|Abstract: ||非酒精性脂肪肝疾病 (non-alcoholic fatty acid liver disease, NAFLD) 係由肝脂肪變性 (hepatic steatosis) 或脂肪肝 (fatty liver) 轉變為非酒精性肝炎 (non-alcoholic steatohepatitis)、肝纖維化 (liver fibrosis)、肝硬化 (hepatic cirrhosis)，發展為肝癌 (hepatocellular carcinoma) 等慢性肝病之總稱，估計全球人口 10%~24% 罹患各式 NAFLD；而減緩肝臟之脂質累積為治療 NAFLD 策略之一。因此，本研究目的為調查植物油對肝細胞脂質累積之調節作用。首先，以脂肪酸混合物 (oleic acid：palmitic acid = 2：1；FFA) 誘導人類肝臟 HepG2 細胞脂質累積，以 FFA (148 μg/mL) 處理 48 小時後發現細胞之中性脂質含量顯著增加且呈現時間效應，後續以此為誘導非酒精性脂肪肝之細胞模式 (FFA 組)。當以黑芝麻脂溶性萃取物 (sesame fat-soluble extract, SFE) 或苦茶油 (camellia oil, CO) 分別部分取代 74 μg/mL FFA (部分取代組)，發現 SFE 及 CO 可顯著延緩 FFA 誘導之中性脂質累積，分別為 FFA 組之 0.67 或 0.64 倍；148 μg/mL SFE 組及 74 μg/mL CO 組細胞內三酸甘油酯含量分別為 FFA 組之 0.74 及 0.61 倍。進一步分析發現，FFA 組之脂肪酸合成酶 (fatty acid synthase, FAS) 活性顯著高於 SFE 及 CO 組，但各組之乙醯輔酶A羧化酶 (acetyl-CoA carboxylase) 活性並未改變。以西方點墨法分析各組之 FAS 蛋白表現發現並無差異，但磷酸化 AMP-activated protein kinase α (pAMPKα)/AMPKα 表現量在 74 μg/mL SFE 組較 FFA 組上升 1.93 倍；SFE 或 CO 部分取代組均可提升 pAMPKα 為 FFA 組之 2.59 或 2.94 倍，而且 AMPKα 所調節之 sterol regulatory element-binding protein 1 (SREBP-1)，於 CO 部分取代組降低為 FFA 組 0.57 倍。CO 組之活性氧分子 (reactive oxygen species, ROS) 顯著減少，為 FFA 組之 0.73 倍，但 SFE 或 CO 對介白素-1β (interleukin-1β, IL-1β)、IL-6、IL-8 及腫瘤壞死因子-α (tumor necrosis factor-α, TNF-α) 之分泌無顯著影響。綜上，黑芝麻脂溶性萃取物及苦茶油可能透過抑制脂質生合成及促進熱量代謝，而達到減緩肝細胞脂質累積之作用。|
Non-alcoholic fatty liver disease (NAFLD) is a chronic disease and becoming a server public health problem with an estimated prevalence 10% to 24% in worldwide. The progression stages of NAFLD include hepatic steatosis, non-alcoholic steatohepatitis, liver fibrosis, hepatic cirrhosis and hepatocellular carcinoma. Therefore, to attenuate lipid accumulation in liver is potent therapeutic strategy to NAFLD. This study aimed to investigate the regulatory effects of vegetable oils on lipid accumulation in hepatocytes. In this study, treatment with a mixture of oleic acid and palmitic acid (2:1, 148 μg/mL; FFA) for 48 hr was used to induce lipid accumulation in hepatic HepG2 cells. The results showed that treatment with 148 μg/mL FFA significantly induced accumulation of lipid droplets in a time dependent manner. Half amount of FFA (74 μg/mL) cotreament with 74 μg/mL of sesame fat-soluble extract (SFE) or camellia oil (CO) significantly decreased intracellular lipid accumulation to 0.67- or 0.64-folds of FFA group, respectively. Besides, SFE (148 μg/mL) or CO (74 μg/mL) significantly decreased triacylglycerol content to 0.74- or 0.61-folds of FFA group. Furthermore, the activity of FAS was significantly decreased by treatment with SFE or CO, but the activity of acetyl-CoA carboxylase was not changed by SFE or CO. However, the protein expression level of FAS was not changed by SFE or CO. Alternatively, pAMPKα/AMPKα was significantly promoted by cotreatment with SFE (2.59-folds of FFA) or CO (2.94-folds). Cotreatment with CO also reduced SREBP-1 protein expression levels to 0.57-folds of FFA group, as well as reduced intracellular ROS contents to 0.73-folds. However, treatment with SFE or CO have no significant effect on secretion of interleukin-1β (IL-1β), IL-6, IL-8 and TNF-α. In conclusion, SFE and CO may suppress lipogenesis and activate energy metabolism to ameliorate lipid accumulation in hepatocytes.