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Fetal maturation and the timing of parturition in both sheep and primates are thought to be controlled by the hypothalamic-pituitary-adrenal axis but little is known about the endocrinology of the equine fetus. We investigated the ontogeny of plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol and corticosteroid binding capacity in the late-gestation fetal horse. We also wished to determine whether there is ultradian rhythmic release of ACTH and cortisol in fetal horses and we compared fetuses to maternal and non-pregnant adult horses. Six fetuses, 278-304 days gestation (term approximately 335), were catheterized and sampled daily until delivery. Mean (+/- S.E.M.) ACTH concentrations increased significantly from 159 +/- 21 to 246 +/- 42 pg/ml over the last 2 days before parturition. Fetal cortisol increased significantly from 3.1 +/- 1.0 to 13.4 +/- 3.7 ng/ml (mean +/- S.E.M.) over the last 9 days before delivery. The slope of regressions for ACTH and cortisol concentrations with respect to time were positive in all subjects and statistically significant in 3 of 6 for ACTH and 5 of 6 for cortisol. Fetal corticosteroid binding capacity declined from 49.5 +/- 20.5 to 16.1 +/- 2.2 ng/ml (mean +/- S.E.M.) over the last 10 days before parturition. However, the greatest changes in ACTH, cortisol and corticosteroid binding capacity occurred very late in gestation, during the last 48 to 72 h before parturition.(ABSTRACT TRUNCATED AT 250 WORDS)
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
February 1998,
Biology of reproduction,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
May 1992,
Endocrinology,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
July 1987,
Biological psychiatry,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
July 1991,
Endocrinology,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
February 1991,
The American journal of physiology,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
September 1979,
Developmental psychobiology,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
June 1987,
Journal of endocrinological investigation,
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
December 1978,
Science (New York, N.Y.),
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
December 1978,
Science (New York, N.Y.),
T A Cudd, and
M LeBlanc, and
M Silver, and
W Norman, and
J Madison, and
M Keller-Wood, and
C E Wood
April 1979,
The Journal of endocrinology,
