碩士 / 國立成功大學 / 行為醫學研究所 / 89 / The transcription factor cAMP responsive element binding (CREB) is essential for long-term memory. However, it is unknown which specific genes are downstream of CREB during memory formation. CREB can be activated by the cAMP/protein kinase A (PKA) signaling pathway. In this study, the effect of CREB activity modulation on memory performance for the inhibitory avoidance learning in rats was firstly examined by intrahippocampal infusion of the PKA agonist, Sp-cAMPS, and antagonist, Rp-cAMPS. Results showed that intrahippocampal infusion of Rp-cAMPS 3 hr but not immediately after training significantly impair memory performance. Unexpectedly, intrahippocampal infusion of Sp-cAMPS immediately or 3 hr after training did not enhance memory performance. The candidate genes downstream of CREB after inhibitory avoidance learning were then studied in the hippocampus. Tissue plasminogen activator (tPA) and fibronectin genes, which contain cAMP response elements in their promoters, were examined. Ribonuclease protection assay revealed that tPA mRNA levels in the hippocampus of rats tested 3, 6, and 24 hr after training were significantly higher than those of naive animals. Increases of tPA mRNA expression at 3 hr after learning are specific for memory processing since behavioral handling or electric shock alone did not induce the expression of tPA gene. Fibronectin mRNA was increased at 3 hr after learning, but did not reach the significant level. The fibronectin mRNA also did not increase 6 or 24 hr after learning. These results suggest that the cAMP/PKA signaling pathway is involved in the late phase of memory processing of the inhibitory avoidance learning and tPA and fibronectin genes are differentially regulated during this phase for this kind of learning task.
| Identifer | oai:union.ndltd.org:TW/089NCKU0666002 |
| Date | January 2001 |
| Creators | Chien Hui Hung, 洪千惠 |
| Contributors | A- Min Huang, 黃阿敏 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 52 |
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