Tumor necrosis factor receptor fragment attenuates interferon-gamma-induced non-REM sleep in rabbits

Although the somnogenic actions of interferon-alpha (IFNalpha) and IFNbeta have been reported, the sleep effects of IFNgamma remained unknown. Thus, we investigated the effects of intracerebroventricular injection of human IFNgamma on sleep in rabbits. IFNgamma dose-dependently increased nonrapid eye movement sleep (NREMS), electroencephalographic slow wave activity and brain temperature (Tbr). These effects were markedly attenuated after the heat treatment of IFNgamma. IFNgamma suppressed rapid eye movement sleep if given during the light period, but not if given at dark onset. Although a tumor necrosis factor receptor fragment did not affect any sleep parameters when given at dark onset, it significantly attenuated IFNgamma-induced NREMS and Tbr. These data suggest that IFNgamma may be involved in the sleep responses during infection. Further, IFNgamma may have a synergistic interaction with intrinsic TNFalpha in the brain.