title: Viability, acrosome morphology and fertilizing capacity of boar spermatozoa treated with strontium chloride.
abstract: The positive effect of strontium ions (Sr2+) on sperm motility, capacitation and acrosome reaction has been demonstrated in the mouse, human, guinea pig and hamster. In the present study, we have evaluated the effect of Sr2+ on the viability and acrosome morphology of boar spermatozoa, and on the fertilization and development after the microinjection of Sr(2+)-treated spermatozoa into porcine oocytes. Before incubation, 79% of spermatozoa were classified as propidium iodide (PI)-negative (live) using the LIVE/DEAD Sperm Viability Kit. After incubation with strontium chloride (SrCl2), 39% (0 mM; no divalent cations), 25% (1.9 mM) and 24% (7.5 mM) of them were classified as PI-negative. The proportion of spermatozoa that had initiated the acrosome reaction was higher in Sr(2+)-containing medium than in Sr(2+)-free medium, when assessed by electron microscopy. There was no significant difference in percentage of spermatozoa initiating the acrosome reaction between Sr2+-treated groups (1.9 mM: 22%, 7.5 mM: 33%, p>0.05). After the microinjection of spermatozoa incubated with SrCl2, 67% (1.9 mM) and 61% (7.5 mM) of injected oocytes were successfully fertilized, and then 43% (1.9 mM) and 41% (7.5 mM) contained a fully decondensed sperm head. Sham-injected oocytes were significantly activated at a lower rate than Sr(2+)-treated groups (27%, p<0.05). Next, after microinjection of spermatozoa incubated with 1.9 mM SrCl2 (n=51), 45% of injected oocytes cleaved on day 2, and 18% developed to blastocysts on day 7 (sham-injection, n=48: 15% to cleavage and 0% to blastocyst). These results demonstrate that Sr2+ is likely to positively affect the fertilizing capacity of spermatozoa in the pig.
authors.affiliation: Department of Animal Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-0023, Japan. okada@nvlu.ac.jp
authors.forename: Konosuke
authors.initials: K
authors.lastname: Okada
authors.forename: Chiara
authors.initials: C
authors.lastname: Palmieri
authors.forename: Leonardo
authors.initials: L
authors.lastname: Della Salda
authors.forename: Irena
authors.initials: I
authors.lastname: Vackova
mesh_terms: D000177:Acrosome / Q000502:physiology*; D020101:Acrosome Reaction / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D002470:Cell Survival / Q000187:drug effects*; D005307:Fertilization in Vitro; D008297:Male; D008845:Microinjections; D009865:Oocytes / Q000502:physiology*; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000502:physiology*; D013324:Strontium / Q000494:pharmacology*; D034421:Sus scrofa; D013552:Swine
chemical_list: C025700:strontium chloride; D013324:Strontium