title: Sperm binding to the human zona pellucida and calcium influx in response to GnRH and progesterone.
abstract: In this study the effect of the sequential exposure of spermatozoa to progesterone and gonadotrophin-releasing hormone (GnRH) upon zona binding and the intracellular free Ca2+ concentration was evaluated. Sperm aliquots were treated as follows: (a) 0.7 micro mol l(-1) progesterone or 0.1% DMSO (progesterone solvent) followed by 50 nmol l(-1) of GnRH; (b) 50 nmol l(-1) of GnRH or distilled water (GnRH solvent) followed by 0.7 micro mol l(-1) of progesterone. Additional aliquots were incubated with DMSO or distilled water (controls) and with 0.7 micro mol l(-1) of progesterone or 50 nmol l(-1) of GnRH. All treatments were for 5 min. Motile spermatozoa were incubated in modified Tyrode's medium, at 37 degrees C, 5% CO2, 10 x 10(6) spermatozoa ml(-1), for 4.5 h. Intracellular Ca2+ concentration and sperm-zona binding was evaluated using fura 2 and the hemizona assay, respectively. GnRH and progesterone increased sperm-zona binding and the Ca2+ concentration. Regarding zona binding, the effect of GnRH was significantly greater when the spermatozoa had been previously treated with progesterone (progesterone-->GnRH=185 +/- 116 zona-bound spermatozoa versus DMSO-->GnRH=99 +/- 15, P < 0.001). On the other hand, previous treatment with GnRH did not modify their subsequent response to progesterone (GnRH-->progesterone= 114 +/- 19 zona-bound spermatozoa versus distilled water-->progesterone=108 +/- 22, NS). The results regarding intracellular Ca2+ showed a similar pattern. These findings suggest a priming effect of progesterone upon a GnRH-induced increase in sperm-zona binding and intracellular Ca2+.
authors.affiliation: Unit of Reproductive Biology, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile. pmorales@uantof.cl
authors.forename: P
authors.initials: P
authors.lastname: Morales
authors.forename: E
authors.initials: E
authors.lastname: Pizarro
authors.forename: M
authors.initials: M
authors.lastname: Kong
authors.forename: C
authors.initials: C
authors.lastname: Pasten
mesh_terms: D002118:Calcium / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011374:Progesterone / Q000494:pharmacology*; D013084:Sperm-Ovum Interactions / Q000187:drug effects* / Q000502:physiology; D013094:Spermatozoa / Q000166:cytology* / Q000378:metabolism; D015044:Zona Pellucida / Q000378:metabolism*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D002118:Calcium