title: Non-invasive monitoring of L-2-oxothiazolidine-4-carboxylate metabolism in the rat brain by in vivo 13C magnetic resonance spectroscopy.
abstract: The cysteine precursor L-2-oxothiazolidine-4-carboxylate (OTZ, procysteine) can raise cysteine concentration, and thus glutathione levels, in some tissues. OTZ has therefore been proposed as a prodrug for combating oxidative stress. We have synthesized stable isotope labeled OTZ (i.e. L-2-oxo-[5-(13)C]-thiazolidine-4-carboxylate, (13)C-OTZ) and tracked its uptake and metabolism in vivo in rat brain by (13)C magnetic resonance spectroscopy. Although uptake and clearance of (13)C-OTZ was detectable in rat brain following a bolus dose by in vivo spectroscopy, no incorporation of isotope label into brain glutathione was detectable. Continuous infusion of (13)C-OTZ over 20 h, however, resulted in (13)C-label incorporation into glutathione, taurine, hypotaurine and lactate at levels sufficient for detection by in vivo magnetic resonance spectroscopy. Examination of brain tissue extracts by mass spectrometry confirmed only low levels of isotope incorporation into glutathione in rats treated with a bolus dose and much higher levels after 20 h of continuous infusion. In contrast to some previous studies, bolus administration of OTZ did not alter brain glutathione levels. Even a continuous infusion of OTZ over 20 h failed to raise brain glutathione levels. These studies demonstrate the utility of in vivo magnetic resonance for non-invasive monitoring of antioxidant uptake and metabolism in intact brain. These types of experiments can be used to evaluate the efficacy of various interventions for maintenance of brain glutathione.
authors.affiliation: UNC/NCSU Joint Department of Biomedical Engineering, Campus Box 7115, Raleigh, NC 27695, USA. mgamcsi@ncsu.edu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Gamcsik
authors.forename: M Daniel
authors.initials: MD
authors.lastname: Clark
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ludeman
authors.forename: James B
authors.initials: JB
authors.lastname: Springer
authors.forename: Michael A
authors.initials: MA
authors.lastname: D'Alessandro
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Simpson
authors.forename: Roxana
authors.initials: R
authors.lastname: Pourdeyhimi
authors.forename: C Bryce
authors.initials: CB
authors.lastname: Johnson
authors.forename: Stephanie D
authors.initials: SD
authors.lastname: Teeter
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blackband
authors.forename: Peter E
authors.initials: PE
authors.lastname: Thelwall
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D005260:Female; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D018384:Oxidative Stress; D011761:Pyrrolidonecarboxylic Acid / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D053778:Thiazolidines / Q000378:metabolism*
chemical_list: D053778:Thiazolidines; D011761:Pyrrolidonecarboxylic Acid; C029536:2-oxothiazolidine-4-carboxylic acid