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Calcium and phospholipase A 2 are both required for the acrosome reaction mediated by G‐proteins stimulation in human spermatozoa
Author(s) -
Domínguez L.,
Yunes R.M.F.,
Fornés M.W.,
Burgos M.,
Mayorga L.S.
Publication year - 1999
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/(sici)1098-2795(199903)52:3<297::aid-mrd7>3.0.co;2-t
Subject(s) - biology , acrosome reaction , stimulation , calcium , microbiology and biotechnology , phospholipase a2 , phospholipase , oocyte activation , andrology , endocrinology , medicine , biochemistry , oocyte , human fertilization , anatomy , embryo , enzyme
G‐proteins, calcium, and phospholipase A 2 (PLA 2 ) have all been implicated in the cascade of signaling events leading to the acrosome reaction in human spermatozoa. In order to study the role of Ca +2 and PLA 2 during the acrosome reaction triggered by G‐proteins, we treated human spermatozoa incubated for 3 hr under capacitating conditions with several reagents (GTPγS, A23187, ONO‐RS‐082, arachidonic acid, BAPTA‐AM, and TPEN), alone or in different combinations. Our results suggest that GTP‐binding proteins require Ca +2 and PLA 2 to accomplish their stimulatory effect, and that Ca +2 is also required when the acrosome reaction—bypassing the action of PLA 2 —is stimulated by AA. Accordingly, when treated with GTPγS or AA, the cells loaded with Fura 2‐AM showed a steady increase of [Ca +2 ] i . On the other hand, a massive influx of Ca +2 was completely unable to induce the acrosome reaction if PLA 2 was inhibited, suggesting that both an increase of [Ca +2 ] i and PLA 2 activation are required for the acrosome reaction to occur. Mol. Reprod. Dev. 52:297–302, 1999. © 1999 Wiley‐Liss, Inc.