Giant Glial Cell: New Insight Through Mechanism-Based Modeling
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The paper describes a detailed mechanism-based model of a tripartite synapse consisting of P- and R-neurons together with a giant glial cell in the ganglia of the medical leech (Hirudo medicinalis), which is a useful object for experimental studies in situ. We describe the two main pathways of the glial cell activation: (1) via IP3 production and Ca2 + release from the endoplasmic reticulum and (2) via increase of the extracellular potassium concentration, glia depolarization, and opening of voltage-dependent Ca2 + channels. We suggest that the second pathway is the more significant for establishing the positive feedback in glutamate release that is critical for the self-sustained activity of the postsynaptic neuron. This mechanism differs from the mechanisms of the astrocyte-neuron signaling previously reported.
KeywordsTripartite synapse Glia Neuron Modeling
This work was partly supported by the European Union through the Network of Excellence BioSim (contract no. LSHB-CT-2004-005137). N. B. and A. B. acknowledge support from Lundbeck foundation. O. S. acknowledges support from Forskningsrådet for Natur og Univers (Skou stipendium). We are grateful to Ljudmila Erokhova for useful discussions.
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