title: Within-subject correlations between evening-related changes in body temperature and melatonin in the spinal cord injured.
abstract: BACKGROUND
  Individuals with a spinal cord injury (SCI) demonstrate altered circadian variation in thermoregulatory control. Recently, we reported that tetraplegia is associated with a blunted release of melatonin in the evening. In order to examine whether this finding relates to circadian thermoregulation, we compared the correlations between evening changes in melatonin, core and skin temperature between thoracic and cervical SCI and able-bodied participants.
  
  
  METHODS
  In 10 able-bodied, 9 paraplegic and 8 tetraplegic participants, we measured, between 1900 and 2300 h, core temperature, proximal skin temperature (above and below the level of the lesion) and physical activity. Salivary melatonin was also sampled during this period and analyzed using enzyme linked immunosorbant assay.
  
  
  RESULTS
  Between 1900 and 2300 h, core and upper limb skin temperature gradually decreased in all groups (p = 0.01). A significant group × time interaction was evident in lower body skin temperature (p = 0.03). Lower body skin temperature was significantly higher in able-bodied controls compared with tetraplegics between 1900 and 2000 h (p < 0.05). In able-bodied and paraplegic participants, the changes in melatonin and core temperature were inversely correlated (r = -0.44 and -0.54, respectively, both p = 0.01). Melatonin and mean skin temperature changes were also inversely correlated (able-bodied controls: r = -0.24; p = 0.05 and paraplegics: r = -0.30; p= 0.02).
  
  
  CONCLUSIONS
  The inverse correlation between evening changes in melatonin and thermoregulation is of a similar magnitude in paraplegic and able-bodied controls. In contrast, changes in skin temperature, below the level of the lesion, are unrelated to changes in melatonin in tetraplegics.
authors.affiliation: Research Institute for Sport and Exercise Science, Liverpool John Moores University , Liverpool , UK .
authors.forename: Helen
authors.initials: H
authors.lastname: Jones
authors.forename: Thijs M H
authors.initials: TM
authors.lastname: Eijsvogels
authors.forename: Jean
authors.initials: J
authors.lastname: Nyakayiru
authors.forename: Rebecca J H M
authors.initials: RJ
authors.lastname: Verheggen
authors.forename: Andrew
authors.initials: A
authors.lastname: Thompson
authors.forename: Jan T
authors.initials: JT
authors.lastname: Groothuis
authors.forename: Greg
authors.initials: G
authors.lastname: Atkinson
authors.forename: Maria T E
authors.initials: MT
authors.lastname: Hopman
authors.forename: Dick H J
authors.initials: DH
authors.lastname: Thijssen
mesh_terms: D000328:Adult; D001833:Body Temperature Regulation; D016022:Case-Control Studies; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D008875:Middle Aged; D010264:Paraplegia / Q000378:metabolism* / Q000503:physiopathology*; D011782:Quadriplegia / Q000378:metabolism* / Q000503:physiopathology*; D012463:Saliva / Q000378:metabolism*; D012881:Skin Temperature; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D008550:Melatonin