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Orexin A activates retrotrapezoid neurons in mice
Roman M Lazarenko1, Ruth L Stornetta, Douglas A Bayliss
1Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, United States.
Respiratory Physiology & Neurobiology
|December 15, 2010
Summary
Orexin neurons excite retrotrapezoid nucleus (RTN) chemoreceptors, influencing breathing regulation. This study reveals orexin A excites RTN neurons, supporting their role in respiratory control.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Cellular Biology
Background:
- The retrotrapezoid nucleus (RTN) contains Phox2b-expressing neurons crucial for respiratory chemoreception.
- RTN neurons relay hypothalamic pathways regulating breathing, potentially involving orexinergic neurons.
Purpose of the Study:
- To investigate the cellular interaction between orexinergic neurons and RTN chemoreceptor neurons.
- To determine the effect of orexin A on RTN neuron activity.
Main Methods:
- Immunohistochemistry in adult Phox2b-eGFP transgenic mice to visualize orexin and RTN neuron proximity.
- Electrophysiological recordings in brain slices from neonatal Phox2b-eGFP mice to assess orexin A's effects.
Main Results:
- Demonstrated close appositions between orexin-containing axonal varicosities and RTN chemoreceptor neurons.
- Showed that orexin A robustly and dose-dependently excites acid-sensitive RTN neurons (ED50 ~250nM).
Conclusions:
- RTN neurons are a convergence point for multiple neuronal groups, including orexinergic neurons, involved in respiratory chemoreflexes.
- Orexinergic input contributes to the regulation of breathing by exciting RTN chemoreceptor neurons.
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