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Lipid diffusion in sperm plasma membranes exposed to peroxidative injury from oxygen free radicals
Author(s) -
Christova Yonka,
James Peter S.,
Jones Roy
Publication year - 2004
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.20084
Subject(s) - lipid peroxidation , superoxide dismutase , catalase , vitamin e , biochemistry , membrane fluidity , chemistry , reactive oxygen species , dabco , antioxidant , ascorbic acid , butylated hydroxytoluene , sperm , biology , membrane , food science , botany , catalysis
Unsaturated lipids in sperm plasma membranes are very susceptible to peroxidation when exposed to reactive oxygen species (ROS). In this investigation we have incubated ram spermatozoa in the presence of two ROS generating systems, ascorbate/FeSO 4 and potassium peroxychromate (K 3 CrO 8 ), and examined their effects on membrane fluidity by measuring fluorescence recovery after photobleaching (FRAP) of a lipid reporter probe 5‐( N ‐octadecanoyl)‐aminofluorescein (ODAF). Peroxidation was monitored by malonaldehyde formation and changes in fluorescence emission of 4,4‐difluoro‐5‐(4‐phenyl‐1,3‐butadienyl)‐4‐bora‐3a,4a‐diaza‐s‐indacene‐3‐undecanoic acid (C 11 ‐BODIPY 581/591 ). Ascorbate/FeSO 4 ‐induced peroxidation was inhibited by Vitamin E, butylated hydroxyanisole (BHA), 1,4‐diazobicyclo(2,2,2)octane (DABCO), and to a lesser extent by ethanol. Added superoxide dismutase (SOD), gluthathione peroxidase (GPX), and catalase were ineffective scavengers. K 3 CrO 8 induced very rapid peroxidation that could be delayed, but not prevented, by Vitamin E, BHT, DABCO, ethanol, and mannitol; once again SOD, GPX, and catalase were ineffective scavengers. Neither peroxidation with ascorbate/FeSO 4 nor K 3 CrO 8 , or added H 2 O 2 or malonaldehyde perturbed ODAF diffusion in any region of the sperm plasma membrane. Vitamin E tended to enhance diffusion rates. Exogenous cumene hydroperoxide, however, reduced ODAF diffusion to low levels on the sperm head. These results suggest that the adverse effects of ROS on spermatozoa are more likely to be caused by direct oxidation of proteins and membrane permeabilisation than disturbance of lipid fluidity. Mol. Reprod. Dev. 68: 365–372, 2004. © 2004 Wiley‐Liss, Inc.