title: Alkaline phosphatase added to capacitating medium enhances horse sperm-zona pellucida binding.
abstract: Alkaline phosphatase (AP) is present in equine seminal plasma and spermatozoa, but its functional role is not fully understood yet. Being that, sperm-oocyte interaction in equine species has been reported to be enhanced at a slightly basic pH, this work aimed at verifying whether exogenous alkaline phosphatase exerts any role on stallion spermatozoa and sperm-oocyte interaction at different pHs (7.4; 8.0; 9.0). Stallion spermatozoa were capacitated in Tyrode's medium at pH 7.4, 8.0, and 9.0 for 4 hours at 38 °C, 5% CO2with 2.5-IU AP (AP group) or without AP (capacitated spermatozoa group); viability with mitochondrial activity, motility, and acrosome integrity were measured. In addition, a homologous binding assay was carried out: stallion spermatozoa were capacitated 1 hour at 38 °C, 5% CO2with 2.5-IU AP (AP group) or without AP (capacitated spermatozoa group). Oocytes were then added to sperm suspensions and coincubated for 1 hour. Our results indicate that AP at pH 9.0 significantly increases the percentage of living cells with active mitochondria, whereas it significantly reduces the percentage of acrosome-damaged cells at pH 8.0. No significant differences were registered in motility parameters. The homologous binding assay showed a strong effect of AP, that increased the number of sperm bound to the oocyte's zona pellucida at all pHs tested. In conclusion, AP can induce some modifications on sperm membranes thus enhancing their capacity to bind to the zona pellucida of equine oocytes.
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy. Electronic address: diego.bucci3@unibo.it.
authors.forename: Diego
authors.initials: D
authors.lastname: Bucci
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Giaretta
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Merlo
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Iacono
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Marcella
authors.initials: M
authors.lastname: Spinaci
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Gadani
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy; AUB INFA National Institute of Artificial Insemination, Bologna, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Mari
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Tamanini
authors.affiliation: Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, Bologna, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Galeati
mesh_terms: D000177:Acrosome / Q000187:drug effects; D000469:Alkaline Phosphatase / Q000494:pharmacology*; D000818:Animals; D005307:Fertilization in Vitro / Q000662:veterinary; D006736:Horses / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D013081:Sperm Motility / Q000187:drug effects; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D015044:Zona Pellucida / Q000502:physiology*
chemical_list: D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase; Capacitation; Equine spermatozoon; Zona-binding; pH