Dim Light at Night Dysregulates Immune Function and Exacerbates Stroke Outcome

Jacob Payne*, Jennifer A. Liu, Jacob R. Bumgarner, William H. Walker II, O. Hecmarie Meléndez-Fernández, Ning Zhang, James C. Walton, A. Courtney DeVries, and Randy J. Nelson

Department of Neuroscience, West Virginia University, Morgantown, WV, 26505

Presentation Category: Biological & Biochemical Sciences (Poster Presentation #103)

Student’s Major: Biology

Circadian rhythms are endogenous physiological processes that have evolved, synchronizing physiology and behavior to exogenous environmental light cues such as light, to optimize function and survival. Disruption of circadian rhythms through exposure to lighting during the incorrect phase has been linked to several negative outcomes including increased neuroinflammation and altered immune function. Previous work in our lab has demonstrated that exposure to dim light at night (dLAN) increased mortality and neuronal damage following stroke, thus, aimed to investigate how exposure to dim light at night affects acute immune activation post stroke. We hypothesized that exposure to dLAN accelerates infarct progression via dysregulated gene expression related to immune activation. Male CFW mice received a right middle cerebral artery occlusion (MCAO) and were returned to normal light dark conditions (LD) or dLAN (5 lux). 24 hours post stroke, mice were collected for infarct size, determined through 2,3,5-Triphenyltetrazolium chloride (TTC) staining and found that mice in dim light at night had increased infarct sizes compared to LD. A second cohort of mice was collected after the night phase 12 hours post stroke and was assessed for neurological deficits, then the ipsilateral and contralateral hemisphere of the brain was collected for RNA sequencing. We observed that acute exposure to 12 hours of dLAN increased general deficit scores and spleen weights. These findings play a vital role in increasing our understanding of circadian rhythm disruption and its impact on stroke recovery and highlight the importance of reducing circadian disruption during cerebrovascular dysfunction.

Funding: NIH

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course