臺灣博碩士論文加值系統

在清醒的SD大鼠研究中發現，慢性間歇性低氧(Chronic intermittent hypoxia, CIH)引發的系統性高血壓和動物體交感神經活性增加有關。在細胞培養或動物模式中也發現，CIH會增加反應性氧衍生物(reactive oxygen species, ROS)之生成，而且這種ROS導引的訊息機制所造成的細胞與系統反應包含高血壓和心跳過速。此外，雖然機制尚未清楚，然已有一些文獻指出CIH會造成中樞神經細胞和周邊頸動脈體上功能性NMDA受體(N-methy-D-asparate receptors, NMDARs)表現量增加。由於正常血壓大鼠(Wistar-Kyoto, WKY)與自發性高血壓大鼠(spontaneously hypertensive rats, SHR)對反覆施於壓力時呈現不同之心血管反應；因此，我們企欲了解清醒的WKY 和SHR在CIH期間，此兩品系之動物，會產生何種心血管反應，以及是否藉由NMDA受體與反應性氧衍生物兩者而產生該心血管作用。我們利用無線遙測發報器偵測記錄清醒SHR與WKY大鼠血壓之變化；西方墨點法則用來偵測，中樞交感興奮性腦幹核區，前腹外側延腦區(rostral ventrolateral medulla, RVLM)上NMDA受體次單位與抗氧化酵素的表現量。CIH的實驗模式是利用SHR及WKY大鼠於光亮時間中的6小時，交替給予灌流30秒純氮氣後45秒空氣，連續三天、七天或十四天。我們實驗結果顯示WKY大鼠在CIH處理前四天，血壓有明顯逐漸下降趨勢且達統計上意義，但低氧處理後第五天至第七天，WKY血壓上升至與空氣組相似程度。同時，CIH七天處理後，NMDA次單元NR2A表現量明顯增加；低氧處理七天，則SOD1與SOD2蛋白質表現量明顯下降，兩者皆達統計意義。CIH處理後SHR與WKY大鼠基礎血壓值並無顯著變化。SHR大鼠在CIH七天與十四天處理後，RVLM上NMDA受體次單元NR1與NR2B有明顯上升趨勢；而低氧處理七天，SOD2與Catalase(CAT)蛋白質表現量明顯下降。我們猜測WKY大鼠在CIH處理過程中NR2A表現量增加與SOD1及SOD2蛋白質表現量降低，與其血壓恢復有相關聯。然而，改變NMDA受體次單位與抗氧化酵素，是否參與了SHR在間歇性低氧後的心血管調控，則仍然未知。SHR與WKY大鼠在CIH處理後反應上之差異，可能與不同品系動物對低氧適應能力不同有關。

Chronic intermittent hypoxia (CIH) induced systemic hypertension is associated with increased sympathetic outflow in conscious SD rats. IH also increases reactive oxygen species (ROS) generation both in cell culture and in intact animals and ROS-mediated signalling mechanisms contribute to cellular and systemic responses including hypertension and tachycardia. In addition, although the details aren，t worked out yet, there are several studies that observed an increase of expression of functional NMDA receptors in the rat central neurons or peripheral carotid body after IH. Because the cardiovascular responses of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) to repeated stress are different, it interests us to know the responses in conscious SHR and WKY rats during IH, and whether NMDA receptor or ROS contributes the cardiovascular effects of IH in both strains of rat. In the present study, radiotelemetry was use to record the blood pressure in conscious SHR and WKY rats during IH treatment and western blot analysis was use to detect the expression of NMDA receptor subunits or antioxidant enzymes in central sympathoactivating brainstem nuclei, rostral ventrolateral medulla (RVLM). The IH was designed by applied 30 s pure nitrogen followed by 45 s air to SHR and WKY rats during the light phase (6 h) for 3, 7 or 14 consecutive days. Our results showed that the blood pressure of WKY rats was falling down gradually and significantly during IH challenge throughout the first 4-days treatment, then increasing to room air treated WKY rat level by day 5 of the 7-day regimen. Meanwhile, the NR2A subunits increased significantly after 7 day’s IH challenge and the expression of SOD1, SOD2 decreased significantly after 7 day’s IH treatment. The baseline blood pressure was not changed in both WKY and SHR after 7 day’s IH. The expression of NR1 and NR2B subunits on the RVLM were elevated significantly after 7- and 14-day IH treatment, yet the SOD2 and CAT decreased significantly after 7 day’s IH treatment in SHR. We speculated that the increase of NR2A subunit express and decreased of SOD1 and SOD2 express in RVLM is related to restoration of the blood pressure during IH challenge in WKY. However, it remains unclear whether the changes of NMDA receptor subunits and antioxidant enzymes can contribute the cardiovascular regulation of SHR after IH treatment. The differential response to IH challenge between WKY and SHR may imply the different adaptation ability of animals to hypoxia condition.

目錄

中文摘要 3
英文摘要 4
壹、背景介紹 6
1、間歇性低氧與生理反應： 6
2、間歇性低氧引發高血壓作用機制： 7
3、間歇性低氧與前腹外側延腦(rostral ventrolateral medulla, RVLM)之相關研究 8
4、間歇性低氧與反應性氧衍生物(reactive oxygen species, ROS)之相關性 10
貳、研究目的與實驗設計 13
一、理論基礎 13
二、實驗假說與目的 13
三、實驗設計 14
參、實驗方法材料與詳細步驟 17
(一) 實驗動物 17
(二) 間歇性低氧模式 17
(三) 正常氧分壓模式 17
(四) 血壓之測量 17
(五) 體內實驗(in vivo studies) 18
(六) 體外實驗(in vitro studies) 19
(七) 統計分析 21
肆、實驗結果 21
伍、討論 25
陸、結論 31
柒、參考文獻 32
附錄一 55

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