Bimbiryte, D. | Search bioRxiv

bioRxiv2024

Pharmacological enhancement of slow-wave activity improves cognition and reduces amyloidosis at an early stage in a mouse model of Alzheimer's disease

Improving sleep in murine Alzheimers disease (AD) is associated with reduced brain amyloidosis. However, the window of opportunity for successful sleep-targeted interventions regarding reduction of pathological hallmarks and related cognitive performance remains poorly characterized. Here, we enhanced slow-wave activity (SWA) during sleep via sodium oxybate (SO) oral administration for 2 weeks at early (6 months old) or moderately late (11 months old) disease stages in Tg2576 mice, and evaluated resulting neuropathology and behavioral performance. We observed that cognitive performance of 6 months old Tg2576 mice significantly improved upon SO treatment, whereas no change was observed in 11 months old mice. Histochemical assessment of amyloid plaques demonstrated that SO-treated 11 months old Tg2576 mice had significantly less plaque burden than placebo-treated ones, whereas ELISA of insoluble protein fractions from 6 months old Tg2576 mice brains indicated lower A{beta}-42/A{beta}-40 ratio in SO-treated group vs. placebo-treated controls. Altogether, our results suggest that SWA-dependent reduction of brain amyloidosis leads to alleviated behavioral impairment in Tg2576 mice only if administered early in the disease course, potentially highlighting the key importance of early sleep-based interventions in clinical cohorts. Significance statementA staggering amount of people worldwide live with AD. Despite extensive efforts from academy and industry, no cure is available to date. Sleep may be a modifiable factor involved in onset, progression and potentially also treatment of AD. However, knowledge regarding important aspects of sleep-targeted treatments is missing, e.g. adequate window of opportunity for their efficacious application, their minimal duration or their effect onto both pathology and cognition. We found that pharmacologically enhanced sleep depth is associated with reduced amyloid neuropathology in AD mice brains at both early- and moderately advanced-stage disease. However, only early-stage disease mice significantly benefited from sleep-enhancing treatment. Our results strongly encourage further mechanistic research and the launch of larger scale preclinical investigations in early AD populations.

neuroscience↗

bioRxiv2021

Natural age-related sleep-wake alterations onset prematurely in the Tg2576 mouse model of Alzheimer disease

Sleep insufficiency or decreased quality have been associated with Alzheimers disease (AD) already in its preclinical stages. Whether such traits are also present in rodent models of the disease has been poorly addressed, somewhat disabling the preclinical exploration of sleep-based therapeutic interventions for AD. We investigated age-dependent sleep-wake phenotype of a widely used mouse model of AD, the Tg2576 line. We implanted electroencephalography/ electromyography headpieces into 6 months old (plaque-free, n=10) and 11 months old (moderate plaque-burdened, n=10) Tg2576 and age-matched wild-type (WT) mice and recorded vigilance states for 24 hours. Tg2576 mice exhibited significantly increased wakefulness and decreased non-rapid eye movement sleep over a 24-hour period compared to WT mice at 6, but not at 11 months of age. Concomitantly, delta power appeared decreased in 6-month old Tg2576 mice in comparison to age-matched WT controls, yielding a reduced slow-wave energy phenotype in the young mutants. Lack of genotype-related differences over 24 hours in overall sleep-wake phenotype at 11 months of age appears to be the result of the natural aging of WT mice. Therefore, our results indicate that at plaque-free stages of the disease, diminished sleep quality is present in Tg2576 mice which resembles aged healthy controls, suggesting an early-onset of sleep-wake deterioration in murine AD. Whether such disturbances in the natural patterns of sleep could in turn worsen disease progression warrants further exploration.

neuroscience↗