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Updated: Aug 13, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Potent regulation of microglia-derived oxidative stress and dopaminergic neuron survival: substance P vs. dynorphin
1Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA. Block@niehs.nih.gov
Abstract:
Unregulated microglial activation has been implicated as a pivotal factor contributing to Parkinson's disease. Using mesencephalic neuron-glia cultures, we address the novel possibility that peptides endogenous to the substantia nigra (SN), substance P and dynorphin (10(-13)-10(-14) M), are opposing mediators of microglial activation and consequent DA neurotoxicity. Here, we identify that substance P (10(-13)-10(-14) M) is selectively toxic to DA neurons in a microglia-dependent manner. Mechanistically, substance P (10(-13)-10(-14) M) activated microglial NADPH oxidase to produce extracellular superoxide and intracellular reactive oxygen species (ROS). Neuron-glia cultures from mice lacking a functional NADPH oxidase complex (PHOX-/-) were insensitive to substance P (10(-13)-10(-14) M) -induced loss of DA neuron function. Mixed glia cultures from (PHOX-/-) mice failed to show a significant increase in intracellular ROS in response to substance P compared with control cultures (PHOX+/+). Further, dynorphin (10(-14) M) inhibited substance P (10(-13) M) -induced loss of [3H] DA uptake. Here we demonstrate a tightly regulated mechanism governing microglia-derived oxidative stress, where the neuropeptide balance of dynorphin and substance P is critical to DA neuron survival.
Insights
Substance P triggers microglial activation and dopamine neuron damage in Parkinson's disease models. Dynorphin counteracts this, suggesting neuropeptide balance is key for neuron survival.
Area of Science:
- Neuroscience
- Neuroimmunology
- Cell Biology
Background:
- Microglial activation is central to Parkinson's disease pathogenesis.
- The substantia nigra contains peptides like substance P and dynorphin that may influence neuroinflammation.
Purpose of the Study:
- To investigate the opposing roles of substance P and dynorphin in microglial activation and dopamine neuron toxicity.
- To elucidate the mechanism by which substance P induces neurotoxicity.
Main Methods:
- Primary mesencephalic neuron-glia cultures were utilized.
- Microglial activation and reactive oxygen species (ROS) production were assessed.
- NADPH oxidase (PHOX) knockout mice were used to determine the role of this enzyme.
- Dopamine (DA) neuron function was measured via [3H] DA uptake.
Main Results:
- Substance P (10^-13-10^-14 M) selectively induced microglia-dependent dopamine neuron toxicity.
- Substance P activated microglial NADPH oxidase, leading to superoxide and ROS production.
- Mice lacking functional NADPH oxidase were resistant to substance P-induced DA neuron dysfunction.
- Dynorphin (10^-14 M) inhibited substance P (10^-13 M)-induced loss of [3H] DA uptake.
Conclusions:
- A neuropeptide-mediated mechanism regulates microglia-derived oxidative stress in the substantia nigra.
- The balance between dynorphin and substance P is critical for dopamine neuron survival in Parkinson's disease contexts.
