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NMDA‐type glutamate receptors mediate the acrosome reaction and motility initiation in newt sperm
Author(s) -
Endo Daisuke,
Kon Shinnosuke,
Sato Tae,
Toyama Fubito,
Katsura Yohei,
Nakauchi Yuni,
TakayamaWatanabe Eriko,
Watanabe Akihiko
Publication year - 2019
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.23225
Subject(s) - biology , acrosome reaction , nmda receptor , glutamate receptor , acrosome , microbiology and biotechnology , receptor , motility , sperm , sperm motility , neuroscience , genetics
The N ‐methyl d ‐aspartate type glutamate receptor (NMDAR) is a ligand‐gated cation channel that causes Ca 2+ influx in nerve cells. An NMDAR agonist is effective to the sperm motility in fowls, although the actual role of NMDAR in sperm function is unknown. In the present study, RNA‐seq of the spermatogenic testes suggested the presence of NMDAR in the sperm of the newt Cynops pyrrhogaster . Glutamate of at least 0.7 ± 0.5 mM was detected in the egg‐jelly substances along with acrosome reaction‐inducing substance (ARIS) and sperm motility‐initiating substance (SMIS). In the egg‐jelly extract (JE) that included the ARIS and SMIS, the acrosome reaction was inhibited by a NMDAR antagonists, memantine and MK801. MK801 also inhibited the spontaneous acrosome reaction in Steinberg's salt solution (ST). Furthermore, memantine and MK801 suppressed the progressive motility of the sperm in JE and spontaneous waving of the undulating membrane, which is the tail structure giving thrust for forward motility, in ST. The spontaneous waving of the undulating membrane was promoted when Mg 2+ , which blocks Ca 2+ influx through gated NMDARs, was removed from the ST. In addition, the ARIS‐induced acrosome reaction was inhibited by a selective antagonist of the transient receptor potential vanilloid 4, whose activation might result in the membrane depolarization to release Mg 2+ from the NMDAR. These results suggest that NMDAR acts together with other cation channels in the induction of the acrosome reaction and motility of the sperm during the fertilization process of C. pyrrhogaster .