Prevention of ischemia/reperfusion-induced alterations in synaptosomal membrane-associated proteins and lipids by N-tert-butyl-alpha-phenylnitrone and difluoromethylornithine.
Previous studies in our laboratory demonstrated the alteration in the physical state of synaptosomal membrane lipids and proteins in ischemia/reperfusion injury using selective spin labels and electron paramagnetic resonance spectroscopy [Hall et al. (1995) Neuroscience 61, 84-89]. Since many investigations have provided evidence for free radical generation during ischemia/reperfusion injury, we investigated whether a free radical scavenger would prevent the membrane damage, in gerbils. Further, experiments to determine if a secondary effect of polyamine generation at 14 h reperfusion could be blocked by this free radical scavenger or by an inhibitor of ornithine decarboxylase were also carried out. The alterations in synaptosomal membrane integrity observed during ischemia/reperfusion injury were selectively neutralized by treatment with the free radical spin trap N-tert-butyl-alpha-phenylnitrone or an inhibitor of ornithine decarboxylase, difluoromethylornithine. Administration of N-tert-butyl-alpha-phenylnitrone prior to ischemia totally abrogated both lipid and protein alterations observed at 1 and 14 h reperfusion. Pretreatment with difluoromethylornithine neutralized only the 14 h change in lipid label motion. Treatment with N-tert-butyl-alpha-phenylnitrone at 6 h post ischemia showed only a slight attenuation of the 14 h lipid effect and no change in the protein effect. Difluoromethylornithine treatment at 6 h post ischemia negated the 14 h ischemia/reperfusion injury-induced lipid effect and had no effect on the protein change. These data support previous suggestions that free radicals and polyamines play a critical role in neuronal damage and cell loss following ischemia/reperfusion injury and that the polyamine effect is dependent upon free radical generation during ischemia/reperfusion injury.
Hall
N C
NC
Department of Chemistry, University of Kentucky, Lexington 40506, USA.
Carney
J M
JM
Cheng
M
M
Butterfield
D A
DA
D000704:Analysis of Variance; D000818:Animals; D002545:Brain Ischemia / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D000518:Eflornithine / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D005849:Gerbillinae; D050356:Lipid Metabolism; D008297:Male; D008565:Membrane Proteins / Q000187:drug effects*; D013574:Synaptosomes / Q000187:drug effects*
D016166:Free Radical Scavengers; D008565:Membrane Proteins; D000518:Eflornithine