Effects of Nickel on Autonomic Regulation: Role of Oxidative Stress and Inflammation

大氣微粒的成分，在許多的研究中証實會引起不良的健康效應，除了肺部傷害之外，也可能導致心血管的毒性。流行病學研究顯示氧化壓力與發炎反應對於易感受族群的心率變異性有顯著的相關性，然而實際影響心率變異性的機制為何，需要毒理學研究的証實。 我們以自發性高血壓大鼠(SHR)與正常大鼠(WKY)作比較，探討抗氧化壓力較差的大鼠在暴露鎳以後，其心率變異性的表現與健康大鼠的差異，更進一步給予自發性高血壓大鼠抗氧化劑(N-Acetylcysteine, NAC)及抗發炎藥物(Celecoxib)調控其抗氧化能力及抗發炎反應，探討氧化壓力與發炎反應在鎳引起心率變異性改變中所扮演的角色。本研究以self-control為實驗設計，於實驗動物暴露NiSO4後連續72小時收集心跳資料，進一步分析其心率變異性。 研究發現，相較於WKY，自發性高血壓大鼠的心率變異改變量較高，就ANN而言，從暴露後12到72小時，SHR的改變量皆明顯高於WKY，經過NAC及Celecoxib的給予之後，SHR的改變幅度減少，給予NAC四次或Celecoxib四次之後，SHR的ANN在各時間點上則與WKY無達到統計上顯著差異，LnSDNN及LnRMSSD也有同樣的趨勢但不如ANN明顯。以統計模式比較SHR各組與WKY的差異，使用二次曲線可描述SHR扣掉WKY後的HRV改變趨勢，其ANN估計值為-0.001(95%CI: -0.0014, -0.0005)；LnSDNN為-0.0191(95%CI: -0.0244, -0.0138)，LnRMSSD為-0.0235(-0.0300, -0.0170)，p value<0.05。給予四次NAC和Celecoxib後則與WKY無顯著差異。 整體而言，鎳對於心血管的效應可能與抗氧化壓力與抗發炎反應有關，並且隨著藥物給予的劑量不同，在心率變異性上反應出的表現也不同。微粒中的成分眾多，本研究使用單一成分的暴露雖然並不能完全呈現微粒影響HRV的機制，但也顯示出氧化壓力與發炎反應在此的重要性，後續的毒理學研究需要嘗試更多種類的微粒成分，以及更深入的探討微粒影響心臟調節功能的機制。The components of ambient particle may induce not only pulmonary injury but also cardiovascular diseases. Epidemiology studies have observed that oxidative stress and inflammation may be associated with the alterations of heart rate variability, especially in some susceptible persons. But the mechanism of these associations is unclear. Spontaneously hypertensive rats (SHR) were compared with Wistar Kyoto (WKY) rats after nickel sulfate exposure. We investigated the difference of HRV change between SHR and WKY. Additionally, in order to establish the role of oxidative stress and inflammatory effect on HRV, we used N-acetylcysteine (NAC) and Celecoxib to modify the anti-oxidative and anti-inflammatory capability of SHR. This study was based on a self-control study design. We used telemetry transmitters and collected 72 hours ECG data after NiSO4 exposure. The parameters of HRV such as ANN, LnSDNN, and LnRMSSD were calculated from the ECG data. After NiSO4 exposure, we found that SHR had greater ANN change than WKY (p<0.05). After four doses of NAC and Celecoxib treatment, the alterations of ANN on SHR were reduced to the levels caused by WKY. In summary, nickel-induced HRV change may be caused by oxidative stress and inflammation. Further toxicological studies are needed to establish the mechanism of oxidative stress and inflammation affect on HRV.致謝............................................i錄...........................................ii目錄........................................iii目錄.........................................iv要............................................1bstract........................................3、前言........................................4、文獻探討....................................5 2-1 微粒污染與心血管疾病......................5 2-2 微粒與心率變異性..........................5 2-3 微粒導致的氧化壓力、發炎反應與心血管效應..7 2-4 微粒成分中之過渡金屬-鎳.................. 9 2-5 微粒毒性研究的疾病動物模式...............10 2-6 抗氧化壓力與抗發炎反應藥物...............11、材料與方法.................................12 3-1 動物模式及飼養環境.......................12 3-2 硫酸亞鎳溶液與暴露方式...................12 3-3 抗氧化劑N-acetylcysteine及抗發炎藥物Celecoxib...13 3-4 生理循環監測系統.........................13 3-5 實驗設計.................................14 3-6 資料處理及分析...........................14 3-7 統計檢定.................................15、實驗結果...................................17 4-1 原始資料分佈.............................17 4-2 Generalized estimation equation model....17 4-3 淨效應趨勢比較...........................18 4-4 統計模式比較.............................19、討論.......................................21 5-1 GEE model呈現各參數的變動趨勢............21 5-2 各時間點淨效應比較.......................22 5-3 統計模式比較.............................22 5-4 研究限制.................................24 5-5 結論.....................................24、參考文獻...................................41、附錄.......................................45目錄一、實驗動物分組及其藥物給予.................25二、SHR各組與WKY之ANN的差異估計值............35三、SHR各組與WKY之LnSDNN的差異估計值.........36四、SHR各組與WKY之LnRMSSD的差異估計值........37目錄一、各組實驗動物暴露後ANN原始資料分佈........26二、各組實驗動物暴露後LnSDNN原始資料分佈.....27三、各組實驗動物暴露後LnRMSSD原始資料分佈....28四、GEE model呈現NiSO4對於各組實驗動物ANN之效應...29五、GEE model呈現NiSO4對於各組實驗動物LnSDNN之效應..30六、GEE model呈現NiSO4對於各組實驗動物LnRMSSD之效應..31七、比較SHR實驗組與WKY在各時間點上的ANN的差異........32八、比較SHR實驗組與WKY在各時間點上的LnSDNN的差異.....33九、比較SHR實驗組與WKY在各時間點上的LnRMSSD的差異....34十、各組ANN估計曲線..........................38十一、各組LnSDNN估計曲線.....................39十二、各組LnRMSSD估計曲線....................4