| Project/Area Number |
61570893
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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 |
Functional basic dentistry
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| Research Institution | Showa University |
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Principal Investigator |
HAMBA Michiko Department of Physiology, School of Dentistry, 歯学部, 講師 (40119251)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | arcuate nucleus / electroacupuncture analgesia / Opioids / 針刺激 |
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| Research Abstract |
To evaluate the possible role of the arcuate nucleus of hypothalamus (ARH) in the antinociceptive system, the following experiments were carried out, using male Wistar rats. 1) The effect of ARH lesion on pain control and electroacupuncture (EA) analgesia. The ARH-lesioned rats showed a significantly high value in pain rating of the formalin test 30 days after, indicating that they were hypersensitive to nociceptive stimuli. An analgesic effect was induced in the control rats by EA stimulation (3 Hz, 300-600 <micr>A) applied at Ho-Ku, but scarcely seen in the lesioned rats. 2) EA effect on the neuronal activity of ARH. The majority of ARH neurons significantly changed their spontaneous frequency rates (the rate increased or decreased) by EA stimulation. The activity change lasted for about 60 min and its time course agreed with that of the analgesic effect of EA. It suggested that the majority of ARH neurons took part in the analgesia. 3) Relationship between tha analgesic effect of the EA and the possible involvement of endogenous opioids. The analgesic effects and the neuronsl change in ARH induced by EA stimulation were both antagonized by injected naloxone (1mg/Kg, i.p.).<bat>-endorphin in the medialbasal hypothalamus was significantly higher in the animal group immediately killed after reciving EA stimulation for 15 min than in the control animal group. 4) The effect of ARH stimulation on the neuronal activity of the lateral hypothalamic area (LHA). ARH stimulation (20-45 <micr>A, 1-3 Hz, 30 s) induced the suppressive effect on the spontaneous activity of the neurons in the LHA and on the response of the LHA neurons to noxious stimuli. ARH resion thus appears to be an important part in the central pain control system and in the induction of EA analgesia.
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