Neural and endocrinological regulation on the mucosal defence system in fish intestine

为了用原位杂交技术检测虹鳟鱼肠道中IgM产生细胞，制备了膜结合型IgM（mIgM）和分泌型IgM（sIgM）特异性引物，并分别对石蜡切片进行原位杂交。表达sIgM的细胞分布在肠粘膜下区域非常少。检测到mIgM产生细胞，可能是由于其表达水平较低。这些结果表明，非特异性防御分子在鱼类消化道中发挥着更重要的作用。海鳗素是从海鳗皮肤粘液中提取的一种半乳糖凝集素，也存在于海鳗的上消化道中。在目前的研究中，通过蛋白质印迹法阐明了congerin到达肠腔。用海鳗胃匀浆的消化试验表明，即使在6小时后，congerin仅部分降解，而牛血清白蛋白在30分钟内被完全消化。这些结果表明，从消化道分泌的congerin可以成功地到达并在肠腔的愤怒作为防御剂的功能。温度胁迫导致珠被中congerin含量下降。然而，腹腔注射皮质醇对Congerin含量没有影响。这表明，congerin的吸入或分泌是由皮质醇以外的未知因素调节的。在相同条件下，上消化道中的康杰林含量没有显著变化。这表明，在皮肤和上消化道中产生康杰林的俱乐部细胞以不同的方式受到调节。

In order to detect IgM producting cells in the gut cf rainbow trout by in situ hybridization, specific primer for membrane-binding IgM (mIgM) and secretory IgM (sIgM) was prepared and to paraffin sections, respectively. Cells expressing sIgM were distributed very scarcely in the submucosal region in the intestine. mIgM producing cells were to be detected, probably due to low level of its expression. These results suggest that non-specific defence molecules play more significant roles in fish alimentary canals. Congerin, a proto-type galectin purified from skin mucus cf Japanese conger is also distributed in the upper digestive tract of conger. In the current study it is clarified by western blotting that congerin reaches intestinal lumen. Digestion test using homogenates of conger stomach exhibited that congerin were degraded only partially even after 6 hours, while bovine serum albumin was completely digested within 30 min. These results indicate that congerin secreted from the digestive tract can successfully arrive to and function in the intestinal lumen of anger as defensive agents. Temperature stress induced decrease of congerin in the integument. However, intraperitoneal administration of cortisol showed no effect on the congerin contents. This indicates that congerin suction or secretion is regulated by unknown factors other than cortisol. On the other hand, congerin content in the upper digestive tract was not changed significantly under the same condition. This indicates that club cells, which produce congerin, in the skin and the upper digestive tract are regulated in the different way.