1995 Fiscal Year Final Research Report Summary
Change of opioid receptor binding nature in rat brain and spinal cord following acute or chronic noxious stimulation
| Project/Area Number |
06671512
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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 |
Anesthesiology/Resuscitation studies
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| Research Institution | Gifu University School of Medicine |
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Principal Investigator |
OHTA Shuichiro Gifu University School of Medicine, Department of Anesthesiology and Critical Care Medicine, Assistant Professor, 医学部附属病院, 講師 (50144027)
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| Co-Investigator(Kenkyū-buntansha) |
NOZAKI Masakatu The Foundation of Research Institute for Production Development, Senior chief re, 参与 (30021380)
DOHI Shuzi Gifu University School of Medicine, Department of Anesthesiology and Critical Ca, 医学部, 教授 (40155627)
SHIMONAKA Hiroyuki Gifu University School of Medicine, Department of Anesthesiology and Critical Ca, 医学部, 助教授 (90135202)
NIWA Masayuki Gifu University School of Medicine, Department of Pharmacology, Assistant profes, 医学部, 講師 (40156146)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Opioid receptor / Receptor binding assay / Morphine / Noxious stimulation / Formalin / Carrageenan / complete Freund's adjuvant |
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| Research Abstract |
Although previous reports demonstrated the regulation of opioid and their receptor in nociception, it is not clear how nociceptive activation may alter opioid receptor binding nature. We determined the change of mu, delta and kappa opioid receptor types in brain and spinal cord homogenates obtained from animal models received nociceptive treatment.
1) Rats received a subcutaneous injection of formalin, carageenan or Freund's complete adjuvant into planter aspect of a hindpaw. These agent-injected animals were observed for a apperance of pain-related behavior (guarding of the treated paw) within 2-3 hour after treatment. Following these pain behavior, rats were decapitated and brain and spinal cord rapidly removed.
2) The binding of ^3H-DAGO (mu agonist), ^3H-DPDPE (delta agonist) and ^3H-EKC(kappa agonist) to brain and spinal cord membranes prepared from nociceptive treatment and control rats was determined. Using these tracer ^3H-opioid ligands, we failed to see any change in the total number of opioid binding sites (Bmax values)or the affinity constant(Kd values)for binding in whole brain and spinal cord.
These results indicate that in these animal models which use experimentally induced inflammation to stimulate a condition of nociception, there appears to be no alteration in the levels of mu, delta or kappa binding sites.
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