Interleukin-1β has a role in cerebral cortical state-dependent electroencephalographic slow-wave activity

Abstract

Study Objectives: To investigate the hypothesis that interleukin (IL)-1β is involved in mediating localized electroencephalogram synchronization. Design: We evaluated bilateral cortical electroencephalograms after unilateral local application of IL-1β onto the somatosensory cortex of rats. Furthermore, we investigated the effects of unilateral application of an IL-1β inhibitor, the IL-1 soluble receptor, on spontaneous sleep and sleep rebound after sleep deprivation. Setting: University research laboratory. Interventions: N/A. Participants: Rats Measurements and Results: Neither dose of IL-1β or the IL-1 soluble receptor affected the duration of non-rapid eye movement sleep or rapid eye movement sleep. Unilateral application of IL-1β induced state- and frequency-dependent electroencephalogram asymmetries. During non-rapid eye movement sleep, but not during other states, electroencephalographic slow-wave activity was greater on the side that received IL-1β (10- and 50-ng doses). Electroencephalographic power in the higher frequencies was not affected by IL-1β in any state. Unilateral application of the IL-1 soluble receptor (0.1, 1.0 and 5.0 μg) had no effect on the spontaneous sleep electroencephalogram. In contrast, unilateral application of the IL-1 soluble receptor (5.0 μg) attenuated sleep deprivation-enhanced electroencephalographic slow-wave power ipsilaterally during non-rapid eye movement sleep. Conclusions: Results suggest that IL-1β can induce state-dependent localized increases of electroencephalographic delta wave power, suggesting an enhancement of sleep intensity within the cortex.