Neuroscience 2003 Abstract
| Presentation Number: | 769.9 |
|---|---|
| Abstract Title: | Microinjections of serotonergic and noradrenergic antagonist into the XII nucleus abolish the carbachol-induced, REM sleep-like atonia of hypoglossal motoneurons. |
| Authors: |
Fenik, V. B.*1
; Davies, R. O.1
; Kubin, L.1
1Animal Biol, Univ. of Pennsylvania, Philadelphia, PA |
| Primary Theme and Topics |
Autonomic, Neuroendocrine and Other Homeostatic Systems - Biological Rhythms and Sleep -- Sleep |
| Secondary Theme and Topics | Motor Systems<br />- Brainstem<br />-- Physiology |
| Session: |
769. Sleep II Slide |
| Presentation Time: | Wednesday, November 12, 2003 10:00 AM-10:00 AM |
| Location: | Morial Convention Center - Room 273 |
| Keywords: | PONS, EEG, THETA, RESPIRATION |
We previously reported (Fenik et al., SFN Abstr. 2002) that simultaneous antagonism of serotonergic (5-HT), noradrenergic (NE) and GABAA receptors in the hypoglossal (XII) nucleus region abolishes the depression of XII nerve activity that occurs during the REM sleep-like episodes elicited by pontine carbachol (cREM). The episodes comprise XII depression, cortical activation, hippocampal theta and silencing of NE neurons (J.Appl.Physiol 93:1448, 2002). We now tested whether the antagonism of only 5-HT and NE receptors is sufficient to achieve this effect. In 6 urethane-anesthetized, paralyzed and artificially ventilated rats, cREM was elicited before, and at different times after, 3 injections (40 nl each) of the 5-HT receptor antagonist methysergide (1 mM) and α1 adrenergic receptor antagonist prazosin (0.2 mM) into the XII nucleus. Integrated XII nerve activity was expressed as a percentage of its level at the beginning of the experiment. Prior to injecting the antagonists, XII nerve activity was depressed during cREM to 25%±8.7 (SD) of control (p<0.001). At 49 min±17 after the antagonists, the spontaneous XII nerve activity was reduced to 27%±6.7 of control and remained unchanged during cREM (25%±9.9; n=6, p=0.4); importantly, the characteristic changes in the cortical and hippocampal signals and slowing of the respiratory rate still occurred. At 187 min±29 after the antagonists, XII nerve activity partially recovered, to 59%±29, and so did the depressant effect of cREM (activity was depressed during cREM to 22%±10; n=6, p<0.01). In additional rats, prazosin alone (n=2), or methysergide alone (n=2), did not abolish the cREM-related depression of XII nerve activity. We conclude that the antagonism of both 5-HT and NE receptors is necessary and sufficient to abolish the REM sleep-like depression of XII motoneurons.
Supported by HL-60287, 47600
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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