title: Interleukin-6 alters sleep of rats.
abstract: Although it is well established that the cytokines tumor necrosis factor (TNF) and interleukin (IL)-1 regulate sleep, there is no direct evidence implicating IL-6 in the regulation/modulation of sleep. We tested the hypotheses that central administration of rat recombinant IL-6 increases non-rapid eye movements (NREM) sleep of rats, and that central administration of anti-IL-6 antibodies reduces NREM sleep. Effective doses of IL-6 (100 and 500 ng) initially enhance NREM sleep, after which NREM sleep may be suppressed. IL-6 induces febrile responses at doses lower (50 ng) than those required to alter sleep. Rapid eye movements (REM) sleep is not altered by the doses of IL-6 tested. Central administration of monoclonal or polyclonal anti-rat IL-6 antibodies does not alter any of the parameters determined in this study. Collectively, these results support the hypothesis that IL-6 possesses sleep modulatory properties. However, this cytokine may not be involved in the regulation of spontaneous sleep in healthy animals because antagonizing the IL-6 system using antibodies does not alter sleep. The interpretation of these data is consistent with those of previous studies demonstrating correlations between increased IL-6 and excessive daytime sleepiness during some pathophysiological conditions.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Dale
authors.initials: D
authors.lastname: Hogan
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Morrow
authors.forename: Eric M
authors.initials: EM
authors.lastname: Smith
authors.forename: Mark R
authors.initials: MR
authors.lastname: Opp
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D001831:Body Temperature / Q000187:drug effects / Q000276:immunology; D001921:Brain / Q000187:drug effects / Q000276:immunology; D007276:Injections, Intraventricular; D015850:Interleukin-6 / Q000276:immunology / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012890:Sleep / Q000187:drug effects / Q000276:immunology*; D012894:Sleep Stages / Q000187:drug effects / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015850:Interleukin-6