title: Association between plasma concentrations of linoleic acid-derived oxylipins and the perceived pain scores in an exploratory study in women with chronic neck pain.
abstract: BACKGROUND
  Chronic musculoskeletal pain may be associated with changes in the balance of algogenic and anti-nociceptive compounds, and such changes may be visible in plasma samples. We have undertaken an exploratory study to measure the levels of endocannabinoids, related N-acylethanolamines and oxylipins (primarily those derived from linoleic acid) in plasma samples from women with chronic neck pain (NP) and chronic widespread pain (CWP), and to investigate whether the observed levels are associated with the pain experienced by these women.
  
  
  METHODS
  Blood samples from 35 women with NP, 15 with CWP and 27 age-matched controls were analysed for the lipids using ultra performance liquid chromatography coupled to tandem mass spectrometry. Current pain ("NRSday") and the average pain during the last week ("NRSweek") were rated by the participants using a numerical rating scale.
  
  
  RESULTS
  There were no significant differences in the plasma concentrations of the fifteen lipids investigated between the women with pain and the controls. However, significant correlations were seen for the NP group between the NRSday scores and the plasma concentrations of the linoleic acid derivatives 9- and 13-hydroxy-octadecadienoic acid (Spearman's rho values 0.51 [P = 0.0016]) and 0.53 [P = 0.0011], respectively).
  
  
  CONCLUSIONS
  The data obtained in this exploratory study indicate that although no group differences are seen in plasma lipid concentrations, there is an association between the NRSday scores and the 9- and 13-hydroxy-octadecadienoic acid levels. Whether or not the association reflects a causality (i.e. that the circulating lipids contribute to the perceived pain of the pain participants), requires further investigation.
authors.affiliation: Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research, University of Gävle, SE 907 13, Umeå, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Hellström
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden.|Department of Pharmacology and Clinical Neuroscience, Umeå University, SE-901 87, Umeå, Sweden.
authors.forename: Sandra
authors.initials: S
authors.lastname: Gouveia-Figueira
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Umeå University, SE-901 87, Umeå, Sweden.
authors.forename: Malin L
authors.initials: ML
authors.lastname: Nording
authors.affiliation: Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research, University of Gävle, SE 907 13, Umeå, Sweden.|Department of Community Medicine and Rehabilitation, Umeå University, Umeå, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Björklund
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Umeå University, SE-901 87, Umeå, Sweden. cf@pharm.umu.se.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Fowler
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D059350:Chronic Pain / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D019787:Linoleic Acid / Q000097:blood*; D008875:Middle Aged; D019547:Neck Pain / Q000097:blood* / Q000175:diagnosis; D054883:Oxylipins / Q000097:blood*; D010147:Pain Measurement / Q000379:methods; D058748:Pain Perception / Q000502:physiology*
chemical_list: D015415:Biomarkers; D054883:Oxylipins; D019787:Linoleic Acid