Brown adipose tissue plays a central role in systemic inflammation-induced sleep responses

• Published in: PloS one 2018-05, Vol.13 (5), p.e0197409
• Main Authors: Szentirmai, Éva, Kapás, Levente
• Format: Article
• Language: English
• Subjects: Adipocytes; Adipocytes, Brown - metabolism; Adipose tissue; Adipose tissue (brown); Adipose Tissue, Brown - metabolism; Animal models; Animals; Biology and Life Sciences; Bisphosphonates; Body fat; Body Temperature; Brown adipose tissue; Clodronic acid; Clodronic Acid - chemistry; Cytokines; Denervation; Diabetes; Electrodes; Electroencephalography; Electromyography; Experiments; Eye movements; Fever; Genotype; Health aspects; Heat; Homeostasis; Hypothermia; Inflammation; Interleukin 1; Interleukin-1beta - metabolism; Ion Channels - metabolism; Laboratory animals; Lipopolysaccharides; Lipopolysaccharides - chemistry; Liposomes; Liposomes - chemistry; Male; Medical research; Medicine and Health Sciences; Metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondrial Proteins - metabolism; NREM sleep; Pharmacology; Physiological aspects; Proteins; Rapid eye movement state; REM sleep; Research and Analysis Methods; Rodents; Sleep; Sleep - physiology; Sleep deprivation; Telemetry; Temperature; Thermogenesis; Thermogenesis - drug effects; Tumor Necrosis Factor-alpha - metabolism; Tumor necrosis factor-α; Uncoupling protein 1; Uncoupling Protein 1 - metabolism; Viral infections
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0197409

We previously identified brown adipose tissue (BAT) as a source of sleep-inducing signals. Pharmacological activation of BAT enhances sleep while sleep loss leads to increased BAT thermogenesis. Recovery sleep after sleep loss is diminished in mice that lack uncoupling protein 1 (UCP-1), and also in wild-type (WT) mice after sensory denervation of the BAT. Systemic inflammation greatly affects metabolism and the function of adipose tissue, and also induces characteristic sleep responses. We hypothesized that sleep responses to acute inflammation are mediated by BAT-derived signals. To test this, we determined the effects of systemic inflammation on sleep and body temperature in UCP-1 knockout (KO) and WT mice. Intraperitoneal injections of lipopolysaccharide, tumor necrosis factor-α, interleukin-1 beta and clodronate containing liposomes were used to induce systemic inflammation. In WT animals, non-rapid-eye movement sleep (NREMS) was elevated in all four inflammatory models. All NREMS responses were completely abolished in UCP-1 KO animals. Systemic inflammation elicited an initial hypothermia followed by fever in WT mice. The hypothermic phase, but not the fever, was abolished in UCP-1 KO mice. The only recognized function of UCP-1 is to promote thermogenesis in brown adipocytes. Present results indicate that the presence of UCP-1 is necessary for increased NREMS but does not contribute to the development of fever in systemic inflammation.