Hydrogen peroxide is involved in hamster sperm capacitation in vitro.
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Results suggest that H2O2 produced by hamster sperm plays a significant role during capacitation, possibly in membrane reorganization to facilitate the fusion that takes place during exocytosis of the acrosomal contents.Abstract:
We have investigated the possibility that the generation of hydrogen peroxide (H2O2) by spermatozoa plays a physiological role during capacitation. Capacitation is defined as the incubation period required for fertilization in mammals. Capacitation culminates in an exocytotic event, the acrosome reaction (AR). Mammalian sperm generate H2O2 during aerobic incubation and do not contain catalase, the enzyme that promotes scavenging of H2O2. In the present work we show that added catalase inhibited the AR, while glucose oxidase (GO), an enzyme that generates H2O2, accelerated the onset of the AR. Direct addition of H2O2 also stimulated the AR; catalase inhibited both the stimulation by GO and by H2O2. The onset of the AR was always preceded by the appearance of hyperactivated motility. The stimulation of the AR by H2O2 was manifest 1-2 h after the addition of H2O2. Catalase added at 3 h of incubation was less effective in inhibiting the AR than catalase added at the beginning. Incubation of sperm with catalase prevented the induction of the AR by the membrane-perturbing lipid, lysophosphatidyl choline. Taken together, these results suggest that H2O2 produced by hamster sperm plays a significant role during capacitation, possibly in membrane reorganization to facilitate the fusion that takes place during exocytosis of the acrosomal contents.read more
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TL;DR: Results are consistent with a causative role for lipid peroxidation in the etiology of defective sperm function and also suggest a possible physiological role for the reactive oxygen species generated by human spermatozoa in mediating sperm-zona interaction.
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TL;DR: The results suggest that superoxide dismutase plays the major role in protecting human spermatozoa against lipid peroxidation, and the superoxide Dismutase activity of a fresh sperm sample appears to be a good predictor of the lifetime (up to the complete loss of motility) of that particular sample, and so may prove useful in semen analysis.
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TL;DR: It is not unreasonable to expect on the basis of present data that the healthy life span can be increased by 5-10 or more years by keeping body weight down, at a level compatible with a sense of well-being, while ingesting diets adequate in essential nutrients but designed to minimize random free radical reactions in the body.
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Role of glutathione peroxidase in protecting mammalian spermatozoa from loss of motility caused by spontaneous lipid peroxidation.
Juan G. Alvarez,Bayard T. Storey +1 more
TL;DR: A mechanism for spontaneous lipid peroxidation in mammalian sperm is postulated which involves reaction of lipid hydroperoxide and O2 as the rate-determining step and the key intermediate is lipid hydro peroxide generated by a chain reaction initiated by and utilizing superoxide.