Elevation of brain glutathione by gamma-glutamylcysteine ethyl ester protects against peroxynitrite-induced oxidative stress.
Elevation of glutathione (GSH) has been recognized as an important method for modulating levels of reactive oxygen species (ROS) in the brain. We investigated the antioxidant properties of gamma-glu-cys-ethyl ester (GCEE) in vitro and its ability to increase GSH levels upon in vivo i.p. injection. GCEE displays antioxidant activity similar to GSH as assessed by various in vitro indices such as hydroxyl radical scavenging, dichlorofluorescein fluorescence (DCF), protein specific spin labeling, glutamine synthetase (GS) activity, and protein carbonyls. Intraperitoneal injection of GCEE to gerbils resulted in a 41% increase in brain total GSH levels in vivo as determined by the DTNB-GSH reductase recycling method. Gerbils injected with buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, had 40% less total brain glutathione. Gerbils injected with BSO followed by a GCEE injection had GSH levels similar to vehicle-injected controls, suggesting that GCEE upregulates GSH biosynthesis by providing gamma-glutamylcysteine and not cysteine. Cortical synaptosomes from GCEE-injected animals were less susceptible to peroxynitrite-induced oxidative damage as assessed by DCF fluorescence, protein-specific spin labeling, and GS activity. These experiments suggest that GCEE is effective in increasing brain GSH levels and may potentially play an important therapeutic role in attenuating oxidative stress in neurodegenerative diseases associated with oxidative stress such as Alzheimer disease.
Department of Chemistry and Center of Membrane Sciences, University of Kentucky, Lexington, Kentucky, 40506, USA.
Jennifer
J
Drake
Jaroslaw
J
Kanski
Sridhar
S
Varadarajan
Maria
M
Tsoras
D Allan
DA
Butterfield
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism*; D004151:Dipeptides / Q000494:pharmacology*; D005849:Gerbillinae; D005978:Glutathione / Q000378:metabolism*; D008297:Male; D016877:Oxidants / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D000975:Antioxidants; D004151:Dipeptides; D016877:Oxidants; C067744:N-gamma-glutamylcysteine ethyl ester; D030421:Peroxynitrous Acid; D005978:Glutathione