| Project/Area Number |
11680744
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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 |
Nerve anatomy/Neuropathology
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| Research Institution | Shiga University of Medical Science (2000)
Fujita Health University (1999) |
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Principal Investigator |
ARAI Ryohachi Shiga Univ.of Medical Science, School of Medicine, Professor, 医学部, 教授 (20159487)
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| Co-Investigator(Kenkyū-buntansha) |
HIDA Takehiko Fujita Health University, School of Medicine, Associate Professor, 医学部, 助教授 (20097736)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Noradrenergic neuron / Serotoninergic neuron / Dopaminergic neuron / Mo-noamine oxidase / Sympathetic neuron / Intermediolateral nucleus / 交感神経 / 自律神経 / 脊髄 / 側角 |
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| Research Abstract |
We examined monoamine oxidase (MAO) activity in the intermediolateral nucleus (IML) of the rat thoracic spinal cord by histochemistry with tyramine as a common substrate for both MAO types A and B.Light microscopy showed MAO activity in neuronal cell bodies, processes, and varicosities. Electron microscopic examination showed both MAO-positive and-negative neuronal cell bodies. MAO histochemistry in the IML was also performed using serotonin (a MAO type A preferential substrate) and β-phenylethylamine (a MAO type B preferential substrate). Light microscopy identified MAO activity for serotonin in a plexus of varicosities but not in any neuronal cell bodies. The activity for β-phenylethylamine was detected frequently in neuronal cell bodies but rarely in varicosities. Our findings indicate that two groups of sympathetic preganglionic neurons can be chemically distinguished, one contains MAO type B while the other lacks both MAO types A and B.
We also examined by immunohistochemistry the effects of MAO inhibition on the content of dopamine (DA) and noradrenaline (NA) in locus coeruleus (LC) neurons of the rat. Rats treated with intraperitoneal injections of pargyline, an MAO inhibitor, showed significantly stronger DA-and NA-staining intensities in LC neurons compared to normal rats. In LC noradrenergic neurons, it is believed that DA is formed in the cytoplasm and then transported into the storage vesicles where it is converted to NA, and the secreted NA is recycled by a reuptake mechanism and transported back into storage vesicles via the cytoplasm. Furthermore, LC neurons of the rat have been shown to contain DA-and NA-degrading MAO activities on the outer membranes of the mitochondria. Therefore, our findings suggest that endogenous MAO degrades not only part of the DA formed in the cytoplasm of LC neurons, but also part of the secreted NA that has been transported back into the cytoplasm.
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