Matthies D L, Jacobs F A
Department of Anatomy and Cell Biology, University of North Dakota School of Medicine, Grand Forks 58202.
J Nutr. 1993 May;123(5):852-9. doi: 10.1093/jn/123.5.852.
Adult male Sprague-Dawley rats were treated with USP-grade L-tryptophan at a level of 250 mg/kg seven times over 14 d or three times over 3 d by gastric gavage. At autopsy liver specimens were prepared for histological study by stains specific for lipids, for glycoprotein and glycogen, and for fine structure by electron microscopy. Liver lipid did not accumulate as a result of tryptophan treatment. In a series of unfed animals, however, liver lipid had accumulated within 24 h of food withdrawal. Tryptophan has been implicated in fatty liver development by several reports that cite each other, but, in all cases but one, unfed animals were used, and the data show that liver lipid was already present in the unfed animals at the beginning of the experiment. Tryptophan has also been cited as causing abnormal liver morphology, but our evidence suggests that such observations are the result of artifact induced by frozen section preparation and not the result of tryptophan treatment. Our experiments indicate that tryptophan administered to rats at dosages in excess of those recommended for humans does not induce fatty liver or other morphological changes detectable by the methods described.
成年雄性Sprague-Dawley大鼠通过胃管饲法，以250毫克/千克的USP级L-色氨酸水平，在14天内给药7次，或在3天内给药3次。尸检时，制备肝脏标本，通过对脂质、糖蛋白和糖原特异的染色以及电子显微镜进行精细结构研究。色氨酸处理并未导致肝脏脂质积累。然而，在一系列未喂食的动物中，禁食24小时内肝脏脂质就已积累。一些相互引用的报告表明色氨酸与脂肪肝的发展有关，但除了一个案例外，所有案例均使用了未喂食的动物，且数据显示在实验开始时未喂食的动物肝脏中就已存在脂质。色氨酸也被认为会导致肝脏形态异常，但我们的证据表明，此类观察结果是冷冻切片制备引起的假象，而非色氨酸处理的结果。我们的实验表明，以超过人类推荐剂量给大鼠施用色氨酸，不会诱发用所述方法可检测到的脂肪肝或其他形态变化。
