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Use-dependent facilitation of electrical transmission involves changes to postsynaptic K+ current
Yueling Gu1, Kelly H Lee1, Alex B Prosserman1
1Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Journal of Neurophysiology
|May 31, 2023
Summary
Electrical transmission between bag cell neurons shows short-term facilitation. This facilitation, crucial for synchrony and reproductive function, is driven by postsynaptic K+ current inactivation, not junctional current changes.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
- Synaptic Transmission
Background:
- Electrical transmission modulation typically involves Ca2+ influx affecting gap junctions.
- Bag cell neurons in Aplysia californica are electrically coupled and secrete reproductive hormone.
- Understanding activity-dependent facilitation of electrical transmission is incomplete.
Purpose of the Study:
- To describe short-term use-dependent facilitation of electrical transmission between Aplysia bag cell neurons.
- To elucidate the underlying mechanisms of this facilitation.
- To investigate the role of facilitation in neuronal synchrony and reproductive function.
Main Methods:
- Dual whole-cell voltage-clamp and current-clamp recordings from pairs of cultured bag cell neurons.
- Stimulation with action potential-like waveforms to elicit electrotonic potentials.
- Manipulation of postsynaptic K+ channels to investigate their role in facilitation.
Main Results:
- Electrical transmission facilitation occurred over time with repeated stimulation, independent of junctional current changes.
- Facilitation was correlated with cumulative inactivation of postsynaptic voltage-gated K+ current.
- Blocking postsynaptic K+ channels occluded facilitation; active neurons recruited silent partners via facilitation.
Conclusions:
- Short-term use-dependent facilitation of electrical transmission in bag cell neurons is mediated by postsynaptic K+ current run-down.
- This facilitation enhances electrotonic potentials, boosting responsiveness to successive junctional currents.
- Facilitation promotes synchronous firing among bag cell neurons, potentially enhancing neurosecretion and reproductive function.
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