1999 Fiscal Year Final Research Report Summary
Identification and characterization of enkephalinergic neurons in spinal cord dorsal horn: Single cell RT-PCR analysis
| Project/Area Number |
09680818
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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 |
神経・脳内生理学
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| Research Institution | Dokkyo University School of Medicine |
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Principal Investigator |
HORI Yuuichi Dokkyo University School of Medicine, Department of physiology, Professor, 医学部, 教授 (60190229)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Single cell RT-PCR / Path Clamp Methods / Superficial dorsal horn, / Enkephalin / Reverse Transcripcion / Polymerase Chain Reaction |
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| Research Abstract |
1. We adapted the technique of single-cell reverse transcription- polymerase chain reaction (RT-PCR) for small neurons in the superficial dorsal horn of rat spinal cord slices. Nethionin-enkephalin sequence-specific PCR products were observed in more than half of superficial dorsal horn neurons studied. This is reminiscent of the previous immunohistochemical reports that a high density of enkephalin neurons are present in the superficial dorsal horn
2. Under current clamp conditions, depolarizing current injection stimulated dorsal horn neurons to generate spikes. Characteristically, enkephalinergic neurons usually displayed marked spike accommodation with a progressive prolongation of interspike intervals. In addition, enkephalinergic neurons seldom showed an initial sag upon hyperpolarizing current injection, indicating enkephalinergic neurons lack a time-dependent inwardly rectifying channel.
3. Under voltage clamp conditions, ionic currents evoked by voltage command was investigated. The following potassium currents were observed in enkephalinergic neurons: transient IA currents (in 39 of 46 enkephalinergic neurones studied); Inward rectifier ( in 18 of 39); Ca2+-dependent potassium currents (in 14 of 31); and delayed rectifier (in all enkephalinergic neurones studied).
4. Barbiturates hyperpolarized enkephalinergic neurons and suppressed spike generation in response to depolarizing currents injection.
5. It was also found that mRNA of 5-HT3 receptors was detected in some 40% of enkephalin-containing neurons. It is strongly suggested that enkephalinergic inhibitory neurons mediate Serotonin-induced spinal analgesia, owing at least partly to activation of 5-HT3 receptors expressed in enkephalinergic neurons.
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