Calcium signalling in medial intercalated cell dendrites and spines

Strobel, Cornelia, Sullivan, Robert K. P., Stratton, Peter and Sah, Pankaj (2017) Calcium signalling in medial intercalated cell dendrites and spines. The Journal of Physiology, 595 16: 5653-5669. doi:10.1113/JP274261

Author Strobel, Cornelia
Sullivan, Robert K. P.
Stratton, Peter
Sah, Pankaj
Title Calcium signalling in medial intercalated cell dendrites and spines
Journal name The Journal of Physiology   Check publisher's open access policy
ISSN 1469-7793
Publication date 2017-08-01
Year available 2017
Sub-type Article (original research)
DOI 10.1113/JP274261
Open Access Status Not yet assessed
Volume 595
Issue 16
Start page 5653
End page 5669
Total pages 17
Place of publication Chichester, West Sussex United Kingdom
Publisher Wiley-Blackwell
Language eng
Subject 1314 Physiology
Abstract The amygdala plays a central role in fear conditioning and extinction. The medial intercalated (mITC) neurons are GABAergic cell clusters interspaced between the basolateral(BLA) and central amygdala (CeA). These neurons are though t to play a key role in fear and extinction, controlling the output of the CeA by feed-forward inhibition. BLA to mITC cell inputs are thought to undergo synaptic plasticity, a mechanism underlying learning, which is mediated by NMDA receptor-dependent mechanisms that require changes in cytosolic calcium. Here, we studied the electrical and calcium signalling properties of mITC neurons in GAD67-eGFP miceusing whole-cell patch clamp recordings and two-photon calcium imaging. We show that action potentials back-propagate (bAP) into dendrites, and evoke calcium transients in both the shaft and the dendritic spine. However, bAP-mediated calcium rises in the dendrites attenuate with distance due to shunting by voltage-gated potassium channels. Glutamaterg ic inputs make dual component synapses on spines. At these synapses, post synaptic AMPA receptors can have linear or rectifying I–V relationships, indicating that some synapses express GluA2-lacking AMPAreceptors. Synaptic NMDA receptors had intermediate decay kinetics, and were only partly blocked by GuN2B selective blockers, indicating these receptors are GluN1/GluN2A/GluN2Btrimers. Low- or high-frequency synaptic stimulation raised spine calcium, mediated by calcium influx via NMDA receptors, was locally restricted and did not invade neighbouring spines. Our results show that in mITC neurons, post synaptic calcium is tightly controlled, and acts as a local signal.
Keyword amygdala
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID APP1128427
Institutional Status UQ

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