Related Experiment Videos
Cell surface-binding sites for progesterone mediate calcium uptake in human sperm
P F Blackmore1, J Neulen, F Lattanzio
1Department of Pharmacology, Eastern Virginia Medical School, Norfolk 23501.
The Journal of Biological Chemistry
|October 5, 1991
Summary
This study identifies progesterone receptors on the human sperm surface, demonstrating a nongenomic mechanism for progesterone to increase intracellular calcium and trigger the acrosome reaction.
Area of Science:
- Reproductive Biology
- Cell Biology
- Biochemistry
Background:
- Progesterone rapidly increases intracellular free calcium ([Ca2+]i) in human sperm, inducing the acrosome reaction.
- The precise location and nature of progesterone receptors involved in this rapid response remain under investigation.
Purpose of the Study:
- To identify the cell surface location of progesterone receptors in human sperm.
- To characterize the mechanism of progesterone-induced calcium influx and acrosome reaction.
Main Methods:
- Utilized immobilized progesterone on bovine serum albumin (BSA) and its derivatives to probe for cell surface receptors.
- Employed fluorescence microscopy to validate the exclusion of BSA-fluorescein isothiocyanate from intact sperm.
- Assessed the effects of progesterone and its derivatives on intracellular calcium levels and the efficacy of specific steroid receptor inhibitors.
Main Results:
- Immobilized progesterone and its derivative acted as full agonists, rapidly increasing [Ca2+]i via calcium influx, though with reduced potency compared to free progesterone.
- Potent inhibitors of genomic progesterone responses (RU38486, ZK98.299) were ineffective in blocking the progesterone-mediated [Ca2+]i increase.
- Synthetic progestins did not mimic progesterone's effect on increasing [Ca2+]i, suggesting a distinct receptor.
Conclusions:
- Evidence supports the existence of a distinct, nongenomic cell surface receptor for progesterone in human sperm.
- This receptor mediates rapid increases in intracellular calcium and likely plays a role in sperm function, independent of traditional genomic pathways.