Basic Science and Pathogenesis

Area of Science:

• Neuroscience
• Neurodegenerative Diseases

Background:

• Alzheimer's disease (AD) involves amyloid plaque accumulation, leading to neuronal dysfunction and cognitive impairment.
• An imbalance between excitatory and inhibitory activity, specifically increased somatostatin (SOM) interneuron activity near plaques, is observed in AD mouse models.
• This study investigates targeting SOM interneurons to restore neural balance and improve memory in AD.

Purpose of the Study:

• To determine if inhibiting SOM interneurons can restore excitatory neuron activity and ameliorate memory deficits in Alzheimer's disease (AD) mouse models.
• To evaluate the efficacy of acute and chronic chemogenetic inhibition of SOM interneurons.

Main Methods:

• In vivo calcium imaging was used to assess neuronal activity in APP and wild-type (WT) mice.
• Acute and chronic chemogenetic approaches were employed to inhibit SOM interneurons in APP/PS1 and WT mice.
• Behavioral tests assessed locomotion, working memory, and fear memory after chronic inhibition.

Main Results:

• Calcium imaging confirmed an excitation-inhibition (E/I) imbalance in awake APP mice, with increased SOM and decreased excitatory neuron activity.
• Acute chemogenetic inhibition of SOM interneurons successfully enhanced excitatory neuron activity in APP/PS1 mice.
• Chronic, brain-wide inhibition of SOM interneurons did not significantly improve locomotor activity or memory consolidation in APP/PS1 mice.

Conclusions:

• Acute inhibition of SOM interneurons can transiently restore excitatory neuron activity in an AD model.
• Chronic, brain-wide inhibition of SOM interneurons is not sufficient to rescue cognitive deficits in APP/PS1 mice under these conditions.