2001 Fiscal Year Final Research Report Summary
Fundamental study on the mechanisms and treatments for paresthesia and dysesthesia following traumatic injury of trigeminal nerve
| Project/Area Number |
12671930
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Surgical dentistry
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| Research Institution | Niigata University |
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Principal Investigator |
SEO Kenji Graduate School of Medical and Dental Sciences, Niigata University, Associate Professor, 大学院・医歯学総合研究科, 助教授 (40242440)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Naoshi Faculty of Medicine, Niigata University, Associate Professor, 医学部, 助教授 (70181419)
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| Project Period (FY) |
2000 – 2001
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| Keywords | TRIGEMINAL CAUDALIS / OPTICAL IMAGING / SLICE / RH414 / CNQX / MK-801 / NK1-RECEPTOR |
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| Research Abstract |
It is well known that traumatic injury of trigeminal nerve sometimes follows a long time paresthesia and dysesthesia and we hypothesized that these symptoms might come from the long-term excitation of trigeminal nucleus. Therefore, using high-speed optical imaging technique, we observed the propagation of neuronal excitation in the nociceptive afferent transmission and modulating site the trigeminal subnucleus caudalis (Vc), which was evoked by stimulation of primary afferent fibers.
Medulla was removed from mice or rats, and coronal, sagittal or horizontal sectioned slices of 400 μm thicknesses were stained with a voltage-sensitive fluorescence dye RH414. Fluorescence and differential fluorescence images of a slice preparation were recorded using a high-speed imaging system. The tract of each slice was stimulated directly by single shock or a train of 30 pulses at 100 s^<-1>. Either in the sagittal or coronal slices, membrane excitation evoked by single stimulation of the tract did not expand in any directions. Larger propagations of evoked by the single stimulation to the marginal layer or substantia gelatinosa were observed in the sagittal rather than coronal slices. In contract, in the horizontal slices, propagations of membrane excitation, which were evoked by single stimulation, expanded from the Marginal layer (Mar) to the substantia gelatinosa (SG). And an exposure to CNQX suppressed these propagations. High frequency stimulation induced widely propagated and long-lasting membrane depolarizations within Mar, Mg and Magnocellularis area (Mar). Exposure to MK-801 suppressed the depolarization expansion to SG.
These results suggest that horizontal slice is suitable for the study on the excitation propagation evoked by the afferent fiber stimulation within the trigeminal caudalis. Moreover, these results also support that glutamate might also be a neurotransmitter within the trigeminal afferent pathway in Vc.
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