Noguchi Makiko, Kurose Masayuki, Yamamura Kensuke, Inoue Makoto, Taguchi Yo, Sessle Barry J, Yamada Yoshiaki
Division of Oral Physiology, Department of Oral Biological Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan.
Brain Res Bull. 2005 Oct 15;67(3):182-8. doi: 10.1016/j.brainresbull.2005.06.013.
The aim of this study was to determine the effect of unilateral acute inflammation of craniofacial deep tissues on the ipsilateral and contralateral jaw-opening reflex (JOR). The effects of mustard oil (MO), injected into the temporomandibular joint region, were tested on the JOR recorded in the digastric muscle and evoked by low-intensity electrical stimulation of the ipsilateral and contralateral inferior alveolar nerve in anesthetized rats. The MO injection induced a long-lasting suppression of the amplitude of both ipsilaterally and contralaterally evoked JOR, although the latency and duration of the JOR were unaffected. The suppressive effect was more prominent for the contralaterally evoked JOR, and observed even when background activity in the digastric muscle was increased by the MO injection. The results indicate that changes in the JOR amplitude following MO injection do not simply reflect alterations in motoneuronal excitability, and suggest that inflammation of deep craniofacial tissues modulates low-threshold sensory transmission to the motoneurons.
