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Senile plaques stimulate microglia to release a neurotoxin found in Alzheimer brain
D Giulian1, L J Haverkamp, J Li
1Department of Neurology, Baylor College of Medicine, Houston, Texas, USA.
Abstract:
Senile plaques found in the brains of patients with Alzheimer's disease (AD) are surrounded by clusters of reactive microglia. Isolated human microglia placed in contact with plaques in vitro are activated to release a factor which is toxic to neurons. This same neurotoxin is found in AD brain tissue and causes damage to pyramidal neurons in vivo when infused into rat hippocampus. Highest concentrations of the neurotoxin are in those brain structures most burdened by reactive microglia, suggesting that plaque-activated cells contribute to the neuronal damage and impaired cognition seen in patients with Alzheimer's dementia.
Insights
Microglia surrounding amyloid plaques in Alzheimer's disease (AD) release a neurotoxin. This toxin, found in AD brains, damages neurons and contributes to cognitive decline in dementia.
Area of Science:
- Neuroscience
- Neuropathology
- Immunology
Background:
- Alzheimer's disease (AD) brains exhibit senile plaques surrounded by reactive microglia.
- Microglia activation near plaques suggests a role in neurodegeneration.
Purpose of the Study:
- To investigate the neurotoxic potential of plaque-activated microglia in Alzheimer's disease.
- To identify the source and impact of neurotoxins in AD neuropathology.
Main Methods:
- In vitro activation of human microglia with amyloid plaques.
- Detection of neurotoxin in AD brain tissue and in vitro cultures.
- In vivo infusion of neurotoxin into rat hippocampus.
Main Results:
- Activated microglia release a neurotoxin toxic to neurons in vitro.
- The same neurotoxin is present in Alzheimer's disease brain tissue.
- Neurotoxin infusion into rat hippocampus caused pyramidal neuron damage.
Conclusions:
- Plaque-activated microglia contribute to neuronal damage in Alzheimer's disease.
- The identified neurotoxin is implicated in the cognitive impairment associated with AD dementia.