Interleukin-1beta Has a Role in Cerebral Cortical State-dependent Electroencephalographic Slow-wave Activity

Study Objectives: To investigate the hypothesis that interleukin (IL)-1beta is involved in mediating localized electroencephalogram synchronization.

Design: We evaluated bilateral cortical electroencephalograms after unilateral local application of IL-1beta onto the somatosensory cortex of rats. Furthermore, we investigated the effects of unilateral application of an IL-1beta 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-1beta or the IL-1 soluble receptor affected the duration of non-rapid eye movement sleep or rapid eye movement sleep. Unilateral application of IL-1beta 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-1beta (10- and 50-ng doses). Electroencephalographic power in the higher frequencies was not affected by IL-1beta in any state. Unilateral application of the IL-1 soluble receptor (0.1, 1.0 and 5.0 microg) had no effect on the spontaneous sleep electroencephalogram. In contrast, unilateral application of the IL-1 soluble receptor (5.0 microg) attenuated sleep deprivation-enhanced electroencephalographic slow-wave power ipsilaterally during non-rapid eye movement sleep.

Conclusions: Results suggest that IL-1beta can induce state-dependent localized increases of electroencephalographic delta wave power, suggesting an enhancement of sleep intensity within the cortex.