22-Neuron-glia_interaction - Neuron-Glia Interaction Part I...

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Neuron-Glia Interaction Part I
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Neuron-Glial Network Neuron Oligodendrocyte Myelination on axon fiber Astrocyte Blood vessel Microglia Axon terminal Spine
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Neuron-Glial Association Neuronal axons are mostly covered by glial cells, a phenomenon called myelination In peripheral nervous system, axon-associated glial cells are Schwann cells . They are mostly derived from neural crest cells. In central nervous system, axon-associated glias include oligodendrocytes and astrocytes , which originate from progenitor cells in the ventricular zone of the neural tube. Axons and glia develop together during maturation of nervous system, and influence each other’s phenotype and possibly survival throughout life.
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Glial Functions 1. Promote survival and differentiation of neurons 2. Guide axons to target areas 3. Axonal myelination by glial cells speeds action potential propagation—Nodes of Ranvier 4. Astrocytes express ligand-gated receptors, including glutamate and GABA receptors to detect neurotransmission. 5. Astrocytes are electrically coupled by gap junctions, which may contribute to long-range information processing in the brain 6. Participate in the brain-blood-barriers to protect neurons from chemical fluctuations in the blood. 7. Absorb excess K + ions and neurotransmitters such as glutamate to reduce excitotoxicity. 8. Control the entry of inflammatory cells into the CNS to minimize inflammation. 9. Facilitate synapse formation. 10. Following injury, help axon regeneration. 11. Glial cells do not fire action potentials —they don’t have many voltage-dependent sodium channels. 12. Take part in tripartite synapse. Modulate synaptic neurotransmission. 13. Release ATP and glutamate for neuromodulation.
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Glial Fate: G lial G rowth F actor in PNS If a crest cell migrating to an environment with GGF, it will develop into a glial cell GGF is critical in promoting crest cell to adopt glial fate. GGF is a member of EGF/TGF- α family of ligands. Mostly Schwann cells
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Glial Fate: Oligodendrocyte in CNS Oligodendrocyte is critical for central neuron myelination . Platelet-derived growth factor (PDGF) is important for the differentiation of oligodendrocytes from progenitor cells. PDGF KO: die shortly after birth, CNS demyelination, spinal cord only 10% normal O-2A progenitor cells. Neuron-derived PDGF, neuregulin, axon activity, all affects oligodendrocyte differentiation. Axon myelination is precise in timing during development, suggesting oligodendrocyte differentiation under rigorous control.
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This note was uploaded on 08/26/2011 for the course BIOL 426 taught by Professor Profgongchen during the Spring '08 term at Pennsylvania State University, University Park.

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22-Neuron-glia_interaction - Neuron-Glia Interaction Part I...

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