Description:
Rapid steroid effects, reported in several cell types, have pointed out the possibility of non‐genomic mechanisms of action, presumably on cell surface receptors. Here we analyzed the effects of antibody‐mediated aggregation of a novel type of progesterone receptor on the plasma membrane of human sperm cells. We report that aggregation of hormone‐receptor complexes induces Ca2+ influx and a Ca2+‐dependent exocytotic event in this system. These data suggest a possible mechanism for rapid steroid‐induced events. Further research is warranted to examine if a similar mechanism is involved in rapid steroid effects in other cell types.