Holt P R, Luk G D
Department of Medicine, St. Luke's/Roosevelt Hospital Center, New York, New York 10025.
Exp Gerontol. 1990;25(2):173-81. doi: 10.1016/0531-5565(90)90048-7.
Hyperproliferation and delayed expression of enzyme activity occur in small intestinal enterocytes of aging rats, and starvation and refeeding result in impaired control of these processes. Since altered polyamine metabolism may accompany changes in enterocyte proliferation, we studied the effects of nutrient manipulation upon cell numbers, ornithine decarboxylase (ODC) activity and polyamine content in jejunum and ileum of 4- to 5- and 26- to 27-month Fischer rats. In both groups, cell numbers fell during starvation and and increased during refeeding. Crypt cell hyperplasia was found in aging animals. Jejunal putrescine, spermine and spermidine content were greater in older rats, fell during starvation, and rose during refeeding. Ileal ODC activity was 66% greater in the aging rats, but jejunal ODC activity was modestly increased in young animals. Intestinal polyamine content correlates with proliferative changes and polyamine metabolism responds appropriately to nutrient manipulation during aging. Dissociation of ODC activity and polyamine content in aging jejunum probably occurred because enterocyte differentiation was delayed. Investigation of intestinal polyamine metabolism may be useful in elucidating deranged proliferative activities found in the intestine of aging rodents.
衰老大鼠小肠肠上皮细胞出现增殖过度和酶活性延迟表达，饥饿和再喂养会导致这些过程的控制受损。由于多胺代谢改变可能伴随肠上皮细胞增殖变化，我们研究了营养调控对4至5月龄和26至27月龄Fischer大鼠空肠和回肠细胞数量、鸟氨酸脱羧酶（ODC）活性及多胺含量的影响。两组大鼠在饥饿期间细胞数量均减少，再喂养期间细胞数量增加。在衰老动物中发现隐窝细胞增生。老年大鼠空肠腐胺、精胺和亚精胺含量更高，饥饿期间下降，再喂养期间上升。衰老大鼠回肠ODC活性高66%，但幼龄动物空肠ODC活性略有增加。肠道多胺含量与增殖变化相关，衰老过程中多胺代谢对营养调控有适当反应。衰老空肠中ODC活性与多胺含量的分离可能是因为肠上皮细胞分化延迟。研究肠道多胺代谢可能有助于阐明衰老啮齿动物肠道中紊乱的增殖活动。
