Propose: The present study examined whether regulation of progesterone-enhanced hyperactivation of spermatozoa is associated with the production of inositol 1,4,5-trisphosphate (IP) and diacylglycerol (DAG) by phospholipase C (PLC) and cyclic adenosine monophosphate (cAMP) by adenylate cyclase (AC), as well as activation of protein kinase C (PKC) and protein kinase A (PKA). Methods: Hamster spermatozoa were hyperactivated by incubation for 4 h in modified Tyrode's albumin lactate pyruvate (mTALP) medium. In order to examine the effects of IP receptor (IPR), PKC and PKA on progesterone-enhanced hyperactivation, their inhibitors (xestospongin C, bisindolylmaleimide 1 and H-89) were used. Results: Progesterone-enhanced hyperactivation was significantly suppressed by the inhibitors of IPR, PKC and PKA. Conclusions: The results suggest that progesterone-enhanced sperm hyperactivation occurs through two signal pathways. One is an intracellular Ca signal through production of IP and DAG by PLC, binding of IP to IPR and activation of PKC by DAG and Ca. The other is a cAMP-PKA signal through production of cAMP by AC and activation of PKA by cAMP. [ABSTRACT FROM AUTHOR]