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C-fiber activation exacerbates sleep-disordered breathing in rats.
D W Carley1, S Pavlovic, M Malis
1Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA. DWCarley@uic.edu
Sleep & Breathing = Schlaf & Atmung
|September 25, 2004
Summary
Capsaicin (CAP) selectively activates C-fibers, increasing sleep apnea during non-rapid eye movement (NREM) sleep in rats. This study clarifies the specific role of C-fiber activity in sleep-disordered breathing.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Sleep Medicine
Background:
- Vagal feedback activation by agents like protoveratrines and serotonin can worsen sleep apnea.
- These agents activate multiple afferent fiber types, making it difficult to isolate the effect of specific fibers.
Purpose of the Study:
- To investigate the specific impact of C-fiber activity on sleep apnea.
- To determine if C-fiber stimulation exacerbates sleep-disordered breathing.
Main Methods:
- Utilized capsaicin (CAP), a C-fiber stimulant, in Sprague-Dawley rats.
- Administered intraperitoneal injections of saline or varying doses of CAP (0.1, 1.0, 10.0 mg/kg).
- Monitored respiration via plethysmography and scored apneas during polysomnography recordings.
Main Results:
- CAP significantly increased apnea frequency during non-rapid eye movement (NREM) sleep (p < 0.05).
- Respiratory minute ventilation decreased by approximately 15% across all behavioral states (waking, NREM, REM sleep).
Conclusions:
- Selective pharmacological activation of C-fibers using capsaicin induces a predisposition to sleep-disordered breathing.
- The observed effects are specific to NREM sleep, highlighting C-fibers' role in this sleep stage.