INTESTINAL FUNCTION IN A HIBERNATOR: ADAPTIVE CHANGES

冬眠动物的肠粘膜似乎保持吸收 尽管缺乏管腔营养， 在冬眠期间。 相反，非冬眠哺乳动物的禁食 导致3天后吸收功能显著降低。 这个项目的目的是确定是否季节性变化， 肠内营养物质和电解质的运输发生在年周期中 冬眠的地松鼠，并确定其机制， 导致肠道转运功能适应性调节的信号 在年度周期中。 肠道糖和电解质运输将 在春季、夏季、秋季和 冬天 冬季研究将涉及冬眠的松鼠以及 松鼠被允许在温暖的房间里保持活跃和进食。 葡萄糖、钠和氯化物的跨上皮通量将在 空肠段设置在改良的Ussing型腔室中。 葡萄糖内流 将测量刷状缘膜的厚度， 在葡萄糖载体位点的数量或葡萄糖对其的亲和力方面， 载体负责运输功能的适应性变化。 的 每组松鼠中吸收细胞的质量将通过 测量粘膜湿重、干重、蛋白质和DNA含量 从与生理学中使用的那些片段相邻的片段中收获 实验 将从松鼠身上采集血液和组织样本 在运输实验中用于肽和其他 可能参与肠道季节性变化的信使 结构和功能。 药理学工具将用于识别 介导粘膜对肠神经刺激的反应的信号。 这些研究有望提供对自然节律的深入了解， 胃肠道和导致适应性调节的信号 在冬眠期间。

The intestinal mucosa of the hibernator appears to maintain absorptive capacity until spring emergence despite the lack of luminal nutrition during hibernation. In contrast, fasting in non-hibernating mammals results in a significant reduction in absorption function after 3 days. The aims of this project are to determine if seasonal variations in intestinal nutrient and electolyte transport occur during the annual cycle of the hibernating ground squirrel, and to identify the mechanisms and signals that lead to adaptive regulation of intestinal transport function during the annual cycle. Intestinal sugar and electrolyte transport will be assessed in ground squirrels during the spring, summer, fall and winter. Winter studies will involve hibernating squirrels as well as squirrels that were allowed to remain active and feeding in a warm room. Transepithelial fluxes of glucose, sodium and chloride will be measured in jejunal segments set up in modified Ussing-type chambers. Glucose influx across the brush border membrane will be measured to determine if changes in the number of glucose carrier sites or the affinity of glucose for its carrier are responsible for adaptive changes in transport function. The mass of absorptive cells in each group of squirrels will be estimated by measuring the wet and dry weights, protein and DNA content of mucosa harvested from segments adjacent to those used in physiological experiments. Blood and tissue samples will be collected from squirrels used in the transport experiments for later analysis of peptides and other messengers that might be involved in seasonal changes in intestinal structure and function. Pharmacological tools will be used to identify the signals that mediate the mucosal response to enteric neural stimulation. These studies are expected to provide insight into the natural rhythms of the gastrointestinal tract and the signals that lead to adaptive regulation during hibernation.