探討飲食中油脂含量及品質對大鼠結直腸病變
Effects of dietary oil amount and quality on colorectal carcinogenesis in rats
中文摘要
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。
英文摘要
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.
