許多研究已經指出長期運動訓練可增進學習記憶及長期增益現象(一種至今最受青睞的學習與記憶之神經生物學模式)。一直以來，血清素系統被認為扮演了一個抑制恐懼記憶形成的角色。一篇近期的研究報告指出，四週跑步機運動訓練可藉由抑制杏仁體及海馬這兩個與被動迴避試驗學習高度相關的腦區中之血清素系統，來增強大白鼠對被動迴避試驗的學習。然而長期運動訓練是否亦透過抑制血清素系統來增強杏仁體及海馬的長期增益現象則不得而知。因此在本研究中，我們利用胞外電生理紀錄及藥理學的方法，探討四週跑步機運動對於高頻電刺激所誘發大白鼠杏仁體側核與海馬齒狀回長期增益現象的影響作用，以及血清素系統在這些影響作用中所扮演的角色。我們的結果顯示，四週跑步機運動可增強雄性大白鼠高頻電刺激所誘發的杏仁體側核及齒狀回之長期增益現象。此外，投予8-OH-DPAT(一種血清素1A受體促效劑)，則可以消除運動增強杏仁體側核及齒狀回長期增益現象的效果。綜合上述，運動訓練可增強杏仁體側核及齒狀回之長期增益現象，且此增強作用可能是經由降低此二腦區中血清素1A受體的活化程度而達成的。

Several studies have indicated that chronic exercise training facilitates learning and memory as well as long-term potentiation (LTP), the best-described neurobiological substrate of learning and memory to date. It has been suggested that the serotonin (5-HT) system plays a suppressing role in fear memory formation. A recent study has shown that four-week treadmill exercise enhances passive avoidance (PA) learning in rats by down-regulating the 5-HT system in the amygdala and hippocampus, brain areas highly associated with PA learning. However, whether chronic exercise training can improve LTP in the amygdala and hippocampus through down-regulation of the 5-HT system is still unknown. In the present study, we used the extracellular electrophysiological recording technique and pharmacological methods to characterize the effects of four-week treadmill exercise on high-frequency stimulation (HFS)-induced LTP in the rat lateral amygdala (LA) and hippocampal dentate gyrus (DG), as well as the role that the 5-HT system plays in these effects. Our results revealed that four-week treadmill exercise enhanced both HFS-induced LA- and DG-LTP in male rats. Moreover, bath perfusion of 8-hydroxy-di-n-propylaminotetralin (8-OH-DPAT), a 5-HT1A receptor agonist, abolished exercise-induced enhancement of LA- and DG-LTP. In summary, these data demonstrate that exercise training promotes LA- and DG-LTP, and the promoting effect of exercise training on LTP in these two brain regions may act through attenuating the activation of 5-HT1A receptors.

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