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Corticosteroid-binding globulin status at the fetomaternal interface during human term pregnancy
C Benassayag1, I Souski, T M Mignot
1INSERM U.361, Maternité Port-Royal Cochin, Université René Descartes, 75014 Paris, France. u361@cochin.inserm.fr
Biology of Reproduction
|February 24, 2001
Summary
Corticosteroid-binding globulin (CBG) levels and characteristics differ at the fetomaternal interface compared to maternal and fetal circulation. This highlights the unique steroid environment and CBG-steroid interactions during late pregnancy.
Area of Science:
- Reproductive Endocrinology
- Biochemistry
- Maternal-Fetal Medicine
Background:
- Corticosteroid-binding globulin (CBG) plays a crucial role in regulating steroid hormone bioavailability.
- Understanding CBG status at the fetomaternal interface is vital for comprehending pregnancy physiology.
Purpose of the Study:
- To investigate and compare corticosteroid-binding globulin (CBG) status in the maternal intervillous blood space (I) versus maternal (M) and fetal (umbilical arteries [A] and vein [V]) circulations.
- To analyze the microheterogeneity, origin, and steroid-binding characteristics of CBG at the fetomaternal interface.
Main Methods:
- Immunoquantitation of plasma CBG concentrations.
- Immunoaffinoelectrophoresis and Western blotting to assess CBG microheterogeneity.
- Analysis of steroid profiles (progesterone:cortisol molar ratio).
- Steroid-binding affinity studies of CBG.
Main Results:
- CBG concentration in the intervillous space (I) was 30% lower than maternal (M) and threefold higher than umbilical cord blood.
- CBG in I was primarily of maternal origin and distinct from fetal CBG.
- The intervillous space exhibited a significantly higher progesterone:cortisol ratio (75-fold vs. M).
- CBG affinity for cortisol was lower in I, A, and V compared to M plasma, influenced by the local hormonal milieu.
Conclusions:
- CBG at the fetomaternal interface displays unique characteristics reflecting its maternal origin and the distinct steroid environment.
- The altered CBG-steroid interactions at the interface are physiologically relevant during late pregnancy, particularly concerning high progesterone levels.