Aβ Accumulation in Vmo Contributes to Masticatory Dysfunction in 5XFAD Mice

Area of Science:

• Neuroscience
• Pathology
• Animal Models

Background:

• Alzheimer's disease (AD) is characterized by cognitive decline and neural circuit disruption.
• Sensory dysfunctions are recognized early indicators of AD.
• The link between AD and the masticatory system remains unclear, particularly in animal models.

Purpose of the Study:

• To investigate the pathological hallmarks of AD and their impact on masticatory behavior in 5XFAD mice.
• To establish changes in the masticatory system associated with AD progression.

Main Methods:

• Assessment of masticatory efficiency and biting force in 5XFAD mice.
• Evaluation of general motor function.
• Immunohistochemical analysis of the trigeminal motor nucleus (Vmo) and other cranial motor nuclei for amyloid-beta (Aβ) deposition, microglia activation, and cell death.
• Measurement of masseter muscle weight and muscle fiber size.

Main Results:

• 5XFAD mice exhibited decreased masticatory efficiency and maximum biting force.
• No significant changes in general motor function were observed.
• Significant Aβ accumulation, increased microglia, and cell death were found in the Vmo of 5XFAD mice.
• Reduced masseter muscle weight and muscle fiber size were noted in 5XFAD mice.

Conclusions:

• Amyloid-beta accumulation in the Vmo contributes to masticatory dysfunction in 5XFAD mice.
• These findings suggest a strong association between masticatory dysfunction and dementia in Alzheimer's disease.