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Updated: Oct 23, 2026
Primary Microglia Isolation from Mixed Glial Cell Cultures of Neonatal Rat Brain Tissue
Published on: August 15, 2012
Role of protein kinase C in microglia-induced neurotoxicity in mesencephalic cultures
M K McMillian1, P J Vainio, R K Tuominen
1Department of Pharmacology and Toxicology, Institute of Biomedicine, University of Helsinki, Finland.
Abstract:
Microglial activation selectively kills certain neuron populations in mixed neuronal/glial cultures, which may prove useful for modeling neurodegenerative diseases such as Parkinson's disease. In mesencephalic mixed neuronal/glial cultures, microglial activation by zymosan A killed more dopaminergic neurons, assessed by [3H]dopamine uptake and by counting tyrosine hydroxylase-immunoreactive neuron number, than did microglial activation by lipopolysaccharide (LPS). The additional toxicity of zymosan resulted from microglial protein kinase C (PKC) activation. Both zymosan and PMA, but not LPS, activated PKC in enriched microglial preparations. In the mixed neuronal/glial cultures, activation of PKC by phorbol myristate acetate (PMA) increased LPS-induced nitric oxide (NO; by nitrite measurements), but not zymosan-induced NO production, and increased LPS-induced dopaminergic neurotoxicity, but not zymosan-induced dopaminergic neurotoxicity. Additive effects of PMA and LPS, similar to zymosan effects alone, reflected activation of distinct neurotoxic pathways in the microglia. The NO synthase inhibitor N-nitro-L-arginine methyl ester (NAME) totally blocked the neurotoxicity of LPS, and partially blocked zymosan-induced neurotoxicity; NAME did not block the PKC component of neurotoxicity. In addition to stimulating NO production as effectively as LPS, zymosan also activates microglial PKC and associated non-NO-mediated neurotoxic pathways that may be important in human neurodegenerative diseases. Since the role of NO in human microglia-induced neurotoxicity is controversial, zymosan may prove more useful than LPS as a microglial activator in the rodent mixed neuronal/glial culture model.
Insights
Zymosan A activates microglial protein kinase C (PKC), causing greater dopaminergic neurotoxicity than lipopolysaccharide (LPS). This zymosan-induced neurotoxicity involves non-nitric oxide (NO) pathways, making it a potentially better model for neurodegenerative diseases.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglial activation plays a role in neurodegenerative diseases.
- Modeling neurodegenerative diseases requires understanding microglial-neuron interactions.
- Lipopolysaccharide (LPS) is a common activator of microglia.
Purpose of the Study:
- To compare the neurotoxic effects of zymosan A and LPS on dopaminergic neurons.
- To investigate the role of protein kinase C (PKC) and nitric oxide (NO) in zymosan- and LPS-induced neurotoxicity.
- To evaluate zymosan A as a potential activator for modeling neurodegenerative diseases.
Main Methods:
- Primary mesencephalic mixed neuronal/glial cultures were used.
- Microglial activation was induced by zymosan A or LPS.
- Neurotoxicity was assessed by [3H]dopamine uptake and tyrosine hydroxylase-immunoreactive neuron counting.
- Protein kinase C (PKC) activation was measured.
- Nitric oxide (NO) production was assessed by nitrite measurements.
- The effect of NO synthase inhibitor N-nitro-L-arginine methyl ester (NAME) was evaluated.
Main Results:
- Zymosan A induced greater dopaminergic neurotoxicity than LPS.
- Zymosan A's additional toxicity was mediated by microglial PKC activation.
- Both zymosan A and phorbol myristate acetate (PMA) activated PKC, unlike LPS.
- PMA enhanced LPS-induced NO production and neurotoxicity, but not zymosan-induced effects.
- NO synthase inhibition partially blocked zymosan-induced neurotoxicity but not the PKC component.
- Zymosan A activates both NO-dependent and non-NO-mediated neurotoxic pathways.
Conclusions:
- Zymosan A is a more potent activator of dopaminergic neurotoxicity than LPS in mixed cultures.
- Microglial PKC activation contributes to zymosan A-induced neurotoxicity via non-NO pathways.
- Zymosan A may be a more suitable activator than LPS for modeling neurodegenerative diseases due to its distinct neurotoxic mechanisms.
