Progesterone-mediated efflux of cytosolic chloride during the human sperm acrosome reaction.
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.
Turner
K O
KO
Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis 95616-8643, USA.
Meizel
S
S
D000177:Acrosome / Q000378:metabolism*; D000328:Adult; D018118:Chloride Channels / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D005453:Fluorescence; D005456:Fluorescent Dyes; D006801:Humans; D017136:Ion Transport; D008297:Male; D011374:Progesterone / Q000494:pharmacology*; D011806:Quinolinium Compounds; D011963:Receptors, GABA-A / Q000378:metabolism
D018118:Chloride Channels; D002712:Chlorides; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds; D011963:Receptors, GABA-A; C070311:6-methoxy-N-ethylquinolinium; D011374:Progesterone