| Project/Area Number |
07671552
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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 |
Cerebral neurosurgery
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| Research Institution | Kinki University |
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Principal Investigator |
KURODA Ryotaro Kinki University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (10161803)
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| Co-Investigator(Kenkyū-buntansha) |
NIIYAMA Kazuhide Kinki University, School of Medicine, Dept.of Neurosurgery, Assistance, 医学部・脳神経外科, 助手 (50228136)
KONDO Sumio Kinki University, School of Medicine, Dept.of Neurosurgery, Assistance, 医学部・脳神経外科, 助手 (30225619)
YORIMAE Akira Kinki University, School of Medicine, Dept.of Neurosurgery, Instructor, 医学部・脳神経外科, 講師 (90210799)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | Pain / c-fos / electrical stimulation of motor-sensory cortex / trigeminal nerve / formalin-induced pain / ホルマリン発痛 / 中枢神経 |
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| Research Abstract |
Objective :
Expression of the proto-oncogene c-fos has been demonstrated in CNS neurons to be a "third messenger" in long term response to painful stimuli and to be useful as a metabolic marker of brain activity. On the other hand, electrical stimulation of the motor cortex was reported to alleviate the intractable pain. Mechanism of this cortical stimulation therapy has not well recognized. We, therefore, examined the stimulation effect in the sensory-motor cortex on expression of c-fos after formalin injection into the trigeminal periphery of the rat.
Methods :
After induction of urethane anesthesia, either 0.1ml of 5% formalin or physiological saline was injected into the right mandibular region of the trigeminal nerve in each five rats. Electrical stimulation (1mA,10Hz) in the left sensory-motor cortex for the period of one hour was applied two hours after the facial injection of formalin or saline in another five rats each. All these rats were perfused and fixed three hours after the
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facial injection and processed immuno-histochemicaly to visualize c-fos expression in CNS.The number of Fos positive neurons in the nucleus caudalis of spinal trigeminal nucleus was statistically analyzed in each group using ANOVA methods.
Results and Conclusion :
Formalin injection induced c-fos expression strongly in I/II layr of the trigeminal caudalis nucleus of the same side, compared with the saline injection group. C-fos was also expressed in the brain stem, hypothalamus and cerebral cortex in both groups. The electrical stimulation induced c-fos expression in the cerebral cortex of the stimulated side, compared with the contralateral side. ANOVA demonstrated that electrical stimulation reduced significantly the expression of c-fos in the I/II layr of the caudalis nucleus, while increased the expression in the III/IV layr of the formalin injected rats, compared with other groups.
This fact suggests that cortical stimulation suppresses the activity of small neurons in the I/II layr and enhances large neurons in the III/IV layr of the trigeminal caudalis nucleus, which is reminiscent of the gate theory. Electrical stimulation also activated the cortical neurons not only in the sensory-motor area, but in the neighboring areas. The full significance of this study and mechanism of the motor cortex stimulation therapy are still to be studied. Less
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