Abstract
One objective of this experiment was to evaluate our hypotheses that estradiol-17β regulates secretion of pregnancy specific protein B (PSPB) and that secretion of progesterone during pregnancy is regulated by a prostanoid by examining the effects of prostaglandin F(2α) (PGF(2α)), a luteolyic agent; indomethacin, a prostanoid synthesis inhibitor; tamoxifen, an estrogen receptor antagonist; estradiol 17-β; and interaction of these factors on the incidence of abortion and progesterone and PSPB secretion. Another objective was to determine if there is a luteal source of PSPB. Weights of corpora lutea were decreased (P ≤ 0.05) by PGF(2α), indomethacin, PGF(2α) + tamoxifen, PGF(2α) + indomethacin, and PGF(2α) + estradiol-17β but not (P ≥ 0.05) by tamoxifen or estradiol-17β alone. No ewe treated with PGF(2α) alone aborted (P ≥ 0.05). Forty percent of ewes treated with PGF(2α) + estradiol-17β aborted (P ≤ 0.05), but ewes were not aborted by any other treatment within the 72-h sampling period. Profiles of progesterone in jugular venous blood differed (P ≤ 0.05) among control, indomethacin-, tamoxifen-, and PGF(2α) + indomethacin-treated ewes. Progesterone in jugular venous blood of control ewes decreased (P ≤ 0.05) by 24 h, followed by a quadratic increase (P ≤ 0.05) from 24 to 62 h. Progesterone in jugular venous blood of indomethacin-, PGF(2α)-, PGF(2α) + tamoxifen-, PGF(2α) + indomethacin-, PGF(2α) + estradiol-17β-, and tamoxifen-treated ewes was reduced (P ≤ 0.05) by 18 h and did not vary (P ≥ 0.05) for the remainder of the 72-h sampling period. Progesterone in vena cava and in uterine venous blood was reduced (P ≤ 0.05) at 72 h in PGF(2α)-, indomethacin-, tamoxifen- , PGF(2α) + indomethacin-, PGF(2α) + tamoxifen-, and PGF(2α) + estradiol- 17β-treated ewes. Weights of placentomes did not differ among treatment groups (P ≥ 0.05). Profiles of PSPB in inferior vena cava blood differed (P ≤ 0.05) among control, estradiol-17β-, indomethacin-, tamoxifen-, PGF(2α) + indomethacin-, and PGF(2α) + tamoxifen-treated 88- to 90-day pregnant ewes. Concentrations of PSPB in inferior vena cava blood were increased (P ≤ 0.05) in indomethacin-, estradiol-17β-, tamoxifen-, PGF(2α) + tamoxifen-, and PGF(2α) + indomethacin-treated 88- to 90-day pregnant ewes within 6 h and did not vary (P ≥ 0.05) for the remainder of the 72-h sampling period. Concentrations of PSPB in uterine venous blood of indomethacin-, tamoxifen-, PGF(2α) + tamoxifen-, and PGF(2α) + indomethacin-treated ewes were greater (P ≤ 0.05) at 72 h than at 0 h. PSPB in ovarian venous blood did not differ (P ≥ 0.05) adjacent or opposite to the ovary with the corpus luteum. It is concluded from these data that estrogen regulates placental secretion of PSPB and that a prostanoid, presumably prostaglandin E, regulates placental secretion of progesterone during 88-90 days of gestation in sheep and that there is no luteal source of PSPB.
| Original language | English |
|---|---|
| Pages (from-to) | 113-124 |
| Number of pages | 12 |
| Journal | Prostaglandins and Other Lipid Mediators |
| Volume | 58 |
| Issue number | 2-4 |
| DOIs | |
| State | Published - Oct 1999 |
Bibliographical note
Funding Information:☆ This research was supported in part by USDA CSREES Special Grant No. 95–34135-1776 to C.W. Weems and managed by the Pacific Basin Advisory Group and Hawaii Hatch Project 259 as its contribution to USDA W-112 Regional Research Project. The authors are also indebted for support given by Mr Bruce Robinson, Niihau Ranch, and Mr Eric Johnson of Hawaii Mega Cor Inc. Original Articles
Keywords
- Estradiol- 17β
- Indomethacin
- PGF(2α)
- Pregnancy
- Pregnancy specific protein B
- Progesterone
- Tamoxifen
ASJC Scopus subject areas
- Biochemistry
- Physiology
- Pharmacology
- Cell Biology