Peripheral chemoreceptor activation enhances 5-hydroxytryptamine release in the locus coeruleus of conscious rats.
Intravenous bolus injection of KCN (40 microg) elicited brief but pronounced tachypnea, bradycardia and pressor response, and led to a 37% increase in 5-hydroxytryptamine (serotonin) (5-HT) release in the locus coeruleus (LC) of freely moving rats. Slow infusion of KCN (15 microg/min) for 10 min induced only a slight pressor response, but increased the respiration rate (+39 breaths/min), as well as 5-HT release in the LC (+60%) throughout the infusion. In rats with transected chemoreceptor afferents, neither injection or infusion of KCN changed 5-HT release, suggesting that in intact animals, the effect on extracellular 5-HT was due to activation of peripheral chemoreceptors. In summary, we report that peripheral chemoreceptor activation enhances 5-HT release in the LC, indicating that 5-HT might be involved in the modulation of LC activity by ascending chemosensory information.
Singewald
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Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Peter-Mayr-Strasse 1, A-6020, Innsbruck, Austria. nicolas.singewald@uibk.ac.at
Kouvelas
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D
Kaehler
S T
ST
Sinner
C
C
Philippu
A
A
D000818:Animals; D001143:Arousal; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008125:Locus Coeruleus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008297:Male; D011190:Potassium Cyanide / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013238:Stereotaxic Techniques; D013997:Time Factors
D012701:Serotonin; D011190:Potassium Cyanide