Sleep/Wake Disruption in a Mouse Model of BLOC-1 Deficiency.

Area of Science:

• Neuroscience
• Chronobiology
• Genetics

Background:

• Intellectual and developmental disabilities are associated with cognitive and behavioral impairments, including sleep disturbances.
• The underlying mechanisms, particularly the role of the circadian timing system, remain unclear.

Purpose of the Study:

• To investigate sleep/circadian malfunctions and their mechanisms in Biogenesis of Lysosome-related Organelles Complex 1 (BLOC-1)-deficient pallid mice.
• To explore the impact of BLOC-1 deficiency on the central circadian clock (suprachiasmatic nucleus) and hippocampus.

Main Methods:

• Behavioral analysis of sleep patterns and activity rhythms in pallid mice under light-dark conditions.
• Assessment of anxiety-like behavior (elevated plus maze) and cognitive function (novel object recognition).
• Morphological and molecular analysis of the suprachiasmatic nucleus (SCN) and hippocampus, including clock gene expression (Per2) and protein levels (pCREB/tCREB).

Main Results:

• BLOC-1 deficient mice exhibited reduced sleep, fragmented sleep patterns, and weakened activity rhythms.
• Pallid mice showed altered anxiety-like behavior and impaired novel object recognition performance.
• Loss of BLOC-1 led to SCN enlargement, increased daytime PER2 levels, but normal neuronal activity rhythms. Hippocampal alterations included Dentate Gyrus cytoarchitecture anomalies, altered PER2, and reduced pCREB/tCREB ratio.

Conclusions:

• Lack of BLOC-1 in mice disrupts the sleep/wake cycle and behavioral test performance.
• These disruptions are associated with specific alterations in brain cytoarchitecture and protein expression, particularly in the hippocampus.
• The findings suggest a role for BLOC-1 in regulating sleep and cognitive functions via central circadian and hippocampal pathways.