title: Light/dark patterns of interleukin-6 in relation to the pineal hormone melatonin in patients with acute myocardial infarction.
abstract: OBJECTIVE
  Atherosclerosis is a chronic disease that, from its origin to its ultimate complications, involves inflammatory cells, inflammatory proteins, and inflammatory responses from vascular cells. It has been demonstrated that cytokine activities are under neuroendocrine control, in part exerted by the pineal gland through the circadian secretion of its main product melatonin. Melatonin is mainly released during the night, but the precise relationship between melatonin and the light/dark rhythm of interleukin-6 in patients with acute myocardial infarction is still unclear.
  
  
  RESULTS
  The study included 60 patients diagnosed with acute myocardial infarction and 60 healthy volunteers whose venous blood samples were collected at 09:00 h (light period) and 02:00 h (dark period). Our results demonstrate that interleukin-6 concentrations presented a light/dark pattern with mean serum concentrations being higher in the acute myocardial infarction group than in the control group (101.26 +/- 13.43 and 52.67 +/- 7.73 pg/ml at 02:00 h, 41.93 +/- 5.90 and 22.98 +/- 4.49 pg/ml at 09:00 h, respectively, p < 0.05). Differences in the day/night changes in melatonin levels in control subjects (48.19 +/- 7.82 at 02:00 h, 14.51+/- 2.36 at 09:00 h, pg/ml) and acute myocardial infarction patients (25.97 +/- 3.90 at 02:00 h, 12.29 +/- 4.01 at 09:00 h, pg/ml) (p < 0.05) were a result of a reduced nocturnal elevation of melatonin in the acute myocardial infarction group.
  
  
  CONCLUSIONS
  The current findings suggest that the circadian secretion of melatonin may be responsible at least in part for light/dark variations of endogenous interleukin-6 production in patients with acute myocardial infarction. In this study, the melatonin seems to have an anti-inflammatory effect.
authors.affiliation: Department of Cardiology, Hospital Universitario de Canarias, Spain. pabreu@ull.es
authors.forename: Alberto
authors.initials: A
authors.lastname: Dominguez-Rodriguez
authors.forename: Pedro
authors.initials: P
authors.lastname: Abreu-Gonzalez
authors.forename: Martin
authors.initials: M
authors.lastname: Garcia
authors.forename: Julio
authors.initials: J
authors.lastname: Ferrer
authors.forename: Alejandro
authors.initials: A
authors.lastname: de la Rosa
authors.forename: Manuel
authors.initials: M
authors.lastname: Vargas
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
mesh_terms: D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000378:metabolism*; D010870:Pineal Gland / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D008550:Melatonin