title: Maitotoxin potently promotes Ca2+ influx in mouse spermatogenic cells and sperm, and induces the acrosome reaction.
abstract: Maitotoxin (MTX), a potent marine toxin, activates Ca2+ entry via nonselective cation channels in a wide variety of cells. The identity of the channels involved in MTX action remains unknown. In mammalian sperm, Ca2+ entry through store-operated channels regulates a number of physiological events including the acrosome reaction (AR). Here we report that MTX produced an increase in the intracellular concentration of Ca2+ ([Ca2+]i) in spermatogenic cells that depended on extracellular Ca2+. Ni2+ and SKF96365 diminished the MTX-activated Ca2+ uptake, at concentrations they inhibit store-operated channels, and in a similar manner as they inhibit the Ca2+ influx activated following depletion of intracellular stores by thapsigargin (Tpg). In addition, MTX significantly increased [Ca2+]i in single mature sperm and effectively induced the AR with a half-maximal concentration (ED50) of approximately 1.1 nM. Notably, SKF96365 similarly inhibited the MTX-induced increase in sperm [Ca2+]i and the AR triggered by the toxin, Tpg and zona pellucida. These results suggest that putative MTX-activated channels may be involved in the Ca2+ influx required for mouse sperm AR.
authors.affiliation: Department of Genetics of Development and Molecular Physiology, Institute of Biotechnology, UNAM, Cuernavaca, Mexico.
authors.forename: Claudia L
authors.initials: CL
authors.lastname: Treviño
authors.forename: José L
authors.initials: JL
authors.lastname: De la Vega-Beltrán
authors.forename: Takuya
authors.initials: T
authors.lastname: Nishigaki
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
authors.forename: Alberto
authors.initials: A
authors.lastname: Darszon
mesh_terms: D000177:Acrosome / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D008297:Male; D008387:Marine Toxins / Q000494:pharmacology*; D051379:Mice; D035964:Oxocins / Q000494:pharmacology*; D013075:Sperm Capacitation; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism*; D013997:Time Factors; D000095702:Polyether Toxins
chemical_list: D002118:Calcium; D008387:Marine Toxins; D035964:Oxocins; C020394:maitotoxin; D000095702:Polyether Toxins