Differential effects of placental restriction on IGF-II, ACTH receptor and steroidogenic enzyme mRNA levels in the foetal sheep adrenal.
We have investigated the effects of restriction of placental growth on foetal adrenal growth and adrenal expression of mRNAs for Insulin-like Growth Factor II (IGF-II), the IGF binding protein IGFBP-2, Steroidogenic Factor 1 (SF-1) and adrenocorticotrophic hormone (ACTH) receptor (ACTH-R) and the steroidogenic cytochrome P-450 enzymes: cholesterol side chain cleavage (CYP11A1), 17alpha-hydroxylase (CYP17) and 21-hydroxylase (CYP21A1); and 3beta-hydroxysteroid dehydrogenase/Delta5Delta4 isomerase (3betaHSD). Endometrial caruncles were removed from non-pregnant ewes before mating (placental restriction group; PR). The total adrenal: foetal weight ratio was higher in PR (n=6 foetuses) than in control foetuses (n=6 foetuses). There was no difference in plasma ACTH concentrations between the PR and control foetuses between 130 and 140 days gestation. Adrenal IGF-II mRNA levels were lower (P<0.05) in the PR group, however, adrenal IGFBP-2 mRNA levels were not different between the PR and control groups. Adrenal ACTH-R mRNA levels were also lower whilst CYP11A1 mRNA levels were increased (P<0.005) in the PR group. We conclude that foetal adrenal growth and steroidogenesis are stimulated as a consequence of foetal growth restriction and that factors other than ACTH are important in foetal adrenal activation during chronic, sustained hypoxaemia.
Ross
J T
JT
Department of Physiology, The University of Adelaide, Adelaide 5005, SA, Australia.
Phillips
I D
ID
Simonetta
G
G
Owens
J A
JA
Robinson
J S
JS
McMillen
I C
IC
D000311:Adrenal Glands / Q000196:embryology* / Q000378:metabolism; D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D005260:Female; D005333:Fetus / Q000502:physiology; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D009097:Multienzyme Complexes / Q000235:genetics*; D009929:Organ Size; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D011375:Progesterone Reductase / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018043:Receptors, Corticotropin / Q000235:genetics*; D012016:Reference Values; D012756:Sheep; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics; D013255:Steroid 21-Hydroxylase / Q000235:genetics; D013251:Steroid Isomerases / Q000235:genetics*; D014158:Transcription, Genetic
C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D018043:Receptors, Corticotropin; D007335:Insulin-Like Growth Factor II; D003577:Cytochrome P-450 Enzyme System; D011375:Progesterone Reductase; D013255:Steroid 21-Hydroxylase; D013254:Steroid 17-alpha-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D013251:Steroid Isomerases