| Project/Area Number |
12671798
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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 |
Functional basic dentistry
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
HAYASHI Haruhide TOHOKU UNIVERSITY, GRADUATE SCHOOL OF DENTISTRY, PROFESSOR, 大学院・歯学研究科, 教授 (90107293)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2001: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | NK-1 receptor / nociceptine neuron / C-fiber response / pain / raphe magnus / descending inhibition / spinal dorsal horn / nociception / 慢性炎症性疼痛動物 / α_2受容体 / Yohimbine |
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| Research Abstract |
NK-1 receptor antagonist inhibited the late discharges evoked by C-fiber input in the spinal nociceptive neurons, suggesting the role of substance P in acute pain. The antagonist, however, failed to inhibit them in the majority of spinothalamic neurons. This experiment was aimed to investigate the role of NK-1 receptor in the spinal interneurons during the descending inhibition via the nucleus raphe magnus (NRM).
Under pentobarbital sodium anesthesia (50 mg/kg) and immobilization with pancronium bromide, single unit recordings were made from the nociceptive specific or wide dynamic range neurons in the lamina I of lumber dorsal horn of Wistar rats. They were tested for projections to C_3 or higher levels of brain and the late discharges (100-400 ms) evoked by electrical stimulations of the receptive fields and the effects of NRM electrical stimulations (a train of 20 pulses, 0.2 ms duration, 40 Hz). After physiological characterization, a dose of 18-37 nmol of RP-67580 (rat NK-1 receptor antagonist) was applied onto the cord surface and washed out after 10-20 min. The C-discharges were counted every 10-15 min for 60-90 min.
Sixty three neurons were recorded and 43 interneurons were analyzed. A significant relationship was found between the magnitudes of maximum inhibitions by the antagonist and NRM stimulation (correlation 0.73).
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