2005 Fiscal Year Final Research Report Summary
Analysis of the roles of NO-cGMP signaling cascade for long-term memory formation in an insect.
| Project/Area Number |
15370031
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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 |
Animal physiology/Animal behavior
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
MIZUNAMI Makoto Tohoku University, Graduate School of life sciences, Associate Professor, 大学院・生命科学研究科, 助教授 (30174030)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Cricket / Olfactory learning / Nitric oxide / Long-term memory / Cyclic GMP / Insect / Cyclic AMP |
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| Research Abstract |
Cyclic AMP pathway plays an essential role in formation of long-term memory (LTM). In some species, the nitric oxide (NO)-cyclic GMP pathway has been found to act in parallel and complementary to the cAMP pathway for LTM formation. The aim of this study was to clarify the roles of the NO-cGMP pathway for the LTM formation. We have studied the signaling cascade underlying LTM formation by systematically co-injecting various 'LTM-inducing' and 'LTM-blocking' drugs in crickets. Multiple-trial olfactory conditioning led to LTM that lasted for several days, while memory induced by single-trial conditioning decayed away within several hours. Injection of inhibitors of the enzyme forming NO, cGMP or cAMP into the hemolymph prior to multiple-trial conditioning blocked LTM, whereas injection of an NO donor, cGMP analogue or cAMP analogue prior to single-trial conditioning induced LTM. Induction of LTM by injection of an NO donor or cGMP analogue paired with single-trial conditioning was blocked by inhibitors of the cAMP pathway, but induction of LTM by a cAMP analogue was unaffected by inhibitors of the NO-cGMP pathway. Inhibitors of cyclic nucleotide gated channel (CNG channel) or calmodulin blocked induction of LTM by cGMP analogue paired with single-trial conditioning, but they did not affect induction of LTM by cAMP analogue. This study suggests, for the first time, that the cAMP pathway is a downstream target of the NO-cGMP pathway for the formation of LTM and that the CNG channel and calcium-calmodulin intervene between the NO-cGMP pathway and the cAMP pathway.
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