1999 Fiscal Year Final Research Report Summary
Function of Receptors of neuroactive Substances in the ascending neurons conveying oro-facial, visceral and derma pain
| Project/Area Number |
10671733
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Functional basic dentistry
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
HAYASHI Haruhide School of Dentistry, Tohoku University, Professor, 歯学部, 教授 (90107293)
|
|---|
| Project Period (FY) |
1998 – 1999
|
| Keywords | NK-1 receptor / nociceptive neuron / C-fiber response / spinal dorsal horn / pain / substance P / chronic information animal / spinothalamic neuron |
|---|
| Research Abstract |
The effects of local spinal application of new, specific NK-1 receptor antagonist for rodents, RP-67580 on the electrically-evoked late discharges of spinothalamic and non-projection neurons in the rat superficial spinal dorsal horn were examined.
Under pentobarbital sodium anesthesia, single-unit recordings were made from the nociceptive neurons in lamina I of the lumber spinal cord. They were tested for the projections to thalamus and cervical cord (C3) and for the late discharges evoked by electrical stimulation of the receptive fields. Doses of 0.4-37 nmol of RP-67580 were applied directly onto the cord surface close to the recording site. Drug effects were examined every 10-30 min for 30-180 min. they also were tested for the effects of NRM electrical stimulations (a train of 20 pulses, 0.2 ms duration, 40Hz).
The rate discharges of majority of non-projection neurons were inhibited by the application of RP-67580. On the other hand, the responses of the majority of spinothalamic neurons were not affected or rather increased. A significant relationship was found between the magnitudes of maximum inhibitions by the antagonist and NRM stimulation (correlation 0.73).
This study demonstrated that RP-67580 inhibited the C-evoked discharges of the nonprojection neurons selectively. The results suggest that the role of SP was different between the spinothalamic and non-projection neurons, and that SP plays an important role in nociceptive transmission or modulation mediated by primary afferent C-fibers mainly in the interneurons in normal acute pain. This study also demonstrated that the nociceptive responses mediated by NK-1 receptor are inhibited by NRM stimulation.
|
