大鼠杏仁核對循環功能調控之電生理、神經解剖及行為研究

Abstract

本研究利用電刺激、神經解剖追蹤技術以及行為的測試探討大鼠杏仁核在循環功能調控所扮演的角色。在第一部分的實驗，我們將刺激電極埋在大鼠兩側的杏仁核，觀察在不同的麻醉藥影響之下，刺激杏仁核產生的血壓心跳反應，並與清醒狀態比較。我們發現在清醒的狀態下刺激杏仁核中的中央核(central nucleus, Ce)、內側核(medial nucleus, Me)與基底外側核(basolateral nucleus, BL)都可以產生血壓心跳的反應；這些反應跟大鼠的狀態即清醒或麻醉比較有關。 杏仁核中與其他循環功能相關區域的連結，重點大多放在Ce上，其他的部份的連結不是很清楚。在第二組實驗中，我們利用正向神經追蹤劑，追蹤Ce、Me與BL投射到其他循環功能區域的連結，並比較彼此之間的投射模式。我們發現，Me與BL也有投射到這些循環相關的區域，而且神經末梢分布的模式與Ce十分類似。在杏仁核中，不是只有Ce有向下的投射，Me與BL也有類似的投射，而這些投射與循環功能的調節有關。 最後，我們利用熱板踏下式抑制型躲避學習作業與約束大鼠行動，來測試毀壞Ce與Me之後，大鼠在這些作業中的血壓心跳的反應。我們發現，血壓心跳的反應與控制組相比，毀壞Me所產生的效果比毀壞Ce大，雖然兩者之間的差異上並沒有達到統計的顯著。 綜合以上的結果，我們推論在杏仁核中，除了Ce，Me與BL也有參與循環功能的調控，而且Me與BL也有與循環相關核區的連結，連結分布的模式與Ce相類似。在行為測試方面，Me是否扮演了比較重要的角色還需要再進一步的研究。

This study examined the role of the amygdala in cardiovascular control with electrical stimulation, tracer-tracking and behavioral tasks. In the first experiment, stimulating electrodes were implanted into the amygdala bilaterally. We compared the cardiovascular changes after electrical stimulation of the amygdala under different anesthetics and conscious state. We found that electrical stimulation of the central, medial and basolateral nuclei of the amygdala all produced cardiovascular changes. And these changes were related best to the conscious states of the rat. In the amygdala, central nucleus has been the focus in studying the connection to other cardiovascular control region. The projection of central nucleus to the other nuclei is not clear. In the second experiment, we injected biotinylated dextran amine (BDA) into central, medial and basolateral nuclei of the amygdala. We analyzed the projection areas and pattern of these projections. We found that medial and basolateral nuclei of the amygdala also project to other cardiovascular control regions as well as the central nucleus. And the projection patterns were similar. Therefore in the amygdala, medial and basolateral nuclei also had cardiovascular control-related connections. In the third experiment, we used step down inhibitory avoidance task and restrained stress task to test changes of the cardiovascular performance after lesions of central or medial nuclei. We found lesioning medial nucleus produced stronger effect on the cardiovascular changes than central nucleus lesions. However, this difference was not significantly different. In conclusion, we suggested that medial and basolateral nuclei of the amygdala, as well as central nucleus and also involved in cardiovascular control. Their cooperation and segregation in central cardiovascular control in different emotional and stressful conditions need to be further studied.