INSTITUTO DE INVESTIGACIONES BIOTECNOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
TREATMENT OF CRYOPRESERVED SPERM WITH CALCIUM IONOPHORE A23187 INCREASES IN VITRO EMBRYO PRODUCTION IN CATTLE
GARAGUSO, ROCIO; BUFFONE, MARIANO; WAREMKRAUT, MAGALI; VISCONTI, PE; MUTTO, ADRIAN; OSYCKA SALUT, CLAUDIA; FRANCO, MARIA JOSE; KRAPF, DARÍO
Congreso; Fertilization & Activation of Development, Gordon Research Conference; 2019
To fertilize an oocyte, mammalian spermatozoa must undergo a number of physiological modifications in the female reproductive tract, collectively known as capacitation. At the functional level, capacitation enables sperm to undergo acrosome reaction and to exhibit vigorous motility called hyperactivation, events regulated by different signaling pathways modulated by Ca2+. In this way, calcium ionophores such as A23187, are commonly used to study these events in different mammalian species. Specifically, mouse spermatozoa incubated with A23187 do not present protein tyrosine phosphorylation induced by the cAMP/PKA pathway (associated with sperm capacitation) but fertilize intact oocytes indicating that a Ca2+ elevation could be enough to induce capacitation through another signaling pathway.In vitro fertilization (IVF) has great potential for speeding up genetic improvement in cattle so increasing IVF success rate could have an important impact on livestock industry. The aim of this work was to study hyperactivation and capacitation induction by A23187 in cryopreserved sperm and also its effect in spermatozoa fertilizing ability, with the purpose of increasing IVF rates in cattle. Our results suggest that A23187 (5uM) induces events associated with sperm capacitation such us pattern B of CTC increased, or LPC-induced acrosome reaction increase through a signaling pathway that would omit PKA activation (studied by western blot). Also, we performed CASA studies where results showed that bovine spermatozoa were immobilized by this ionophore, but they initiated hyperactive motility after A23187 wash by centrifugation and BSA addition. We evaluated the fertilizing ability of sperm previously incubated with A23187. A transitory sperm exposure to A23187 does not affect cleavage rates. Also, we obtained embryos in vitro using A23187 as a capacitating inducer. Moreover, in vitro embryo production was similar for A23187 treatment in comparison with production obtained for heparin treatment during IVF. Finally, we used A23187 and heparin together in IVF protocols. This combination resulted in higher percentages of embryo development and higher hatching blastocyst frequency suggesting the activation of two different signaling pathways during bovine sperm capacitation under these conditions. Taking into account our results, a combination of sperm pre-treatment with A23187 and sperm incubation with heparin during an IVF protocol could be very useful to increase in vitro embryo production in bovine and even to apply in other species and in causes of infertility.