Effects of sex hormones, forskolin, and nicotine on choline acetyltransferase activity in human isolated placenta

The activity of choline acetyltransferase (ChAT) was investigated in the human placenta before and after long-term incubation (24 h) to test the effects of sex hormones, nicotine and forskolin. ChAT activity differed considerably between the amnion (0.03 mumol/mg protein/h) and the villus (0.56). After long-term incubation, ChAT activity persisted in the latter but declined in the amnion. Neither sex hormones (D-estradiol, testosterone, progesterone; 10 or 100 nM each) nor follicle stimulating hormone and luteinizing hormone (FSH/LH; 8.4 U/ral each) modified ChAT activity. Also nicotine (1 nM-100 muM) did not affect ChAT activity. Forskolin, an activitor of adenylyl cyclase, reduced ChAT activity in the villus but not in amnion. The present model offers the possibility to investigate ChAT regulation in intact tissue under long-term incubation. The risks of maternal smoking during pregnancy cannot be attributed to an effect of nicotine on placental ChAT activity. Differences in the regulation of ChAT appear to exist between neuronal and nonneuronal cells.