1999 Fiscal Year Final Research Report Summary
Morpho-functional study of nitric oxide synthase-positive neurons in the brain stem that are involved in oral sensori-motor function.
| Project/Area Number |
09671852
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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 |
Morphological basic dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
TAKEMURA Motohide Osaka University Faculty of Dentistry, Osaka University, Assistant Professor, 歯学部, 講師 (70192169)
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| Co-Investigator(Kenkyū-buntansha) |
NAGASE Yoshitaka Osaka University Faculty of Dentistry, Osaka University, Research Associate, 歯学部, 助手 (50252698)
YONEHARA Norifumi Osaka University Faculty of Dentistry, Osaka University, Assistant Professor, 歯学部, 講師 (70124534)
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| Project Period (FY) |
1997 – 1999
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| Keywords | nitric oxide / NADPH-diaphorase / trigeminal nucleus / sensory / motor / regeneration / neurotoxicity / pain |
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| Research Abstract |
Neurons that express neuronal nitric oxide synthase (nNOS) or Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) are considered to produce nitric oxide (NO) on demand. NADPH-d activity and the spatial distribution were characterized histochemically with nerve insults and the WGA-HRP-labeled central terminal fields from the intra- and peri-oral afferents. In the subnucleus caudalis (SpVc), most labeled neurons were in the superficial zone, and smaller numbers were in the magnocellular zone. The NADPH-d-positive neurons in the SpVo/Sn and the dorsomedial SpVc overlapped mostly with the transganglionically labeled terminal field from the lingual nerve, partly with the terminal field from the inferior alveolar, mental and chorda tympani nerves. A statistically significant reduction in the number of NADPH-d-positive neurons was seen bilaterally in SpVo/Sn when the lingual nerve was transected. Inflammatory insults to the lingual nerve and/or tooth pulps significantly increased
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the number of NADPH-d-positive neurons in SpVo/Sn, and SpVc. Thus NADPH-d-positive neurons in the SpVo/Sn and SpVc could receive and be regulated by primary afferent inputs from intra-oral structures especially from the tongue. Activity of nNOS that expressed in primary neurons after nerve transection is involved in nerve regeneration. Because systemic administration of L-nitro arginine methyl ester (L-NAME; NOS blocker) decreased the number of regenerated inferior alveolar nerve into the tooth pulp. Injection of complete Freund's adjuvant (CFA) into hind foot pad induces prolonged hyperalgesia for more than one week. Three days after injection of CFA the number of NADPH-d or NOS-positive neurons increased in the L4-5 dorsal horn. Administration of L-NAME reduced adjuvant induced prolonged thermal hyperalgesia but not normal nociception and acute hyperalgesia. Thus increased NO in the spinal dorsal horn could be involved in maintenance of hyperalgesia and/or prolonged pathological nociception. Less
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