共軛亞麻油酸 (conjugated linoleic acid, CLA) 是 ω-6必需脂肪酸亞麻油酸的同分異構物，具有降低小鼠脂肪組織與體重的效應，因此備受矚目。本實驗室先前已經發現在低油餵飼的 CLA 小鼠會顯著大幅提升肝臟與其他各組織的維生素 E 含量，並且調控肝臟的生育醇轉移蛋白的表現，推測部分原因可能與體脂肪大量降低有關係，由於有研究指出 CLA 對於動物體脂肪的影響會因為飼料中油脂含量不同而有不同效應，因此本實驗目的為探討小鼠在高油餵飼下，CLA 對於體脂肪的變化以及體內的維生素 E 營養及抗氧化系統之調節情形。實驗動物採用 24 隻 7 週大 C57BL / 6J 雄性小鼠適應兩週後依飼料不同分成下列三組：LF 組 (5％ soybean oil)、HF 組 (3％ soybean oil + 17％ lard)、CLA 組 (2％ soybean oil + 1％ CLA + 17％ lard)，飼養八週，犧牲當天取得血液、肝臟、脂肪及其他組織。分析項目如下：血漿脂聯素 (adiponectin)，維生素 E 的營養狀態(各組織的維生素 E 濃度)、肝臟及血液中的 TG、TC 等，肝臟的抗氧化酵素 catalase (CAT)、superoxide dismutase (SOD)、glutathione peroxidase (GPx)、glutathione-s-transferase (GST)、glutathione reductase (GR) 活性以及脂質過氧化指標如各組織的 thiobarbituric acid-reactive substances (TBARS) 與尿液 8-isoprostane、CYP3A11、COX-2 等。結果顯示 CLA 組血漿和肝臟 α-生育醇濃度顯著高於其餘兩組。而腎臟 TBARS 含量以 CLA 組顯著低於 LF 組 ( P<0.05 )，肺臟 TBARS 含量以 CLA 組顯著低於 HF 組 ( P<0.05 )。給予小鼠餵食 CLA 後對尿液中 8-isoprostane 之排出量有顯著上升。 CLA 組會降低肝臟 COX-2 蛋白質含量。另外，肝臟抗氧化酵素 CAT、 SOD、GPx 含量均以 CLA 組顯著低於其他兩組 ( P<0.05 )。血漿中的adiponectin 濃度以 LF 組顯著高於 HF 組，其 CLA 組濃度最低，另外血漿中膽固醇含量以 CLA 組顯著高於其他兩組，CLA 組肝臟中三酸甘油酯含量最為顯著。使用高油脂飲食誘導小鼠肥胖之模式下，CLA 仍具有降低腹膜脂肪與附睪脂肪的效應，此外亦提升血漿和肝臟中 α-生育醇含量和降低血漿中adiponectin 濃度等現象與前人餵食低油試驗的結果一致。然而 CLA 降低肝臟中酵素 CAT、SOD、GPx 活性等現象則與前人餵食低油試驗的結果不盡相同。所以指出在高油飼料餵飼下，CLA 對於體內維生素 E 與抗氧化酵素的影響是與油脂本身所引發的代謝與氧化機制產生交互作用，因此得知油脂的多寡是與體內維生素 E 和抗氧化系統有極大的關係。 Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of the omega-6 essential fatty acid, linoleic acid. The reduction effect of CLA on the adipose tissue and body weight in mice has been noticed and widely studied. In our previous study, CLA also increased vitamin E status in mice fed with low-fat diet. The aim of this study was to investigate the effects of conjugated linoleic acid on the antiobesity and antioxidants systems in mice fed with high-fat diet. Twenty-four seven-week-old male C57BL/6J mice were assigned to three groups: LF group (containing 5% soybean oil), HF group (containing 3% soybean oil of +17% lard), and CLA group (containing 2% soybean oil +1% CLA +17% lard) were fed with experimental diets for 8 wk. The results showed that α-tocopherol levels of plasma and liver were significantly highest in CLA group. The TBARS concentration of kidney in CLA group was significantly lower than that in LF group (P < 0.05). The TBARS concentration of lung in CLA group was significantly lower than that in HF group (P < 0.05). The levels of urine 8-isoprostane significantly increased in CLA fed mice. CLA group showed a reduction of COX-2 protein expression in liver. In addition, the activities of CAT, SOD, GPx of liver in CLA group showed significantly lower than that in the other two groups (P <0.05). The concentration of plasma adiponectin was significantly lower in CLA group than that in the other two groups. In CLA group, the cholesterol levels in plasma and the triglyceride levels in liver both showed significantly higher than the other groups. In conclusion, CLA could reduced the retroperitoneal fat and epididymal fat mice fed with high-fat diet. CLA increased the α-tocopherol content in plasma and liver and decreased plasma adiponectin levels. The changes of vitamin E status and antioxidant enzyme activity by CLA were also observed in mice when fed with high-fat diet. However, this could be due to the reduction of body fat (where the vitamin E stored) and the oxidative stress increased by high dietary fat.
