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Microinjection of methysergide into the raphe nucleus attenuated phrenic long-term facilitation in rats.

Authors :
Valic, Maja
Pecotic, Renata
Pavlinac, Ivana
Valic, Zoran
Peros, Kristina
Dogas, Zoran
Source :
Experimental Brain Research. May2010, Vol. 202 Issue 3, p583-589. 7p. 1 Color Photograph, 1 Diagram, 4 Graphs.
Publication Year :
2010

Abstract

Exposure to acute intermittent hypoxia (AIH) evokes persistent increase in respiratory activity that lasts up to 60 min after hypoxic episodes have ceased. This persistent increase in phrenic nerve activity (PNA) is known as phrenic long-term facilitation (LTF). AIH-induced phrenic LTF in anesthetized rats is serotonin dependant. The present study was performed to determine whether microinjection of methysergide (4 mM, 20 ± 5 nl), a broad spectrum 5-HT receptor antagonist, into the caudal raphe nuclei influences phrenic LTF. Peak integrated PNA and respiratory frequency were recorded at 15, 30, and 60 min after five 3-min episodes of normocapnic hypoxia in urethane-anesthetized, vagotomized, paralyzed and ventilated male Sprague–Dawley rats. In control animals, phrenic nerve amplitude was elevated 66.7 ± 8.6% from baseline 1 h after episodic hypoxia, indicating phrenic LTF. Experimental microinjections of methysergide prior to AIH exposure attenuated phrenic LTF (amplitude increase 2.62 ± 2.9% over baseline). We conclude that methysergide microinjections into the caudal raphe region attenuated phrenic LTF induced by AIH, indicating involvement of 5-HT receptor activation at a supraspinal level. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00144819
Volume :
202
Issue :
3
Database :
Academic Search Index
Journal :
Experimental Brain Research
Publication Type :
Academic Journal
Accession number :
50217526
Full Text :
https://doi.org/10.1007/s00221-010-2161-2