Progesterone-mediated efflux of cytosolic chloride during the human sperm acrosome reaction

Biochem Biophys Res Commun. 1995 Aug 24;213(3):774-80. doi: 10.1006/bbrc.1995.2197.


Progesterone is capable of initiating the mammalian sperm acrosome reaction in vitro and is a putative initiator of this essential fertilization event in vivo. Our previous work has suggested that progesterone initiates the human sperm acrosome reaction, at least in part, by activating a unique steroid receptor/Cl- channel resembling a gamma-aminobutyric acidA receptor/Cl- channel (gamma-aminobutyric acidA-like receptor/Cl- channel). Here, the fluorescent intracellular Cl- probe, 6-methoxy-N-ethylquinolinium, was used to detect qualitative changes in sperm cytosolic Cl-. We demonstrate that progesterone can mediate a rapid transient decrease of human sperm cytosolic Cl- inhibitable by the gamma-aminobutyric acidA receptor/Cl- channel antagonists picrotoxin and (+)-bicuculline (which also inhibit the acrosome reaction). These results support the involvement of a gamma-aminobutyric acidA-like receptor/Cl- channel in the P-mediated human acrosome reaction and are the first to demonstrate that a rapid Cl- efflux plays a role in that event.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acrosome / metabolism*
  • Adult
  • Chloride Channels / metabolism
  • Chlorides / metabolism*
  • Cytosol / drug effects
  • Cytosol / enzymology
  • Fluorescence
  • Fluorescent Dyes
  • Humans
  • Ion Transport
  • Male
  • Progesterone / pharmacology*
  • Quinolinium Compounds
  • Receptors, GABA-A / metabolism


  • Chloride Channels
  • Chlorides
  • Fluorescent Dyes
  • Quinolinium Compounds
  • Receptors, GABA-A
  • 6-methoxy-N-ethylquinolinium
  • Progesterone