Cellular- and systems-level profiling of amyloid-beta effects on circadian timing

Area of Science:

• Neuroscience
• Chronobiology
• Molecular Biology

Background:

• Circadian timing system disruption is an early Alzheimer's disease (AD) hallmark.
• The brain's circadian system has a central pacemaker (SCN) and peripheral clocks.
• Amyloid-beta is a key factor in familial early-onset AD and may disrupt circadian physiology.

Purpose of the Study:

• Investigate how amyloid-beta affects circadian clock timing in the SCN and hippocampus.
• Examine the impact of amyloid-beta on SCN and hippocampal neuronal populations in AD models.

Main Methods:

• Utilized the 5xFAD mouse model for Alzheimer's disease research.
• Performed ex vivo single-cell profiling and circadian profiling of mice.
• Used in vitro SCN slice explant and dispersed SCN culture models.

Main Results:

• 5xFAD mice showed modest changes in SCN rhythm but enhanced light re-entrainment.
• Exogenous amyloid-beta did not significantly affect SCN clock timing in vitro.
• Cultured hippocampal neurons exhibited dose-dependent sensitivity to amyloid-beta, altering rhythm properties.

Conclusions:

• Amyloid-beta differentially affects central (SCN) and peripheral (hippocampal) circadian clocks.
• AD-related circadian disruptions may arise from peripheral oscillator destabilization and SCN decoupling.
• Findings suggest peripheral clock dysregulation contributes to AD pathophysiology.