探討飲食中油脂含量及品質對大鼠結直腸病變

1. 探討飲食中油脂含量及品質對大鼠結直腸病變 • 本研究之目的乃在探討含高量炸油及新鮮大豆油之飲食，對以DMH（1,2-dimethylhydrazine）誘發雄鼠結直腸腫瘤異常腺窩病灶（Aberrant crypt foci, ACF）生成之影響。40隻大鼠以皮下注射30 mg DMH/kg BW，每週一次，連續六週。40隻依同樣方式注射等量生理食鹽水。再分別依重量隨機各分為4組（n=10），分別餵食含5%新鮮油之FD5、FS5，炸油之OD5、OS5，及含20%新鮮油之FD20、FS20，炸油之OD20、OS20等飼料。繼續餵食實驗飼料32週後，經禁食後並犧牲。取下肝臟及結直腸部位組織，分別進行肝臟解毒酵素、結直腸部位之癌前病灶生成及相關檢測。結果顯示，油脂經24小時油炸後其酸價、共軛雙烯值、過氧化物質及總極性物質含量皆顯著高於新鮮大豆油組，顯示油脂已有裂解及敗壞現象。Quinone reductase活性於FD5、FD20、OS5、OS20組分別顯著高於FS5、FS20、OD5、OD20組。Glutathione S-transferase 活性受餵食油脂品質不同之影響，OS5、OS20組分別高於FS5、FS20組。>4 crypts/foci在FD5組顯著低於FD20、OD5、OD20組，OD5、OD20組則無顯著差異。發現增殖細胞核抗原（Proliferating cell nuclear antigen, PCNA）受餵食油脂品質不同影響，OS5、OS20、OD5組表現量分別高於FS5、FS20、FD5組。鳥胺酸脫羧酵素（Orithine decarboxylase, ODC）表現量則是FS20、OS20、FD20三組分別高於FS5、OS5、FD5三組，而OD20組表現量則低於OD5組。由以上結果可知，在餵食新鮮大豆油時其會隨著比例提高而有增加癌化的趨勢，但只要有炸油之存在，則不論其油含量之多寡，均會促使結直腸癌化的發生。

2. Effects of dietary oil amount and quality on colorectal carcinogenesis in rats • The effect of amount (5% & 20%) and quality of dietary oil (fresh oil & oxidized frying oil, OFO)on DMH (1,2-dimethylhydrazine)-induced colonic Aberrant crypt foci（ACF）putative preneoplastic lesions in male Fisher 344 rats were investigated. Rats received DMH s.c. once weekly for 6 weeks at a dose of 30 mg/kg BW. Vehicle-treated groups received an equal volume of normal saline. Rats were assigned to eight groups which diets containing 5 ﹪or 20 ﹪either FO or OFO （FS5、FD5、OS5、OD5、FS20、FD20、OS20、OD20） respectively. Rats were sacrificed after 32 weeks of feeding experimental diets, and colorectum and liver were evaluated for ACF、Proliferating cell nuclear antigen（PCNA）、Orithine decarboxylase（ODC） protein expression and cytosolic quinone reductase（QR）、Glutathione S-transferase（GST）, respectively. Colorectum were fixed in formalin and ACF were quantified after staining. At termination, the numbers of ACF. The results showed QR and GST activity were elevated by OFO feeding than saline-treated group. The numbers of ACF（>4 crypts/foci）were lowest in FD5 diet, no significantly different among FD20、OD5、OD20 diets. PCNA protein expression was also affected by intake of OFO. On diet of FS20、OS20、FD20, an increase in ODC protein expression, however, OD20 diet was lower than OD5. Our results suggested that high-amount dietary oil may promote the colorectal carcinogenesis of rats, and OFO may have deteriorated effect, once it have consumed, no matter how dose it had.