| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Research Abstract |
Electrophysiological study:
I studied the role of spinal PAC1 receptor on the nociceptive information transmission using an isolated neonatal rat spinal cord preparation. Application of maxadilan to the spinal cord, a PAC1 receptor agonist, resulted in a long lasting ventral root depolarizaion in a dose dependent manner. An application of Max.d.4, a PAC1 receptor antagonist, to the spinal cord produced the depressant effect on the dorsal root evoked slow ventral root potential (slow VRP) in a dose dependent manner. These results suggested that PAC1 receptor in the rat neonatal spinal cord plays an important role in the nociceptive information transmission.
Behavioral and Immunohistochemical Study
I examined the role of the opioid receptor like 1 (ORL1) receptor on the nociceptive transmission and thfe expression of Fos-like immunoreactivity of the spinal cord. Intrathecal injection of nociceptin, an ORL1 receptor agonist, depressed the agitation behavior induced by paw formalin injection and inhibited the expression of Fos-like immunoreactivity in the laminae I-II of L5 rat spinal cord. In the study of neuropathic pain model, pre-emptively administered nociceptin delayed the development of thermal hyperalgesia induced by the chronic constriction injury of the sciatic nerve, but not by the partial sciatic nerve injury and depressed the expression of Fos-like immunoreactivity induced by the chronic constriction injury of the sciatic nerve, but not by the partial sciatic nerve injury. These data suggested that activation of spinal ORL1 receptor suppressed the nociceptive transmission in the rat spinal cord.
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