Induction of uterine prostaglandin H synthase 2 by estradiol following fetal adrenalectomy.
Journal Article (Journal Article)
In sheep, fetal cortisol stimulates the conversion of progesterone to estradiol in late gestation initiating labor. It is unclear whether an intact fetal hypothalamic-pituitary-adrenal (HPA) axis is required to induce the estradiol-triggered subsequent endocrine changes including enhanced intrauterine prostaglandin (PG) synthesis associated with the onset of labor. We have shown that maternal estradiol administration stimulates PG H synthase (PGHS)-2 expressions in pregnant ovine intra-uterine tissues. The current study was undertaken to determine whether the fetal adrenal mediates estradiol's stimulation of the intrauterine PGHS-2 in pregnant sheep. Placenta, myometrium, and endometrium were collected from two groups of ewes at 123-127 d of gestational age (dGA) after fetal adrenalectomy and vehicle treatment (ADX; n = 5); or fetal ADX and maternal estradiol administration (5 mg twice a day for 2 d, ADX+E2, n = 5). PGHS-2 mRNA and protein were analyzed by Northern and Western Blot analyses in both groups and presented as the ratios to beta actin mRNA for Northern and G protein beta subunit for Western blot analysis. Fetal plasma cortisol was measured by radioimmunoassay. Data were analyzed by Student's t test. Fetal plasma cortisol levels were low in ADX and ADX+ E2 groups (<6 ng/mL). The cervix of all ADX+E2 treated ewes was dilated at necropsy. Three out of five ADX+ E2-treated ewes delivered within 48 h. The cervix was closed in all fetal ADX ewes at necropsy. PGHS-2 mRNA and protein increased (p < 0.05) in myometrium and endometrium, but not placenta in ADX+E2-treated ewes compared with ADX group. These data provide the first in vivo evidence for estradiol upregulation of intrauterine PGHS-2 in late gestation in the absence of an intact fetal HPA axis. Thus, the fetal adrenal is not required to mediate estradiol's stimulation of uterine PGHS-2 expression associated with the onset of labor.
Full Text
Duke Authors
Cited Authors
- Wu, WX; Wolf, R; Chakrabarty, K; Collins, V; Unno, N; Nathanielsz, PW; Rose, JC
Published Date
- March 2005
Published In
Volume / Issue
- 26 / 2
Start / End Page
- 153 - 159
PubMed ID
- 15888927
Electronic International Standard Serial Number (EISSN)
- 1559-0100
International Standard Serial Number (ISSN)
- 1355-008X
Digital Object Identifier (DOI)
- 10.1385/endo:26:2:153
Language
- eng