Reactive oxygen species block sperm-egg fusion via oxidation of sperm sulfhydryl proteins in mice.
The effects of reactive oxygen species (ROS) on mouse sperm-egg fusion were determined. Sperm were treated with superoxide and hydrogen peroxide generated by addition of xanthine oxidase (XO: 10-200 mlU/ml) to hypoxanthine (HX: 1 mM). While XO at concentrations higher than 100 mlU/ml decreased the motility and lipid peroxidation of sperm, XO at less than 50 mlU/ml had no such effect. However, 20-50 mlU/ml XO significantly suppressed sperm fusion with zona-free eggs. Two ROS scavengers, superoxide dismutase and catalase, attenuated the inhibition of sperm-egg fusion by HX-XO. The sulfhydryl (SH) reductant, dithiothreitol, also reversed the inhibition. The sperm SH-rich fusion-related proteins were highly sensitive to ROS. These results suggest that ROS at low concentrations may inhibit sperm-egg fusion via oxidation of the SH-proteins in the sperm membrane, without causing loss of motility.
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
A
A
Mammoto
N
N
Masumoto
M
M
Tahara
Y
Y
Ikebuchi
M
M
Ohmichi
K
K
Tasaka
A
A
Miyake
D000818:Animals; D002374:Catalase / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D005260:Female; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species; D013081:Sperm Motility / Q000187:drug effects; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000378:metabolism / Q000494:pharmacology
D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D013481:Superoxides; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D004229:Dithiothreitol