Sidransky H, Verney E, Kurl R N
Department of Pathology, George Washington University Medical Center, Washington, D.C. 20037.
Exp Mol Pathol. 1989 Aug;51(1):68-79. doi: 10.1016/0014-4800(89)90008-7.
In earlier studies the acute administration of tryptophan (TRP) to rats was reported to induce enhanced in vivo [14C]orotate-labeled hepatic nuclear RNA release in vitro. This change was considered to possibly be related to the induction of more and larger gamma-glutamyl transpeptidase-positive foci in the livers of rats treated with diethylnitrosamine and fed long-term elevated TRP in a choline-supplemented (CS) but not in a choline-deficient (CD) diet (comparisons with respective controls). In this study we investigated whether feeding a CD compared to a CS diet for 1 week would affect selected hepatic nuclear responses to TRP. Rats fed the CS but not the CD diet and tube-fed TRP 10 min before being killed revealed enhanced labeled hepatic nuclear RNA release in vitro. In all experiments, comparisons were made with the control groups (rats fed the CS or stock diet). When rats were fed elevated TRP (2%) in the diets (CS or CD) for 1 week, labeled hepatic nuclear RNA release was increased with the CS + TRP but not with the CD + TRP diet group. [3H]TRP binding to hepatic nuclei in vitro revealed no change in the CS + TRP group, decreased in the CD group, and markedly increased in the CD + TRP group in comparison with the control (CS) group. Hepatic nuclear nucleoside triphosphatase activity was increased only in the CS + TRP group while hepatic nuclear poly(A) polymerase activity was increased in the CS + TRP and in the CD +/- TRP groups. Serum cholesterol and triglycerides were decreased in the CD group and increased to control levels in the CD + TRP group.
在早期研究中，据报道，向大鼠急性注射色氨酸（TRP）可诱导体内[14C]乳清酸盐标记的肝细胞核RNA在体外释放增强。这种变化被认为可能与在用二乙基亚硝胺处理并长期喂食高剂量TRP的大鼠肝脏中，γ-谷氨酰转肽酶阳性灶数量增多且体积增大有关，这些大鼠分别喂食补充胆碱（CS）的饮食而非胆碱缺乏（CD）的饮食（与各自的对照组比较）。在本研究中，我们调查了与CS饮食相比，喂食1周CD饮食是否会影响肝脏对TRP的特定核反应。喂食CS饮食而非CD饮食且在处死前10分钟经管饲给予TRP的大鼠，其体外标记的肝细胞核RNA释放增强。在所有实验中，均与对照组（喂食CS或基础饮食的大鼠）进行比较。当大鼠在饮食（CS或CD）中喂食高剂量TRP（2%）1周时，CS + TRP饮食组的标记肝细胞核RNA释放增加，而CD + TRP饮食组则未增加。与对照组（CS）相比，体外[3H]TRP与肝细胞核的结合在CS + TRP组无变化，在CD组降低，而在CD + TRP组显著增加。肝细胞核核苷三磷酸酶活性仅在CS + TRP组增加，而肝细胞核聚（A）聚合酶活性在CS + TRP组以及CD + / - TRP组均增加。CD组血清胆固醇和甘油三酯降低，而CD + TRP组则升高至对照水平。
