大氣懸浮微粒對健康大鼠肺部組織DNA損傷研究

Effects of Ambient Particulate Matter on DNA-damage Capacity in Lung Tissue of Healthy SD Rats

萬書帆(Shu-Farn Wan)

指導教授 ： 鄭尊仁

國立臺灣大學/公共衛生學院/職業醫學與工業衛生研究所/碩士(2017年)

https://doi.org/10.6342/NTU201702003

摘要

根據臺灣衛生福利部的資料顯示，癌症為國人10大死因之首，而其中肺癌的死亡率一直位居所有癌症死亡率中的第一位。空氣污染物之中的大氣懸浮微粒被認為是急性與慢性肺部疾病的危險因子。流行病學也有研究顯示肺癌的發生與暴露大氣懸浮微粒相關。另外，許多體外細胞實驗證實大氣懸浮微粒會造成細胞內DNA的損傷；然而，大氣懸浮微粒對動物體內DNA損傷的研究仍然不足。因此，本研究的目的為探討健康的雄性SD大鼠在急性暴露不同粒徑的大氣懸浮微粒之後，其體內肺部組織及周邊血液的DNA損傷程度，同時也分析微粒上化學成分與生物效應之間的相關性。
本實驗暴露所用的大氣微粒來自台北市大安區鄰近基隆高架道路的區域，該區域為台北市交通繁忙的地帶，因此採樣的微粒可以代表台北市交通污染區的微粒特性。採樣時間點為2012年的冬季與2013年的夏季，採樣的粒徑分別為小於10微米的粗懸浮微粒以及小於2.5微米的細懸浮微粒。將採集回來的樣本使用99.9%的甲醇進行超音波震盪將微粒萃取下來，再將萃取下來的微粒分成兩部分，皆使用氮氣將甲醇吹乾，得到乾燥的微粒。一部分的微粒用二氯甲烷回溶，使用氣相層析質譜儀進行多環芳香烴類的成分分析；另一部分的微粒則使用磷酸緩衝溶液回溶進行動物實驗的暴露。本實驗所使用的動物為8週大的雄性SD大鼠，暴露方式為急性的氣管灌注，在暴露之後的24小時後將動物進行犧牲，並且採集新鮮的肺組織與周邊血液立即使用彗星分析法進行DNA損傷的分析，此外也採集肺泡灌洗液進行巨噬細胞與嗜中性球的計數，作為肺部組織發炎反應的指標。
本研究的結果顯示兩個季節的細懸浮微粒比起粗懸浮微粒和控制組在肺部組織與周邊血液皆明顯造成較大程度的DNA損傷以及肺部的發炎反應。此外，我們也發現DNA損傷與微粒上的多環芳香烴類有顯著的相關性。
依據本研究的結果可以得出較小粒徑的大氣懸浮微粒在健康的動物體內會造成較嚴重的DNA損傷，而這樣的結果可能與微粒上的多環芳香烴成分有關。

關鍵字

細懸浮微粒 ； 粗懸浮微粒 ； DNA損傷 ； 彗星分析法 ； 多環芳香烴類

並列摘要

According to the Ministry of Health and Welfare in Taiwan, lung cancer holds the highest mortality rate among all kinds of cancer. However, ambient particulate matter (PM) has been recognized as a significant risk factor for the acute or chronic pulmonary diseases. Epidemiological studies have also shown the associations between PM exposure and the occurrence of lung cancer. Many in vitro toxicological research have proved that PM would induce DNA damage in cells, whereas in vivo studies about DNA damage caused by the exposure of PM are still insufficient. As a result, the aim of this study is to evaluate the extent of DNA breaks in lung tissue and peripheral blood of healthy SD rats after acute exposure to different size fraction of ambient PM.
PM_2.5 and PM_10 were collected from 2012 winter and 2013 summer in Gongguang, a traffic-related area in Taipei. Samples underwent extraction by methanol. Part of the particles were resuspended in PBS (with < 0.01% vol DMSO) for animal studies, and the rest were used for PAHs analysis through GC/MS. 8-week-old Sprague Dawley rats received particles by intratracheal instillation. 24 hours after exposure, lung tissue and peripheral blood were collected to detect DNA breaks by comet assay. Other inflammatory indicators such as the numbers of macrophage and neutrophil in bronchial alveolar lavage fluid (BALF) were also investigated after the sacrifice of the animals.
Results showed that PM_2.5 from winter and summer both caused larger extent of inflammatory responses in lung tissue and DNA breaks in lung tissue and peripheral blood than PM_10 and control group. In addition, we found significantly positive correlation between DNA breakage and PAHs content of PM.
In conclusion, out study indicates that smaller fraction of PM will result in more serious DNA breaks in healthy animals, which might be related to its chemical composition.

並列關鍵字

Ambient particulate matter ； DNA breaks ； comet assay ； PAHs

參考文獻

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