Metabolic characterization of distinct neuroanatomical regions in rats by magic angle spinning 1H nuclear magnetic resonance spectroscopy

Abstract

High-resolution magic angle spinning (HRMAS) (1)H NMR spectroscopy has been applied to the biochemical characterization of specific brain regions in rats in order to establish baseline levels of tissue metabolite profiles with which to compare models of neuropathology or toxic lesion. Cores of tissue (20 mg) from the brain stem, cerebellum, frontal cortex, and hippocampus were obtained from histologically defined coronal slices of brain from 18 male Sprague-Dawley rats. HRMAS (1)H NMR spectra were acquired for each of the regions sampled and the degree of intersample variability, as assessed by principal components analysis and discriminant analysis by projection to latent structure was found to be low. Clear region-specific differences in the biochemical profiles were observed using both comparison of metabolite ratios and/or pattern recognition methods. Relatively low concentrations of GABA in the cerebellum, high concentrations of taurine and N-acetylaspartate in the cortex, and high levels of choline, glycerophosphocholine, and phosphocholine in the hippocampus predominantly influenced the classification of the different brain regions. Additionally, N-acetylaspartylglutamate was detected in the brain stem, but was largely absent from the other regions examined. Such analyses provide a baseline reference for further HRMAS NMR spectroscopic studies to monitor disease and pharmacological insults in specific regions of the brain.