title: Determination of oxidative glucose metabolism in vivo in the young rat brain using localized direct-detected ¹³C NMR spectroscopy.
abstract: Determination of oxidative metabolism in the brain using in vivo ¹³C NMR spectroscopy (¹³C MRS) typically requires repeated blood sampling throughout the study to measure blood glucose concentration and fractional enrichment (input function). However, drawing blood from small animals, such as young rats, placed deep inside the magnet is technically difficult due to their small total blood volume. In the present study, a custom-built animal holder enabled temporary removal of the animal from the magnet for blood collection, followed by accurate repositioning in the exact presampling position without degradation of B₀ shimming. ¹³C label incorporation into glutamate C4 and C3 positions during a 120 min [1,6-¹³C₂] glucose infusion was determined in 28-day-old rats (n = 4) under α-chloralose sedation using localized, direct-detected in vivo ¹³C MRS at 9.4T. The tricarboxylic acid cycle activity rate (V(TCA)) determined using a one-compartment metabolic modeling was 0.67 ± 0.13 μmol/g/min, a value comparable to previous ex vivo studies. This methodology opens the avenue for in vivo measurements of brain metabolic rates using ¹³C MRS in small animals.
authors.affiliation: Department of Pediatrics, Division of Neonatology, University of Minnesota, Mayo Mail Code 39, 420 Delaware Street, SE, Minneapolis, MN 55455, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Ennis
authors.forename: Dinesh Kumar
authors.initials: DK
authors.lastname: Deelchand
authors.forename: Ivan
authors.initials: I
authors.lastname: Tkac
authors.forename: Pierre-Gilles
authors.initials: PG
authors.lastname: Henry
authors.forename: Raghavendra
authors.initials: R
authors.lastname: Rao
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D002952:Citric Acid Cycle; D005947:Glucose / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002247:Carbon Isotopes; D005947:Glucose