The developmental expression of adrenocortical steroid hydroxylases was studied in bovine fetuses from 40 to 280 days gestational age. The expression of P-450(17α) is first detected at a gestational age of 50 days and reaches a maximum at 60-70 days. The expression of P-450(17α) then declines and is nondetectable at a gestational age of 100 days. P-450(17α) is not expressed again until about 240 days, i.e. shortly before birth (~280 days). P-450(scc), P-450(c21), P-450(11β) and adrenodoxin were present in fetal adrenals throughout gestation. This 'on-off-on' pattern of P-450(17α) expression during fetal development was associated with a corresponding episodic production of cortisol. Immunoreactive corticotropin (ACTH) levels in fetal plasma were elevated in small fetuses (corresponding to ≤ 100 days) and in near-term fetuses (corresponding to > 250 days) compared with those in mid-gestation fetuses. In primary culture, adrenal cells from mid-gestation fetuses contained no detectable P-450(17α) but rapidly responded to ACTH with an increase in P-450(17α) protein and mRNA. The tissue specificity of the developmental patterns is emphasized by the fact that both P-450(17α) and P-450(scc) were detectable throughout the development of the fetal testes, whereas only P-450(scc) was detectable in fetal bovine ovary prior to 200 days. Thus, in fetal bovine adrenal it appears that ACTH is the major regulatory factor effecting the intermittent presence of P-450(17α), whereas the presence of the other steroid hydroxylases is either regulated by additional factors or shows a much different sensitivity to ACTH.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1988|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology