Abstract

Frozen-thawed spermatozoa from different mammalian species successfully undergo capacitation invitro under specific and defined conditions, however the induction in of vitro capacitation of equine spermatozoa still needs optimizations. The aim of this study was to evaluate the effects of different culture media on inductioin of vitro capacitation of thawed stallion sperm. To do this, the sperm were thawed and incubated with different combinations of capacitating inducers for 2 h. In our studyfiverentdiffemedia: no capacitation medium (NC), basal medium that included BSA and bicarbonate, basal mediium plus capacitating inducer dibutyryl cyclic-AMP (dbcAMP) as a PKA activator, a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) and a cholesterolacceptor, methyl-beta-cyclodextrin (M beta CD). The membrane fluidity, acrosome reaction and intracellular calcium levels were evaluated after incubation, but we did not find any differences among groups. Different behavior between stallions was also observed.Finallythesperm, treatments were evaluated using a homologues zona pellucida binding assay. This assay showed that incubation in basal mediumcludingin M beta CD increased the number of spermatozoa adhered to the zona pellucida of mare oocytes. Further studies are needed to eevaluate effect of these conditions oin vitro fertilization of equine species using thawed sperm.