title: Cingulate metabolites during pain and morphine treatment as assessed by magnetic resonance spectroscopy.
abstract: BACKGROUND
  Experimental investigation of cerebral mechanisms underlying pain and analgesia are important in the development of methods for diagnosis and treatment of pain. The aim of the current study was to explore brain metabolites in response to pain and treatment with morphine.
  
  
  METHODS
  Proton magnetic resonance spectroscopy of the anterior cingulate cortex was performed in 20 healthy volunteers (13 males and seven females, aged 24.9±2.6 years) during rest and acute pain before and during treatment with 30 mg of oral morphine or placebo in a randomized, double-blinded, cross-over study design. Pain was evoked by skin stimulation applied to the right upper leg using a contact heat-evoked potential stimulator.
  
  
  RESULTS
  Data from 12 subjects were valid for analysis. Painful stimulation induced an increase in N-acetylaspartate/creatine compared with rest (F=5.5, P=0.04). During treatment with morphine, painful stimulation induced decreased glutamate/creatine (F=7.3, P=0.02), myo-inositol/creatine (F=8.38, P=0.02), and N-acetylaspartate/creatine (F=13.8, P=0.004) concentrations, whereas an increase in the pain-evoked N-acetylaspartate/creatine concentration (F=6.1, P=0.04) was seen during treatment with placebo.
  
  
  CONCLUSIONS
  This explorative study indicates that neuronal metabolites in the anterior cingulate cortex, such as N-acetylaspartate, glutamate, and myo-inositol, could be related to the physiology of pain and treatment with morphine. This experimental method has the potential to enable the study of brain metabolites involved in pain and its treatment, and may in the future be used to provide further insight into these mechanisms.
authors.affiliation: Mech-Sense, Department of Radiology, Aalborg University, Aalborg, Denmark.
authors.forename: Tine Maria
authors.initials: TM
authors.lastname: Hansen
authors.affiliation: Mech-Sense, Department of Gastroenterology, Aalborg University, Aalborg, Denmark.
authors.forename: Anne Estrup
authors.initials: AE
authors.lastname: Olesen
authors.affiliation: Mech-Sense, Department of Radiology, Aalborg University, Aalborg, Denmark.
authors.forename: Carsten Wiberg
authors.initials: CW
authors.lastname: Simonsen
authors.affiliation: Mech-Sense, Department of Gastroenterology, Aalborg University, Aalborg, Denmark ; Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Asbjørn Mohr
authors.initials: AM
authors.lastname: Drewes
authors.affiliation: Mech-Sense, Department of Radiology, Aalborg University, Aalborg, Denmark.
authors.forename: Jens Brøndum
authors.initials: JB
authors.lastname: Frøkjær
keywords: anterior cingulate cortex; magnetic resonance imaging; morphine; pain; spectroscopy