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Updated: May 29, 2026
07:31
Profiling Voltage-gated Potassium Channel mRNA Expression in Nigral Neurons using Single-cell RT-PCR Techniques
Published on: September 27, 2011
Tonic dopamine induces persistent changes in the transient potassium current through translational regulation
Edmund W Rodgers1, Wulf-Dieter C Krenz, Deborah J Baro
1Department of Biology, Georgia State University, Atlanta, Georgia 30303, USA.
Summary
Dopamine (DA) transmission modes differentially regulate neuronal ion currents. Phasic DA causes immediate shifts, while tonic DA induces persistent changes in maximal conductance, opposing immediate effects and suggesting a role for tonic modulators in ion channel regulation.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
- Neurotransmission
Background:
- Neuromodulatory effects depend on dopamine (DA) transmission modes: phasic (micromolar, transient) and tonic (nanomolar, persistent).
- DA is known to alter voltage-dependent ionic conductances, specifically the transient potassium current (I(A)).
Purpose of the Study:
- To investigate whether phasic and tonic dopamine transmissions similarly regulate voltage-dependent ionic conductances.
- To elucidate the distinct mechanisms underlying immediate and persistent effects of DA on I(A) in specific neurons.
Main Methods:
- Electrophysiological recordings from identified neurons (LP and PD) in the stomatogastric ganglion of the spiny lobster.
- Application of micromolar and nanomolar concentrations of DA to assess immediate and persistent effects on I(A).
- Investigation of underlying molecular mechanisms, including translation-dependent pathways involving target of rapamycin (TOR).
Main Results:
- Phasic micromolar DA caused immediate, opposing shifts in I(A) voltage dependence for LP (depolarizing) and PD (hyperpolarizing) neurons.
- Tonic nanomolar DA induced persistent increases in LP I(A) maximal conductance (G(max)) via TOR, and decreases in PD I(A) G(max) via a non-TOR pathway.
- Persistent effects on G(max) were independent of neuronal activity.
Conclusions:
- Phasic and tonic dopamine transmissions exert opposing effects on neuronal excitability by differentially regulating I(A).
- Tonic neuromodulation plays a role in regulating the number of voltage-gated ion channels.
- Dopaminergic systems may possess mechanisms to limit the extent of circuit modulation.
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