Transforming growth factor-beta stimulates, and glucocorticoids and epidermal growth factor inhibit brain natriuretic peptide secretion from cultured human amnion cells

We previously reported the massive secretion of brain natriuretic peptide (BNP) from human amnion cells and suggested the possible role of BNP in the maintenance of human pregnancy. In this study, to elucidate the regulatory mechanism of BNP secretion from amnion cells, we measured the BNP level in the culture medium of amnion cells by RIA after incubation in the presence of various substances. Among the agents examined, cortisol (1 × 10(^-7) to 1 × 10(^-6) mol/L), dexamethasone (1 × 10(^-8) to 1 × 10(^-6) mol/L), and epidermal growth factor (EGF; 2 × 10(^-11) to 2 × 10(^-8) mol/L) inhibited BNP secretion from the cultured amnion cells in a dose-dependent manner. By contrast, transforming growth factor-β (TGF β; 4 × 10(^-11) to 4 × 10(^-9) mol/L) caused a 3- to 5-fold increase in BNP secretion. TGF β-augmented BNP secretion was abolished by the addition of cortisol or EGF to the culture medium. Moreover, in this study, we revealed the presence of bioactive TGF β in human amniotic fluid (approximately 4 × 10(^-10) mol/L). The present finding of tight regulation of BNP secretion from amnion cells by cortisol, EGF and TGF β, all at the concentrations physiologically present in human amniotic fluid, implies a physiological role of BNP secretion from amnion cells in the pregnant uterus.