Medium-throughput Screening Assays for Assessment of Effects on Ca2+-Signaling and Acrosome Reaction in Human Sperm

Ca²⁺-signaling is essential to normal sperm cell function and male fertility. Similarly, the acrosome reaction is vital for the ability of a human sperm cell to penetrate the zona pellucida and fertilize the egg. It is therefore of great interest to test compounds (e.g., environmental chemicals or drug candidates) for their effect on Ca²⁺-signaling and acrosome reaction in human sperm either to examine the potential adverse effects on human sperm cell function or to investigate a possible role as a contraceptive. Here, two medium-throughput assays are described: 1) a fluorescence-based assay for assessment of effects on Ca²⁺-signaling in human sperm, and 2) an image cytometric assay for assessment of acrosome reaction in human sperm. These assays can be used to screen a large number of compounds for effects on Ca²⁺-signaling and acrosome reaction in human sperm. Furthermore, the assays can be used to generate highly specific dose-response curves of individual compounds, determine potential additivity/synergism for two or more compounds, and to study the pharmacological mode of action through competitive inhibition experiments with CatSper inhibitors.