Effects of recombinant ovine interferon tau, placental lactogen, and growth hormone on the ovine uterus

Studies were conducted to determine effects of intrauterine administration of recombinant ovine interferon τ (IFNτ), placental lactogen (PL), and growth hormone (GH) on endometrial function. In the first study, administration of IFNτ to cyclic ewes for one period (Days 11-15) resulted in an interestrous interval (IEI) of ~30 days, whereas administration for two periods (Days 11-15 and Days 21-25) extended the IEI to greater than 50 days. Administration of IFNτ from Days 11 to 15 and of PL or GH from Days 21 to 25 failed to extend the IEI more than for IFNτ alone. In the second study, effects of IFNτ, PL, and GH on endometrial differentiation and function were determined in ovariectomized ewes receiving ovarian steroid replacement therapy. Endometrial expression of mRNAs for estrogen receptor (ER), progesterone receptor (PR), and oxytocin receptor (OTR) were not affected by PL or GH treatment; however, uterine milk protein mRNA levels and stratum spongiosum gland density were increased by both PL and GH treatments. Collectively, results indicated that 1) PL and GH do not regulate endometrial PR, ER, and OTR expression or affect corpus luteum life span; 2) down- regulation of epithelial PR expression is requisite for progesterone induction of secretory gene expression in uterine glandular epithelium; 3) effects of PL and GH on endometrial function require IFNτ; and 4) PL and GH regulate endometrial gland proliferation and perhaps differentiated function.