Chewing reduces sympathetic nervous response to stress and prevents poststress arrhythmias in rats

Reducing stress is important in preventing sudden death in patients with cardiovascular disease, as stressful events may cause autonomic imbalance and trigger fatal arrhythmias. Since chewing has been shown to inhibit stress-induced neuronal responses in the hypothalamus, we hypothesized that chewin...

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Bibliographic Details
Published in:American journal of physiology. Heart and circulatory physiology 2011-10, Vol.301 (4), p.H1551-H1558
Main Authors: Koizumi, So, Minamisawa, Susumu, Sasaguri, Kenichi, Onozuka, Minoru, Sato, Sadao, Ono, Yumie
Format: Article
Language:English
Subjects:
Adrenergic beta-Antagonists - pharmacology
Animals
Arrhythmias, Cardiac - prevention & control
Brain
Cardiac arrhythmia
Cardiovascular disease
Catecholamines - blood
Electrocardiography - drug effects
Heart Rate - drug effects
Heart Rate - physiology
Male
Mastication - physiology
Neurons
Parasympathetic Nervous System - physiology
Physiology
Propranolol - pharmacology
Rats
Rats, Sprague-Dawley
Restraint, Physical
Rodents
Stress, Psychological - complications
Stress, Psychological - physiopathology
Sympathetic Nervous System - drug effects
Sympathetic Nervous System - physiopathology
Telemetry
Ventricular Premature Complexes - prevention & control
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Summary:Reducing stress is important in preventing sudden death in patients with cardiovascular disease, as stressful events may cause autonomic imbalance and trigger fatal arrhythmias. Since chewing has been shown to inhibit stress-induced neuronal responses in the hypothalamus, we hypothesized that chewing could ameliorate stress-induced autonomic imbalance and prevent arrhythmias. To test this hypothesis, we analyzed changes in radiotelemetered electrocardiograms in rats that were allowed to chew a wooden stick during a 1-h period of immobilization stress. Chewing significantly reduced the occurrence of ventricular premature beats (VPBs) and complex ventricular ectopy after immobilization and prevented stress-induced prolongation of the QT interval of VPBs throughout the 10-h experimental period. It also prevented prolongation of the QRS complex and fluctuations in the QT interval in normal sinus rhythm beats preceding VPBs during both immobilization and in the poststress period. Fast Fourier transform-based spectral analysis of heart-rate variability further showed that chewing significantly inhibited the stress-induced increase in the power ratio of low-to-high frequency activity (LF/HF: a marker of sympathetic activity) during immobilization and in addition was associated with blunting of the stress-induced increase in plasma noradrenaline observed at the termination of immobilization. Similar suppressive effects on the occurrence of VPBs and the LF/HF were observed in rats that were administered the β-adrenergic blocker propranolol before immobilization. These results indicate that chewing can ameliorate sympathetic hyperactivity during stress and prevent poststress arrhythmias and suggest that chewing may provide a nonpharmacological and cost-effective treatment option for patients with a high risk of stress-induced fatal arrhythmia.
ISSN:0363-6135
1522-1539
DOI:10.1152/ajpheart.01224.2010