Effects of Recombinant Ovine Interferon Tau, Placental Lactogen, and Growth Hormone on the Ovine Uterus1

Abstract

Studies were conducted to determine effects of intrauterine administration of recombinant ovine interferon tau (IFNtau), placental lactogen (PL), and growth hormone (GH) on endometrial function. In the first study, administration of IFNtau to cyclic ewes for one period (Days 11-15) resulted in an interestrous interval (IEI) of approximately 30 days, whereas administration for two periods (Days 11-15 and Days 21-25) extended the IEI to greater than 50 days. Administration of IFNtau from Days 11 to 15 and of PL or GH from Days 21 to 25 failed to extend the IEI more than for IFNtau alone. In the second study, effects of IFNtau, 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 IFNtau; and 4) PL and GH regulate endometrial gland proliferation and perhaps differentiated function.

Evaluation of the uterine environment early in pregnancy establishment to characterise cows with a potentially superior ability to support conceptus survival

“…Another conceptus-related signal may be responsible for the difference in expression of UTMP in the uteri of large pregnancies. One such candidate is CSH1, as it has been reported to stimulate the number of glands present in ovine endometrium and, hence, the levels of UTMP and SPP1 mRNA present (Spencer et al 1999).…”

Litter-size-dependent intrauterine growth restriction in sheep

“…GH is expressed in the sheep placenta mainly during the early stages of pregnancy and it is involved in regulating endometrial gland proliferation and function (Spencer et al, 1999). Interestingly, Valinsky et al (1990), showing the occurrence of gene duplication in the ovine GH locus, found two alleles: the GH1 allele with a single GH copy, and the GH2 allele with two gene copies designated GH2-N and GH2-Z.…”

Comparative aspects of implantation

“…Early studies of endocrine regulation of expression of proteins secreted by uteri of pigs (uteroferrin, ACP5; Knight et al 1973) and sheep (serine protease inhibitors or uterine milk proteins; Moffat et al 1987) revealed a requirement for longterm treatment with P 4 , indicating that effects of P 4 were not mediated by a 'classical' steroid receptor-type mechanism of action. Based on current evidence, longterm treatment with P 4 is required in order to downregulate PGR as a prerequisite to expression of proteins such as uteroferrin and uterine milk proteins in response to one or more progestamedins (Spencer et al 1999, Spencer & Bazer 2002. P 4 , the hormone of pregnancy, is required for establishment and maintenance of pregnancy in all mammals (see Bazer et al 2009).…”