The Effect of Traumatic Brain Injury on Sleep Architecture and Circadian Rhythms in Mice—A Comparison of High-Frequency Head Impact and Controlled Cortical Injury

Abstract

Traumatic brain injury (TBI) is a significant risk factor for the development of sleep and circadian rhythm impairments. In this study we compare the circadian rhythms and sleep patterns in the high-frequency head impact (HFHI) and controlled cortical impact (CCI) mouse models of TBI. These mouse models have different injury mechanisms key differences of pathology in brain regions controlling circadian rhythms and EEG wave generation. We found that both HFHI and CCI caused dysregulation in the diurnal expression of core circadian genes (Bmal1, Clock, Per1,2, Cry1,2) at 24 h post-TBI. CCI mice had reduced locomotor activity on running wheels in the first 7 d post-TBI; however, both CCI and HFHI mice were able to maintain circadian behavior cycles even in the absence of light cues. We used implantable EEG to measure sleep cycles and brain activity and found that there were no differences in the time spent awake, in NREM or REM sleep in either TBI model. However, in the sleep states, CCI mice have reduced delta power in NREM sleep and reduced theta power in REM sleep at 7 d post-TBI. Our data reveal that different types of brain trauma can result in distinct patterns of circadian and sleep disruptions and can be used to better understand the etiology of sleep disorders after TBI.

Persistent Hypersomnia Following Repetitive Mild Experimental Traumatic Brain Injury: Roles of Chronic Stress and Sex Differences

“…More detailed analysis of the sleep-wake architecture using EEG/EMG may inform interpretation of the hypersomnia observed. For example, analysis of sleep-wake microarchitecture can detect differences in the power of delta and theta frequency bands which identified effects of controlled cortical impact TBI in male mice [41]. Furthermore, our experiments compared the effects using two TBI models and showed that the sleep effects did not require rotational force or even head injury, so the TBI pathology was not a focus in the current study.…”

Sequential Isolation of Microglia and Astrocytes from Young and Aged Adult Mouse Brains for Downstream Transcriptomic Analysis

“…In addition, we pass the Cd11b + cell homogenate through the MS filter columns twice before the elution of positively selected cells. We believe this step is critical to increase the purity and yield of Cd11b + microglial cells selected, especially given our preparations are from a relatively small starting amount of tissue (singular micro punch <50 mg, as would be used in traumatic brain injury models of ipsilateral injury [ 34 ]).…”

Persistent hypersomnia following repetitive mild experimental traumatic brain injury: Roles of chronic stress and sex differences

“…More detailed analysis of the sleep–wake architecture, including REM and non‐REM phases using EEG/EMG, may support a more detailed interpretation of the sleep–wake dysfunction. For example, analysis of sleep microarchitecture can detect differences in the power of delta and theta frequency bands which identified effects of controlled cortical impact TBI in male mice (Korthas et al, 2022). Furthermore, our experiments showed that the sleep effects did not require rotational force, and could result from UCMS without head injury.…”