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Enhancement of slow-wave sleep by endotoxin and lipid A
Abstract:
Some muramyl peptides derived from bacterial peptidoglycan enhance slow-wave sleep (SWS). The purpose of this study was to test whether another cell wall component, lipopolysaccharide (LPS), and its lipid A moiety also have an effect on sleep. When injected intravenously, both LPS and lipid A enhanced the duration of SWS, increased electroencephalogram delta-wave amplitudes, suppressed rapid eye movement (REM) sleep, and induced biphasic fevers. The effects of intravenously administered lipid A and LPS on SWS were present primarily during the first 3 h postinjection. Intraventricular lipid A administration enhanced SWS, did not suppress REM, and induced a monophasic fever; the SWS effect had a 3-h latency, whereas temperature started to rise during the second hour. Regardless of the route of administration, within the dose range used here, sleep was normal by the following criteria: sleep was episodic, animals could be easily aroused, and brain temperature, although elevated to "febrile" levels, continued to fluctuate during sleep-state transitions indistinguishably from control conditions. We conclude that LPS and lipid A are capable of modulating sleep.
Insights
Bacterial cell wall components, lipopolysaccharide (LPS) and lipid A, were found to enhance slow-wave sleep (SWS) and alter sleep patterns. These substances also induced fevers, demonstrating their capacity to modulate sleep.
Area of Science:
- Neuroscience
- Immunology
- Sleep Science
Background:
- Bacterial peptidoglycan components, like muramyl peptides, are known to enhance slow-wave sleep (SWS).
- The impact of other bacterial cell wall components, specifically lipopolysaccharide (LPS) and its lipid A moiety, on sleep regulation remains less understood.
Purpose of the Study:
- To investigate the effects of lipopolysaccharide (LPS) and lipid A on sleep architecture and physiological responses.
- To determine if LPS and lipid A, similar to muramyl peptides, can modulate sleep patterns.
Main Methods:
- Intravenous and intraventricular administration of LPS and lipid A in animal models.
- Monitoring of electroencephalogram (EEG) for sleep stages (SWS, REM) and delta-wave amplitudes.
- Measurement of body temperature to assess fever responses.
Main Results:
- Intravenous LPS and lipid A administration enhanced SWS duration, increased EEG delta-wave amplitudes, suppressed REM sleep, and induced biphasic fevers.
- Intraventricular lipid A enhanced SWS with a latency, did not suppress REM sleep, and induced a monophasic fever.
- Sleep remained episodic and easily arousable, with normal brain temperature fluctuations during sleep-state transitions.
Conclusions:
- Lipopolysaccharide (LPS) and lipid A are capable of modulating sleep, particularly slow-wave sleep.
- The route of administration influences the specific effects on sleep stages and fever patterns.
- These findings highlight the role of bacterial components in regulating sleep physiology.