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Higher Glutamate to Glutamine Ratios in Occipital Regions in Women With Migraine During the Interictal State

2012; Wiley; Volume: 53; Issue: 2 Linguagem: Inglês

10.1111/head.12030

1526-4610

Jesús González de la Aleja, Ana Regina Lima Ramos, Virginia Mato‐Abad, Antonio Martínez‐Salio, Juan A. Hernández‐Tamames, José Antonio Molina, Jesús Hernández‐Gallego, Juan Álvarez‐Linera,

Transcranial Magnetic Stimulation Studies

Background Glutamate ( G lu) and glutamine ( G ln) are strongly compartmentalized (in neurons for G lu and in astrocytes for G ln). 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 G lu 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 G lu 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 G lu and G ln to generate G lu/ G ln 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 LCM odel, allowing a separation of G lu and G ln using a 3 T machine. Results The main result was a significantly higher G lu/ G ln 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 G lu levels (6.98 for migraineurs [ SD = 0.85] and 6.22 for controls [ SD = 0.97], P = .007) and G lu/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 G lu/ G ln ratio (2.79 for migraineurs [ SD = 1.11] and 2.63 for controls [ SD = 1.61], P = .68). Conclusion These findings are consistent with glutamatergic differences in migraine patients during the interictal period compared with healthy controls. We hypothesize that an increased G lu/ G ln ratio could arise from neuronal–glial coupling of glutamatergic metabolism differences or an increased neuron/astrocyte ratio in the OC .