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Progesterone and RU486: opposing effects on human sperm
J Yang1, C Serres, D Philibert
1Laboratoire d'Histologie-Embryologie-Cytogénétique, Faculté de Médecine, Université Paris-Sud, Kremlin-Bicêtre, France.
Summary
Progesterone triggers calcium influx and sperm hyperactivation, while the antagonist RU486 inhibits these effects. Steroid structure influences calcium influx in human sperm.
Area of Science:
- Reproductive biology
- Molecular endocrinology
Background:
- Progesterone is known to play a role in human sperm function.
- The specific mechanisms and receptors involved are not fully elucidated.
Purpose of the Study:
- To investigate the effects of progesterone and its antagonist RU486 on human sperm intracellular calcium levels and function.
- To explore the influence of steroid structure on these effects.
Main Methods:
- Measurement of intracellular free calcium in human sperm.
- Assessment of sperm hyperactivation and acrosome reaction.
- Administration of progesterone and the progesterone antagonist RU486 (mifepristone).
- Investigation of various steroids with 11 beta-phenyl substitutions.
Main Results:
- Progesterone induced a rapid, dose-dependent increase in intracellular calcium, followed by enhanced sperm hyperactivation and acrosome reaction.
- RU486 caused a transient decrease in intracellular calcium and inhibited sperm hyperactivation.
- RU486 counteracted the effects of progesterone on calcium influx, sperm movement, and acrosome reaction.
- Steroid structure, particularly 11 beta-phenyl substitutions, influences calcium influx.
Conclusions:
- Progesterone and RU486 exert opposing effects on human sperm calcium signaling and function.
- The progesterone antagonist RU486 inhibits key sperm parameters essential for fertilization.
- Steroid chemical structure is a critical determinant of effects on sperm calcium influx.