發酵樟芝中Antrosterol在慢性酒精攝取下對肝臟保護功效

Abstract

酒精濫用為引起致病率(morbility)及致死率(mortaility)的主要原因之一，根據世界衛生組織(World Health Organization, WHO)統計，2004年酒精濫用在全球所造成的死亡率即高達3.8%，而疾病負擔指標DALYs (Disability adjusted life-years)也高達4.6%，雖然自有紀錄以來，酒即為人類文化的一部分，但飲酒除了引起社會問題外，對健康亦有重大影響。 本實驗使用40隻八週齡雄性C57BL/6小鼠隨機分為五組：(1) control組：餵飼正常流質飼糧+管灌生理食鹽水；(2) EtOH組：餵飼酒精流質飼糧+管灌生理食鹽水；(3) ST1_1X：餵飼酒精流質飼糧+管灌1 mg Antrosterol (ergostatrien-3β-ol, ST1)/Kg BW；(4) ST1_5X：餵飼酒精流質飼糧+管灌5 mg ST1/Kg BW；(5) ST1_10X：餵飼酒精流質飼糧+管灌10 mg ST1/Kg BW，進行實驗的同時記錄小鼠採食量及體重變化，並於四週後犧牲小鼠採取其血清、肝臟及糞便進行分析。由結果發現，control體重與採食量皆顯著高於其他組別(p<0.05)，補充ST1之組別，其體脂肪含量、血清及肝臟中脂質含量皆顯著低於EtOH組(p<0.05)，顯示ST1可有效改善因酒精攝取造成的脂質累積，而肝臟損傷指標AST及ALT活性在補充ST1之組別也明顯低於EtOH組(p<0.05)。同時，補充ST1之組別其小鼠肝臟TBARS值顯著低於EtOH組，而抗氧化酵素活性及能力則顯著高於EtOH組(p<0.05)，由此可知，ST1可有效改善肝臟氧化壓力並提升其抗氧化能力。在酒精代謝方面，補充ST1之組別有顯著較高的ADH活性(p<0.05)，會導致自由基產生的CYP2E1其基因表現與蛋白質含量以及與血清中酒精濃度也顯著較EtOH組低(p<0.05)。導致肝臟發炎的TNF-α與IL-1β含量在補充ST1之組別中明顯低於EtOH組。由肝臟切片中可知，EtOH組其肝細胞之間出現了許多油滴空泡，肝臟外觀也較其他組別白，顯示了較多脂肪的累積，補充ST1之組別則可以改善脂質累積的現象。在基因表現方面，補充ST1之組別與EtOH組相較之下，脂質氧化相關之基因(PPAR-α, RXR-α, CPT1, and UCP2)表現有顯著的上升(p<0.05)，脂質合成相關之基因(LXR-α, SREBP-1c, ACC, FAS, and ME)表現則顯著下降(p<0.05)，而發炎與纖維化相關之基因(TLR4, MyD88, NF-κB, iNOS, COX-2, and α-SMA)表現明顯減少(p<0.05)。綜觀上述，ST1可藉由調節脂質恆定、抗氧化能力、酒精代謝及抗發炎能力來改善慢性酒精攝取對肝臟造成的傷害。

Alcohol abuse is a major cause morbidity and mortality in the world. According to data from WHO, morbidity of alcohol abuse accounts for 4.6% DALYs (disability adjusted life-years) which is an indicator of disease burden and mortality of alcohol abuse is 3.8%. Although alcohol has been a part of human culture, alcohol consumption shows social and healthy problems. Forty 8 week-old male B6 mice were used in the experiment and divided randomly into five groups: (1) control group: control liquid diet + normal saline; (2) EtOH group: ethanol liquid diet + normal saline; (3) ST1_1X: ethanol liquid diet + 1 mg antrosterol (ergostatrien-3β-ol, ST1)/Kg BW; (4) ST1_5X: ethanol liquid diet + 5mg ST1/Kg BW; (5) ST1_10X: ethanol liquid diet + 10mg ST1/Kg BW. After 4 weeks of experiment, supplementing ST1 reduced (p<0.05) serum and liver lipids in alcohol-fed mice while fecal lipid and bile acid outputs were increased (p<0.05). Supplementing ST1 promoted (p<0.05) hepatic antioxidant capability and lowered lipid peroxidation in alcohol-fed mice. Regarding the alcohol metabolism, alcohol-fed mice cotreated with ST1 had a higher (p<0.05) alcohol dehydrogenase (ADH) activity and gene expression of ADH, ALDH, and catalase; moreover, supplementing ST1 decreased (p<0.05) serum alcohol concentration and gene expression of CYP2E1. Western blot also showed that ST1 could reduce the protein content of CYP2E1. Lower (p<0.05) hepatic TNF-α and IL-1β contents were also measured in alcohol-fed mice cotreated with ST1. Moreover; a histological analysis (H&E staining) indicated that alcohol-fed groups existed clear and large lipid drops in livers but ST1 supplementation decreased them. Regarding the molecular mechanism of lipid homeostasis, ST1 upregulated (p<0.05) fatty acid oxidation, such as PPAR-α, RXR-α, CPT1, and UCP2, but downregulated (p<0.05) lipogenesis, such as LXR-α, SREBP1c, ME, ACC, and FAS. Besides, inflammation and fibrosis related genes, such as TLR4, MyD88, NF-κB, iNOS, COX-2, and α-SMA were downregulated (p<0.05) by supplementing ST1 as well. Based on current results, hepatoprotection of ST1 is attributed to its regulations of lipid homeostasis, antioxidant capability, alcohol metabolism, and anti-inflammation.