Pathological substrate of memory impairment in multiple system atrophy.

Area of Science:

• Neuroscience
• Pathology
• Molecular Biology

Background:

• Synaptic dysfunction in Parkinson's disease (PD) stems from alpha-synuclein propagation.
• Multiple system atrophy (MSA) involves abnormal alpha-synuclein in oligodendrocytes and is linked to memory impairment.
• Previous work associated memory deficits in MSA with hippocampal alpha-synuclein-positive neuronal cytoplasmic inclusions (NCIs).

Purpose of the Study:

• To investigate the mechanism by which abnormal alpha-synuclein in the hippocampus leads to memory impairment in MSA.
• To explore the role of alpha-synuclein oligomers in hippocampal synaptic dysfunction and memory deficits in MSA.

Main Methods:

• Pathological and biochemical analyses were conducted on a mouse model of adult-onset MSA and human MSA, PD, Alzheimer's disease, and control brain tissues.
• Behavioral and physiological assessments were performed on the MSA mouse model.
• Quantification of NCIs, alpha-synuclein oligomers, and dendritic spine density, along with electrophysiological recordings (long-term potentiation), were utilized.

Main Results:

• In the MSA model, alpha-synuclein expression in oligodendrocytes preceded accumulation in hippocampal neurons (NCIs) and memory impairment.
• Increased alpha-synuclein oligomers and decreased dendritic spine density were observed in the hippocampus of MSA model mice, correlating with impaired long-term potentiation.
• Human MSA cases with memory impairment exhibited more hippocampal NCIs and alpha-synuclein oligomers compared to those without.

Conclusions:

• Alpha-synuclein oligomers accumulating in hippocampal excitatory neurons are implicated as a pathological cause of memory impairment in MSA.
• These findings highlight a potential therapeutic target for memory dysfunction in MSA.