| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
To clarify the neurochemical basis for intra-operative awareness, the changes of acetylcholine release by the painful stimulation in rat cerebral cortex during general anesthesia were studied using brain microdialysis. The contents in extracellar acetylcholine during anesthesia and after the 4 hours of 5% formalin injection subcutaneously at the hind paw were measured with high performance liquid chromatography.
In non-anesthetized animals, the release of acetylcholine significantly increased to the twice of basal values with peak level at 30-45 minutes after formalin injection and then it gradually declined to the basal level. The acetylcholine release was significantly decreased by 1 MAC of halothane, isoflurane, enflurane, or sevoflurane anesthesia to 7, 16, 5, or 21% of basal values, respectively. However, no significant change of acetylcholine release was observed at the delivery of the pain stimulation under administration of these inhalation anesthetics.
Acetylcholine is one of the major excitatory neurotransmitters in the central nervous system (CNS). Cholinergic neurons have been assumed to play an important role in regulating the state of consciousness, and it has been shown that acetylcholine release in the CNS decreases in the transition from wakefulness to sleep. Therefore, the results of this study provide the neurochemical basis for the fact that the occurrence of intra-operative awareness is less during the administration of inhalation anesthetics than intravenous one.
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