Inhibition of phosphatidylinositol 3-kinase modifies boar sperm motion parameters

Motility is the most widely used indicator of sperm quality. Besides modulation by the cAMP pathway little is known regarding the intracellular pathways that regulate boar sperm motility. Recently the role of phosphatidylinositol 3-kinase (PI3-K) in the regulation of human sperm motility has been described. Therefore, the aim of this study was to investigate the role of PI3-K in boar sperm kinematics by using the specific PI3-K inhibitor, LY294002. Boar sperm was incubated up to 1 h in non-capacitating medium in the presence or absence of the cAMP analog, 8Br-cAMP or the PI3-K inhibitor, LY294002 or both. Boar sperm incubated in capacitating medium was treated in the presence or absence of LY294002. First, we have clearly identified that PI3-K is present in whole lysates of boar spermatozoa. Inhibition of PI3-K significantly increased boar sperm straight-line velocity, circular velocity and average velocity without an effect on the percentage of progressively motile spermatozoa in both media. Inhibition of PI3-K induced the same effects on boar sperm velocities as activation of the cAMP/protein kinase A (PKA) pathway and treatment with the PI3-K inhibitor, LY294002 had neither summatory nor synergic effects on boar sperm motion parameters when treated simultaneously with the cAMP analog 8Br-cAMP. Our data suggest that PI3-K plays a negative role, regulating boar sperm motion parameters through a possible inhibition of the cAMP/PKA activating pathway, and since some Computer Aided Sperm Analysis (CASA)-derived parameters have been related to field fertility our results point to the possibility of modulating sperm motile quality by modifying the PI3-K cellular pathway.