Effect of protein kinase C on guinea pig sperm acrosome reaction induced by progesterone.

AIM

To investigate the effect of protein kinase C (PKC) on the guinea pig sperm acrosome reaction (AR) induced by progesterone (P4).

METHODS

Guinea pig spermatozoa were preincubated in MCM-Ca2+ DF medium at 38.5 degrees C under 5% CO2/air for 6-6.5 h for capacitation, and were then washed through a three-step gradient Percoll, resuspended in MCM-Ca2+ DF and adjusted to 5 x 10(9) cells/L. The AR was assessed by means of phase-contrast microscopy (expressed as percent of AR) 15 min after different reagents were added.

RESULTS

In the presence of Ca2+ 2 mmol/L, phorbol 12,13-dibutyrate (PDB) or the permanent synthetic diacylglycerol, 1-oleoyl-2-acetyl-sn-glycerol (OAG) initiated the AR of spermatozoa in a concentration-related manner, whereas staurosporine (STA) exhibited an inhibition of the AR. PDB and OAG significantly enhanced P4-induced AR that was greater than that treated with either agonist separately. STA markedly inhibited the P4-induced AR. The AR induced by PDB was completely antagonized by inclusion of egtazic acid. Also, both egtazic acid and nifedipine antagonized the AR induced by P4 and PDB + P4. In addition, neomycin also prevented the P4-induced AR. This effect could be partly reversed by PDB.

CONCLUSION

Activation or inhibition of PKC significantly plays an important role in the signal transduction pathway for the physiological AR.