臺灣博碩士論文加值系統

恐懼（fear）進程可略分為恐懼制約（conditioning）及消除（extinction），恐懼消除係指習得對恐懼制約刺激（conditioned stimulus）不再感到害怕的現象。恐懼進程主要涉及腦區有，杏仁核（amygdala）、海馬迴（hippocampus）以及前額葉皮質（prefrontal cortex）。特別是杏仁核，主要表達恐懼及建立恐懼制約，其子腦區基底外側杏仁核（basolateral amygdala, BLA）更是參與恐懼記憶的儲存、恐懼消除記憶的獲得及表現，但其神經生化機制仍尚未被釐清。神經傳遞物質也參與恐懼進程調控，近年來研究指出杏仁核多巴胺（dopamine, DA）系統在恐懼制約間扮演關鍵角色，但對於恐懼消除上的調控作用仍尚未釐清。因此，本研究利用在大鼠雙側基底外側杏仁核微注射（micro-infusion）多巴胺及多巴胺D1 [ SCH23390（dopamine D1R antagonist, SCH）]與D2接受器 [ raclopride（dopamine D2R antagonist, Rac）]拮抗劑（antagonist），探討基底外側杏仁核在恐懼消除後多巴胺系統扮演之角色及其下游共同路徑的蛋白 (p-PKA、PKA、p-CREB、CREB) 表現。研究結果證實基底外側杏仁核中的多巴胺有助於恐懼表達，而當多巴胺D1接受器與D2接受器遭阻斷後會導致恐懼表達及恐懼消除的學習機制受損，並且推測基底外側杏仁核中的多巴胺系統在對恐懼表達及恐懼消除機制調控上是必須透過多巴胺D1R與D2R共同所調節，且p-CREB的活化是恐懼消除的關鍵步驟。

Fear response involves neuronal circuit of hippocampus, prefrontal cortex, and especially basolateral amygdala (BLA). BLA closely participates in the fear memory and is mediated by mesolimbic dopaminergic system. However, the role of BLA dopaminergic system in mediation of expression and extinction in conditioned fear is less understood. This study aims to investigate the roles of BLA dopaminergic system and D1 and D2 receptors associated PKA-CREB pathway during fear expression and extinction by employing cue-dependent fear conditioning and bilateral BLA-micro-infusion technique in rats. We used bilaterally guide cannula which were implanted in male Sprague-Dawley rats in the BLA. The 2-day paradigm of cue-dependent fear conditioning [Day1: fear conditioning (CS+US), Day2: fear extinction (CS only)] was employed to measure the freezing behavior (referring to the degree of conditioned fear). The rats received bilateral BLA-micro-infusion with dopamine, SCH23390, or raclopride before the fear extinction test. The rats were then sacrificed and their brains were removed at different time points (0h, 1h and 3h after extinction) to analysis protein expression of PKA-CREB pathway. In conclusion, we demonstrated that BLA dopamine may be elevated the fear expression of conditioned fear and blockade of dopamine D1, D2 receptor in BLA would impair fear expression and extinction learning. Finally, BLA dopaminergic system mediates the mechanism of fear expression and extinction via D1 and D2 receptors. Furthermore, p-CREB is a critical step in fear extinction mechanism.

第一章 前言 1
第一節 何謂恐懼 1
第二節 恐懼迴路及調控 1
壹、杏仁核 2
貳、海馬迴 4
參、前額葉皮質 4
第三節多巴胺及其參與之恐懼調控機制 5
壹、多巴胺與恐懼進程 6
貳、多巴胺接受器及其下游傳遞路徑 6
第四節 研究假說 8
第二章 研究目的 10
第三章 材料與方法 11
第一節 實驗動物 11
第二節 實驗設計與方法 11
壹、實驗設計 11
貳、實驗流程 12
參、實驗藥物與分組 12
肆、腦區定位埋管手術 13
伍、動向活動力測試 15
陸、提示依賴性恐懼制約-消除試驗 15
柒、西方墨點法 17
一、藥品配製 17
二、蛋白質萃取 19
第三節 統計方法 18
第四章 研究結果 20
第一節 基底外側杏仁核埋管後對大鼠活動力之影響 22
第二節 提示依賴性恐懼制約-消除試驗之凍結行為表現 22
第三節 給予多巴胺、SCH23390及raclopride對恐懼消除行為之影響 23
第四節 杏仁核腦區中多巴胺D1/D2-PKA-CREB蛋白表現變化量 24
壹、PKA磷酸化 (p-PKA/t-PKA ratio) 活化表現 24
貳、CREB磷酸化 (p-CREB/t-CREB ratio) 活化表現 24
第五章 討論 26
第六章 結論 30
附圖 31
參考文獻 35

圖表目錄
Figure A. 恐懼神經迴路 2
Figure B. 多巴胺D1/D2接受器下游傳遞路徑 7
Figure 1. Locomotor activity was performed in normal rats (Sham) and postoperative rats (Sal-Sal, Sal-DA, SCH-DA, Rac-DA). 31
Figure 2. Cue-dependent fear conditioning-extinction test. 32
Figure 3. Effects of dopamine, SCH23390, raclopride on fear extinction learning. 33
Figure 4. Effects of dopamine, SCH23390, raclopride on PKA and CREB activation after fear extinction test. 34

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