| Project/Area Number |
05454497
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
NAKAMURA Yoshio Tokyo Medical and Dental University, Department of Physiology, Professor, 医学部, 教授 (10010026)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1993: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Keywords | rats / newborn / in vitro / brainstem-spinal cord preparation / sucking / rhythm / hypoglossus / NMDA / glutamate / 呼啜リズム / 三叉神経 / セロトニン |
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| Research Abstract |
The recent development of in vitro CNS preparations of mammals has provided important tools for physiological investigation of central rhythm generation of respiration and locomotion. The aim of this research was to induce rhythmical oro-facial motor activities in an isolated brain of mammals, by the use of an in vitro brainstem-spinal cord preparation from 0-4 day-old rats, some of which were isolated together with the oral-facial organs, in a modified Krebs solution at 26ﾟC.Neural activities were monitored from the hypoglossal (XII) nerve as well as the ventral roots of the fourth or fifth cervical spinal cord (C4-5) with suction electrodes, and EMG was recorded from the tongue muscle with wire electrodes. Tongue movements were also recorded with a CCD camera system. Bath application of various neuroactive substances revealed the following results : (1) N-methyl-D-aspartate (NMDA) induced rhythmical burst activities in the XII nerve as well as in the tongue muscle, representing sucking-like tongue movements (rhythmical elevation of the tip with depression of the body) ; (2) these rhythmical activities were distinct from spontaneous respiratory activities, and had a shorter cycle lengty (from 2.5 to 6.0 seconds) than that of respiration (more than 10.0 seconds) ; (3) the NMDA-induced rhythmical activities were completely blocked with simultaneous application of DL-2-amino-5-phsphonovalerate (DL-AP5). The results demonstrate that, in an isolated brainstem-spinal cord preparation from newborn rats, NMDA can induce rhythmical activities in the XII motoneurons, reminiscent of sucking movements. This in vitro preparation will be useful for the investigation of neural mechanisms underlying the central rhythm generation of food ingestive movements including sucking.
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