Hursting S D, Switzer B R, French J E, Kari F W
Department of Nutrition, University of North Carolina, Chapel Hill 27599.
Carcinogenesis. 1994 Feb;15(2):193-9. doi: 10.1093/carcin/15.2.193.
Corn oil administered by oral gavage decreases the spontaneous incidence of mononuclear cell leukemia (MNCL) in male Fischer rats used as vehicle controls in long-term carcinogenesis experiments. We used an MNCL transplant model, an in situ MNCL cell proliferation assay and immune competence assays to explore mechanism(s) underlying the effects of corn oil gavage on MNCL development in male rats. Relative to non-gavaged or water-gavaged rats, corn oil-gavaged rats had approximately 25% lower MNCL incidence as well as longer MNCL latency and increased survival. There were no differences in body weight or caloric intake between treatment groups, as corn oil-gavaged rats compensated for calories supplied by the gavaged oil by consuming less food. These data indicate that transplanted MNCL cells grew slower in corn oil-gavaged rats than in non-gavaged or water-gavaged rats and suggest that corn oil gavage may exert its effects through a decrease in protein or other nutrients. Five-day proliferation rates of cultured MNCL cells in diffusion chambers implanted in male corn oil-gavaged rats were 40% less than in water-gavaged rats, suggesting nutrition-sensitive endogenous factors mediate the suppression of MNCL cell proliferation in corn oil-gavaged rats. Corn oil-gavaged rats had 54% lower serum growth hormone (GH) levels, and replacement of GH into corn oil-gavaged rats by osmotic minipump infusion increased in situ MNCL cell proliferation to rates observed in water-gavaged animals. Corn oil-gavaged rats also showed enhanced cellular immune competence as measured by mitogen stimulation, natural cytotoxicity and immunofluorescence assays. Taken together, these findings suggest corn oil administered by oral gavage may decrease MNCL development by slowing MNCL cell proliferation, mediated at least in part by altered levels of diffusible factors such as GH, and/or by enhancing immune competence.
在长期致癌实验中，经口灌胃给予玉米油可降低作为溶剂对照的雄性Fischer大鼠单核细胞白血病（MNCL）的自发发病率。我们使用MNCL移植模型、原位MNCL细胞增殖测定和免疫能力测定来探究玉米油灌胃对雄性大鼠MNCL发生影响的潜在机制。与未灌胃或灌胃水的大鼠相比，灌胃玉米油的大鼠MNCL发病率降低约25%，MNCL潜伏期延长，存活率提高。各治疗组之间体重或热量摄入无差异，因为灌胃玉米油的大鼠通过减少食物摄入量来补偿灌胃油提供的热量。这些数据表明，移植的MNCL细胞在灌胃玉米油的大鼠中生长比未灌胃或灌胃水的大鼠慢，提示玉米油灌胃可能通过减少蛋白质或其他营养物质发挥作用。植入雄性灌胃玉米油大鼠的扩散室中培养的MNCL细胞的五日增殖率比灌胃水的大鼠低40%，表明营养敏感的内源性因素介导了灌胃玉米油大鼠中MNCL细胞增殖的抑制。灌胃玉米油的大鼠血清生长激素（GH）水平降低54%，通过渗透微型泵输注向灌胃玉米油的大鼠补充GH可使原位MNCL细胞增殖增加至灌胃水动物中观察到的速率。通过丝裂原刺激、自然细胞毒性和免疫荧光测定，灌胃玉米油的大鼠还表现出增强的细胞免疫能力。综上所述，这些发现表明经口灌胃给予玉米油可能通过减缓MNCL细胞增殖来降低MNCL的发生，这至少部分是由诸如GH等可扩散因子水平的改变介导的，和/或通过增强免疫能力。
