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Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons
Published on: April 18, 2017
Developmental Changes to the M-Current Shape the Direction of Its Neuromodulation in Zebrafish Motoneurons
Stephanie F Gaudreau1,2, Tuan V Bui3
1Department of Biology, Brain and Mind Research Institute, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Summary
Serotonin and acetylcholine dynamically modulate the M-current in zebrafish motoneurons during development. This neuromodulation shifts direction as the M-current
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Spinal circuits mature during development, refining movements through neuromodulation.
- Targets of neuromodulation in developing spinal circuits are largely unknown.
- The M-current, a subthreshold potassium current, is a known target for neuromodulation.
Purpose of the Study:
- To investigate whether neuromodulators target the M-current in primary motoneurons during zebrafish development.
- To determine the specific effects of acetylcholine and serotonin on the M-current in developing motoneurons.
Main Methods:
- Patch-clamp electrophysiology in zebrafish primary motoneurons (3-5 days post-fertilization).
- Pharmacological manipulation using receptor agonists/antagonists and PIP2 modulation.
- Evoked swimming assays to measure motor output.
Main Results:
- Serotonin (via 5-HT1A receptors) inhibits the M-current, promoting repetitive firing at 3 dpf.
- Acetylcholine (via M2 receptors) enhances the M-current, limiting repetitive firing at 4-5 dpf.
- Neuromodulatory effects on the M-current reverse as its amplitude changes during development.
Conclusions:
- Developmental changes in M-current amplitude dictate the direction of neuromodulatory control over motoneuron firing.
- This dynamic neuromodulation shapes motor activity transitions from ballistic to coordinated swimming.
- PIP2 signaling may mediate M-current neuromodulation in developing motoneurons.
