利用核磁共振光譜儀為基礎的代謝體學探討萘毒性耐受性小鼠在萘暴露下的毒理機制

萘是環境中常見的多環芳香烴，許多研究指出當小鼠暴露在萘後會造成呼吸道非纖毛細胞(Clara細胞)的嚴重傷害；然而當小鼠重複暴露於萘卻能使Clara 細胞對萘的傷害產生抵抗。為了釐清萘的單一劑量暴露與重複暴露所引發的毒理及解毒機制，藉由核磁共振光譜儀為基礎的代謝體學能了解小鼠各組織在不同萘暴露方式之下內生性代謝物的變化，並探討萘毒性耐受性小鼠在萘暴露下可能的毒理及解毒機制。本研究利用腹腔注射ICR品種的雄性小鼠進行動物實驗，對照組連續八天注射橄欖油；單一劑量暴露組連續七天注射橄欖油，再於第八天注射300 mg/kg萘；重複劑量暴露組則連續七天注射200 mg/kg萘，再於第八天注射300 mg/kg萘。24小時後犧牲採集肺、肝、腎臟組織及支氣管肺泡沖洗液，接著利用核磁共振光譜儀分析及主成分分析來研究各組織的代謝體變化。從研究結果發現，各組織在單一萘劑量暴露與重複萘暴露後的代謝反應皆可由主成分分析加以區分，經傳統統計檢定後發現許多重要代謝物有顯著變化。呼吸系統在單一劑量暴露組及重複暴露組出現的代謝物變化和能量代謝干擾及細胞膜結構損害有關，此外重複暴露還會誘發Glutathione 所主導的抗氧化機制並對萘的傷害產生耐受性，但重複暴露之下也有引發肺腫瘤細胞的疑慮，分別反應在Glucose量的下降及Glutamine量的上升。我們的結果也指出不只在呼吸系統這個主要的標的會受到萘重複暴露的影響，肝臟及腎臟組織也都會有能量擾動的情形。透過代謝體的分析可以部分解釋不同萘暴露方式對小鼠的毒性作用，尤其是過去較少研究的重複暴露所引發的毒性耐受性，本研究也證明了核磁共振光譜儀為基礎的代謝體學研究方法對於了解環境毒物的毒理機制是相當有力的工具。

關鍵字

萘毒性；耐受性；肺；支氣管肺泡沖洗液； glutathione ；代謝體學；核磁共振光譜儀

並列摘要

Naphthalene which is widely spread in the environmental is a common polycyclic aromatic hydrocarbon. Several studies indicated that single dose exposure of naphthalene cause acute injury on mouse Clara cell, a bronchiolar epithelial cell type. However, when mice are administered repeated doses of naphthalene, the susceptible Clara cell become refractory to injury. In this study, we intended to investigate the mechanisms of naphthalene toxicity in various mouse tissues among injured, tolerant, and the control mice using 1H NMR-based metabolomics. Male ICR mice were administered seven repeated injections (ip) of NA (0, 200 mg/kg/day; single and repeated naphthalene exposure, respectively) in olive oil and gave a challenge dose (300 mg/kg/day) at eighth day. Bronchoalveolar lavage fluid and both hydrophilic and hydrophobic extracts from the lung, liver and kidney were analysed by 1H NMR followed by principal component analysis. Our results showed that, the metabolites effect of single naphthalene which cause cell injury on respiratory system are associated with cellular membrane damages and energy metabolism disturbance. However, the repeated exposure may induce the antioxidation mechanism associated with glutathione; Therefore mice become tolerant to naphthalene. In addition, we also suspected that repeated exposed to naphthalene would cause lung tumor development, since declination of glucose and increase of glutamine was found in the lung of repeated exposure group. In the liver, the upregulation of glutathione in repeated exposure mice may play an important role in leading to naphthalene toxicity tolerance, too. The metabolome disturbance of single exposure in the liver and kidney are associated with energy metabolism. In this study, we have partially explained the mechanisms of naphthalene toxicity and detoxification within single dose and repeated exposure. In conclusion, 1H NMR-based metabolomics is useful in understanding the toxicity and detoxifying mechanisms due to xenobiotic interventions.

並列關鍵字

naphthalene ； toxicity ； tolerant ； lung ； BALF ； glutathione ； metabolomics ； nuclear magnetic resonance (NMR)

參考文獻

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利用核磁共振光譜儀為基礎的代謝體學探討萘毒性耐受性小鼠在萘暴露下的毒理機制

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