1998 Fiscal Year Final Research Report Summary
Age - related modifications of effects of ketamine and propofol on rat hippocampal acetylcholine release studied by in vivo brain microdialysis
| Project/Area Number |
09470334
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | Yokohama City University |
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Principal Investigator |
OKUMURA Fukuichiro Yokohama City University, School of Medicine, Professor, 医学部, 教授 (50028487)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Tatsuaki Yokohama City University Hospital, Faculty Member, 医学部・付属病院, 助手 (70285138)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Microdialysis / Acetylcholine / Anesthetics / Propofol / Ketamine / Aging / Hippocampus |
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| Research Abstract |
Background : Hippocampal cholinergic neurons are supposed to be involved in learning and memory. There has been no report on age-related modifications of cholinergic neurotransmitter action by anesthetics. The aim of this study was to examine age-related modifications of the effects of ketamine and propofol on rat hippocampal acetylcholine (ACh) release.
Methods : The experiments were performed on male Wistar young rats (two months old) and aged rats (18 months old), using in vivo brain microdialysis technique under freely moving condition. After sampling initial three collections, test drugs were administered. The ACh release was determined by HPLC-ECD method.
Results : In aged rats, the hippocampal basal ACh release was significantly lower than in young rats. Ketamine 25 mg kg-1 i.p. increased the hippocampal ACh release in young rats to 181% of the basal release, while in aged rats the same dose of ketamine i.p. increased the hippocampal ACh release to 229 % of the basal release. On the other hand, propofol 25 mg kg-1 i.p. produced inhibitory effects on the hippocampal ACh release in young rats (by 39 %) and in aged rats (by 48 %). Although the maximal inhibitory peak effects of propofol did not differ significantly between young and aged rats, decrease of the hippocampal ACh release in aged rats persisted longer than in young rats.
Conclusion : Ketamine produced more pronounced facilitatory effects on the hippocampal ACh release in aged rats, as compared to in young rats. On the other hand, propofol has inhibitory effects on the hippocampal ACh release in young and aged rats and aging process may suppress the abilities to recover from inhibitory anaesthetic state induced by propofol.
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