EFFECT OF 2-CYCLOHEXENE-1-ONE-INDUCED GLUTATHIONE DIMINUTION ON ISCHEMIA REPERFUSION-INDUCED ALTERATIONS IN THE PHYSICAL STATE OF BRAIN SYNAPTOSOMAL MEMBRANE-PROTEINS AND LIPIDS/

Glutathione is able to protect membrane proteins from oxidative stress . In ischemia/reperfusion injury, free radicals cause synaptosomal mem brane protein and lipid oxidation that is prevented by the free radica l scavenger N-tert-butyl-alpha-phenylnitrone (Hall N. C. et al. (1995) Neuroscience 64, 81-89; 69, 591-600). We wondered if diminution of gl utathione would lead to further membrane alterations. Accordingly, the effects of glutathione depletion, by intraperitoneal administration o f 2-cyclohexene-1-one, on the physical state of cortical synaptosomal membrane proteins and lipids, with and without global ischemia/reperfu sion, were studied in vivo and in vitro in adult and aged gerbils util izing electron paramagnetic resonance spectrometry. 2-Cyclohexene-1-on e (100 mg/kg, i.p.) was administered 30 min prior to 10-min ischemia f ollowed by 1 or 14h reperfusion. This glutathione reduction agent was also administered to gerbils under the same temporal schedule in the a bsence of ischemia and compared to untreated controls. Synaptosomal me mbranes were labeled with a protein specific spin label, 2,2,6,6-tetra methyl-4-maleimidopiperidine-1-oxyl, or a lipid-specific spin probe, 5 -doxylstearic acid. There were no significant changes in the physical stale of the lipid portion of synaptosomal membranes when comparing is chemia reperfusion and 2-cyclohexene-1-one-treated ischemia reperfusio n in either the adult or aged gerbils. However, glutathione depletion without ischemia/reperfusion caused significant changes in the physica l state of the protein portion of cortical synaptosomal membranes in b oth the adult and aged models. Glutathione depletion, without ischemia /reperfusion, in the adult model showed a maximum change at 3 h that r eturned to control values by 14 h. In contrast, the aged model showed significant changes at 1 h reperfusion, which did not return to contro l Values by 14 h reperfusion. Glutathione depletion combined with isch emia/reperfusion caused initial protein change in both adult and aged models at 1 h reperfusion, which did not return toward control values by 14 h reperfusion. The results of this study suggest that glutathion e depletion increases the severity of membrane protein damage associat ed with ischemia/reperfusion injury. Copyright (C) 1997 IBRO.