Effects of increased cortisol concentration on ovine fetal leucine
kinetics and protein metabolism.
Milley, J. Ross.
Division of Neonatology, Department of Pediatrics, University of
Utah School of Medicine, Salt Lake City, Utah 84132
APStracts 2:0022E, 1995.
Fetal protein accretion decreases as gestation progresses, primarily
because protein synthesis decreases. Also, glucocorticoid
concentrations increase late in gestation and restraint of growth is
one of the most consistently noted effects of glucocorticoids.
Therefore, this study was done to find if fetal protein accretion is
decreased by increased cortisol concentration and whether such an
effect might be due to decreased protein synthesis or increased
proteolysis. Six days after surgery, fetal leucine and protein
metabolism was measured in eight pregnant ewes (114-119 d of
gestation) at normal and elevated cortisol concentrations. Arterial
blood leucine concentration, fetal leucine disposal rate, and
exogenous leucine uptake were unaffected by cortisol infusion. Fetal
leucine decarboxylation, however, increased by 19% (P<0.001).
Increased fetal cortisol concentration increased fetal proteolysis by
11% (P<0.001) but did not affect the use of leucine for protein
synthesis. Consequently, fetal protein accretion fell by 34%
(P<0.002). We conclude that increased fetal plasma cortisol
concentration increases fetal proteolysis, thereby decreasing the
rate of fetal protein accretion, an effect different from the
decreased protein synthesis reported in late gestation.
Received 3 October 1994; accepted in final form 1 February 1995.
APS Manuscript Number E409-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.