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Hypothalamic oxytocin in the developing ovine fetus: interaction with pituitary-adrenocortical function
1Departments of Physiology and Obstetrics and Gynecology, Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. stephen.matthews@utoronto.ca
Brain Research
|February 19, 1999
Summary
Oxytocin (OT) synthesis increases in fetal sheep near term. This hormone stimulates adrenocorticotropin (ACTH) release from the pituitary, suggesting a role in fetal stress response.
Area of Science:
- Endocrinology
- Neuroscience
- Reproductive Biology
Background:
- Oxytocin (OT) is known to stimulate the HPA axis in adults.
- Limited data exists on OT synthesis and its role in fetal HPA function.
Purpose of the Study:
- Examine developmental changes in hypothalamic OT synthesis.
- Investigate OT's action on fetal corticotroph function.
Main Methods:
- In situ hybridization to measure OT mRNA in fetal sheep hypothalami.
- In vitro studies using fetal pituitary cells treated with OT, CRH, AVP, and cortisol.
Main Results:
- OT mRNA detected by day 60, increasing significantly at term in PVN and SON.
- OT dose-dependently stimulated ACTH release, without affecting POMC mRNA.
- CRH and OT synergistically increased ACTH release; cortisol attenuated OT's effect.
Conclusions:
- Hypothalamic OT mRNA increases at term in sheep.
- OT stimulates fetal corticotrophs to release ACTH.
- OT may regulate fetal ACTH secretion in late gestation.