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Whole-cell Patch-clamp Recordings from Morphologically- and Neurochemically-identified Hippocampal Interneurons
Published on: September 30, 2014
Synchronized bursts of miniature inhibitory postsynaptic currents
Ion R Popescu1, Linda A Morton, Alier Franco
1Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA.
The Journal of Physiology
|February 4, 2010
Summary
Spike-independent inhibitory postsynaptic current (IPSC) bursts in hypothalamic neurons suggest a novel mechanism for regulating neuronal activity. These bursts, composed of miniature IPSCs (mIPSCs), influence action potential firing and hormone release.
Area of Science:
- Neuroscience
- Neuroendocrinology
- Synaptic Transmission
Background:
- Spike-independent miniature postsynaptic currents are typically stochastic and not considered information carriers.
- Hypothalamic magnocellular neurons play a crucial role in hormone release.
Purpose of the Study:
- To investigate the nature and function of endogenous bursts of inhibitory postsynaptic currents (IPSCs) in hypothalamic magnocellular neurons.
- To determine the role of these IPSC bursts in regulating neuronal activity and hormone release.
Main Methods:
- Electrophysiological recordings (in the presence and absence of TTX) of hypothalamic magnocellular neurons.
- Calcium dependency studies.
- Current injections to simulate IPSC bursts.
- Dual recordings to assess synchronization.
Main Results:
- Endogenous bursts of IPSCs, composed of miniature IPSCs (mIPSCs), were recorded in hypothalamic magnocellular neurons.
- These IPSC bursts were modulated by action potential activity and required extracellular calcium, but not voltage-gated calcium channels or intracellular stores.
- Simulated IPSC bursts could trigger and terminate action potential trains.
- A subset of IPSC bursts were synchronized in onset between pairs of neurons, suggesting shared GABA synapses.
Conclusions:
- Synchronized bursts of inhibitory synaptic inputs represent a novel mechanism for action potential burst generation, termination, and synchronization.
- This mechanism may contribute to pulsatile hormone release from neuroendocrine cells.
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