Evaluation of nitric oxide in the capacitation of criop reserved equine sperm by flow cytometry and computerized motility analyses

Abstract

Nitric oxide (NO) is synthetized in vitro during L-arginine conversion to L-citruline by oxidative reactions cathalysed by the nitric oxide synthase enzyme (NOS). There are three isoforms of NOS, two are constitutive ones dependent on calcium, neuronal-NOS (nNOS) and endothelial-NOS (eNOS); and one inducible (ÍNOS) calcium independent. The localization and function of some NOS isoforms have been described in spermatozoa of several animal species, such as bovine, rodents, humans, being present in the acrosome and the tail of bovine and human spermatozoa acting in the motility, hyperactivity, capacitation and acrosome reaction. It should be stressed that as far as it was possible to research no reports were found on the identification and placement of the several NOS isoforms in equine spermatozoa post-ejaculation, nor of the function of nitric oxide in equine sperm cell physiology. Considering the afore-mentioned this project aims at, through five experiments, helping to understand the function of this oxygen reactive form in capacitation and integrity of equine spermatozoa function, using as analyses tools the techniques of flow cytometry and computer-assisted assessment of sperm motility (CASA). (AU)