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Intertrigeminal region attenuates reflex apnea and stabilizes respiratory pattern in rats
Miodrag Radulovacki1, Sasa Pavlovic, Jasna Saponjic
1Department of Pharmacology, M/C 868, University of Illinois at Chicago, 901 S. Wolcott Ave., Chicago, IL 60612, USA. mradulo@iuc.edu
Brain Research
|May 24, 2003
Summary
The pontine intertrigeminal region (ITR) attenuates vagally-induced reflex apnea. This brainstem area modulates breathing, with medullary circuits also capable of generating apnea independently.
Area of Science:
- Neuroscience
- Respiratory Physiology
Background:
- The pontine intertrigeminal region (ITR) is a newly described anatomical pathway.
- The role of the ITR in vagally-induced reflex apnea is not well understood.
Purpose of the Study:
- To determine if the ITR plays a physiological role in modulating vagally-induced reflex apnea.
- To investigate the ITR's impact on apnea elicited by intravenous 5-HT in rats.
Main Methods:
- Rats were administered 5-HT intravenously to induce apnea.
- Glutamate and kynurenic acid (a glutamate receptor antagonist) were microinjected into the ITR.
- Respiration was monitored using a piezo-electric crystal.
Main Results:
- Intravenous 5-HT induced a 3-second apnea.
- Glutamate microinjections into the ITR produced apnea, which was blocked by kynurenic acid.
- Antagonism of glutamate receptors in the ITR prolonged 5-HT-induced apnea to 8 seconds.
- Ponto-medullary transection further prolonged 5-HT-induced apnea.
Conclusions:
- The ITR attenuates vagally-induced reflex apneas, indicating a modulatory role in respiration.
- Pontine structures generally modulate autonomic activities, including respiration.
- Medullary circuits can independently produce 5-HT-induced reflex apnea without pontine involvement.