We studied the effect of stimulation of the red nucleus (RN) on the jaw-opening reflex (JOR) in anesthetized rats. The JOR was evoked by electrical stimulation of the tooth pulp of a lower incisor, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the RN was found to suppress the JOR bilaterally. Microinjection of monosodium glutamate into the RN also suppressed the JOR bilaterally. The suppressive effect of the magnocellular part of the RN was significantly larger than that of the parvicellular part of the RN. These results imply that the RN is involved in control of the JOR evoked by noxious stimulus.
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http://dx.doi.org/10.1016/j.brainres.2012.07.053 | DOI Listing |
Pain is the anticipated output of the trigeminal sensory neurons that innervate the tooth's vital interior ; however, the contribution of intradental neurons to healthy tooth sensation has yet to be defined. Here, we employ in vivo Ca imaging to identify and define a population of myelinated high-threshold mechanoreceptors (intradental HTMRs) that detect superficial structural damage of the tooth and initiate jaw opening to protect teeth from damage. Intradental HTMRs remain inactive when direct forces are applied to the intact tooth but become responsive to forces when the structural integrity of the tooth is compromised, and the dentin or pulp is exposed.
View Article and Find Full Text PDFAm J Physiol Gastrointest Liver Physiol
March 2024
Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
The external carotid artery (ECA) plays a major role in supplying blood to the head and neck. Although impeded blood flow in the ECA is expected to affect orofacial functions, few studies have shown how blood flow obstruction in the ECA contributes to impairment of these functions, including chewing and swallowing. This study was performed to investigate the effects of ECA ligation (ECAL) on immediate and long-term changes in masticatory and swallowing functions as well as the jaw-opening reflex evoked in the digastric muscle.
View Article and Find Full Text PDFEur J Oral Sci
April 2023
Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, Sagamihara, Japan.
Although eicosapentaenoic acid (EPA) application in vitro inhibits voltage-gated Na (Nav) channels in excitable tissues, the acute local effect of EPA on the jaw-opening reflex in vivo remains unknown. The aim of the present study was to determine whether local administration of EPA to adult male Wistar rats could attenuate the excitability of the jaw-opening reflex in vivo, including nociception. The jaw-opening reflex evoked by electrical stimulation of the tongue was recorded by a digastric muscle electromyogram (dEMG) in pentobarbital-anesthetized rats.
View Article and Find Full Text PDFJ Acupunct Meridian Stud
August 2021
Integrative Sensory Physiology, Institute of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
Background: Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient's age on the effectiveness of electroacupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacupuncture- induced analgesia between juvenile and adult rats.
Methods: In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats.
Background: Marin-Amat syndrome is a rare acquired oculofacial synkinesis first reported in 1918. It manifests as involuntary eyelid closure on jaw opening or on lateral movement of the jaw following a peripheral facial nerve palsy. The increased orbicularis tone due to aberrant connections between the cranial nerve (CN) V and CN VII results in an undesirable wink with major psychosocial impact.
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