Ca ²⁺ ionophore A23187 can make mouse spermatozoa capable of fertilizing in vitro without activation of cAMP-dependent phosphorylation pathways

Abstract

Ca2+ ionophore A23187 is known to induce the acrosome reaction of mammalian spermatozoa, but it also quickly immobilizes them. Although mouse spermatozoa were immobilized by this ionophore, they initiated vigorous motility (hyperactivation) soon after this reagent was washed away by centrifugation. About half of live spermatozoa were acrosome-reacted at the end of 10 min of ionophore treatment; fertilization of cumulus-intact oocytes began as soon as spermatozoa recovered their motility and before the increase in protein tyrosine phosphorylation, which started 30-45 min after washing out the ionophore. When spermatozoa were treated with A23187, more than 95% of oocytes were fertilized in the constant presence of the protein kinase A inhibitor, H89. Ionophore-treated spermatozoa also fertilized 80% of oocytes, even in the absence of HCO 3 − , a component essential for cAMP synthesis under normal in vitro conditions. Under these conditions, fertilized oocytes developed into normal offspring. These data indicate that mouse spermatozoa treated with ionophore are able to fertilize without activation of the cAMP/PKA signaling pathway. Furthermore, they suggest that the cAMP/PKA pathway is upstream of an intracellular Ca 2+ increase required for the acrosome reaction and hyperactivation of spermatozoa under normal in vitro conditions. sperm capacitation | calcium

5’-AMP-Activated Protein Kinase Regulates Goat Sperm Functions via Energy Metabolism In Vitro

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Central role of soluble adenylyl cyclase and cAMP in sperm physiology

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Effect of sodium fluoride on male mouse fertility

“…To answer these questions, we investigated the effect of NaF on sperm motility and motion kinematic parameters. The intracellular Ca 2+ and ATP concentrations were measured to observe time-dependent occurrence of several fundamental events in spermatozoa, where Ca 2+ and ATP extensively involved in almost every step (Tateno et al, 2013;Krapf et al, 2014;Rahman et al, 2014a). We also evaluated capacitation status of spermatozoa and alterations protein kinase-A (PKA) activity and protein tyrosine phosphorylation patterns that regulate intracellular changes (Naz & Rajesh, 2004;Visconti, 2009;Kwon et al, 2014a).…”