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Updated: Sep 28, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Microglia enhance beta-amyloid peptide-induced toxicity in cortical and mesencephalic neurons by producing reactive
Liya Qin1, Yuxin Liu, Cynthia Cooper
1Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA. qin1@niehs.nih.gov
Abstract:
The purpose of this study was to assess and compare the toxicity of beta-amyloid (Abeta) on primary cortical and mesencephalic neurons cultured with and without microglia in order to determine the mechanism underlying microglia-mediated Abeta-induced neurotoxicity. Incubation of cortical or mesencephalic neuron-enriched and mixed neuron-glia cultures with Abeta(1-42) over the concentration range 0.1-6.0 microm caused concentration-dependent neurotoxicity. High concentrations of Abeta (6.0 microm for cortex and 1.5-2.0 microm for mesencephalon) directly injured neurons in neuron-enriched cultures. In contrast, lower concentrations of Abeta (1.0-3.0 microm for cortex and 0.25-1.0 microm for mesencephalon) caused significant neurotoxicity in mixed neuron-glia cultures, but not in neuron- enriched cultures. Several lines of evidence indicated that microglia mediated the potentiated neurotoxicity of Abeta, including the observations that low concentrations of Abeta activated microglia morphologically in neuron-glia cultures and that addition of microglia to cortical neuron-glia cultures enhanced Abeta-induced neurotoxicity. To search for the mechanism underlying the microglia-mediated effects, several proinflammatory factors were examined in neuron-glia cultures. Low doses of Abeta significantly increased the production of superoxide anions, but not of tumor necrosis factor-alpha, interleukin-1beta or nitric oxide. Catalase and superoxide dismutase significantly protected neurons from Abeta toxicity in the presence of microglia. Inhibition of NADPH oxidase activity by diphenyleneiodonium also prevented Abeta-induced neurotoxicity in neuron-glia mixed cultures. The role of NADPH oxidase-generated superoxide in mediating Abeta-induced neurotoxicity was further substantiated by a study which showed that Abeta caused less of a decrease in dopamine uptake in mesencephalic neuron-glia cultures from NADPH oxidase-deficient mutant mice than in that from wild-type controls. This study demonstrates that one of the mechanisms by which microglia can enhance the neurotoxicity of Abeta is via the production of reactive oxygen species.
Insights
Microglia enhance beta-amyloid (Abeta) neurotoxicity by producing superoxide anions. This reactive oxygen species production is a key mechanism in Abeta-induced neuronal damage, particularly at lower concentrations.
Area of Science:
- Neuroscience
- Immunology
- Toxicology
Background:
- Beta-amyloid (Abeta) is implicated in neurodegenerative diseases.
- The role of microglia in Abeta-induced neurotoxicity is not fully understood.
- Understanding microglia-mediated neurotoxicity is crucial for developing therapeutic strategies.
Purpose of the Study:
- To compare the toxicity of Abeta on primary cortical and mesencephalic neurons.
- To investigate the mechanism underlying microglia-mediated Abeta-induced neurotoxicity.
- To determine the role of reactive oxygen species in this process.
Main Methods:
- Primary cortical and mesencephalic neurons were cultured with and without microglia.
- Abeta(1-42) was applied at various concentrations to assess neurotoxicity.
- Production of proinflammatory factors, including superoxide anions, was measured.
- Enzymatic and chemical inhibitors were used to explore mechanisms.
- Studies were conducted using NADPH oxidase-deficient mutant mice.
Main Results:
- Abeta caused concentration-dependent neurotoxicity in both neuron-enriched and mixed cultures.
- Lower Abeta concentrations were toxic in mixed neuron-glia cultures but not in neuron-enriched cultures, indicating microglia-mediated potentiation.
- Microglia activation and enhanced neurotoxicity were observed with low Abeta doses.
- Superoxide anion production significantly increased with low Abeta doses, while other factors did not.
- Catalase, superoxide dismutase, and NADPH oxidase inhibition protected neurons.
- Abeta caused less dopamine uptake reduction in NADPH oxidase-deficient mice.
Conclusions:
- Microglia significantly potentiate Abeta-induced neurotoxicity.
- NADPH oxidase-generated superoxide anions are a key mechanism mediating this enhanced toxicity.
- Reactive oxygen species produced by microglia contribute to Abeta neurotoxicity.
