Alterations in oxytocin prohormone processing during early development in the fetal sheep

• Published in: The American journal of physiology Vol. 263; no. 3 Pt 2; pp. R738 - R740
• Main Authors: Morris, M, Castro, M, Rose, J C
• Format: Journal Article
• Language: English
• Published: United States 01-09-1992
• Subjects: Animals; Embryonic and Fetal Development; Fetal Blood; Gestational Age; Oxytocin - blood; Protein Precursors - blood; Protein Processing, Post-Translational; Sheep
• ISSN: 0002-9513
• DOI: 10.1152/ajpregu.1992.263.3.r738

Oxytocin (OT) prohormone processing was studied in fetal sheep. Using specific antisera that recognize the amidated and the COOH-terminal extended forms of OT, we measured arterial and venous levels of the OT peptides in fetal sheep plasma at 94 and 138 days of gestation. Plasma levels of the COOH-terminal extended forms, OT-X, were highest early in development, 35.7 +/- 9.8 vs. 14.3 +/- 5.7 pg/ml (94 vs. 138 days). The ratio of the plasma peptides, OT-X to OT, was higher in the young fetus (35 +/- 11.6 vs. 3.1 +/- 1.3, 94 vs. 138 days). There were also developmental changes in the umbilical artery-umbilical vein differences, with positive values noted in late gestation. These results demonstrate that the changes in the processing of the OT precursor that occur during fetal development are reflected by alterations in the relative amounts of prohormone and amidated hormone found in fetal plasma.