Inhibitory interneuron deficit links altered network activity and cognitive dysfunction in Alzheimer model

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Alzheimer's disease (AD) is characterized by cognitive decline and altered brain network activity.
• The underlying mechanisms driving these network changes in AD remain largely unknown.
• Human amyloid precursor protein (hAPP) transgenic mice serve as a model to study AD-related pathology.

Purpose of the Study:

• To investigate the role of network dysfunction and parvalbumin (PV) cells in Alzheimer's disease pathogenesis.
• To examine the contribution of the voltage-gated sodium channel subunit Nav1.1 to PV cell function in AD.
• To determine if restoring Nav1.1 levels can alleviate AD-like symptoms in a mouse model.

Main Methods:

• Electroencephalographic (EEG) recordings were performed in hAPP transgenic mice.
• Levels of Nav1.1, a sodium channel subunit, were measured in hAPP mice and human AD patients.
• Nav1.1 expression was restored in hAPP mice using Nav1.1-BAC to assess functional recovery.

Main Results:

• hAPP mice exhibited spontaneous epileptiform discharges and reduced gamma oscillations, indicative of network hypersynchrony.
• Decreased levels of Nav1.1 were observed in both hAPP mice and AD patients, particularly in PV cells.
• Restoration of Nav1.1 in hAPP mice normalized inhibitory synaptic activity, gamma oscillations, and reduced hypersynchrony, memory deficits, and mortality.

Conclusions:

• Reduced Nav1.1 levels and subsequent PV cell dysfunction are critical contributors to aberrant network activity in AD.
• Impaired PV cell function and network synchrony correlate with memory deficits and mortality in AD models.
• Targeting Nav1.1 may offer a therapeutic strategy for Alzheimer's disease.