Subtypes of nociceptive units in the rat temporomandibular joint |
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Authors: | Takeuchi Yoshinari Toda Kazuo |
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Institution: | Maxillofacial Surgery, Maxillofacial Reconstruction, Division of Maxillofacial and Neck Reconstruction, Graduate School, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8549, Japan. |
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Abstract: | Response properties of nociceptors in the rat's temporomandibular joint (TMJ) were investigated using an in vitro TMJ-nerve preparation. Recordings were obtained from 33 nociceptive units that responded to mechanical, chemical, and/or thermal stimuli. According to both characteristics of nociceptors and afferent fibers, nociceptive units in the TMJ area were classified into the following four subtypes: Adelta-high-threshold mechanonociceptor (HTM) (12.1%), Adelta-polymodal nociceptor (POLY) (36.4%), C-HTM (12.1%), and C-POLY (39.4%). The mean mechanical threshold of the Adelta units was significantly lower than that of the C units. Bradykinin increased the discharge of Adelta- and C-POLY units. No significant differences of thermal thresholds between Adelta and C units were found. The percentage of Adelta units was 47.2% and of C units was 52.8%, respectively. In the TMJ area, POLY units were predominant (75.8%), suggesting that inflammatory reactions can easily evoke pain sensation. |
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Keywords: | Temporomandibular joint Nociceptor Polymodal unit In vitro Rat |
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