title: [Alteration of the antinociceptive systems in chronic daily headaches].
abstract: BACKGROUND
  Chronic daily headache (CDH) is a chronic painful clinical condition that is frequently found in neurological practice. Diagnosis is clinical and the therapeutic approach is complex. Its mechanism of production is still not altogether clear, but a genetic component is acknowledged as a predisposing factor. Numerous areas are involved in the generation of primary headaches, including the periaqueductal grey matter (PAGM), which plays a role as a neuromodulator both in headaches and in other chronic painful conditions.
  
  
  OBJECTIVE
  In order to evaluate possible biochemical changes in patients with CDH, magnetic resonance imaging was used to study the spectra produced in the PAGM.
  
  
  METHODS
  The spectra in the PAGM were studied in 17 patients with CDH. These were compared with the average spectra in 17 healthy subjects by means of differential spectroscopy.
  
  
  RESULTS
  Subjects with CDH show a reduction of over 70% in the level of the metabolite N-acetyl-aspartyl-glutamate (NAAG) in the PAGM. NAAG is a peptide involved in antinociceptive activity.
  
  
  CONCLUSIONS
  The reduction of NAAG in the PAGM suggests altered neuromodulation of the antinociceptive systems in subjects with CDH. Whether CDH is the cause or the consequence has still to be determined.
authors.affiliation: Facultad de Ciencias Médicas, Universidad Nacional de Cordoba, Cordoba, Argentina. buonanottefederico@arnet.com.ar
authors.forename: F
authors.initials: F
authors.lastname: Buonanotte
authors.forename: C
authors.initials: C
authors.lastname: Schurrer
authors.forename: M
authors.initials: M
authors.lastname: Carpinella
authors.forename: A
authors.initials: A
authors.lastname: Surur
authors.forename: A
authors.initials: A
authors.lastname: Marangoni
authors.forename: S
authors.initials: S
authors.lastname: Palacio
authors.forename: M
authors.initials: M
authors.lastname: Forteza
authors.forename: R
authors.initials: R
authors.lastname: Fernandez
authors.forename: J
authors.initials: J
authors.lastname: Enders
mesh_terms: D000328:Adult; D004151:Dipeptides / Q000378:metabolism; D005260:Female; D020773:Headache Disorders / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000378:metabolism; D010146:Pain / Q000503:physiopathology*; D010487:Periaqueductal Gray / Q000033:anatomy & histology / Q000378:metabolism* / Q000473:pathology
chemical_list: D004151:Dipeptides; D018696:Neuroprotective Agents; C027172:isospaglumic acid