Effects of changes in calorie intake on intestinal nutrient uptake and transporter mRNA levels in aged mice
Effects of changes in calorie intake on intestinal nutrient uptake and transporter mRNA levels in aged mice
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DOI：
10.1093/gerona/52a.6.b300
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发表时间：
1997-11-01
影响因子：
5.1
通讯作者：
Ferraris, RP
中科院分区：
文献类型：
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作者：
Casirola, DM;Lan, Y;Ferraris, RP
在老年，长期热量限制（CR）小鼠，肠道营养摄取显着高于同龄的自由控制。这种慢性限制诱导的摄取增强能被随意喂养逆转吗？我们通过将32个月大的慢性CR小鼠转换为自由采食4周（CRAL）来解决这个问题。肠转运率和总肠道吸收能力的D-糖和几个非必需的L-氨基酸显着降低，在CRAL小鼠。相比之下，切换CR小鼠到一个随意reginen只有3天没有影响肠道营养转运，这表明随意喂养的负面影响需要一个持续时间比大多数肠上皮细胞的3-d寿命更长。肠粘膜对L-葡萄糖的渗透性与饮食的转换无关。通过逆转录-聚合酶链反应在6、24和32月龄小鼠中测定刷状缘葡萄糖转运蛋白SGLT 1、刷状缘果糖转运蛋白GLUT 5和基底外侧糖转运蛋白GLUT 2 mRNA的水平，每个明显独立于热量限制和年龄。我们的结论是，肠营养摄取率高表现出慢性CR小鼠可以逆转随意喂养只有1个月的时间。这些吸收的减少主要是由于单位肠重转运的特异性减少，而不是肠质量的非特异性减少。由慢性CR和年龄引起的糖摄取率的变化显然不伴随着这些转运蛋白的mRNA编码的稳态水平的变化。
In aged, chronically calorie-restricted (CR) mice, intestinal nutrient uptake is significantly higher than in same-age ad libitum controls. Can this chronic restriction-induced enhancement of uptake be reversed by ad libitum feeding? We addressed this question by switching 32-mo-old chronically CR mice to ad libitum feeding for 4 wk (CRAL). Intestinal transport rate and total intestinal absorptive capacity for D-sugars and several nonessential L-amino acids decreased significantly in CRAL mice. In contrast, switching CR mice to an ad libitum reginen for only 3 d had no effect on intestinal nutrient transport, indicating that the negative effects od ad libitum feeding require a duration longer than the 3-d lifetime of most enterocytes. Permeability of the intestinal mucose to L-glucose was independent of the switches in diet. Levels of the brushborder gluscose transporter SGLT1, brushborder fructose transporter GLUT5, and basolateral sugar transporter GLUT2 mRNA as determined by reverse transscription-polymerase chain reaction in 6-, 24-, and 32-mo-old mice were each apparently independent of caloric restriction and age. We conclude that the high rates of intestinal nutrient uptake exhibited by chronically CR mice can be reversed by ad libitum feeding of only 1 mo duration. These decreases in uptake were due mainly to specific decreases in transport per unit weight of intestine and not to nonspecific decreases in intestine mass. Changes in rates of sugar uptake induced by chronic CR and age are apparently not accompanied by changes in steady-state levels of mRNA coding for those transporters.