Orexin A Inhibits Propofol-Induced Neurite Retraction by a Phospholipase D/Protein Kinase C.sub.ζ-Dependent Mechanism in Neurons

The intravenous anaesthetic propofol retracts neurites and reverses the transport of vesicles in rat cortical neurons. Orexin A (OA) is an endogenous neuropeptide regulating wakefulness and may counterbalance anaesthesia. We aim to investigate if OA interacts with anaesthetics by inhibition of the p...

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Bibliographic Details
Published in:PloS one 2014-05, Vol.9 (5)
Main Authors: Bjornstrom, Karin, Turina, Dean, Strid, Tobias, Sundqvist, Tommy, Eintrei, Christina
Format: Article
Language:English
Subjects:
Brain
Evaluation
Neurons
Phenols
Phospholipases
Propofol
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Summary:The intravenous anaesthetic propofol retracts neurites and reverses the transport of vesicles in rat cortical neurons. Orexin A (OA) is an endogenous neuropeptide regulating wakefulness and may counterbalance anaesthesia. We aim to investigate if OA interacts with anaesthetics by inhibition of the propofol-induced neurite retraction. In primary cortical cell cultures from newborn rats' brains, live cell light microscopy was used to measure neurite retraction after propofol (2 µM) treatment with or without OA (10 nM) application. The intracellular signalling involved was tested using a protein kinase C (PKC) activator [phorbol 12-myristate 13-acetate (PMA)] and inhibitors of Rho-kinase (HA-1077), phospholipase D (PLD) [5-fluoro-2-indolyl des-chlorohalopemide (FIPI)], PKC (staurosporine), and a PKCζ translocation inhibitor peptide. Changes in PKCζ Ser.sup.729 phosphorylation were detected with Western blot. The neurite retraction induced by propofol is blocked by Rho-kinase and PMA. OA blocks neurite retraction induced by propofol, and this inhibitory effect could be prevented by FIPI, staurosporine and PKCζ translocation inhibitor peptide. OA increases via PLD and propofol decreases PKCζ Ser.sup.729 phosphorylation, a crucial step in the activation of PKCζ. Rho-kinase is essential for propofol-induced neurite retraction in cortical neuronal cells. Activation of PKC inhibits neurite retraction caused by propofol. OA blocks propofol-induced neurite retraction by a PLD/PKCζ-mediated pathway, and PKCζ maybe the key enzyme where the wakefulness and anaesthesia signal pathways converge.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0097129