Recent studies on molecular mechanisms involved in mammalian sperm capacitation: A review

Sperm capacitation is a physiological event that allows sperm to bind and fuse with the oocyte. Changes associated with this process include removal of cholesterol from the plasma membrane, increases in pH and Ca+2, activation of first and second messenger cascades, an increase in respiration and subsequent changes in the sperm motility pattern. The most significant change in sperm after capacitation is its ability to undergo the acrosome reaction. The purpose of this review is to present some recent achievements towards understanding the molecular mechanisms of mammalian sperm capacitation. The review focuses on regulation of spenn function by seminal plasma derived first messengers, i.e. fertilization-promoting peptide (FPP), adenosine, calcitonin and angiotensin 11, acting to affect production of a second messenger, cAMP. It also discusses the roles in sperm capacitation of speradhesins, platelet-activating factor (PAF) and PAF-acetylhydrolase, roles of Ca+2 ions, bicarbonate ions, and intracellular PH, roles of calmodulin and 1, 4, 5-triphosphate (IP3), Protein tyrosine phosphorylation and actin polymerization, protein translation as well as hyperactivation and acrosome reaction as a final step of capacitation.