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Striatal cholinergic interneurons express a receptor-insensitive homomeric TASK-3-like background K+ current
Allison P Berg1, Douglas A Bayliss
1Department of Pharmacology, 5015 Jordan Hall, University of Virginia, Charlottesville, VA 22908, USA. apb6w@virginia.edu
Journal of Neurophysiology
|December 15, 2006
Summary
Large aspiny cholinergic interneurons utilize TASK-3 channels for essential leak potassium currents, influencing basal ganglia function. These neurons express TASK-3, but receptor modulation appears cell-context dependent.
Area of Science:
- Neuroscience
- Molecular Biology
- Ion Channel Physiology
Background:
- Cholinergic interneurons in the striatum are vital for basal ganglia function, relying on acetylcholine.
- Their firing patterns are influenced by voltage-dependent ion channels and leak conductances, particularly potassium (K+) channels.
- Leak K+ channels are crucial for setting the resting membrane potential in these neurons.
Purpose of the Study:
- To investigate the contribution of TASK-3 subunits to leak K+ currents in striatal cholinergic interneurons.
- To determine the expression pattern of TASK-3 in these neurons.
- To explore the modulation of TASK-3-like currents by Galphaq-linked receptors.
Main Methods:
- Combined molecular neuroanatomy (immunostaining for choline acetyltransferase and TASK-3) with whole-cell electrophysiology.
- Utilized nonradioactive cRNA probes and specific antisera for TASK-3 detection.
- Isolated and characterized TASK-3-like currents based on sensitivity to pH, anesthetics, and zinc (Zn2+).
Main Results:
- Demonstrated universal expression of TASK-3 subunits in striatal cholinergic neurons.
- Identified a TASK-3-like K+ current with characteristic pH, anesthetic, and Zn2+ sensitivity.
- Found no apparent modulation of native interneuron TASK-3-like currents by activation of Galphaq-linked receptors (mGluR1/5, H1).
Conclusions:
- TASK-3 subunits form homomeric channels contributing to background K+ currents in striatal cholinergic interneurons.
- These TASK-3-like currents play a role in establishing the membrane potential of these neurons.
- Receptor modulation of TASK channels is likely dependent on the specific cellular context.
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