Ornithine decarboxylase activity in the rat and human colon.
Ornithine decarboxylase activity in the rat and human colon.
复制标题
大鼠和人结肠中的鸟氨酸脱羧酶活性。
作者：
J. Rozhin;P. Wilson;A. Bull;N. Nigro
我们研究了年龄、高脂饮食、脱氧胆酸钠和鸟氨酸类似物α-二氟甲基鸟氨酸对大鼠结肠中鸟氨酸脱羧酶(ODC)活性的影响。此外，还测定了大鼠和人结肠正常粘膜和肿瘤组织中ODC活性的相对水平。雄性SD大鼠直肠内滴注脱氧胆酸钠诱导的结肠ODC活性在幼年动物中最高，并随着年龄的增长而降低。高水平的饮食脂肪导致基础结肠ODC活性的增加和脱氧胆酸盐诱导的ODC的增加。饮用水中的α-二氟甲基鸟氨酸以剂量依赖的方式抑制脱氧胆酸盐诱导的ODC活性。α-二氟甲基鸟氨酸也能显著降低偶氮甲烷诱发的肠道肿瘤的发生率。由于在致癌过程中已知的促进剂增加了结肠ODC的活性，而肿瘤抑制剂降低了ODC的活性，这种短期检测方法可能为鉴定结肠肿瘤的促进剂和抑制剂提供了一个有用的系统。SD大鼠结肠肿瘤组织中的ODC活性显著高于同一动物的正常粘膜组织。类似地，人类结肠癌中的ODC活性被发现高于同一标本中正常外观的粘膜。这些结果加强了利用大鼠模型进行研究，其结果可能适用于人类的情况。
We have investigated the effect of age, a high-fat diet, sodium deoxycholate, and the ornithine analogue alpha-difluoromethylornithine on ornithine decarboxylase (ODC) activity in the rat colon. The relative levels of ODC activity were also determined in normal mucosa and tumor tissue from rat and human colon. The colonic ODC activity induced by intrarectal instillation of sodium deoxycholate in male Sprague-Dawley rats was highest in young animals, and it decreased with increasing age. A high level of dietary fat caused both an increased in basal colonic ODC activity and enhanced ODC induction by deoxycholate. alpha-Difluoromethylornithine given in drinking water inhibited, in a dose-dependent fashion, deoxycholate-induced ODC activity. The frequency of azoxymethane-induced intestinal tumors was also significantly reduced by alpha-difluoromethylornithine. Since colonic ODC activity is increased in carcinogenesis by known promoting agents and decreased by tumor inhibitors, this short-term assay may provide a useful system for identifying colon tumor promoters and inhibitors. The ODC activity in colon tumors of Sprague-Dawley rats was found to be significantly higher than in normal-appearing mucosa in the same animals. Similarly, ODC activity in human colon cancer was found to be higher than that of the normal-appearing mucosa in the same specimen. These results strengthen the utilization of the rat model for studies, the results of which may apply to the human situation.