| Project/Area Number |
02670030
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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 |
神経解剖学
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| Research Institution | Toho university |
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Principal Investigator |
INOMATA Kenichirou Toho Univ. Sch. of Med., Prof., 医学部, 教授 (20116388)
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| Co-Investigator(Kenkyū-buntansha) |
NASU Fumio Toho Univ. Sch. of Med., Assistant, 医学部, 助手 (10180530)
IGARASHI Hiroaki Toho Univ. Sch. of Med., Assistant, 医学部, 講師 (20120230)
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1990: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | pain-neurons / pain-development / dorsal root ganglion / dorsal horn of spinal cord / degeneration / senescence / 痛みニュ-ロン / 変性 / 脊髄後根神経節 / 脊髄前角 / 変性産物 |
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| Research Abstract |
Capsaicin's actions, a drug which appears to act on the primary sensory neuron from polymodal receptors to the dorsal horn of spinal cord, have a selective effect on the non-myelinated fibers containing substance P, the transmitter for pain. That is to say, the fundamental action of capsaicin releases the substance P from the primary sensory neuron and induces the pain-relief effect. Changes of thiamine monophosphatase (TMPase) activity under the neonatal capsaicin treatment resulted in an irreversible impairment of the function of chemo-sensitive primary sensory neurons. The following results proved to be in an immature state of the primary sensory neurons; (1) the formation of synapses in the central terminal of primary sensory neurons between the postnatal second and seventh day; (2) the appearance of TMPase activity at the postnatal day 2; (3) the synaptic formation after the myelination of small fibers; (4) the apparent myelination after the birth. The capsaicin treatment under the mature states of neurons acted selectively on primary sensory neurons in an reversible appearance. However, capsaicin's broder spectrum of actions in the neonate were due to the immature or undifferentiated states of neurons at this stage of development, as developing neurons were more susceptible to a variety of disturbances. The dynamic appearance of pain-neurons on aging stages was investigated using the experimental animals of accelerated senescence (SAM P-8). On the semi-sections of epoxy-treatment, toluidine-blue-positive bodies were observed in the cytoplasm of spinal ganglion neurons. The following findings were observed by electro-microscopic investigation; (1) the high dense bodies; (2) the lipo-fuscin-like bodies; (3) the myelin-like bodies; (4) the size of vesicles or vacuoles. We couldn't found out remarkable findings with the immuno-histochemical investigation. The lipofuscin-like bodies suggested the dynamic appearance of senescent neurons.
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