Effects of Exogenous Progesterone During the Peri-Implantation Period of Pregnancy on Growth and Development of Ovine Conceptuses
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This study was conducted to confirm that exogenous P4 administered during the peri-implantation period (Days 1.5 to 8) advances conceptus growth, development, and implantation to Day 12 of gestation. This study determined how exogenous P4 affects enzymes involved in the classical (ornithine decarboxylase 1) and novel pathways (arginine decarboxylase and agmatinase) of conversion of arginine to polyamines. Additionally, expression of mRNAs of nutrient transporters for glucose, arginine, and glycine, as well as progestamedins were analyzed. Suffolk ewes (n=40) were assigned randomly to receive daily intramuscular injections of either 25 mg P4 in 1 ml corn oil (P4, n=18) or 1 ml corn oil alone (CO, n=20 from Day 1.5 through Day 8 of pregnancy. Nine P4-treated ewes and 10 CO-treated ewes were hysterectomized on Day 9 of pregnancy and 9 P4-treated ewes and 10 CO-treated ewes hysterectomized on Day 12 of pregnancy. Conceptuses from D12 P4 ewes were elongated, while all D12 CO conceptuses remained spherical at the time of necropsy. CO-treated ewes necropsied on Day 9 of pregnancy had 3-fold greater expression of ODC1 mRNA in comparison to P4-treated ewes necropsied on either Day 9 or Day 12 of pregnancy, and CO-treated ewes necropsied on Day 12 of pregnancy (P < 0.01). Furthermore endometrial expression of FGF7 mRNA increased by approximately 1.5-fold in P4 D9 ewes compared to CO-treated ewes of the same gestation day and D12 ewes in both treatments (P < 0.05) and expression of FGF10 mRNA for CO- and P4-treated ewes necropsied on Day 12 of pregnancy was about 2.5-fold greater than for CO-treated D9 ewes (P <0.01). Finally, P4-treated ewes necropsied on Day 12 of pregnancy had an approximately 3.5- fold greater expression of glycine transporter (SLC6A9) than D12 CO-treated ewes, D9 P4- treated ewes, or D9 CO-treated ewes (P < 0.01).
Hoskins, Emily Claire (2018). Effects of Exogenous Progesterone During the Peri-Implantation Period of Pregnancy on Growth and Development of Ovine Conceptuses. Master's thesis, Texas A & M University. Available electronically from