Maitotoxin potently promotes Ca2+ influx in mouse spermatogenic cells and sperm, and induces the acrosome reaction

✍ Scribed by Claudia L. Treviño; José L. De la Vega-Beltrán; Takuya Nishigaki; Ricardo Felix; Alberto Darszon

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 266 KB
• Volume: 206
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.20487

✦ Synopsis

Abstract

Maitotoxin (MTX), a potent marine toxin, activates Ca^2+^ 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, Ca^2+^ 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 Ca^2+^ ([Ca^2+^]~i~) in spermatogenic cells that depended on extracellular Ca^2+^. Ni^2+^ and SKF96365 diminished the MTX‐activated Ca^2+^ uptake, at concentrations they inhibit store‐operated channels, and in a similar manner as they inhibit the Ca^2+^ influx activated following depletion of intracellular stores by thapsigargin (Tpg). In addition, MTX significantly increased [Ca^2+^]~i~ in single mature sperm and effectively induced the AR with a half‐maximal concentration (ED~50~) of ∼1.1 nM. Notably, SKF96365 similarly inhibited the MTX‐induced increase in sperm [Ca^2+^]~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 Ca^2+^ influx required for mouse sperm AR. J. Cell. Physiol. 206: 449–456, 2006. © 2005 Wiley‐Liss, Inc.