Reflex arc of the teeth clenching-induced pressor response in rats
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Although “teeth clenching” induces pressor response, the reflex tracts of the response are unknown. In this study, dantrolene administration inhibited teeth clenching generated by electrical stimulation of the masseter muscles and completely abolished the pressor response. In addition, trigeminal ganglion block or hexamethonium administration completely abolished the pressor response. Local anesthesia of molar regions significantly reduced the pressor response to 27 ± 10%. Gadolinium (mechanoreceptor blocker of group III muscle afferents) entrapment in masticatory muscles also significantly reduced the pressor response to 62 ± 7%. Although atropine methyl nitrate administration did not change the pressor response, a significant dose-dependent augmentation of heart rate was observed. These results indicate that both periodontal membrane and mechanoreceptors in masticatory muscles are the receptors for the pressor response, and that the afferent and efferent pathways of the pressor response pass through the trigeminal afferent nerves and sympathetic nerves, respectively.
KeywordsTeeth clenching Pressor response Periodontal membrane Mechanoreceptor Trigeminal afferent nerve Sympathetic nerve
The authors would like to thank Dr. Kohsuke Hagisawa and Dr. Hiroyuki Ohta for helpful discussion. The authors are also grateful to the staff of the Department of Oral and Maxillofacial Surgery, and Associate Professor Takaichi Fukuda and the staff of the Center for Laboratory Animal Science, National Defense Medical College for technical assistance.
Compliance with ethical standards
Conflict of interest
No conflicts of interest, financial or otherwise, are declared by the authors.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures involving animals performed in this study were in accordance with the ethical standards of the institution or practice at which the study was conducted.
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