta hCG secretion was inhibited by one minute pulse of the SC buffer extract. In conclusion, the human neural tissue of embryonal origin may modulate placental hCG and P secretion during early pregnancy.