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DOI: 10.1055/s-2004-834485
Copyright © 2004 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.
C-Fiber Activation Exacerbates Sleep-Disordered Breathing in Rats
Publication History
Publication Date:
24 September 2004 (online)
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We reported previously that activation of vagal feedback by protoveratrines or serotonin exacerbates sleep apnea in rats, but each of these agents activates multiple afferent fiber types. To elucidate the specific impact of C-fiber activity on sleep apnea, the present study utilized capsaicin (CAP), which stimulates C-fibers via the CAP receptor. Nine adult Sprague-Dawley rats were instrumented for chronic polysomnography and recorded for 6 hours on four occasions. Prior to each recording, the animals received an intraperitonea injection of either saline (control), or CAP 0.1, 1.0, or 10.0 mg/kg. Respiration was monitored by single-chamber plethysmography and apneas were scored as breaths longer than 2.5 seconds not preceded by a sigh. CAP increased apneas during non-rapid eye movement (NREM) sleep (p < 0.05 vs control) and reduced respiratory minute ventilation by about 15% in all behavioral states (waking, NREM, and REM sleep). We conclude that selective pharmacological activation of C-fibers produces a diathesis of sleep-disordered breathing specific to NREM sleep in rats.
KEYWORDS
Capsaicin - C-fibers - sleep apneas - rats
REFERENCES
- 1 Jacobs L, Comroe Jr J H. Reflex apnea, bradycardia, and hypotension produced by serotonin in cats. Circ Res. 1971; 29 145-155
- 2 Clozel J P, Pisarri T E, Coleridge H M, Coleridge J C. Reflex coronary vasodilatation evoked by chemical stimulation of cardiac afferent vagal C fibers in dogs. J Physiol. 1990; 428 215-232
- 3 Paintal A S. Impulses in vagal afferent fibers from specific pulmonary deflation receptors. The response of these receptors to phenyl diguanide, potato starch, 5-hydroxytryptamine and nicotine and their role in respiratory and cardiovascular reflexes. Q J Exp Physiol. 1955; 40 348-363
- 4 Coleridge H M, Coleridge J CG, Kidd C. Role of pulmonary arterial baroreceptors in effects produced by capsaicin in the dog. J Physiol. 1964; 170 272-285
- 5 Hedner J, Hedner T, Jonason J. Capsaicin and regulation of respiration: interaction with central substance P mechanisms. J Neural Transm. 1985; 61 239-252
- 6 Trbovic S M, Radulovacki M, Carley D W. Protoveratrines A and B increase sleep apnea index in Sprague-Dawley rats. J Appl Physiol. 1997; 83 1602-1606
- 7 Carley D W, Radulovacki M. Role of peripheral serotonin in the regulation of central apneas in rats. Chest. 1999; 115 1397-1401
- 8 Radulovacki M, Trbovic S M, Carley D W. Serotonin 5-HT3-receptor antagonist GR38032F suppresses sleep apnea in rats. Sleep. 1998; 21 131-136
- 9 Veasey S C, Chachkes J, Fenik P, Hendricks J C. The effects of ondansetron on sleep-disordered breathing in the English bulldog. Sleep. 2001; 24 155-160
- 10 Carstens E, Klumpp D, Randic M, Zimmermann M. Effect of iontophoretically applied 5-hydroxytryptamine on the excitability of single primary C- and A-fibers in the cat spinal cord. Brain Res. 1981; 220 151-158
- 11 Holzer P. Capsaicin: cellular targets, mechanism of action, and selectivity for thin sensory neurons. Pharmacol Rev. 1991; 43 203-242
- 12 Diaz V, Arsenault J, Praud J-P. Consequences of capsaicin treatment on pulmonary vagal reflexes and chemoreceptor activity in lambs. J Appl Physiol. 2000; 89 1709-1718
- 13 Bennington J, Kodali S, Heller C. Scoring transitions to REM sleep in rats based on the EEG phenomena of pre-REM sleep: an improved analysis of sleep structure. Sleep. 1994; 17 28-36
- 14 Carley D W, Radulovacki M. Mirtazapine, a mixed-profile serotonin agonist/antagonist, suppresses sleep apnea in the rat. Am J Respir Crit Care Med. 1999; 160 1824-1829
- 15 Carley D W, Trbovic S, Radulovacki M. Hydralazine reduces elevated sleep apnea index in spontaneously hypertensive (SHR) rats to equivalence with normotensive Wistar-Kyoto rats. Sleep. 1996; 19 363-366
- 16 Christon J, Carley D W, Monti D, Radulovacki M. Effects of inspired gas on sleep-related apneas in rats. J Appl Physiol. 1996; 80 2102-2107
- 17 Monti D, Carley D W, Radulovacki M. Adenosine analogs modulate the incidence of sleep apneas in rats. Pharmacol Biochem Behav. 1995; 51 125-131
- 18 Anand A. Influence of bronchial C fibre receptors on respiration in cats: possible role in humans. Respir Physiol. 2000; 123 1-12
- 19 Ravi K, Dev N B. Metoclopramide blocks the phenyl diguanide and 5-hydroxytryptamine induced cardiorespiratory reflexes in cats and dogs. Can J Physiol Pharmacol. 1988; 66 776-782
- 20 Saria A, Skofitsch G, Lembeck F. Distribution of capsaicin in rat tissues after systemic administration. J Pharm Pharmacol. 1982; 34 273-275
David W CarleyPh.D.
Section of Respiratory and Critical Care Medicine, Department of Medicine, MC 787
840 South Wood St.
Chicago, IL 60612
Email: DWCarley@uic.edu