Vías de señalización asociadas a la regulación por bicarbonato del proceso de capacitación de espermatozoides de rata.

DA ROS V, COHEN DJ, PIGNATARO O, VISCONTI P Y CUASNICU PS.

Buenos Aires, Argentina

Jornada; VIII Jornadas Multidisciplinarias de la Sociedad Argentina de Biología.; 2006

Sociedad Argentina de Biología

Results from our lab demonstrated that bicarbonate is required to support rat sperm capacitation by regulating protein tyrosine phosphorylation, migration of protein DE/CRISP-1 to the equatorial segment and expression of sperm fusion ability. However, while phosphorylation occurred even when bicarbonate was replaced by a cAMP analogue, the other 2 parameters seem to require additional properties of bicarbonate. To further study the pathway involve in the bicarbonate regulation of rat sperm capacitation, intracellular cAMP levels were measured (by RIA) in sperm incubated in the presence or absence of the anion. Results showed a time-dependent increase in cAMP levels in sperm incubated in the presence of bicarbonate. To investigate whether this bicarbonate-dependent cAMP accumulation was induced by phorbol esters, sperm were incubated in the presence or absence of bicarbonate, with or without 10 µM PMA. Results showed that PMA produces a significant increase in sperm cAMP levels only in the presence of bicarbonate. In order to test whether the cAMP produced was required for the 3 capacitation parameters previously studied the involvement of PKA was studied using the inhibitor H89. Tyrosine phosphorylation was significant reduced by addition of 30 µM H89 but not by DMSO. However, migration of DE/CRISP-1 was not affected, and the expression of the fusion ability could only be partially inhibited by H89 but not by DMSO, even in the presence of H89 during gamete co-incubation. Taken together, our results provide more information on the regulation of rat sperm capacitation by bicarbonate, confirming that some capacitation-associated events, although bicarbonate-dependent, would be cAMP/PKA-independent.