Control of superoxide and nitric oxide formation during human sperm capacitation |
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| Authors: | Eve de Lamirande Geneviève Lamothe Michèle Villemure |
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| Institution: | 1. Laboratory for Oxidative Stress, Rudjer Boskovic Institute, Zagreb, Croatia;2. Toxicology and Multipurpose Labs, Anti Doping Laboratory Qatar, Sports City Str., Doha, Qatar;3. University of Zagreb, Department of Pathology, Medical Faculty, Clinical Hospital Centre Zagreb, Croatia |
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| Abstract: | We studied the modulation of superoxide anion (O2·?) and nitric oxide (NO·) generation during human sperm capacitation (changes needed for the acquisition of fertility). The production of NO· (diaminofluorescein-2 fluorescence assay), but not that of O2·? (luminescence assay), related to sperm capacitation was blocked by inhibitors of protein kinase C, Akt, protein tyrosine kinase, etc., but not by those of protein kinase A. Extracellular calcium (Ca2+) controlled O2·? synthesis but extra- and intracellular Ca2+ regulated NO· formation. Zinc inhibited capacitation and formation of O2·? and NO·. Zinc chelators (TPEN and EDTA) and sulfhydryl-targeted compounds (diamide and N-ethylmaleimide) stimulated capacitation and formation of O2·? and NO·; superoxide dismutase (SOD) and nitric oxide synthase inhibitor (L-NMMA) prevented these events. Diphenyliodonium (flavoenzyme inhibitor) blocked capacitation and related O2·? synthesis but promoted NO· formation, an effect canceled by SOD and L-NMMA. NADPH induced capacitation and NO· (but not O2·?) synthesis and these events were blocked by L-NMMA and not by SOD. Integration of these data on O2·? and NO· production during capacitation reinforces the concept that a complex, but flexible, network of factors is involved and probably is associated with rescue mechanisms, so that spermatozoa can achieve successful fertilization. |
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