Regulation of protein synthesis in the first trimester human placenta by 17 beta-oestradiol and progesterone.

Addition of 17 beta-oestradiol or progesterone to first trimester human placental explants in vitro resulted in the stimulation of protein synthesis, as seen by autofluorographic analysis of placental tissue and medium proteins. An increase in the incorporation of [35S]methionine into trichloroacetic acid-precipitable proteins was seen, following the addition of 17 beta-oestradiol. Use of aromatase inhibitor to block the synthesis of 17 beta-oestradiol inhibited the protein synthesis and while addition of cyclohexamide blocked both basal- and 17 beta-oestradiol-induced protein synthesis, actinomycin-D blocked only 17 beta-oestradiol induced protein synthesis. Double labelling of placental proteins in the presence and absence of 17 beta-oestradiol also indicated that there is a significant stimulation of protein synthesis by 17 beta-oestradiol. Based on these results it is suggested that oestradiol has a role in regulation of placental protein synthesis.