title: Metabolism of 5-(glutathion-S-yl)-alpha-methyldopamine following intracerebroventricular administration to male Sprague-Dawley rats.
abstract: 5-(Glutathion-S-yl)-alpha-methyldopamine [5-(GSyl)-alpha-MeDA] is a putative metabolite of the serotonergic neurotoxicants 3,4-(+/-)-(methylenedioxy)amphetamine and 3,4-(+/-)-(methylenedioxy)methamphetamine. Glutathione (GSH) conjugates of several polyphenols are biologically (re)active. Therefore, as part of our studies on the role of 5-(GSyl)-alpha-MeDA in MDA-mediated neurotoxicity, we determined the regional brain metabolism of 5-(GSyl)-alpha-MeDA (720 nmol) following intracerebroventricular administration to male Sprague-Dawley rats. 5-(GSyl)-alpha-MeDA was rapidly cleared from all brain regions examined, and regional differences in the distribution of gamma-glutamyl transpeptidase (gamma-GT) correlated with the formation of 5-(cystein-S-yl)-alpha-methyldopamine (5-[CYS]-alpha-MeDA). We also observed the formation of 5-(N-acetyl-L-cystein-S-yl)-alpha-MeDA (5-[NAC]-alpha-MeDA) in all brain regions, indicating that the brain has the ability to synthesize mercapturic acids. Peak concentrations of 5-(NAC)-alpha-MeDA were found in the order: hypothalamus > midbrain/diencephalon/telencephalon > pons/medulla > hippocampus > cortex > striatum. In contrast to 5-(GSyl)-alpha-MeDA and 5-(CYS)-alpha-MeDA, 5-(NAC)-alpha-MeDA was eliminated relatively slowly from the brain. Differences were also found in cystein conjugate N-acetyltransferase activity in microsomes prepared from the various brain regions, but little difference was observed in brain cytosolic N-acetyl-L-cysteine conjugate N-deacetylase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Pharmacology & Toxicology, College of Pharmacy, University of Texas at Austin 78712, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Miller
authors.forename: S S
authors.initials: SS
authors.lastname: Lau
authors.forename: T J
authors.initials: TJ
authors.lastname: Monks
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003846:Deoxyepinephrine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D005723:gamma-Glutamyltransferase / Q000378:metabolism
chemical_list: C096088:5-(glutathion-S-yl)methyldopamine; D005723:gamma-Glutamyltransferase; D005978:Glutathione; D003846:Deoxyepinephrine