Rapid upregulation of snake intestine in response to feeding: a new model of intestinal adaptation.
Rapid upregulation of snake intestine in response to feeding: a new model of intestinal adaptation.
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蛇肠响应进食而快速上调：肠道适应的新模型。
DOI：
10.1152/ajpgi.1994.266.4.g695
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Diamond,J
中科院分区：
文献类型：
--
作者：
Secor,SM;Stein,ED;Diamond,J
哺乳动物的肠道对进食表现出许多适应性反应。然而，对于实验分析来说，反应幅度往往适中得不方便，因为哺乳动物经常进食，而且它们的肠道很少是空的。我们预计静坐觅食的蛇会有更大的反应，因为它们会在很长的时间间隔内消耗大量的食物。因此，我们研究了响尾蛇(Crotalus Cerastes)的代谢率、灌木丛边缘养分运输和肠道形态计量学，作为喂养以来时间的函数。整条蛇的耗氧量反映了消化和重建饥饿肠道的成本，在禁食2天后达到顶峰，是禁食值的8倍。刷状缘葡萄糖、亮氨酸和脯氨酸转运蛋白的活性在禁食后1-3天达到峰值，为禁食的5-22倍。氨基酸和葡萄糖摄取率的比率达到了104的峰值，反映出蛇对肉食(高蛋白低碳水化合物饮食)的极端适应。肠道质量在1天内增加了两倍多，主要是由于粘膜的生长。排便后，肠道萎缩，刷状缘转运蛋白下调，氧耗量恢复到基础水平。这些快速而巨大的反应降低了在两餐之间长时间的静止期间维持肠道的成本。因此，坐等觅食的蛇可能为研究肠道调节和适应提供有利的模式物种。
Mammalian guts exhibit numerous adaptive responses to feeding. However, response magnitudes are often inconveniently modest for experimental analysis, because mammals feed often and their intestines are rarely empty. We anticipated larger responses in sit-and-wait foraging snakes, because they consume huge meals at long intervals. Hence, we studied metabolic rates, brush-border nutrient transport, and intestinal morphometrics in the rattlesnake, Crotalus cerastes, as a function of time since feeding. O2 consumption by the whole snake, a reflection of the cost of digestion and of rebuilding the starved gut, peaked after 2 days at eight times fasting values. Activities of brush-border glucose, leucine, and proline transporters peaked after 1-3 days at 5-22 times fasting values. Ratios of amino acid to glucose uptake rates peaked at 104, reflecting snakes' extreme adaptation to carnivory (a high-protein low-carbohydrate diet). Intestinal mass increased more than twofold within 1 day, primarily because of mucosal growth. After defecation, the intestine atrophied, brush-border transporters were downregulated, and O2 consumption returned to basal. These rapid and large responses reduce costs of gut maintenance during long bouts of quiescence between meals. Hence sit-and-wait foraging snakes may furnish advantageous model species for studying gut regulation and adaptation.
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