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Updated: Jul 31, 2026
14:40
Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings
Published on: October 25, 2015
Adrenal corticosteroid secretion in fetal sheep: pulsatile pattern at rest
B T Jackson1, A F Lee, S H Morrison
1Department of Surgery, Brown University, Providence, Rhode Island.
The American Journal of Physiology
|October 1, 1992
Summary
Fetal sheep exhibit episodic bursts in cortisol secretion, with a distinct ~90-minute oscillation that intensifies with advancing gestation. Adrenocorticotropic hormone (ACTH) also shows pulsatile rhythms, increasing exponentially alongside cortisol secretion.
Area of Science:
- Reproductive Endocrinology
- Fetal Physiology
Background:
- Fetal pituitary-adrenocortical function is crucial for development.
- Understanding fetal endocrine patterns aids in assessing developmental health.
Purpose of the Study:
- To define the resting patterns of fetal pituitary-adrenocortical function in sheep.
- To characterize the pulsatile secretion of cortisol and corticosterone in late-gestation fetuses.
Main Methods:
- Chronic cannulation of fetal peripheral and adrenal vessels in sheep (127-145 days gestation).
- Serial blood sampling for cortisol (F), corticosterone (B), and ACTH measurement.
- Adrenal vein sampling to determine F and B secretion rates.
Main Results:
- High-frequency episodic bursts of fetal cortisol secretion were observed.
- A ~90-minute oscillation in cortisol secretion was identified, increasing in amplitude with gestation.
- Pulsatile ACTH rhythms were detected, with longer periods in more mature fetuses.
- Both cortisol secretion and plasma ACTH increased exponentially with advancing gestation.
Conclusions:
- Fetal sheep display complex, pulsatile patterns of cortisol and corticosterone secretion.
- The developing fetal adrenal axis exhibits significant dynamic regulation prior to birth.
- These findings provide insights into normal fetal endocrine development and potential markers of stress or maturity.
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