Zona pellucida-induced acrosome reaction in human sperm: dependency on activation of pertussis toxin-sensitive G(i) protein and extracellular calcium, and priming effect of progesterone and follicular fluid.
In these studies, we aimed to characterize the effects of the physiological, homologous agonists of the acrosome reaction, i.e. the zona pellucida (ZP) and progesterone/follicular fluid, on human sperm. The specific aims of our studies were: (i) to examine the dependency of the solubilized ZP-induced acrosome reaction on G(i) protein activation and presence of extracellular calcium; and (ii) to determine whether progesterone/follicular fluid exert a priming or synergist effect on the solubilized ZP-induced acrosome reaction. Highly motile sperm from fertile donors were exposed to the agonists in a microassay and the acrosomal status of live sperm was determined by indirect immunofluorescence using PSA-FITC/Hoechst double-staining. Pretreatment with pertussis-toxin (100 ng/ml) and EGTA (2.5 mmol/l) significantly inhibited the ZP-induced acrosome reaction without affecting the spontaneous rate of exocytosis. Progesterone (1.25 microg/ml) and human follicular fluid (10%) exerted a priming, time-dependent effect on the ZP-induced acrosome reaction. These studies demonstrated that: (i) acrosomal exocytosis of capacitated human sperm triggered by the homologous ZP is dependent on the activation of G(i) proteins (pertussis toxin-sensitive) and the presence of extracellular calcium; and (ii) progesterone and follicular fluid exert a priming effect on the ZP-induced acrosome reaction.
Schuffner
Alessandro A
AA
The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, USA.
Bastiaan
Hadley S
HS
Duran
Hakan E
HE
Lin
Zin-Yong
ZY
Morshedi
Mahmood
M
Franken
Daniel R
DR
Oehninger
Sergio
S
D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology*; D000704:Analysis of Variance; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology*; D006801:Humans; D008297:Male; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D013094:Spermatozoa / Q000502:physiology*; D015044:Zona Pellucida / Q000502:physiology*
D011374:Progesterone; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium