Submitted to: Endocrine Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 1995
Publication Date: N/A
Interpretive Summary: Reproductive failure is one of the most costly and limiting factors in the livestock industry. A large majority of reproductive losses in sheep occur during early pregnancy as a result of failed embryo-maternal signalling at the time of pregnancy recognition. The objective of this research is to investigate the biological signal (ovine trophoblast protein-1, oTP-1) produced by the sheep embryo and to examine the effects of a molecule called interleukin-3 (IL-3) on oTP-1 production in vitro. Sheep embryos cultured with IL-3 had increased oTP-1 production, and sheep IL-3 messenger ribonucleic acid (m-RNA) was localized at luminal and glandular epithelial cells of uterine endometrium. Direct treatment of female sheep with oTP-1 and(or) IL-3 during the maternal recognition stage of gestation should result in improved early embryonic survival. Increased embryonic survival will improve lambing rates for the U.S. sheep industry.
The effect of interleukin-3 (IL-3) on conceptus production of ovine interferon tau (oIFN-tau) was examined using two dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE), western blot, northern blot, in situ hybridization and immunohistochemical methodologies. Ovine conceptuses (d 15, n=8; d 17, n=16) were cultured in vitro for 24 h in Eagle's Minimum Essential Medium (MEM) containing various doses of huma recombinant IL-3 (hIL-3). At 75 and 150 colony forming units (units)/ml hIL-3, amounts of oIFN-tau released into the culture media increased three to sixfold over controls while at 300 units/ml (60 pM), hIL-3 did not enhance oIFN-tau production. These variations in production of oIFN-tau paralleled amounts of oIFN-tau mRNA detected by northern blot analysis. Ovine IL-3 mRNA was localized at luminal and glandular epithelia of uterine endometria collected from pregnant ewes on d 15 and 17 but its polypeptide was localized in both epithelial and stromal regions. However, such signal were not detected when d 15 and 17 conceptuses were evaluated. Ovine IL-3 mRNA and its polypeptide were also localized at similar epithelial area of the endometrium obtained from cyclic ewes on d 8 and 12. The effect of hIL-3 on the enhancement of oIFN-tau production in vitro could be mimicked by the addition of phorbol 12-myristate 13-acetate (PMA). The present observations demonstrate that the hemopoietic cytokine, IL-3, stimulates conceptus production of oIFN-tau in vitro, and that ovine IL-3 and its mRNA are localized in the maternal endometrium. These results suggest that a cytokine, IL-3, produced by the maternal endometrium, is involved in conceptus production of oIFN-tau which may result from the activation of a second messenger system, protein kinase C.