探究高糖飲食對小鼠脂代謝基因之影響

Abstract

飲食習慣不良是肥胖與代謝相關疾病發生的原因之一。相關文獻中，已瞭解高果糖飲食、高蔗糖飲食及含蔗糖飲水能誘導嚙齒類產生代謝異常，故進一步探究是否對於peroxisome proliferator-activated receptors (PPARs)與sterol regulatory element-binding proteins (SREBPs)等脂代謝相關基因有所影響。將雄性C57BL/6J小鼠依飲食條件區分為四組：正常飼料 (normal chow, N)、飼料含50%果糖 (high fructose, F)、飼料蔗糖組 (high sucrose, S)之飼料、正常飼料但飲用30%蔗糖水 (sucrose water, W)，進行9週餵養後，分析目標基因相對表現量。結果顯示，F組小鼠肝臟中，PPARα及所調控參與脂肪酸β oxidation之基因CPT1與ACO mRNA表現量相較於N組顯著上升，SREBP1c雖顯著上升，但其所調控參與脂質合成之基因ACC與FAS無顯著差異；肌肉中，CPT1與ACO表現量上升；脂肪組織中，ACC與FAS顯著下降。S組小鼠肝臟中，PPARα與SREBP1c表現相較N組無顯著差異；脂肪組織中，ACC相對表現量下降。W組小鼠中，PPARα雖無顯著差異，但其所調控之基因mRAN表現顯著上升，SREBP1c及其調控基因則皆顯著下降；脂肪組織中，SREBP1c其調控基因mRNA表現亦顯著下降。整體而言，高果糖飲食、高蔗糖飲食及含蔗糖飲水能促進肝臟及肌肉中脂質分解相關基因表現，且降低脂肪組織中參與脂質合成基因表現。此外，蔗糖飲水亦能降低小鼠肝臟中脂質合成相關基因表現。因此，此三種高糖飲食對小鼠脂代謝基因有不同之影響。

Diet represents one environmental factor that influences the onset of metabolic disorder. Numerous studies showed that high fructose diet, high sucrose diet or sucrose containing water induces metabolic derangements in rodents. In this study, we examined the effect of those diets on the genes expressions in mice, including peroxisome proliferator-activated receptors (PPARs), sterol regulatory element-binding proteins (SREBPs), and other genes related to lipid metabolism. C57BL/6J mice were fed with normal chow (N group), high fructose (F group), high sucrose (S group) or sucrose containing water (W group) for 9 weeks. Compared with N group, the genes expressions of hepatic PPARα and fatty acid oxidation enzymes, CPT1 and ACO, were significantly increased in F group. SREBP1c mRNA was significantly increased, but lipogenic related genes, ACC and FAS, were not significantly different. In F group, myotic CPT1 and ACO mRNA were increased, while ACC and FAS mRNA were reduced in adipose tissue. In S group, hepatic PPARα and SREBP1c mRNA were not significantly different compared with N group; adipotic ACC mRNA was reduced. In W group, hepatic PPARα mRNA was not significantly different compared with N group, but CPT1 and ACO were significantly increased. SREBP1c, ACC and FAS were reduced in muscle, and they were also reduced in adipose tissue. On the whole, high fructose diet, high sucrose diet or sucrose containing water increased the expression of lipolysis genes in liver and muscle, and reduced the expression of lipogenesis genes in adipose tissue. Moreover, sucrose containing water also reduced the expression of lipogenesis genes in liver. Therefore, those three different diets have different effects on the expression of genes involved in lipid metabolism.