Detection of oestrogenic activity of steroids present during mammalian gestation using oestrogen receptor alpha- and oestrogen receptor beta-specific in vitro assays.
Numerous steroid hormones are present in the foetus but their potential to activate oestrogen receptor (ER) alpha and/or beta is largely unknown. In this study, in vitro assays were developed to rapidly and specifically detect ERalpha or ERbeta activation by these steroid hormones. Our results showed that several oestrogen precursors and androgens are able to activate both ERalpha and ERbeta. Of special interest is that some of these precursors are able to activate ERalpha and ERbeta at concentrations that are present during human gestation. Moreover, some precursors (dehydroepiandrosterone (DHEA) and 17-hydroxylated pregnenolone sulphate) and androgens (5-androsten-3beta,16alpha,17beta-triol and testosterone) showed a more than 100-fold relative preference for ERbeta transactivation over ERalpha transactivation when compared with 17beta-oestradiol. Due to their relatively high levels, the precursor steroids DHEA and pregnenolone may be of particular importance in the regulation of ERbeta activity in vivo. To obtain information about the oestrogenic activity of the total pool of steroid hormones present during mammalian gestation, steroids were extracted from mouse embryos at different prenatal stages and assayed for oestrogenic activity in the established in vitro assays. Oestrogenic activity was detected in steroid extracts from all stages tested. This study has demonstrated that oestrogen receptor agonists are present in the murine embryo and that oestrogen precursors may contribute to the total pool of agonists during foetal life.
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
J G
JG
Lemmen
C E
CE
van den Brink
J
J
Legler
P T
PT
van der Saag
B
B
van der Burg
D000728:Androgens / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003687:Dehydroepiandrosterone / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000378:metabolism; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000196:embryology* / Q000378:metabolism*; D051379:Mice; D011284:Pregnenolone / Q000378:metabolism; D011485:Protein Binding; D011498:Protein Precursors / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D014162:Transfection / Q000379:methods
D000728:Androgens; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D006728:Hormones; D011498:Protein Precursors; D011960:Receptors, Estrogen; D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate; D011284:Pregnenolone