應用核磁共振譜技術研究機車廢氣對大鼠代謝體的影響

Abstract

在台灣，因為機車的便利性與機動性佳，使其成為主要的交通運輸工具。近年來，許多研究指出，機車排放出來的化學物質會對生物體的健康造成危害。其中，機車廢氣（Motorcycle Exhaust, ME）已被證實會造成細胞突變和基因毒性並且使生物體產生神經、免疫和生殖毒性等不良反應。本研究為瞭解機車廢氣對生物代謝體的影響，利用雄性大鼠作為實驗對象，以瞭解暴露機車廢氣可能的分子毒理危害，並探討抗氧化物在此的角色。 雄性大鼠經過每周五日，每日兩小時的機車廢氣暴露，而維生素E組大鼠除廢氣暴露外，也於每日服用50 mg/kg的維生素E，於四周後犧牲並且取其肝臟、睪丸組織，以有機溶劑萃取組織內的水溶性代謝物質，應用核磁共振儀（Nuclear Magnetic Resonance, NMR）測量其組織樣本內代謝物數量上的改變。樣本圖譜經切割及面積積分處理並使用多變量分析以判定代謝體的變化趨勢。 結果指出，雄性大鼠經過機車廢氣的暴露之後，肝臟組織的水溶性代謝物並無顯著改變；然而睪丸組織的肌醇濃度有顯著地減少，推論可能會造成精子活動力低下。另外，此實驗證明維生素E可降低睪丸中乙醇胺含量，推測可能是細胞修復機制的產生。 本研究藉由核磁共振譜的代謝體學，分析雄性大鼠暴露機車廢氣後體內水溶性代謝物的改變，藉以評估機車廢氣對雄性大鼠的危害及其可能機制，以幫助未來生物標記的發展。

In Taiwan, motorcycles provide the main transportation tool due to their convenience and maneuverability. Previous studies have demonstrated adverse effects of the chemicals emitted from motorcycles. Motorcycle exhaust (ME) may cause mutagenic, genotoxic, neurotoxic, immunotoxic and male reproductive toxicity effects in animal models. The objective of this study is to apply NMR-based metabolomic approach to investigate metabolic effects of ME in the liver and testis tissues using a rat model. Besides, the metabolic effects of vitamin E in this exposure model will also be studied. Male Wistar rats treated with or without vitamin E were exposed to ME 2 hours per day, 5 days per week, for 4 weeks. The liver and testis were excised and snap frozen for metabolite extraction. The hydrophilic tissue extracts were analyzed using Nuclear Magnetic Resonance spectrometer. Each spectrum was binned and integrated for multivariate analysis. The multivariate analyses were used to examine metabolic variation in the spectra among samples. Results indicated that no significant metabolic changes in the liver. In the testis, inositol level decreased in both ME and ME co-treated with vitamin E groups inferred the motility decline of spermatozoa. Moreover, Vitamin E reduced the ethanolamine concentration in the testis which may be due to cell repair. The present findings show that ME inhalation exposure caused hydrophilic metabolic alteration in the rat. These consequences may facilitate the biomarker development in the future.