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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

In vitro characterization of noradrenergic modulation of chemosensitive neurons in the retrotrapezoid nucleus

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Author(s):
Kuo, Fu-Shan ; Falquetto, Barbara ; Chen, Dawei ; Oliveira, Luiz M. ; Takakura, Ana C. ; Mulkey, Daniel K.
Total Authors: 6
Document type: Journal article
Source: Journal of Neurophysiology; v. 116, n. 3, p. 1024-1035, SEP 2016.
Web of Science Citations: 7
Abstract

Chemosensitive neurons in the retrotrapezoid nucleus (RTN) regulate breathing in response to CO2/H+ changes and serve as an integration center for other autonomic centers, including brain stem noradrenergic neurons. Norepinephrine (NE) contributes to respiratory control and chemoreception, and, since disruption of NE signaling may contribute to several breathing disorders, we sought to characterize effects of NE on RTN chemoreception. All neurons included in this study responded similarly to CO2/H+ but showed differential sensitivity to NE; we found that NE activated (79%), inhibited (7%), or had no effect on activity (14%) of RTN chemoreceptors. The excitatory effect of NE on RTN chemoreceptors was dose dependent, retained in the presence of neurotransmitter receptor blockers, and could be mimicked and blocked by pharmacological manipulation of alpha(1)-adrenergic receptors (ARs). In addition, NE-activation was blunted by XE991 (KCNQ channel blocker), and partially occluded the firing response to serotonin, suggesting involvement of KCNQ channels. However, in whole cell voltage clamp, activation of alpha(1)-ARs decreased outward current and conductance by what appears to be a mixed effect on multiple channels. The inhibitory effect of NE on RTN chemoreceptors was blunted by an alpha(2)-AR antagonist. A third group of RTN chemoreceptors was insensitive to NE. We also found that chemosensitive RTN astrocytes do not respond to NE with a change in voltage or by releasing ATP to enhance activity of chemosensitive neurons. These results indicate NE modulates subsets of RTN chemoreceptors by mechanisms involving alpha(1)- and alpha(2)-ARs. (AU)

FAPESP's process: 13/26540-1 - Noradrenergic mechanisms in the retrotrapezoid nucleus in the control of chemoreception
Grantee:Luiz Marcelo Oliveira Santos
Support Opportunities: Scholarships in Brazil - Master