Identification of brain metabolites by magnetic resonance spectroscopy in MND/ALS.
Magnetic resonance spectroscopy (MRS) has provided a novel means of studying the brain biochemistry of motor neurone disease/amyotrophic lateral sclerosis (MND/ALS) patients in vivo in situ. Previous studies have demonstrated changes in the ratios of areas under specific spectral peaks in MND/ALS patients (Jones et al., 1995). However, the significance of such findings cannot be fully elucidated without first ascertaining the biochemical identity of each peak. Each peak in a MRS spectrum corresponds to the resonance of specific protons in a particular chemical environment. Many biochemicals contain similar protons in similar environments so it is possible that a single spectral peak could represent protons from more than one biochemical. In this study of major brain MRS peaks we have demonstrated that peaks are potentially composed of a number of protons from different chemicals. For example, the peak at chemical shift 2.01 ppm, conventionally recognised as the neurotransmitter N-acetyl aspartate, may actually be a result of the protons of the N-acetyl moiety (Frahm et al., 1991). We have consequently shown that other N-acetylated compounds such as N-acetyl glutamate are also capable of producing a peak here, whereas their non-acetylated derivatives are not. We have also shown GABA is capable of producing a peak at chemical shift 3.00 ppm, a peak which is generally assigned to creatine/phosphocreatine. These findings have important implications in the identification of spectral peaks in MRS studies and in the interpretation of spectral differences between MND patients and controls.
Centre for Toxicology, University of Central Lancashire, Preston, UK.
J M
JM
Knight
A P
AP
Jones
J P
JP
Redmond
I C
IC
Shaw
D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D003401:Creatine / Q000032:analysis; D005971:Glutamates / Q000032:analysis; D018698:Glutamic Acid / Q000032:analysis; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D005680:gamma-Aminobutyric Acid / Q000032:analysis
D005971:Glutamates; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C000179:N-acetylaspartate; C016195:N-acetylglutamic acid; D003401:Creatine