Neuroscience 2003 Abstract
| Presentation Number: | 931.6 |
|---|---|
| Abstract Title: | Antagonism of hypothalamic perifornical GABA<sub>A</sub> receptors increases wakefulness during baseline sleep and following sleep deprivation. |
| Authors: |
Lu, W.*1
; Mann, G.1
; Ross, R.1
; Morrison, A. R.1
; Kubin, L.1
1Dept. of Animal Biol., Univ. of Pennsylvania, Philadelphia, PA |
| Primary Theme and Topics |
Autonomic, Neuroendocrine and Other Homeostatic Systems - Biological Rhythms and Sleep -- Sleep |
| Session: |
931. Sleep: Orexin/Hypocretin Poster |
| Presentation Time: | Wednesday, November 12, 2003 2:00 PM-3:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # I3 |
| Keywords: | Arousal, Hypocretin, Hypothalamus, Motor activity |
The perifornical (PF) region of the posterior hypothalamus contains many GABAergic neurons and axon terminals; some of them inhibit cells that synthesize orexins (ORX), peptides important for the regulation of sleep-wake behavior, motor activity and energy balance. We previously reported (Kubin et al., SFN Abstr. 2002) that microinjections of bicuculline (BIC) into the PF region to antagonize the endogenous inhibition mediated by GABAA receptors reduce sleep, increase motor activity and stimulate c-fos expression in ORX neurons. To test whether the wake-promoting effects of BIC can occur without motor activation, we have now used unilateral microdialysis perfusion of the PF region with a low concentration of BIC (20 μM). Five rats were chronically instrumented (cortical, hippocampal and nuchal EMG activity). Sleep-wake and motor activity were recorded for 4 h of either a continuous perfusion with artificial csf or with BIC substituting for csf during the middle two hours. During the test period, BIC increased the amount of wakefulness from 50%±8(SE) to 72%±4 and reduced slow-wave sleep from 41%±7 to 24%±4 (n=10, p<0.01). Since sleep deprivation (SD) increases the mRNA levels for selected GABAA receptor subunits in the PF region (Volgin & Kubin, SFN Abstr. 2002), we tested whether SD enhances the wake-promoting effect of BIC. In rats subjected to SD (8 am-noon), the amount of wakefulness during the 1-3 pm period tended to increase from 22%±8 during perfusion with csf to 28%±9 with BIC (n=5), an effect not stronger than that during baseline sleep. When adjusted for the increased time spent awake, BIC tended to increase the number of separate movements during both baseline sleep and following SD, thus suggesting that the wake-promoting and motor effects of BIC are related.
Supported by HL-71097, MH-2903, Dept. of Veterans Affairs.
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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