M. Lancel et al., LIPOPOLYSACCHARIDE INCREASES EEG DELTA-ACTIVITY WITHIN NON-REM SLEEP AND DISRUPTS SLEEP CONTINUITY IN RATS, American journal of physiology. Regulatory, integrative and comparative physiology, 37(5), 1995, pp. 1310-1318
Activation of the immune system by microorganisms or specific microbia
l 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 t
emperature (Tbr) in rats. Twenty-four hour recordings were made before
and after intraperitoneal injection of vehicle or 30 or 100 mu g/kg L
PS at lights on. During the first 12 h after administration of both do
ses 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 hour
s 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 activi
ty 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 afte
r sleep deprivation, i.e., a physiological intensification of non-REMS
, indicating that both manipulations may activate common sleep EEG reg
ulatory mechanisms. However, the disruption of non-REMS continuity fol
lowing LPS administration at light onset contrasts the changes induced
by sleep deprivation and may reflect an effect of a systemic inflamma
tory response on sleep maintenance.