Effect of epidermal growth factor on mouse sperm acrosome reaction induced by zona pellucida.
OBJECTIVE
The effect of epidermal growth factor (EGF) on the acid-solubilized zona pellucida (ZP)-induced acrosome reaction was investigated in mouse sperm.


METHODS
Mouse epididymal sperm were capacitated in modified Krebs-Ringer bicarbonate buffer (m-KRB) for 120 min and further treated with acid-solubilized ZP(4 zona/microliters) for an additional 60 min to induce the acrosome reaction. The chlortetracycline fluorescence assay was used to monitor the acrosome reaction. The acrosome reacted sperm featured the acrosome reacted (AR) pattern, which demonstrates the lack of fluorescence on the head and bright midpiece.


RESULTS
EGF caused an early increase in the AR pattern in response to the acid-solubilized ZP in a dose-dependent manner. The EGF-dependent stimulation of the ZP-induced acrosome reaction was inhibited by an inhibitor of protein tyrosine kinases, genistein or activators of Ca++ and phospholipid-dependent protein kinase (protein kinase C). Furthermore, the stimulatory effect of EGF was not attenuated when sperm were capacitated in the presence of islet-activating protein, an inactivator of inhibitory guanine nucleotide-binding regulatory protein (Gi protein).


CONCLUSIONS
EGF stimulates the ZP-induced acrosome reaction in a manner that is independent of the Gi protein. The EGF action is regulated by protein tyrosine kinase and protein kinase C.
Furuya
S
S
Department of Obstetrics and Gynecology, Nerima General Hospital, Tokyo, Japan.
Endo
Y
Y
Oba
M
M
Matsui
Y
Y
Suzuki
S
S
Nozawa
S
S
D000177:Acrosome / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002751:Chlortetracycline; D004815:Epidermal Growth Factor / Q000502:physiology*; D005260:Female; D005453:Fluorescence; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D008297:Male; D051379:Mice; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D013084:Sperm-Ovum Interactions; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D015044:Zona Pellucida / Q000502:physiology*
D007529:Isoflavones; D010566:Virulence Factors, Bordetella; D004815:Epidermal Growth Factor; D019833:Genistein; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002751:Chlortetracycline