title: Higher glutamate to glutamine ratios in occipital regions in women with migraine during the interictal state.
abstract: BACKGROUND
  Glutamate (Glu) and glutamine (Gln) are strongly compartmentalized (in neurons for Glu and in astrocytes for Gln). The visual cortex is the brain region with a higher neuron/astrocyte ratio (the highest neuronal density and the relatively lowest density of astrocytes). Elevations in extracellular Glu or potassium above certain thresholds are likely candidates to be the final common steps in the multiple distinct processes that can lead to cortical spreading depression. Astrocytes play a key role in this phenomenon, by acting as a sink for extracellular Glu and potassium, as well as generally acting as a buffer for the ionic and neurochemical changes that initiate and propagate cortical spreading depression.
  
  
  OBJECTIVE
  The purpose of this study was to quantify Glu and Gln to generate Glu/Gln ratios in women with migraine during the interictal state compared with healthy control women.
  
  
  METHODS
  Twenty-seven patients with migraine (8 with aura and 19 without aura) and 19 matched healthy controls were included in the study. We performed proton magnetic resonance spectroscopy in the anterior paracingulate cortex and occipital cortex (OC). Spectral analysis was performed by LCModel, allowing a separation of Glu and Gln using a 3T machine.
  
  
  RESULTS
  The main result was a significantly higher Glu/Gln ratio in the OC of migraine patients compared with healthy control subjects (4.87 for migraineurs [standard deviation (SD) = 2.74] and 3.42 for controls [SD = 1.52], P = .042). We also observed higher Glu levels (6.98 for migraineurs [SD = 0.85] and 6.22 for controls [SD = 0.97], P = .007) and Glu/creatine + phosphocreatine ratio (1.18 for migraineurs [SD = 0.18] and 1.00 for controls [SD = 0.16], P = .001) in anterior paracingulate cortex in migraine patients but saw no differences in Glu/Gln ratio (2.79 for migraineurs [SD = 1.11] and 2.63 for controls [SD = 1.61], P = .68).
  
  
  CONCLUSIONS
  These findings are consistent with glutamatergic differences in migraine patients during the interictal period compared with healthy controls. We hypothesize that an increased Glu/Gln ratio could arise from neuronal-glial coupling of glutamatergic metabolism differences or an increased neuron/astrocyte ratio in the OC.
authors.affiliation: Servicio de Neurología, Hospital Universitario 12 de Octubre, Madrid, Spain. jesus_goal@yahoo.es
authors.forename: Jesús
authors.initials: J
authors.lastname: González de la Aleja
authors.forename: Ana
authors.initials: A
authors.lastname: Ramos
authors.forename: Virginia
authors.initials: V
authors.lastname: Mato-Abad
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Salio
authors.forename: Juan A
authors.initials: JA
authors.lastname: Hernández-Tamames
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Molina
authors.forename: Jesús
authors.initials: J
authors.lastname: Hernández-Gallego
authors.forename: Juan
authors.initials: J
authors.lastname: Alvarez-Linera
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D016022:Case-Control Studies; D004827:Epilepsy / Q000209:etiology*; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008881:Migraine Disorders / Q000150:complications* / Q000473:pathology*; D009778:Occipital Lobe / Q000378:metabolism* / Q000473:pathology; D055815:Young Adult
chemical_list: D005973:Glutamine; D001224:Aspartic Acid; D018698:Glutamic Acid; C000179:N-acetylaspartate