AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 3 738-R740, Copyright © 1992 by American Physiological Society
Alterations in oxytocin prohormone processing during early development in the fetal sheep
M. Morris, M. Castro and J. C. Rose
Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157.
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.
