The effects of recombinant ovine interferon-τ (IFN-τ) and progesterone on oestrogen-stimulated expression of endometrial receptors for oestrogen (ER), progesterone (PR) and oxytocin (OTR) were determined in ovariectomized ewes. Cyclic ewes (n = 16) were ovariectomized and fitted with uterine catheters on Day 4 of the oestrous cycle (Day 0, oestrous) and assigned randomly in a 2 x 2 - factorial arrangement to receive daily intrauterine injections of either recombinant ovine IFN-τ (roIFN-τ; 2 x 107anti-viral units) or control proteins from Day 11 to Day 15 and 50 mg progesterone from either Day 4 to Day 10 (E-P) or Day 4 to Day 15 (E + P). All ewes received 50 μg oestradiol-17β on Days 13, 14 and 15 and were hysterectomized on Day 16. In control ewes, endometrial ER mRNA, PR protein and OTR density were greater in E-P- than E+P-treated ewes. In E-P ewes, roIFN-τ decreased oestrogen-stimulated increases in ER and OTR, but not PR expression compared with control ewes. In ESP ewes, endometrial ER mRNA and protein, PR mRNA and protein, and OTR levels were lower in roIFN-τ-treated ewes than control ewes. Immunoreactive ER and PR were absent in the endometrial luminal and superficial glandular epithelium of roIFN-τ compared with control ewes, but were present in the deep glandular epithelium and stroma regardless of steroid or protein treatment. These results indicate that progesterone affects oestrogen-induced increases in endometrial ER, PR and OTR expression in the PR+deep glandular epithelium and stroma, whereas IFN-τ suppresses oestrogen-induced increases ER, PR and OTR expression in the PR-luminal and superficial glandular epithelium. These combined actions of IFN-τ and progesterone to suppress oestrogen-induced increases in endometrial OTR formation would prevent pulsatile production of luteolytic prostaglandin F(2α) by the endometrium during early pregnancy.
All Science Journal Classification (ASJC) codes
- Reproductive Medicine
- Animal Science and Zoology
- Molecular Biology
- Developmental Biology