Somnogenic relationships between tumor necrosis factor and interleukin-1

Both tumor necrosis factor (TNF) and interleukin (IL)-1 are somnogenic cyto kines. They also induce each other's production and both induce nuclear fac tor kappa B activation, which in turn enhances IL-1 and TNF transcription. We hypothesized that TNF and IL-1 could influence each other's somnogenic a ctions. To test this hypothesis, we determined the effects of blocking bath endogenous TNF and IL-1 on spontaneous sleep and on sleep rebound after sl eep deprivation in rabbits. Furthermore, the effects of inhibition of TNF o n IL-1-induced sleep and the effects of blocking IL-1 on TNF-induced sleep were determined. A TNF receptor fragment (TNFRF), as a TNF inhibitor, and a n IL-1 receptor fragment (IL-1RF), as an IL-1 inhibitor, were used. Intrace rebroventricular injection of a combination of the TNFRF plus the IL-1RF si gnificantly reduced spontaneous non-rapid eye movement sleep by 87 min over a 22-h recording period. Pretreatment of rabbits with the combination of T NFRF and IL-1RF also significantly attenuated sleep rebound after sleep dep rivation. Furthermore, the TNFRF significantly attenuated IL-1-induced slee p but not fever. Finally, the IL-1RF blacked TNF-induced sleep responses bu t not fever. Results indicate that TNF and IL-1 cooperate to regulate physi ological sleep.