Lipopolysaccharide increases EEG delta activity within non-REM sleep and disrupts sleep continuity in rats.
Activation of the immune system by microorganisms or specific microbial constituents promotes non-rapid-eye-movement (REM) sleep (non-REMS). In this study, we assessed the effects of lipopolysaccharide (LPS) on sleep duration, electroencephalogram (EEG) power spectra, and brain temperature (Tbr) in rats. Twenty-four hour recordings were made before and after intraperitoneal injection of vehicle or 30 or 100 micrograms/kg LPS at lights on. During the first 12 h after administration of both doses of LPS, Tbr was elevated, REMS duration was reduced, and non-REMS duration was unchanged, whereas the non-REMS episodes were shortened. EEG activity within non-REMS from 0.5 to 7 Hz was enhanced during hours 3-12. During the second 12-h period, the number of non-REMS and REMS episodes and the total time in both states were increased. EEG activity within non-REMS was mainly reduced in the entire frequency range (0.5-25.5 Hz). The effects of LPS did not differ between the doses. The effects of LPS on EEG power spectra are similar to those observed after sleep deprivation, i.e., a physiological intensification of non-REMS, indicating that both manipulations may activate common sleep EEG regulatory mechanisms. However, the disruption of non-REMS continuity following LPS administration at light onset contrasts the changes induced by sleep deprivation and may reflect an effect of a systemic inflammatory response on sleep maintenance.
Lancel
M
M
Max-Planck Institute of Psychiatry, Department of Neuroendocrinology, Munich, Germany.
Crönlein
J
J
Müller-Preuss
P
P
Holsboer
F
F
D000818:Animals; D001143:Arousal; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000187:drug effects; D003700:Delta Rhythm; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012894:Sleep Stages / Q000187:drug effects* / Q000502:physiology*
D008070:Lipopolysaccharides