INTESTINAL FUNCTION IN A HIBERNATOR: ADAPTIVE CHANGES

冬眠动物的肠粘膜似乎保持不变 吸收能力，直到春季出现，尽管缺乏 冬眠期间的管腔营养。 相反，禁食在非- 冬眠的哺乳动物导致 3天后的吸收功能。 该项目的目的是 确定肠道营养的季节性变化， 电解质运输发生在年周期为 冬眠的地松鼠，并确定机制， 导致肠道运输适应性调节的信号 在年度周期中发挥作用。 肠道糖和电解质 运输将在春季在地松鼠中进行评估， 夏天秋天和冬天 冬季研究将涉及冬眠 松鼠和被允许保持活跃的松鼠 在温暖的房间里进食 葡萄糖的跨上皮流动， 将在空肠段中测量钠和氯， 改进的尤辛型腔室。 葡萄糖流入细胞刷 将测量边界膜，以确定 葡萄糖载体位点的数量或葡萄糖对其的亲和力 载体负责运输功能的适应性变化。 每组松鼠的肠道质量和结构将被 通过测量重量、蛋白质和DNA含量来估计， 和绒毛和隐窝尺寸的粘膜收获自 与生理学实验中使用的片段相邻的片段。 血液和组织样本将从用于 用于稍后分析肽和其他物质的运输实验 可能与季节变化有关的信使， 肠道结构和功能。 药理学和 组织学工具将用于识别介导 粘膜对肠神经刺激的反应。 这些研究 有望提供对自然节奏的洞察力， 胃肠道和信号，导致适应 冬眠期间的调节。

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 absorptive function after 3 days. The aims of this project are to determine if seasonal variations in intestinal nutrient and electrolyte transport occur during the annual cycle for 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. Intestinal mass and structure in each group of squirrels will be estimated by measuring the weights, protein and DNA content, and villus and crypt dimensions of mucosa harvested from segments adjacent to those used in the 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 and histological 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.