Torosian M H, Nguyen H Q
Harrison Department of Surgical Research, University of Pennsylvania School of Medicine, Philadelphia 19104.
J Surg Res. 1989 Nov;47(5):456-9. doi: 10.1016/0022-4804(89)90101-7.
Despite abnormalities in host nitrogen metabolism, animal studies have demonstrated that tumors successfully compete with host tissues for substrates during periods of nutrition support. The present study was performed to determine the effect of protein depletion on protein content of both tumor and host tissues in tumor-bearing animals. Following subcutaneous mammary tumor (AC-33) implantation, 56 female Lewis rats were randomly assigned to one of two nutrient regimens: (1) protein-depleted chow (0.05% protein) or (2) standard rat chow (22.1% protein) ad libitum per os. Animals were sacrificed after 7 or 14 days on each diet and protein content of tumor and three metabolically active host tissues (liver, gastrointestinal mucosa, and bone marrow) was determined. As tumor growth progressed, tumor protein content increased while liver and gastrointestinal mucosa protein content was depleted; no significant change occurred in protein content of bone marrow. These metabolic alterations occurred regardless of protein intake. Thus, tumors are effective nitrogen traps independent of protein intake and despite wasting of normal host tissues (liver and gastrointestinal mucosa).
尽管宿主氮代谢存在异常，但动物研究表明，在营养支持期间，肿瘤能成功地与宿主组织竞争底物。本研究旨在确定蛋白质缺乏对荷瘤动物肿瘤组织和宿主组织蛋白质含量的影响。在皮下植入乳腺肿瘤（AC-33）后，将56只雌性Lewis大鼠随机分为两种营养方案之一：（1）蛋白质缺乏饲料（0.05%蛋白质）或（2）标准大鼠饲料（22.1%蛋白质），随意经口喂食。每种饮食喂养7天或14天后处死动物，测定肿瘤及三种代谢活跃的宿主组织（肝脏、胃肠道黏膜和骨髓）的蛋白质含量。随着肿瘤生长的进展，肿瘤蛋白质含量增加，而肝脏和胃肠道黏膜蛋白质含量减少；骨髓蛋白质含量无显著变化。这些代谢改变与蛋白质摄入量无关。因此，肿瘤是有效的氮陷阱，与蛋白质摄入量无关，尽管正常宿主组织（肝脏和胃肠道黏膜）出现消瘦。
