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This Article Full Text Full Text (PDF) All Versions of this Article: 582/3/1337    most recent jphysiol.2007.132639v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tobin, V. A. Articles by Ludwig, M. Search for Related Content PubMed PubMed Citation Articles by Tobin, V. A. Articles by Ludwig, M. Related Collections Integrative

¹ Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK

Magnocellular neurons of the supraoptic nucleus (SON) can differentially control peptide release from the somato/dendritic and axon terminal compartment. Dendritic release can be selectively regulated through activation of intracellular calcium stores by calcium mobilizers such as thapsigargin (TG), resulting in preparation (priming) of somato/dendritic peptide pools for subsequent activity-dependent release. As dynamic modulation of the actin cytoskeleton is implicated in secretion from synaptic terminals and from several types of neuroendocrine cells, we studied its involvement in oxytocin and vasopressin release from SON neurons. Confocal image analysis of the somata revealed that the normally continuous cortical band of F-actin is disrupted after high potassium (K⁺, 50 mM) or TG (200 nM) stimulation. The functional importance of actin remodelling was studied using cell-permeable actin polymerizing (jasplakinolide, 2 µM) or depolymerizing agents (latrunculin B, 5 µM) to treat SON and neural lobe (NL) explants in vitro and measure high K⁺-induced oxytocin and vasopressin release. Latrunculin significantly enhanced, and jasplakinolide inhibited, high-K⁺-evoked somato/dendritic peptide release, while release from axon terminals was not altered, suggesting that high-K⁺-evoked release in the SON, but not the NL, requires depolymerization of the actin cytoskeleton. TG-induced priming of somato/dendritic release was also blocked by jasplakinolide and latrunculin, suggesting that priming involves changes in actin remodelling.

(Received 16 March 2007; accepted after revision 30 April 2007; first published online 3 May 2007)
Corresponding author M. Ludwig: Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK. Email: mike.ludwig{at}ed.ac.uk

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