title: 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.
abstract: 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.
authors.affiliation: The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, USA.
authors.forename: Alessandro A
authors.initials: AA
authors.lastname: Schuffner
authors.forename: Hadley S
authors.initials: HS
authors.lastname: Bastiaan
authors.forename: Hakan E
authors.initials: HE
authors.lastname: Duran
authors.forename: Zin-Yong
authors.initials: ZY
authors.lastname: Lin
authors.forename: Mahmood
authors.initials: M
authors.lastname: Morshedi
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Franken
authors.forename: Sergio
authors.initials: S
authors.lastname: Oehninger
mesh_terms: 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*
chemical_list: D011374:Progesterone; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium