Amino acid neurotransmitter receptor/chloride channels of mammalian sperm and the acrosome reaction.
Two different amino acid neurotransmitter receptor/Cl-channels, a gamma-aminobutyric acid (GABA) receptor-like/Cl- channel and a glycine receptor/Cl- channel, have recently been found in mammalian sperm and shown to be involved in the sperm acrosome reaction (AR), an exocytotic event essential to mammalian fertilization. The identity of the receptor/channel involved in the AR depends upon the stimulatory ligand. The AR initiated by the egg zona pellucida requires the participation of the sperm glycine receptor/Cl- channel, whereas the AR initiated by another putative physiological AR initiator, progesterone, involves the sperm GABA receptor-like/Cl- channel. Cl- efflux through the latter has been shown to occur during the progesterone-initiated AR. Activation of sperm amino acid neurotransmitter receptor/Cl- channels may result in plasma membrane depolarization and thereby exert at least a partial control over voltage-sensitive sperm Ca2+ channels and Ca2+ influx important to the AR.
Meizel
S
S
Department of Cell Biology and Human Anatomy, University of California School of Medicine, Davis 95616-8643, USA. smeizel@ucdavis.edu
D000177:Acrosome / Q000502:physiology*; D000818:Animals; D018118:Chloride Channels / Q000378:metabolism*; D006801:Humans; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018079:Receptors, GABA / Q000378:metabolism; D018009:Receptors, Glycine / Q000378:metabolism; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*
D018118:Chloride Channels; D018377:Neurotransmitter Agents; D018079:Receptors, GABA; D018009:Receptors, Glycine; D017981:Receptors, Neurotransmitter