| Project/Area Number |
63570920
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
補綴理工系歯学
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| Research Institution | Showa University |
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Principal Investigator |
SHINYA Akiyuki Showa University, School of Dentistry, LECTURER, 歯学部, 講師 (10119208)
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| Co-Investigator(Kenkyū-buntansha) |
TSURUOKA Masayoshi Showa University, School of Dentistry, LECTURER, 歯学部, 講師 (60103305)
MATSUI Yoichiro Showa University, School of Dentistry, PROFESSOR, 歯学部, 教授 (60034170)
FURUYA Ryoichi Showa University, School of Dentistry, ASSOCIATE PROFESSOR, 歯学部, 助教授 (80092435)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | TEMPOROMANDIBULAR JOINT SYNDROME / PAIN / TRIGEMINAL SUBNUCLEUS CAUDALIS / RAT |
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| Research Abstract |
The physiological properties of the afferent fibers from the masseter muscle ( MM ) and temporomandibular joint ( TMJ ) to the caudal part of the spinal trigeminal nucleus were studied using a microelectrode technique in rats. When the electrical stimulation was applied to MM the evoked potentials were recorded with a shorter latency ( about 1.4 ms, : SR ) or a longer latency ( about 6, 2 ms, : LR ). The conduction velocities of these responses were in the range of that of A-delta fibers, Although the SR and LR were recorded from the superficial layers of the trigeminal subnucleus caudalis, only the SR were recorded from the adjacent reticular formation The relationship between the amplitudes of these responses and the stimulus intensities almost followed the power function with the exponent of about 2.7 , 1.9 and 7,0 , respectively. These results suggest that at least three types of neurons contribute to transmit the nociceptive informations to the central nervous systems.
According to the responsiveness to natural stimulation in MM and/or TMJ, these neurons could be classified in following three groups : low threshold mechanoreceptive neurons ( LTM ) excited by only innocuous stimuli ; nociceptive specific neurons ( NS ) excited by only noxious stimuli ; wide dynamic range neurons ( WDR ) excited by both. The most of these neurons ( 108/135 ) received afferent inputs from both MM and TMJ. Moreover, 79% of these convergent neurons received nociceptive information from MM and/or TMJ. The results suggest that convergent caudalis neurons should play an important role in complicated pain sensation, as referred pain, associated with dysfunction of the masticatory systems.
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