Regulation of Epithelia Solute Transport in Elasmobranch Fish

板鳃鱼上皮细胞溶质运输的调节

• 批准号: RGPIN-2015-05348
• 负责人: Anderson, W
• 金额: $ 2.4万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684969
• 关键词: Regulation; Epithelia; Solute; Transport; Elasmobranch

The retention of urea for osmotic purposes in elasmobranch fish has been known for over 125 years yet we know little about solute transport across epithelia in this ancient group of fishes. Attempts have been made to understand urea transport mechanisms using gill and renal tissue, however, these studies are hampered by the complexity of the tissue used. Intestinal tissue lends itself well to transport physiology studies as it has a relatively flat surface and uniform epithelia. Recent advances have been made in establishing a viable preparation in elasmobranchs and data have consistently shown that feeding results in a net uptake of urea from the lumen of the intestine against a concentration gradient, and starvation leads to a net loss of urea to the intestinal lumen. These studies suggest significant repositioning of transport proteins in intestinal epithelia and/or remodeling of intestinal epithelia cell morphology in response to the presence of food. Either way such physiological responses would require substantial coordination through the actions of gastro-entero-pancreatic (GEP) hormones, many of which have been identified in the intestine of elasmobranch fish. While a number of studies have examined regulatory roles for these hormones in blood flow and smooth muscle contraction research investigating their role in the regulation of intestinal solute transport in elasmobranch fish is non-existent. Using isolated intestinal preparations, the proposed research will establish this tissue as a primary resource for understanding the mechanisms of solute transport in elasmobranchs. Using a classic Ussing chamber setup selective screening of specific inhibitors and agonists will identify key transport proteins involved in the movement of urea and other solutes across the intestinal epithelia. Molecular techniques will quantify mRNA expression of these proteins in fed and starved fish. These studies combined with immunohistochemical techniques will result in the development of a urea and solute transport model for elasmobranchs based on direct empirical evidence from a relatively homogeneous epithelia. Light, scanning and transmission microscopy will be used to identify morphological changes in the intestinal epithelia in response to feeding. The Ussing chamber preparation will be used to screen candidate GEP hormones for the control of urea and solute transport. Once identified, receptor expression for inhibitory and stimulatory hormones will be examined. Similarly a pancreatic in situ perfusion preparation will be established to determine if the hormones regulating solute movement across the intestine are also involved in regulating pancreatic exocrine and possibly endocrine activity. The overall goal of this proposed research program is to describe solute transport mechanisms in the elasmobranch intestine and ultimately functional evolution of vertebrate GEP hormones.**

125 年前，人们就知道软骨鱼中尿素的渗透作用，但我们对这一古老鱼类中跨上皮细胞的溶质转运知之甚少，然而，人们已经尝试了解利用鳃和肾组织的尿素转运机制。这些研究因所用组织的复杂性而受到阻碍。由于肠组织具有平坦的表面和均匀的上皮，因此很适合进行相对的生理学研究。在软骨鱼中建立可行的制剂时，数据一致表明，喂食会导致肠腔内尿素的净吸收，而饥饿会导致肠腔内尿素的净损失。这些研究表明，这一影响是显着的。肠上皮中转运蛋白的重新定位和/或肠上皮细胞形态的重塑以响应食物的存在，无论哪种方式，这种生理反应都需要通过以下作用进行实质性协调。胃肠胰（GEP）激素，其中许多已在软骨鱼的肠道中被发现，而许多研究已经检查了这些激素在血流和平滑肌收缩中的调节作用，研究了它们在调节中的作用。软骨鱼类的肠道溶质转运是不存在的，该研究将利用分离的肠道制剂，将这种组织作为了解软骨鱼类溶质转运机制的主要资源。使用腔室设置选择性筛选特定抑制剂和激动剂将识别参与尿素和其他溶质穿过肠上皮细胞运动的关键转运蛋白。这些研究与免疫组织化学技术相结合，将量化这些蛋白质在喂食和饥饿鱼中的 mRNA 表达。将基于来自相对均质上皮的直接经验证据，开发软骨鱼的尿素和溶质运输模型，并将使用光、扫描和透射显微镜来识别。肠上皮因进食而发生的形态变化将用于筛选控制尿素和溶质转运的候选 GEP 激素，类似地，将检查胰腺中的抑制性和刺激性激素的受体表达。将建立原位灌注准备，以确定调节溶质跨肠道运动的激素是否也参与调节胰腺外分泌和可能的内分泌活动。该拟议研究计划的总体目标是描述。软骨鱼肠道中的溶质转运机制以及脊椎动物 GEP 激素的最终功能进化。**