Biology subjects

Egebjerg, C.

Publications and source records attributed to Egebjerg, C..

4 recordsLinked to original sources

bioRxiv2026

Cell-type targeted CRISPR/Cas9 Clock knockdown in mouse VTA dopamine neurons alter sleep, behavior, and cellular excitability

Bipolar disorder (BD) is a severe psychiatric disease characterized by recurrent mania, depression, and circadian rhythm disruption. Among circadian regulators implicated in mood-related dysfunction, Clock has emerged as a particularly strong mechanistic candidate. However, cell type-specific functions of Clock within mood-relevant circuits remain incompletely defined. Here, we developed and applied a Cre-dependent AAV-SaCas9 gene-editing strategy to disrupt Clock selectively in ventral tegmental area dopamine neurons. We first established a rapid in vitro screening pipeline for guide RNA selection that accurately predicted in vivo editing efficiency. We then targeted Clock in vivo using a single AAV-based editing strategy and observed robust titer-dependent reduction of Clock expression, by targeted sequencing, in situ hybridization, and immunohistochemistry. We assessed the functional consequences of Clock disruption across analysis levels, including a behavioral battery, circadian and sleep-wake measurements using EEG and EMG, and electrophysiological recordings. These results establish a practical framework for rapid, cell-type-specific disruption of candidate psychiatric risk genes and provide a mechanistically grounded model for investigating how loss of Clock function in mesolimbic dopaminergic circuits contributes to BD-relevant phenotypes.

neuroscience↗

bioRxiv2026

Lack of Consensus for Manual Mouse Sleep Scoring Limits Implementation of Automatic Deep Learning Models

Scientists have for decades attempted to automate the manual sleep staging problem not only for human polysomnography data but also for rodent data. No model has, however, succeeded in fully replacing the manual procedure across clinics and laboratories. We hypothesize that this is due to the models limited ability to generalize to data from unseen laboratories. Our findings show that despite the high performance of four state-of-the-art models reported in initial publications, the published models struggle to generalize to other laboratories. We further show a significant improvement in model performance across labs by re-training them on a diverse dataset from five different sites. To assess the contribution of variability in manual scoring, ten experts from five laboratories all labelled the same nine mouse sleep recordings. The result revealed substantial scoring variability, particularly for rapid eye movement (REM) sleep, both within and between labs. In conclusion our study demonstrates that key challenges in the generalizability of state-of-the-art sleep scoring models are signal variability and label noise. Our study highlights the need for a standardized set of mouse sleep scoring guidelines to enable consistency and collaboration across the field. Until such a consensus is reached, we present four sufficiently robust models trained on diverse datasets that can serve as standardized tools across labs.

neuroscience↗

bioRxiv2024

A sleep disturbance method by novel objects in the home cage to minimize stress

BackgroundThe increasing prevalence of low sleep quality is a significant issue, particularly among adolescents, necessitating a deeper understanding of its biological consequences. In sleep research, various protocols are used for sleep deprivation or disturbance, each presenting its own set of confounding factors crucial to consider. New MethodWe developed a standardized seven-day sleep disturbance (SD) protocol using daily four-hour exposures to novel objects to minimize rodent stress. Objects were selected and characterized for wake-promoting properties, and exposure timing was structured to reduce variability and enhance experimental reliability and reproducibility. ResultsDuring the four hours of SD, the mice were efficiently sleep-deprived on the first and seventh day of SD. Thus, the selected objects efficiently sleep restricted the mice. On the first day of SD, the protocol induced sleep deprivation effect when measured over 24h, but by the seventh day, the mice recovered the sleep loss. Thus, this method is a sub-chronic sleep disturbance and not sleep deprivation. Fecal corticosterone concentrations remained unchanged during the seven days of SD. Comparison with existing methodsThis approach reduced the risk of stress through voluntary rather than forced wakefulness. Previously, novel objects have been exchanged randomly during mouse sleep initiation causing protocol variability and very frequent disturbances. Our protocol minimizes this by introducing the novel object in a structured manner. ConclusionWe effectively disturbed the sleep of the mice during seven days without inflicting substantial stress. We further demonstrate the value of validating the efficiency of an SD protocol with 24h recordings. HighlightsO_LIStandardized sleep disruption method by object exposure in mice C_LIO_LIMice are sleep-restricted during the four-hour SD intervention all 7 days C_LIO_LIMice habituate to a subchronic sleep deprivation setup by recovering sleep outside of the SD period C_LIO_LIFecal corticosterone samples showed no difference before and after SD intervention C_LI

neuroscience↗

bioRxiv2023

Molecular Consequences of Peripheral Influenza A Infection on Cell Populations in the Murine Hypothalamus

Infection with Influenza A virus (IAV) causes the well-known symptoms of the flu, including fever, loss of appetite and excessive sleepiness. These responses, mediated by the brain, will normally disappear once the virus is cleared from the system, but a severe respiratory virus infection may cause long-lasting neurological disturbances. These include encephalitis lethargica and narcolepsy. The mechanisms behind such long lasting changes are unknown. The hypothalamus is a central regulator of the homeostatic response during a viral challenge. To gain insight into the neuronal and non-neuronal molecular changes during an IAV infection, we intranasally infected mice with an H1N1 virus and extracted the brain at different time points. Using single-nucleus RNA sequencing (snRNA-seq) of the hypothalamus, we identify transcriptional effects in all identified cell populations. The snRNA-seq data showed the most pronounced transcriptional response at 3 days past infection, with a strong downregulation of genes across all cell types. General immune processes were mainly impacted in microglia, the brain resident immune cells, where we found increased numbers of cells expressing pro-inflammatory gene networks. In addition, we found that most neuronal cell populations downregulated genes contributing to the energy homeostasis in mitochondria and protein translation in the cytosol, indicating potential reduced cellular and neuronal activity. This might be a preventive mechanism in neuronal cells to avoid intracellular viral replication and attack by phagocytosing cells. The change of microglia gene activity suggest that this is complemented by a shift in microglia activity to provide increased surveillance of their surroundings.

neuroscience↗